NORTH AMERICAN SCIENTIFIC INC
8-K, 1998-02-19
IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES
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<PAGE>

                   SECURITIES AND EXCHANGE COMMISSION

                        Washington, D.C.  20549

                                FORM 8-K

                             CURRENT REPORT


                   Pursuant to Section 13 or 15(d) of
                 the Securities and Exchange Act of 1934



Date of Report (Date of earliest event reported): February 6, 1998
                                                  ----------------

                     North American Scientific, Inc.
          ------------------------------------------------------
          (Exact name of registrant as specified in its charter)




        Delaware                      0-26670                 51-0366422
- -----------------------------   -------------------     ----------------------
(State or other jurisdiction       (Commission             (I.R.S. Employer
     of incorporation)             File number)            Identification No.)



7435 Greenbush Avenue, North Hollywood, CA                    91605
- -------------------------------------------               --------------
(Address of principal executive offices)                    (Zip Code)



Registrant's telephone number, including area code: (818) 503-9201
                                                    ---------------


          -----------------------------------------------------------
          Former name or former address, if changed since last report


<PAGE>

Item 2.   ACQUISITION OR DISPOSITION OF ASSETS.

    On February 6, 1998, the Company entered into agreements with PracSys 
Corp., a privately held Massachusetts corporation ("PracSys"), pursuant to 
which (i) PracSys will manufacture and sell to the Company two particle 
accelerators (the "Systems") to be used in the production of certain 
isotopes, which will be utilized by the Company in connection with its new 
brachytherapy product line, and (ii) PracSys will operate the Systems to 
produce required isotopes for an initial 2-year period.  The agreements call 
for total payments to PracSys of approximately $2.7 million, which payments 
are required to be made upon the achievement of certain milestones set forth 
therein.  Such payments are expected to be made from available cash.  In 
addition, PracSys will receive a service fee and also will be entitled to a 
"royalty" on the Company's sales of products which incorporate isotopes 
produced using the Systems.  

    The Company and PracSys have also entered into an Exclusivity and 
Purchase Agreement pursuant to which the Company has been granted certain 
exclusivity rights with regard to the PracSys technology.  Pursuant to the 
Exclusivity Agreement, PracSys also issued to the Company an aggregate of 
140,150 shares of PracSys Common Stock, which is equal to approximately 5% of 
PracSys total outstanding shares on a fully-diluted basis.  In addition, 
PracSys granted the Company a pre-emptive right in the event of certain 
pre-initial public offering private financings and a three-year warrant to 
purchase PracSys Common Stock equal to 5% of the number of shares of Common 
Stock issued in an initial public offering.  

    Irwin J. Gruverman, a director and significant stockholder of both the 
Company and PracSys was instrumental in introducing the parties but was not 
involved in the negotiation or approval of the agreements.  The agreements 
were negotiated between the parties on an arms-length basis.  Copies of the 
Purchase Contract, Service Contract and Exclusivity Agreement are attached 
hereto as Exhibits 10.1, 10.2 and 10.3, respectively.

<PAGE>

                              INDEX



Exhibit
Number       Description of Document
- --------     -----------------------

10.1         Purchase Contract dated February 6, 1998, between North
             American Scientific, Inc. and PracSys Corp. 

10.2         Service Contract dated February 6, 1998, between North
             American Scientific, Inc. and PracSys Corp. 

10.3         Exclusivity and Purchase Contract dated as of December
             31, 1997, as amended February 6, 1998, between North
             American Scientific, Inc. and PracSys Corp.


<PAGE>


                                  SIGNATURE
                                  ---------


    Pursuant to the requirements of the Securities Exchange Act of 1934, the 
Registrant has duly caused this Report to be signed on its behalf by the 
undersigned thereunto duly authorized.


Dated: February 12, 1998        NORTH AMERICAN SCIENTIFIC, INC.
                                (Registrant)

                                By: /s/ L. Michael Cutrer
                                    ------------------------------------------

                                    Name: L. Michael Cutrer
                                    Title: President Chief Executive Officer
                                           (Principal Executive, Financial and
                                           Accounting Officer)




<PAGE>

                                  PURCHASE CONTRACT

     AGREEMENT made this 6th day of February 1998, by and between PracSys 
Corp., a Massachusetts corporation having its principal place of business at 
8E Industrial Way, Unit 10, Salem, New Hampshire 03079 ("PracSys"), and North 
American Scientific, Inc. a California  corporation having its principal 
place of business at 7435 Greenbush Avenue, North Hollywood,  California 
91605 ("NASI").

                                      RECITALS:

     WHEREAS, NASI wishes to purchase certain equipment from PracSys as set 
forth herein; and

     WHEREAS, PracSys desires to sell such equipment to NASI; and

     WHEREAS, PracSys and NASI desire to enter into a purchase contract with 
respect to the foregoing.

     NOW THEREFORE the parties agree as follows:

1.   Sale by PracSys.  PracSys shall perform preproduction engineering, 
     manufacture or have manufactured, deliver, install (unless installation 
     is excluded under the Special Conditions referred to below) and sell the 
     Equipment to NASI in accordance with the terms and conditions of the 
     Contract documents, and shall perform such other ancillary obligations 
     as are set forth therein.

2.   Purchase by NASI.  NASI shall purchase, receive and pay for the 
     Engineering and Equipment in accordance with the Contract Documents as 
     defined below, and shall perform such other ancillary obligations, as 
     are set forth therein.

3.   Payment of Purchase Price.  NASI shall pay the purchase price and such 
     other sums as may be stated in the Contract Documents, at the times 
     stated therein.

4.   Special Manufacture.  NASI recognizes that the Equipment will be 
     specially manufactured for NASI.

*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>


5.   Contract Documents and Entire Agreement.  The entire and exclusive 
     agreement of the parties with respect to the subject matter hereof is 
     set forth in the documents listed in APPENDIX 1 hereto (the "Contract 
     Documents").  The Contract Documents are listed in descending order of 
     precedence, in case of any conflict among them.  The Contract Documents 
     supersede all prior or contemporaneous discussions, representations or 
     writings, none of which shall have any legal effect except insofar as 
     they are listed in or expressly incorporated by reference in one of the 
     Contract Documents.  The Contract Documents may be amended or 
     supplemented only in writing signed by the party to be charged.  By 
     causing this contract to be executed, PracSys and NASI each acknowledges 
     that it has reviewed and that it accepts all of the terms, conditions 
     and provisions of the Contract Documents.

     IN WITNESS WHEREOF the parties have caused this Purchase Contract to be 
     executed as of the first date set forth above.

PracSys Corp.                           North American Scientific, Inc.

By: /s/ Wayne E. Webster                By: /s/ L. Michael Cutrer
    ---------------------------------       ----------------------------------
    Wayne E. Webster, President & CEO       L. Michael Cutrer, President & CEO


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>

                                                                      APPENDIX 1

                                       LIST OF

                                  CONTRACT DOCUMENTS

<TABLE>
<CAPTION>
                               APPENDIX      # OF PAGES      DATE
                               --------      ----------      ----
<S>                            <C>           <C>            <C>
List of Contract                   1              1         2/4/98
Documents                                                         
                                                                  
Special Conditions                 2              8         2/4/98
                                                                  
General Conditions                 3              9         2/4/98

</TABLE>



*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>


                                                                      APPENDIX 2

                                  SPECIAL CONDITIONS

1.   BUYER.  North American Scientific, Inc. ("NASI")

2.   EQUIPMENT.  The equipment being sold hereunder consists of: Two PracSys 
     IP-6, complete integrated isotope production systems (the "Equipment"); 
     each system includes a NHVGx linear accelerator, *** target end station, 
     processing equipment, shielding and control system. System number one 
     serial number shall be SN1 ("System #1") and system number two serial 
     number shall be SN2 ("System #2").

3.   SITE.

     3.1  The site where the Equipment is intended to be installed is as 
     follows, unless notified otherwise by NASI:

     The Equipment is to be installed by PracSys at a production center (the 
     "Production Center") in the PracSys facility at Salem, New Hampshire 
     (the "Site").

     3.2  Special requirements for site preparation not contained in General 
     Conditions:

     Performance of all special site preparation requirements at the Site is 
     the responsibility of PracSys.

4.   INSTALLATION, DELIVERY AND ACCEPTANCE.   

     PracSys is to install the Equipment at the Site as part of the contract. 
     In the event NASI directs that the Equipment be installed at a location 
     other than the Site, PracSys shall have no responsibility for site 
     preparation, installation, set up, calibration, securing permits or 
     licenses, bonding for decommissioning or any and all other post 
     acceptance installation responsibilities notwithstanding any provision 
     of this Agreement to the contrary.  The dates for installation and 
     acceptance are as follows:

     INSTALLATION   System #1      To occur within *** after receipt of order.  
                    System #2      To occur within *** after receipt of order.  


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>

     ACCEPTANCE                    Within 30 days following installation of
     System #1 and System #2, respectively.

5.   TRAINING.  Operational training will be provided at the Production 
     Center by PracSys concurrently for its employees and NASI employees that 
     NASI elects to have participate.  PracSys will provide complete training 
     on all aspects of the operation of the system and its daily maintenance. 
      This training is included in the Purchase Price.  PracSys will provide 
     NASI with 30 days en notice of the date of scheduled training sessions 
     in which NASI may elect to participate.  At any time PracSys is entitled 
     to the Revenue Participation pursuant to the Exclusivity and Purchase 
     Agreement dated as of December 31, 1997, as amended, by PracSys and NASI 
     (the "Exclusivity Agreement"), or in the   event NASI shall exercise its 
     "March in Rights" pursuant to Section 8.6 of the Service Contract 
     between NASI and PracSys of even date herewith (the "Service Contract"), 
     PracSys shall provide additional training at NASI's request.  NASI shall 
     reimburse PracSys for the reasonable expenses of any such additional 
     training.  

6.   DOCUMENTATION AND DATA.  PracSys shall deliver to NASI and to the 
     Production Center complete written documentation sufficient for the 
     operation and daily standard maintenance for the equipment which will be 
     turned over to the production center manager or equivalent at the time 
     of acceptance of the equipment.  The documentation will include the 
     as-built equipment specification ("Equipment Specification") which shall 
     specify maintenance and operating conditions referenced in the Warranty 
     provisions of the General Conditions.

7.   PURCHASE PRICE.  

     7.1  The preproduction engineering required for the specialty equipment 
     (the "Engineering") is separately priced in the amount of $ ***  (the 
     "Preproduction Engineering Price").

     7.2  The total purchase price (the "Purchase Price") for two (2) IP-6 
     Systems installed is $ *** .   Each System  includes the following:

     NHVG-TM- accelerator complete with operating system, shielding and stand 
     with a nominal *** rating.  

     *** target end station and processing equipment.  

     Facilities modification, utility hook-ups and installation at the Site.


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>

8.   PAYMENT TERMS.

     8.1  The Preproduction Engineering Price is to be paid upon execution of 
     the Purchase Contract.  

     8.2  The Purchase Price for both Systems is to be paid as follows:

<TABLE>
<CAPTION>


- --------------------------------------------------------------------------------
MILE-
STONE     DESCRIPTION                                              AMOUNT
- --------------------------------------------------------------------------------
<S>  <C>                                                           <C>
1    Execution of Purchase Order                                           $*** 
- --------------------------------------------------------------------------------
2    Receipt of Long Lead Accelerator Items for Systems #1 & #2            $*** 
- --------------------------------------------------------------------------------
3    Start of Accelerator Assembly Systems #1 & #2                         $*** 
- --------------------------------------------------------------------------------
4    System #1 Proton Beam Demonstration between 0.5-1mA                   $*** 
- --------------------------------------------------------------------------------
5    System #2 Proton Beam Demonstration between 0.5-1mA                   $*** 
- --------------------------------------------------------------------------------
6    Acceptance of System #1                                               $*** 
- --------------------------------------------------------------------------------
7    Acceptance of System #2                                               $*** 
- --------------------------------------------------------------------------------

</TABLE>
 

     In the event Milestone payments are delayed by NASI, PracSys shall have the
     right to delay Equipment delivery and acceptance accordingly and submit a
     change order for increases to the contract price.

     PracSys hereby covenants and agrees that the Purchase Price payments made
     to PracSys pursuant to this Agreement shall be applied solely for the
     purpose of performance of this Agreement and that such payments shall not
     be used by PracSys for any other business purpose without the prior written
     consent of NASI.  PracSys shall set aside a portion of the payments made to
     PracSys pursuant to the Exclusivity Agreement and the Production
     Engineering Price pursuant to this Agreement for payment to North Star
     Research Corp. ("North Star") as necessary to satisfy the milestone and
     other payment provisions of the North Star Contract (as defined in Section
     9.3 below).  PracSys shall make such payments to North Star promptly after
     such payments become due pursuant to the North Star Contract, in order to
     secure title to the North Star Accelerator (as defined in Section 9.3
     below) as soon as reasonably practicable after the date hereof.  In
     addition, PracSys hereby covenants and agrees that no payments made to
     PracSys pursuant to the Exclusivity Agreement or the Production Engineering
     Price pursuant to this Agreement 


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>


     shall be applied against amounts owed by PracSys to Wayne E. Webster and 
     Robert S. Miller, as reflected on the Long Term Obligations of the 
     Balance Sheet (as defined in Section 11 hereof), without the prior 
     written consent of NASI.  These covenants terminate upon the acceptance 
     of System #2.

9.   ACCEPTANCE.  

     9.1  At least 30 days prior to scheduled testing of Equipment for
     acceptance, PracSys shall propose to NASI and PracSys and NASI shall act in
     good faith to agree upon a detailed Equipment acceptance plan designed
     to provide an acceptance testing procedure that will, upon successful
     demonstration through the actual manufacture of product, assure that the
     Equipment will consistently generate *** at a minimum rate of *** mCi per
     hour per system.  Acceptance shall occur upon evidence reasonably
     satisfactory to NASI that the Equipment will consistently generate a
     minimum rate of *** mCi per hour per system (the "Performance Criteria").

     9.2  In the event acceptance of System #1 or System #2 is delayed more than
     90 days beyond the respective scheduled acceptance date pursuant to Section
     4 hereof, PracSys shall be responsible for contracting for delivery of the
     Product from a third party or produce the Product with its or NASI's work
     in process equipment (the "Alternate Supply"), sufficient to meet each
     Monthly Production Estimate provided by NASI to PracSys pursuant to Section
     2 of the Service Contract. In the event System #1 is accepted and System
     #2 acceptance is delayed more than 90 days beyond its scheduled acceptance
     date, PracSys would be required to provide the Alternate Supply only to the
     extent the production of Product by System #1 is insufficient to meet the
     Monthly Production Estimate.  NASI will reimburse PracSys for the Product
     at a per mCi price that would have resulted from the Service Contract based
     on the volume delivered using the pricing factors set forth in Exhibit B of
     the Service Contract.  This shall be NASI's sole remedy for late acceptance
     so long as PracSys provides the Product under these terms.  Provided,
     however, that (i) in the event PracSys shall be unable to provide such
     Alternate Supply for any reason, including lack of financial resources and
     (ii) NASI has perfected its process and facilities for the use of the
     Product for the production of seeds for sale in commercial quantities to
     the Market (the "Commercial Process"), then, after 10 days  notice, NASI
     may terminate this Agreement and transfer title to the work in progress to
     PracSys and PracSys shall promptly refund contract payments made by NASI in
     accordance with and to the extent set forth in the refund provisions of
     Section 9.3 below.
     
     9.3  Notwithstanding the mitigation of late acceptance of System #1 and
     System #2 through PracSys providing for the Alternate Supply of the
     Product, NASI may terminate 

*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>


     this Purchase Contract for default if System #1 or System #2 are not 
     accepted, which acceptance NASI will not unreasonably withhold, within 
     six (6) months after the start of the Alternate Supply, after thirty 
     (30) days written notice by NASI.  

     Upon such termination, PracSys shall refund all contract payments made by
     NASI hereunder and pursuant to the Exclusivity Agreement.  However, if
     System #1 or System #2 is accepted and the other system has not been
     accepted within six (6) months after the start of the respective Alternate
     Supply and NASI elects to terminate after 30 days written notice, then,
     upon such partial termination, PracSys shall refund 50% of each of
     milestones 1, 2, and 3 and 100% of milestone 4 or 5 and 6 or 7 as
     applicable to the extent the contract payments had been made by NASI.  In
     the event of such partial termination, PracSys has no obligation to refund
     the Preproduction Engineering payment or the exclusivity payment made by
     NASI pursuant to the Exclusivity Agreement. 

     Alternatively, NASI may elect not to terminate the Purchase Contract for
     default pursuant to the provisions of either Section 9.2 or 9.3, above,
     but, upon the above events of default and after 30 days notice, may remove
     the work in progress, and take title to and remove any special tools, jigs,
     molds, fixtures, equipment, technical data, books, records, computer
     software and other records relating to the manufacture of the Equipment
     (the "Work In Progress") for the purpose of completing the manufacture of
     the Equipment(the "March In Termination").  PracSys shall cooperate in the
     removal.  If NASI shall be entitled to exercise its March in Termination
     rights with respect to System #1, NASI shall also be entitled
     simultaneously to exercise such March in Termination rights with respect to
     System #2.  In the event of March In Termination, NASI will complete the
     manufacture at its own expense and PracSys will not be entitled to any
     additional payments including any Revenue Participation payment pursuant to
     the Exclusivity Agreement. 

     In the event of March In Termination, PracSys grants to NASI a non
     exclusive, royalty-free, world wide license to manufacture, use and sell
     without limitation the two Systems hereunder.  PracSys represents and
     covenants that it has and will continue to have the requisite power to
     grant such sub-license.

     As security for the performance of its obligations under this Agreement,
     and for the refund when due of all payments now or hereafter made by NASI
     pursuant to this Purchase Contract or the Exclusivity Agreement, PracSys
     hereby grants to NASI a continuing first priority security interest in all
     rights, title and interest of PracSys now existing or hereafter acquired
     in, to and under each of the following: (i) the NHVGx PET accelerator (the
     "North Star Accelerator") being produced for PracSys by North Star 


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>


     Research Corp. ("North Star") pursuant to a contract between PracSys and 
     North Star executed by PracSys July 1, 1996, (the "North Star 
     Contract"), (ii) the North Star Contract, and (iii) all products and 
     proceeds of any of the foregoing, and PracSys hereby pledges, 
     hypothecates, assigns, sets over and delivers to NASI, and grants NASI a 
     first priority security interest in, the common stock of Florida PET 
     Center, Inc. (or such other entity to which title to the North Star 
     Accelerator is transferred by PracSys) held by PracSys or its 
     affiliates, whether through PET Scan Services, LLC, or otherwise (the 
     "Pledged Securities" and with (i), (ii) and (iii) above, the 
     "Collateral") including any   dividends or distributions on the Pledged 
     Securities or any securities issued in addition to, or in exchange or 
     substitution therefor (which shall constitute part of the Pledged 
     Securities) and all voting and other rights pertaining to the Pledged 
     Securities (provided that, prior to a default, PracSys or its affiliate 
     shall have the right to exercise such voting or other like rights in a 
     manner which does not prejudice the rights of NASI hereunder).

     All certificates and instruments representing or evidencing any Pledged
     Securities shall be promptly delivered by PracSys to NASI and shall be
     accompanied by stock powers or other instruments of transfer or assignment,
     undated and duly executed in blank, all in form and substance satisfactory
     to NASI.  NASI shall have the right, at any time after default of refund of
     payments by PracSys in its discretion and without notice to PracSys, and
     without limitation to any other rights, to transfer to or to register in
     the name of NASI or its nominee, any or all of the Pledged Securities.  To
     the extent PracSys now or hereafter owns or holds any right, title and
     interest in any Pledged Securities through one or more persons or entities,
     PracSys shall cause such persons or entities to pledge, collaterally assign
     and deliver to NASI such Pledged Securities, by written instrument in form
     and substance reasonably satisfactory to NASI. 

     PracSys acknowledges and agrees that NASI's payment pursuant to the
     Exclusivity Agreement above is to be applied by it to purchase the
     Collateral referenced in clause (i) above, and accordingly the parties
     acknowledge and agree that the foregoing security interest in such
     Collateral is a purchase money security interest. 

     Without the prior written consent of NASI, PracSys shall not sell, assign,
     transfer, pledge, or otherwise encumber or dispose of any of the Collateral
     or any right or interest therein.  In addition, PracSys shall, at its own
     expense, promptly execute, acknowledge and deliver all such instruments,
     and take all such actions, as NASI from time to time may reasonably request
     in order to preserve, protect, maintain and perfect NASI's security
     interest in the Collateral and other rights of NASI intended to be created
     by this Agreement.  Furthermore, PracSys shall defend its title to the
     Collateral and NASI's lien thereon against the claims of any other person
     or entity so long as any of the obligations secured 


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>


     hereby remain outstanding. NASI shall release the security interest 
     granted pursuant to (i) above upon evidence satisfactory to NASI that 
     Florida PET Center, Inc. shall have received financing in the amount of 
     at least $2,500,000. Subject to the terms hereof, NASI shall within 15 
     days after the acceptance of both Systems execute and deliver to PracSys 
     a written release of the security interests granted hereunder.  

10.  SERVICE CONTRACT.  If NASI chooses to deliver, install and operate the
     Equipment at any single site other than the production center located at
     the PracSys, Salem, New Hampshire facility, NASI may at its option,
     contract with PracSys to provide maintenance services for the Equipment at
     the site for so long as PracSys shall be entitled to receive Revenue
     Participation pursuant to the Exclusivity Agreement.  NASI shall reimburse
     PracSys for the reasonable expenses of such maintenance services.

11.  REPRESENTATIONS AND WARRANTIES.

     A.   PracSys is a corporation duly organized, validly existing and in good
     standing under the laws of its jurisdiction of incorporation; has all
     requisite power to own, lease, license and operate its assets, properties
     and business and to carry on its business, as now conducted and proposed to
     be conducted; and is duly qualified or licensed to do business as a foreign
     corporation and is in good standing in every jurisdiction in which the
     nature of its business or the location of its properties requires such
     qualification or licensing.

     B.   PracSys has taken all actions necessary to authorize it to enter into
     and perform fully its obligations under this Agreement and to consummate
     the transactions contemplated hereby.  This Agreement is the legal, valid
     and binding obligation of PracSys, enforceable in accordance with its
     terms, subject, as to enforcement of remedies, to applicable bankruptcy,
     insolvency, moratorium, reorganization and similar laws affecting
     creditors' rights generally and to general equitable principles.

     C.   PracSys has full power and authority to execute and deliver this
     Agreement and to perform its obligations under and to consummate the
     transactions contemplated by this Agreement.  The execution, delivery, and
     performance by PracSys of this Agreement (i) have been duly authorized and
     approved by all necessary corporate action on the part of PracSys, its
     officers, directors and shareholders, or (ii) will not violate any
     provision of law and will not conflict with, or result in a breach of, any
     of the terms of, or constitute a default under, PracSys's Certificate of
     Incorporation, Bylaws, or any contract or agreement, whether written or
     oral, judgment, decree, order, or other restriction to which PracSys is a
     party or by which it or any of its properties is bound.


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>

     D.   PracSys has in all material respects complied with, and is now in all
     material respects in compliance with, all laws and orders applicable to it.
     Except to the extent, if any, disclosed in writing to NASI, PracSys holds
     all business licenses, permits, franchises, orders and government approvals
     material, excluding permits and licenses specific to the production of
     radioactive materials and the operation of equipment used to produce
     radioactive materials, to or necessary for the conduct of PracSys's
     business as presently conducted or as proposed to be conducted, other than
     those permits, if any, the absence of which would not have an adverse
     effect on PracSys's business, operation or financial condition.  Each
     license and permit is in full force and effect; PracSys is not and has at
     all times in the past been in all material respects in full compliance with
     each thereof; and no proceeding is pending or, to the best of PracSys's
     knowledge, threatened, to revoke, amend or limit any thereof.  There are no
     pending or, the best of PracSys's knowledge, threatened proceedings by or
     before any governmental authority which involve new special assessments,
     assessment districts, bonds, taxes, condemnation actions, laws or orders or
     similar matters which, if instituted, could reasonably be expected to have
     a material adverse effect upon the condition (financial or otherwise),
     assets, liabilities, business or prospectus of PracSys. 

     E.   All documents and other papers delivered or to be delivered, to NASI
     by or on behalf  of PracSys in connection with this Agreement and the
     transactions contemplated herein are, and at the time of delivery will be,
     true, correct and complete in all material respects.  The information
     furnished to NASI by or on behalf of PracSys in connection with this
     Agreement and the transactions contemplated herein does not, and will not
     contain any untrue statement of a material fact and does not, and will not,
     omit to state any material fact necessary to make the statements made, in
     context in which they are made, not false or misleading.  There is no fact
     known to PracSys which PracSys has not disclosed to NASI in writing which
     could reasonably be expected to have a material adverse effect upon the
     condition (financial or otherwise), assets, liabilities, business,
     operations, properties or prospects of PracSys. 

     F.   PracSys has delivered to NASI its unaudited balance sheet as of
     December 31, 1997, (the "Balance Sheet"). which has been certified in
     accordance with this paragraph by the chief financial officer of PracSys. 
     The Balance Sheet sets out and fairly describes in all material respects
     the financial condition of PracSys as of the Balance Sheet date and is a
     true and accurate description thereof.  Since the date of the Balance
     Sheet, there has been no material adverse change, individually or in the
     aggregate, in the business, assets, condition, financial or otherwise or
     net worth of PracSys.  In addition, since the date of the Balance Sheet,
     PracSys has not incurred any liabilities of any type which in the aggregate
     exceed $50,000 whether absolute or contingent. PracSys, effective with the

*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>

     execution of this agreement, will maintain a standard system of accounting
     established and administered in accordance with generally accepted
     accounting principles. 

     G.   There are no actions, suits, or proceedings pending or, to the best of
     the knowledge of PracSys, threatened against PracSys, at law or at equity
     or before any federal, state, municipal or other governmental department,
     commission, board, bureau, agency or instrumentality.  

     PracSys has good and marketable title to, or a valid license interest in,
     all intellectual property used in or material to PracSys's business, and no
     person has asserted any right or interest adverse to PracSys in respect of
     any of PracSys's intellectual property rights which would have a material
     adverse effect on PracSys and its business, other than those  rights, if
     any, that have been disclosed to NASI by PracSys in writing.  The conduct
     of PracSys of its business does not, and as proposed to be conducted will
     not, infringe upon  or violate the intellectual property rights of any
     other person or entity, and there has not been any claim to such effect. 
     The manufacture, use and sale of the Systems by PracSys or NASI pursuant to
     this Agreement (including without limitation pursuant to the March In
     Termination rights pursuant to section 9.3 hereof) and the Service
     Contract, do not and will not conflict with any agreement to which PracSys
     is a party, including, but not limited to, the License Agreement dated
     December 6, 1995, by and between PracSys and North Star or the North Star
     Contract. 

     I.   Other than disclosed to NASI in writing, PracSys has not granted any
     security interest to any third party, and nor has any security interest
     been filed or asserted, with respect to any of PracSys's assets.  Other
     than disclosed to NASI in writing, PracSys is not currently in default of
     any obligation for money borrowed or in default of any other agreement, and
     PracSys knows of no threatened default with respect to any such agreement
     and  reasonably believes no basis exists upon which any such default could
     be asserted. 

12.  NOTICES.  The addresses for notices (see paragraph 17 of General
     Conditions) are as  follows:

     PracSys:                      Wayne E. Webster, President & CEO
                                   PracSys Corp.
                                   8E Industrial Way
                                   Unit 10   
                                   Salem, New Hampshire   03079
                                   Telephone (603) 890-8555


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                                   Facsimile (603) 890-8558

     NASI:                         L. Michael Cutrer, President & CEO
                                   North American Scientific, Inc.
                                   7435 Greenbush Avenue
                                   North Hollywood, California   91605
                                   Telephone (818) 503-9201
                                   Facsimile (818) 503-0764












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                                                                      APPENDIX 3

                                  GENERAL CONDITIONS

1.   DELIVERY, RISK OF LOSS AND TITLE.  If the Equipment is not being installed
     by PracSys at the Site, then unless otherwise stated in the Special
     Conditions, such Equipment is delivered f.o.b. point of shipment and NASI
     shall be responsible for all expenses for preparing for shipment, packing
     and moving the equipment from the location of Equipment acceptance to the
     point of shipment.  If Equipment is being installed by PracSys, then unless
     otherwise stated in the Special Conditions, such Equipment is delivered at
     site when it is accepted.  Where the scheduled delivery of Equipment is
     delayed by NASI, PracSys may deliver such Equipment by moving it to storage
     for the account of and at the sole risk of NASI.  When NASI is ready to
     receive the Equipment, PracSys shall arrange at NASI's expense for removing
     the equipment from storage and shipping it to NASI.  Shipping dates are
     based on prompt receipt of all necessary information from NASI.  PracSys
     reserves the right to make delivery in installments.  Except as otherwise
     provided in the Special Conditions, and except for the security interest
     provided for in paragraph 3 below, risk of loss or damage shall pass to
     NASI upon delivery.  However, risk of loss shall remain with PracSys while
     the Systems are installed at the PracSys Production Center.  Subject to its
     right to terminate this contract in the event of non-acceptance or
     otherwise pursuant to this Agreement and to pass title back to PracSys,
     NASI shall have title to the Work-in-Progress of each System from the date
     of execution of this Contract.

     During the manufacture of the Systems at the Production Center and upon
     installation of the Systems, the Systems or the Work-in-Progress shall be
     segregated from the rest of the facility by partitions or prominent floor
     markings.  A nameplate with model and serial numbers will be clearly
     affixed to each system identifying NASI ownership. 

     NASI is responsible for removing the Equipment from the Site at the end of
     the Term of the Service Contract or at an earlier termination date.  NASI
     shall reimburse PracSys for no more than the actual cost of posting
     performance bonds, if any reasonably requested in the licensing and
     permitting process to secure compliance with this removal obligation.

2.   PAYMENT.  NASI shall pay the Preproduction Engineering Price and the
     Purchase Price as provided in the Special Conditions paragraph 8, Payment
     Terms.

     If shipment or delivery is delayed by NASI, payment shall become due on the
     date PracSys is prepared to make delivery.  Delays in delivery or
     nonconformities in any 


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     installments shall not relieve NASI of its obligation to accept and pay 
     for remaining installments. 

3.   SECURITY INTEREST.  As security for payment of all amounts due from time to
     time under the Purchase Contract (the "Obligations"), NASI hereby grants to
     PracSys a purchase money security interest in the Equipment and each
     component thereof (the "Collateral").  NASI (a) represents and warrants
     that its only offices and places of business are at the address shown in
     the Contract Documents; and (b) agrees that (i) it will not transfer or
     permit the transfer of the Collateral or any interest therein without the
     prior written consent of PracSys, (ii) it will give PracSys prior written
     notice of any change in corporate name or structure or in location of NASI
     or the Collateral from the address referred to above, (iii) it will
     promptly notify PracSys of any execution, levy, attachment, distraint or
     seizure of or on the Collateral, (iv) it will execute and deliver to
     PracSys financing statements in proper form for filing prior to shipment of
     the Equipment or any component thereof, and (v) in the event of a failure
     by NASI to pay the Obligations when due, or to comply with this paragraph
     PracSys shall have all of the rights and may exercise all of the remedies
     of a secured party, holder of a purchase money security interest, under the
     laws of the Commonwealth of Massachusetts.  

     When requested by NASI, PracSys shall promptly cooperate in the filing by
     NASI of a UCC financing statement for information purposes evidencing
     NASI's title to each of the Systems and the Work-in-Progress.

4.   TAXES.  In addition to any price specified herein, NASI shall pay the gross
     amount of any present or future sales, use, excise, value-added, or other
     similar tax applicable to the price, sale or delivery of any equipment or
     services furnished hereunder or to their use by PracSys or NASI, or NASI
     shall furnish PracSys with evidence of exemption acceptable to the taxing
     authorities.  PracSys hereby represents and the parties hereby agree that
     the sale shall take place in the State of New Hampshire.  

5.   CHANGES.  NASI shall have the right to request in writing changes to the 
     configuration, design or delivery date of the Equipment, or additions to 
     or deletions from the general scope of supply hereunder.  PracSys will 
     then prepare a change order reflecting all contract modifications 
     resulting from such request including but not limited to prices, 
     delivery schedules and warranties. PracSys shall have no obligation to 
     proceed with such request or change order until and unless the parties 
     have agreed in writing to the terms of such change order.

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6.   EXCUSABLE DELAY. If delivery or installation of the Equipment is
     prevented, restricted, interfered with or otherwise delayed by reason of 
     any cause beyond the reasonable control of PracSys or its subcontractors 
     or suppliers, including without limit: (i) fire, explosion, strike, 
     lockout by others, labor strike or similar dispute, casualty or 
     accident, lack of appropriate space on any available ship when the 
     Equipment is ready for shipment, epidemic, cyclone, drought, flood, 
     shortages of raw materials or power, or (ii) war, revolution, civil 
     commotion, acts of public enemies, blockade or embargo, or (iii) any law 
     or proclamation, regulation, ordinance, demand or requirement of any 
     applicable government or any subdivision thereof or representative of 
     any such government, then, and in that event, PracSys shall promptly 
     notify NASI of all resulting delays. Upon such notice, PracSys shall, 
     for the duration of its disability, be excused from the performance of 
     such of its obligations as are prevented, restricted, interfered with or 
     otherwise delayed by reason of any such cause and PracSys shall not be 
     deemed to be in default and not be subject to any liability or damage.

7.   RIGHT TO INSPECT. NASI at its election and at its own expense may 
     inspect the manufacturing facility and components thereof at PracSys's 
     plant or plants during construction and factory tests, with reasonable 
     notice to PracSys, and at reasonable times.

8.   ACCEPTANCE.

     8.1 Representatives of NASI and PracSys shall sign each designated item 
     or test in the acceptance document as each is passed.

     8.2 PracSys will supply all testing and calibration equipment for use 
           during these acceptance tests.

     8.3 When all tests set forth in the relevant portion of the Contract 
     Documents for the Equipment (or a subsystem thereof subject to separate 
     testing and acceptance) are complete to the reasonable satisfaction of 
     NASI and have been signed by NASI'S representative, NASI will have 
     accepted the Equipment.

9.   WARRANTY.

     9.1 Except as set forth in paragraph 9.3 below and Paragraph 10 of 
     Appendix 2, PracSys warrants to NASI that the Equipment (i) shall, at 
     the date of completion of the acceptance tests for that equipment or 
     subsystem thereof (if there is a separate acceptance test for the 
     subsystem), comply with the requirements of the Performance Criteria and 
     (ii) shall, for a period of one year from the date of completion of the 
     acceptance tests be free from defect

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     in material and workmanship when maintained and operated in accordance 
     with the Equipment Specifications, as the same may be changed from time 
     to time by mutual agreement.

     9.2 Except as set forth in Paragraph 10 of Appendix 2, should the 
     Equipment or a separately accepted subsystem thereof covered by this 
     warranty fail to comply with the warranty during the aforesaid warranty 
     periods under normal and proper use and maintenance, PracSys shall, upon 
     receipt of prompt notice thereof, promptly correct such noncompliance at 
     its option by either repair or replacement. PracSys shall bear the cost 
     and risk of loss during transport for (i) any defective equipment or 
     parts thereof being returned to PracSys's factory or other site with 
     PracSys's prior consent and (ii) any repaired or replacement items being 
     returned to NASI. Replaced equipment or parts thereof shall become the 
     property of PracSys.

     9.3 If the Equipment includes a computer system with standard data 
     processing systems and commercially available input and output devices, 
     all of which are subject to manufacturers' warranties, these 
     manufacturers' warranties shall be made available to NASI, and PracSys 
     shall not have any warranty obligations to NASI in respect of such 
     system beyond what is provided in these manufacturers' warranties. 
     PracSys shall notify NASI of the availability of manufacturers' 
     maintenance contracts that cover computer equipment after the expiration 
     of the manufacturers' warranties and NASI shall have the responsibility 
     for obtaining such maintenance contracts as it shall desire.

     9.4 Any services provided hereunder and not covered by the Equipment 
     warranty, and any documentation or data to be delivered hereunder, are 
     warrantied for one year after performance or delivery to have been 
     performed or prepared in a workmanlike manner. If any such service, 
     documentation or data was not performed or prepared in the manner 
     warranted and such nonconformity appears during the one year period, 
     PracSys shall re-perform the services or revise the documentation or data 
     in a nonconforming manner.

     9.5 Pracsys MAKES NO WARRANTIES OTHER THAN AS SET FORTH IN THIS 
     PARAGRAPH 9. ALL IMPLIED WARRANTIES ARE HEREBY DISCLAIMED, INCLUDING ANY 
     WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 
     CORRECTION OF NONCONFORMITIES OR DEFECTS AS PROVIDED ABOVE SHALL BE 
     NASI'S EXCLUSIVE REMEDY AND SHALL CONSTITUTE FULFILLMENT OF ALL 
     LIABILITIES OF PracSys OR ITS SUBCONTRACTORS OR AFFILIATES WHETHER IN 
     WARRANTY, CONTRACT, TORT, NEGLIGENCE, STRICT LIABILITY OR OTHERWISE WITH 
     RESPECT TO THE QUALITY OF EQUIPMENT OR SERVICES FURNISHED HEREUNDER.


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10.  Infringement.

     10.1 PracSys shall defend, hold harmless and indemnify NASI from and 
     against any and all liability and expense by reason of any third party 
     claim, suit, action or proceeding for infringement of any third party 
     proprietary rights including, but not limited to, copyrights, trade 
     secrets rights, or patents arising in connection with the manufacture, 
     installation, sale or use of the Equipment including any and all 
     judgments or decrees which may be rendered against NASI and reasonable 
     attorney's fees and settlements made arising out of any such claim, 
     suit, action, or proceeding, provided, however, that:

          10.1.1 PracSys shall not be responsible for any settlement of any 
          such claim, suit, action or proceeding made without its prior 
          written consent, which shall not unreasonably be withheld;

          10.1.2 This indemnity shall not extend to any alleged infringement 
          based upon the combination of the Equipment or any portion thereof 
          with other items or things not furnished hereunder unless PracSys 
          (a) knew of NASI's specific intention to combine the Equipment or 
          any portion thereof with a specific item and (b) in connection 
          therewith PracSys may be held reasonably to have been aware that 
          such a combination would constitute an infringement and PracSys did 
          not so advise NASI; and

          10.1.3 This indemnity shall not extend to any alleged infringement 
          based upon a modification to the Equipment by NASI unless PracSys 
          directs that the modification be made or unless Pracsys (a) knew of 
          NASI's specific intention to modify the Equipment or any portion 
          thereof and (b) in connection therewith PracSys may be held 
          reasonably to have been aware that such a modification would cause 
          an infringement and Pracsys did not so advise NASI.

     10.2 PracSys shall defend at its own expense all suits, actions or 
     proceedings brought against NASI with respect to the matters listed in 
     paragraph 10.1 above. NASI shall have the right, at its option and at 
     its sole expense, to participate in the defense of any such claim, suit, 
     action or proceeding, without relieving PracSys of any obligation 
     hereunder. NASI shall promptly notify PracSys in writing after any such 
     claim is made or suit is brought and shall cooperate with PracSys in 
     writing after any such claim is made or suit is brought and shall 
     cooperate with PracSys, and PracSys agrees to reimburse NASI for its 
     reasonable out-of-pocket expenses incurred in connection with such 
     cooperation, provided PracSys has agreed to the nature of the 
     cooperation in advance.


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     10.3 If, however, as a consequence of a final determination of any suit 
     for infringement or any court decision involving any injunction 
     resulting from or arising in connection with the manufacture, sale or 
     use of the Equipment or any part thereof furnished or employed by 
     PracSys hereunder, NASI is enjoined or limited in any material manner in 
     the use of said Equipment or material part thereof, PracSys shall, at 
     its option and at its own expense.

          10.3.1 Procure for NASI the right to continue use of said Equipment 
          or part; or

          10.3.2 So modify the Equipment or part as to render it 
          non-infringing without any significant effect on the use thereof; or

          10.3.3 Replace the Equipment or part with a materially equivalent 
          non-infringing product.

     10.4 In the event PracSys is unable, after diligent good faith efforts, 
     to provide any of the remedies provided for in clauses 10.3.1 through 
     10.3.3 hereof, PracSys may in fulfillment of its obligation under this 
     paragraph remove such Equipment or part and refund to NASI the purchase 
     price thereof.

     10.5 THIS PARAGRAPH SETS FORTH THE SOLE OBLIGATIONS OF PracSys AND ITS 
     SUBCONTRACTORS AND AFFILIATES, AND THE EXCLUSIVE REMEDIES OF NASI, WITH 
     RESPECT TO INFRINGEMENT OF THIRD PARTY PROPRIETARY RIGHTS. IN NO EVENT 
     SHALL PracSys OR ITS SUBCONTRACTORS OR AFFILIATES BE LIABLE TO NASI FOR 
     LOSS OF USE, REVENUE, OR PROFIT OR ANY OTHER DIRECT, INDIRECT, 
     INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING FROM ANY SUCH INFRINGEMENT.

11.  DISCLAIMER OF LIABILITY. IN NO EVENT SHALL PracSys OR ITS SUBCONTRACTORS 
     OR AFFILIATES BE LIABLE FOR SPECIAL, INDIRECT, CONSEQUENTIAL, OR 
     INCIDENTAL DAMAGES IN CONNECTION WITH THIS AGREEMENT OR THE EQUIPMENT, 
     SERVICES OR INFORMATION SUPPLIED HEREUNDER (INCLUDING LIABILITIES BASED 
     UPON CONTRACT, WARRANTY, NEGLIGENCE, TORT, STRICT LIABILITY OR 
     OTHERWISE) INCLUDING WITHOUT LIMITATION LIABILITY FOR LOSS OF USE, 
     REVENUE OR PROFIT, COST OF ALTERNATIVE SUPPLY AND OR FACILITIES, 
     DOWNTIME COSTS OR CLAIMS OF CUSTOMERS.


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12.  INSURANCE.  Immediately upon execution of this Agreement, except as 
     otherwise provided in this paragraph, PracSys, at its own expense, shall 
     obtain and maintain appropriate insurance as follows:

     12.1  "All risk" property damage insurance covering the replacement cost 
     value of the Equipment while located on the premises of PracSys, or its 
     subcontractors prior to acceptance.

     12.2  Comprehensive General Liability Insurance for property damage and 
     bodily injury liabilities with a combined single limit of not less than 
     $1,000,000.

     12.3  A Workers' Compensation policy as required by the state or other 
     jurisdiction where the Equipment is to be installed, insuring employees 
     of PracSys, or its subcontractors, performing work for NASI at the Site.

     12.4  "All risk" property damage insurance covering the period the 
     Equipment is in transit to and is being installed at the Site.  The 
     PracSys insurance policies shall remain in force until acceptance, shall 
     be for 110% of the purchase price of the Equipment and shall be in the 
     joint names of NASI, PracSys and its subcontractors.

     12.5  NASI shall be added as a named insured under said insurance as 
     respects their interests in the Equipment, including the "All risk" and 
     "Comprehensive General Liability Insurance" policies specified in 
     paragraphs 12.1 and 12.2 above. Each said insurance policy shall 
     specifically provide that it may not be canceled or materially altered 
     without thirty (30) days prior written notice to NASI.

     12.6  PracSys shall furnish NASI with appropriate Certificates of 
     Insurance in forms acceptable to NASI within sixty (60) days of the date 
     hereof. PracSys shall make its policies available for inspection by 
     NASI. PracSys shall not reduce limits on any policy required by the 
     Contract Documents below those stated in the Certificates of Insurance 
     initially furnished to NASI so long as those insurance policies cover 
     activities under the Contract Documents.

     12.7  The insurance described in paragraphs 12.2, 12.3 be required only 
     if PracSys is responsible for installation. The property insurance 
     described in paragraphs 12.1 and 12.4 above does not cover a computer 
     system if separately identified in the Special Conditions, or items 
     which are shipped direct from third party vendors.


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     12.8  Neither PracSys nor its subcontractors or affiliates shall have 
     any liability for personal injuries or death or damage to property 
     occurring to NASI's personnel or property arising from the installation 
     or use of the Equipment, or components thereof, to be delivered 
     hereunder except to the extent that such injuries, death, or property 
     damage are caused by a defect in the design, manufacture or installation 
     of the Equipment or by the negligence of employees, agents consultants 
     and all other persons under the control of PracSys or its subcontractors.

13.  SITE PREPARATION AND OTHER RESPONSIBILITIES OF PRACSYS.

     13.1  PracSys shall have the sole responsibility for securing approvals 
     (a) for the design of the shielding required to maintain any radiation 
     leakage at safe levels and (b) for systems required to handle the 
     disposition of radioactive waste.

     13.2  PracSys shall carry out and complete its work required for Site 
     preparation as defined in the Contract Documents. PracSys shall complete 
     such work prior to the scheduled arrival of the Equipment or any 
     component thereof.

     13.3  PracSys shall be solely responsible for assuring that all 
     licenses, permits, approvals, consents and other authorization that may 
     be required by all Federal, state and local governmental authorities for 
     the installations and operation of the Equipment or any component at the 
     production site are obtained.

     13.4  It is understood by the parties that PracSys can not and will not 
     require PracSys personnel to subject themselves to radiation exposure 
     beyond safe radiation dose limits and that if such a situation arises, 
     PracSys shall stop work until other personnel are available. Any delays 
     that result from radiation exposure shall be deemed to be excusable 
     delays.

14.  PROPRIETY INFORMATION.

     14.1 Information including data and documentation ("Information") in 
     whatever form disclosed by PracSys and identified as confidential or 
     proprietary or which by its nature would be regarded as confidential or 
     proprietary shall be and remain the property of PracSys. NASI shall have 
     a royalty-free license to use such Information in connection with the 
     use, operation and maintenance of the Equipment. NASI shall respect the 
     confidential and proprietary nature of such Information, shall not 
     disclose it to third parties or permit its dissemination to its own 
     employees other than those having a need to know, shall limit and 
     control the copying of such Information and shall keep all copies

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     (which shall be numbered) in a secure place when not in use, shall 
     require its employees to respect the confidential and proprietary nature 
     of the Information, and shall treat such Information with a caution and 
     care not less than that with which it treats its own confidential or 
     proprietary information and will use similar means to protect it from 
     unauthorized disclosure.

     14.2  Without limiting the foregoing, NASI shall not use such 
     Information for the purpose of designing or manufacturing any equipment 
     or parts unless the same is necessary to the operation of the Equipment 
     and PracSys has not been able to provide the needed equipment or parts.

     14.3  No information, data or material shall be considered confidential 
     or proprietary if (i) it is in the public domain without fault of NASI 
     or its employees or is made publicly available by PracSys (ii) is 
     disclosed to NASI by another party under no obligation to maintain its 
     confidentiality, (iii) if it was already known to NASI, such prior 
     knowledge to be demonstrated only by written documents in existence 
     prior to the date of disclosure or (iv) if it corresponds in substance 
     to information which NASI independently develops.

     14.4  Information including data and documentation ("Information") in 
     whatever form disclosed by NASI and identified as confidential or 
     proprietary or which by its nature would be regarded as confidential or 
     proprietary shall be and remain the property of NASI. PracSys shall have 
     a royalty-free license to use such Information in connection with the 
     use, operation and maintenance of the Equipment. PracSys shall respect 
     the confidential and proprietary nature of such Information, shall not 
     disclose it to third parties or permit its dissemination to its own 
     employees other than those having a need to know, shall limit and 
     control the copying of such Information and shall keep all copies (which 
     shall be numbered) in a secure place when not in use, shall require its 
     employees to respect the confidential and proprietary nature of the 
     Information, and shall treat such Information with a caution and care 
     not less than that with which it treats its own confidential or 
     proprietary information and will use similar means to protect it from 
     unauthorized disclosure.

     14.5  Without limiting the foregoing, PracSys shall not use such 
     Information for the purpose of designing or manufacturing any equipment 
     or parts unless the same is necessary to the operation of the Equipment 
     and NASI has not been able to provide the needed equipment or parts.

     14.6  No information, data or material shall be considered confidential 
     or proprietary if it is in the public domain without fault of PracSys Sys 
     or its employees or is made publicly

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     available by NASI or is disclosed to PracSys by another party under no 
     obligation to maintain its confidentiality, or if it was already known 
     to PracSys, such prior knowledge to be demonstrated only by written 
     documents in existence prior to the date of disclosure.

15.  WAIVER OF AUTOMATIC STAY.  PracSys hereby waives any right to prevent 
     NASI from obtaining immediate relief from any automatic stay imposed 
     pursuant to Section 362 of the Bankruptcy Code, or otherwise, on or 
     against the exercise of the rights and remedies otherwise available to 
     NASI as provided herein, in the Contract Documents, or as otherwise 
     provided at law or in equity; (i) PracSys hereby consents to NASI's 
     relief from any aforementioned stay and to NASI's exercise of the rights 
     otherwise available to NASI herein or in the Contract Documents; and 
     (ii) PracSys shall not seek or apply for any expansion of the provisions 
     of Section 362 of the Bankruptcy Code or any injunction against NASI's 
     exercise of its rights herein or in the Contract Documents.

16.  GOVERNING LAW.  All questions relating to this Purchase Contract, 
     including the validity, interpretation and performance thereof, shall be 
     decided in accordance with the laws of the Commonwealth of 
     Massachusetts, United States of America.

17.  NOTICES.  Any notice under the Contract shall be in writing and shall be 
     given by personal delivery, first class air mail, air courier service, 
     telex, telefacsimilie or commercial cable and shall be addressed to the 
     addresses set forth in the Special Conditions.

18.  SEVERABILITY.  If any term or provision of the Contract is held to be 
     illegal or unenforceable, then the Contract, except for such part or 
     parts thereof, shall continue to be in full force and effect to the 
     extent possible without the illegal or unenforceable provision.

19.  WAIVER.  The failure by either party to enforce at any time or for any 
     period of time any of the provisions hereof shall not be a waiver of 
     such provisions nor of the right of such party thereafter to enforce 
     each and every such provision.

20.  BENEFITS OF AGREEMENT.  The Purchase Contract of which these conditions 
     form a part shall inure to the benefit of an be binding upon each of the 
     parties hereto and their respective successors and assigns, but neither 
     the rights nor the duties of either party hereunder may be assigned in 
     whole or part without the prior written consent of the other party.

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21.  ARBITRATION.

     21.1  If a dispute arises out of or related to this Agreement, or the 
     breach thereof, and if the dispute cannot be settled through 
     renogotiation, the parties agree first to try in good faith to settle the 
     dispute by mediation administered by the American Arbitration 
     Association under its Commercial Mediation Rules before resorting to 
     arbitration, litigation or some other dispute resolution procedure.

     21.2  All disputes, controversies or differences which may arise between 
     the parties, out of or in relation to or in connection with this 
     Agreement, or for the breach thereof, shall be finally settled by 
     arbitration proceedings held in Boston, Massachusetts, and conducted in 
     accordance with the rules and procedures of the American Arbitration 
     Association. The award shall be final and binding on all parties hereto. 
     Judgment upon the award rendered may be entered in any court having 
     jurisdiction, or application may be made to such court for judicial 
     acceptance of the award or order of enforcement as the case may be.






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                                SERVICE CONTRACT

    THIS AGREEMENT made this 6th day of February, 1998 by and between North 
American Scientific, Inc., a California corporation with a principal place of 
business at 7435 Greenbush Avenue, North Hollywood, California 91605 
("NASI"), and PracSys Corp., a Massachusetts corporation with a principal 
place of business at 8E Industrial Way, Unit 10, Salem, New Hampshire  03079 
("PracSys").

                                WITNESSETH THAT:

    WHEREAS, PracSys is the exclusive worldwide licensee of a patented ion 
accelerator device, the Nested High Voltage Generator ("NHVG-TM-"); and 

    WHEREAS, NASI is purchasing from PracSys under a separate purchase 
contract of the even date (the "Purchase Contract") two isotope production 
systems (the "Systems") embodying the NHVG-TM-, to be used for the production 
of *** processed targets (the "Product") to be used as a raw material for 
production of seeds for use in brachytherapy (the "Market"); and

    WHEREAS, PracSys will, pursuant to the Purchase Contract, manufacture and 
install the Systems at its Salem, New Hampshire facility (the "Production 
Center") ready for isotope production, unless NASI shall otherwise direct the 
installation site, and

    WHEREAS, NASI wishes to have its Systems operated by PracSys for the 
production of the Product for shipment to NASI for processing into seeds for 
sale to the Market (the "Market Sales"); and

    WHEREAS, NASI and PracSys have entered into a separate Exclusivity and 
Purchase Agreement dated December 31, 1997, as amended as of the date hereof 
(the "Exclusivity Agreement") for production of the Product and other 
isotopes; and

    WHEREAS, the Exclusivity Agreement between NASI and PracSys provides that 
the parties will reduce to writing the terms of a Service Contract.

    NOW THEREFORE, in consideration of the premises and of mutual promises 
and undertakings hereinafter set forth, as well as other good and valuable 
consideration, the receipt and sufficiency of which is hereby acknowledged by 
the parties hereto, it is agreed as follows:


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

1.   Scope

     Acting upon the Monthly Production Estimate (defined in Section 2 
below), subject to the provisions of Section 8 below, PracSys shall operate 
and maintain the Systems to produce *** processed targets which comply with 
the specifications set forth in Exhibit A.  The processed targets shall be 
prepared for shipment in accordance with the provisions of Section 7 below.

2.   Requirements

     Following installation and acceptance of the first system to be 
purchased by NASI pursuant to the Purchase Contract, NASI will provide 
PracSys with a monthly estimate of Curies (Ci) EOB, (as defined  in Exhibit 
B), per week of Product to be produced (the "Monthly Production Estimate"). 
The Monthly Production Estimate shall be provided no less than two weeks in 
advance of the first day of the upcoming Production Month.  The Production 
Month is defined as the period ending with the last Friday of a calendar 
month, with the subsequent Production Month commencing the next day.  PracSys 
will fill all Monthly Production Estimate requirements and use its best 
efforts to accommodate changes to the weekly production requirements that may 
be requested by NASI during the Production Month, except when prevented from 
doing so by strikes, fires, riots, accidents, war, unavailability of raw 
materials and other conditions over which PracSys has no reasonable control.

3.   Payments

     Payments to be made hereunder are for services (the "Services") 
performed by PracSys to produce the Product in the PracSys Production Center, 
utilizing the NASI owned Systems, for shipment to NASI.  It is the intention 
of the parties that the actual costs incurred by PracSys in providing the 
Services will be reimbursed by NASI.  These costs will include direct costs, 
allocated costs, indirect costs, facility costs, general and administrative 
costs and other reasonably allocated costs of doing business, but shall not 
include a profit factor.  In no event shall such costs include or reflect 
obligations owing by PracSys at or prior to the date of this Agreement.

     Payments will be calculated and invoiced as follows:

     3.1   A services pricing formula is established as set forth in Exhibit 
           B with cost categories segregated by fixed, semi-variable, and 
           variable costs (the "Reimbursement Formula").  PracSys hereby 
           represents that the Reimbursement Formula, Pricing Adjustment 
           Factors, and Example Calculation set forth in Exhibit B accurately 
           reflects PracSys' current estimate of the cost of the Services, 
           and thereby the effective cost per Millicurie ("mCi") for the 
           provision of Product, and is a reasonable estimation thereof.


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

     3.2   Upon receipt of the Monthly Production Estimate setting forth the 
           estimated weekly requirements for the Production Month, PracSys 
           will calculate, using the Reimbursement Formula, the payment due 
           for the Production Month requirements and invoice the calculated 
           amount (the "Monthly Billing").  Payment is due upon receipt of 
           the invoice, but no later than the first day of the Production 
           Month.  The Monthly Billing is subject to reasonable retrospective 
           adjustment to reflect the actual cost for Services in accordance 
           with Section 4 below.

4.   Retrospective Payment Adjustments

     PracSys will calculate at the end of each period of three Production 
Months (the "Quarterly Accounting") the actual costs for Services for the 
preceding three Production Months (the "Adjustment Period") utilizing the 
Reimbursement Formula in Exhibit B and compare these actual costs to the 
Monthly Billings for the Adjustment Period.

     4.1   The Quarterly Accounting will be based upon the actual production 
           of Product shipped to NASI during the Adjustment Period; and

     4.2   The Quarterly Accounting will also reflect the actual costs 
           incurred during the Adjustment Period for the elements of costs 
           identified in the Reimbursement Formula (the "Pricing Adjustment 
           Factors").

     4.3   The actual costs for the Adjustment Period will be compared to the 
           total Monthly Billings during the Adjustment Period.

           4.3.1 If the actual costs exceed the Monthly Billings, PracSys 
           will invoice NASI for the difference showing the calculation 
           supporting the amount.  The amount shall be payable by NASI to 
           PracSys within 15 days after receipt of the invoice unless NASI 
           requests clarification of the amount invoiced, in which case the 
           amount would be payable 15 days after NASI's receipt of such 
           clarification.  If during such 15 day period NASI shall dispute 
           the calculation of such adjustment, the parties shall act in good 
           faith to resolve such dispute and, in the absence of agreement 
           between them, shall refer such dispute to an independent certified 
           public accountant selected mutually by NASI and PracSys.  The 
           costs associated therewith shall be borne equally by the parties 
           hereto.

           4.3.2 If the actual costs are less than the Monthly Billings, 
           PracSys will apply such difference as a credit against the next 
           Monthly Billing, identifying the credit and providing the 
           calculation substantiating the amount.  If there is no applicable 
           next Monthly Billing, the credit will be reimbursed promptly to 
           NASI.

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<PAGE>

           4.3.3 The Pricing Adjustment Factors values will be adjusted to 
           reflect the actual costs for the Quarterly Accounting.  The list 
           of Pricing Adjustment Factors will be expanded or modified as 
           appropriate to reflect all elements of incurred costs.  The 
           resulting modified Pricing Adjustment Factors will be used for 
           subsequent calculation of Monthly Billings.  However, PracSys 
           hereby agrees that any pricing adjustment shall be subject to the 
           limitations set forth in Notes 1, 2, and 3 under Pricing 
           Adjustment Factors in Exhibit B.

5.   Records, Cost Accounting, and Audit

     PracSys will maintain separate cost accounting for the PracSys Services 
provided at the Production Center and will record all direct labor and 
material costs, as well as all indirect costs including indirect labor, 
overhead, facility costs, and general and administrative costs that shall be 
allocated on a consistent basis.  The method of allocation will be shown on 
such records and will be certified by the PracSys chief financial officer to 
have been applied consistently.  All direct costs are subject to audit by 
NASI upon reasonable notice.  All indirect costs and the method of allocation 
may be audited by an independent certified public accountant selected 
mutually by NASI and PracSys. The cost of such audit shall be borne equally 
by the parties hereto.

6.   Term

     6.1   Unless sooner terminated as herein provided, this Agreement shall 
           be in force from the date hereof through the end of the second 
           Annual Period (the "Term").  The Annual Period is defined as a 12 
           month period beginning with the calendar date of the first day of 
           the calendar month following the calendar month in which the first 
           System at the Production Center is installed and ready for 
           production of the Product.

     6.2   The Term shall be extended (the "Term Extension") by one year 
           annually subject to agreement of the parties to modification of 
           the Reimbursement Formula and other adjustment provisions for 
           prospective application.  Any proposed adjustment shall be based 
           on actual costs incurred by PracSys during the current Annual 
           Period. The extension adjustments will be made at least 90 days 
           prior to the expiration of the Annual Period. 

7.   Shipping and Handling

     Product shall be shipped FOB the Production Center in reusable certified 
shipping containers provided by NASI.  NASI will provide a quantity of 
shipping containers to maintain a suitable inventory of containers for 
shipments.


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

8.   Termination

     This Agreement shall be terminated prior to its expiration under the 
following conditions:

     8.1   NASI may, upon written notice six (6) months in advance of the 
           expiration of any Annual Period, commencing with the second Annual 
           Period, elect not to extend the Term of this Agreement.  NASI 
           shall be responsible for the removal of the Systems from the 
           Production Center at its expense before or at the end of the Term.

     8.2   Additionally, NASI may, upon six (6) months written notice, elect 
           to relocate or sell the Systems and terminate this Agreement.  In 
           the event of such termination, NASI shall pay a decommissioning 
           charge to PracSys in the amounts and at the times specified in 
           Section 9 below.

     8.3   NASI may, upon 90 days written notice but no later than 90 days 
           prior to the scheduled first acceptance date, direct that the 
           Systems be delivered to a site other than the Production Center.

     8.4   PracSys may terminate this Agreement in the event of default by 
           NASI's material breach of any of the provisions of this Agreement 
           or the Exclusivity Agreement, upon written notice by PracSys of 
           such an event of default and if such default is not cured by NASI 
           within 60 days after such notice.

     8.5   NASI may terminate this Agreement if PracSys is unable to secure 
           the necessary licenses and permits prerequisite to providing the 
           services herein.  PracSys shall provide to NASI a monthly report 
           of the status of such licenses and permits commencing 60 days 
           after the date hereof.

     8.6   In the event of default by PracSys's material breach of any of the 
           provisions of this Agreement (including the failure by PracSys to 
           meet any Monthly Production Estimate) or the Exclusivity 
           Agreement, upon written notice by NASI of such an event of default 
           and if such default is not cured by PracSys within 60 days after 
           such notice, NASI may terminate the Service Contract for default 
           and, at its discretion, may perform the services herein with its 
           own supervisory and operating personnel (the "March In Rights") 
           paying all direct costs and reimbursing PracSys for allocated 
           facility costs until such time as NASI removes the Systems from 
           the Production Center.  PracSys shall have the right to purchase 
           Product from a third party in order to meet the requirements of 
           any Monthly Production Estimate (the "Alternate Supply").  In the 
           event PracSys shall provide an Alternate Supply, NASI shall 
           reimburse PracSys for the Product at a per mCi price that would 
           have resulted from 


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

           this Agreement based upon the volume of Product so purchased, 
           using the pricing factors set forth in Exhibit B hereof.

     8.7   Should either party have reasonable grounds to believe the other 
           party is unable to pay its debts when due or is financially unable 
           to perform its obligations under this Agreement, or if either 
           party makes a general assignment for the benefit of creditors, or 
           institutes proceedings to be adjudicated a voluntary bankrupt, or 
           consents to the filing of a petition of bankruptcy against it, or 
           is adjudicated by a court of competent jurisdiction as bankrupt or 
           insolvent; or should either party seek reorganization under any 
           bankruptcy or similar act, or consent to the filing of a petition 
           seeking such petition; or should either party have a decree 
           entered against it by a court of competent jurisdiction appointing 
           a receiver, liquidator, trustee, or assignee in bankruptcy or in 
           insolvency or providing for the liquidator of such party's 
           property or business affairs; than the other party may, at its 
           option and without notice, terminate this Agreement effective 
           immediately.

9.   Decommissioning Payment

     9.1   In the event of termination pursuant to Section 8.2 above, NASI 
           shall pay to PracSys the following decommissioning payment:

           9.1.1  An amount equal to the reasonable actual costs, including 
                  but not limited to labor and materials for the removal of 
                  the Systems, the preparation of the Systems for shipping 
                  FOB the Production Center, and the restoration of the 
                  facility to its configuration and condition prior to the 
                  installation of the Systems.  The removal costs will 
                  include the cost of handling and disposal of any hazardous 
                  materials.  Payment will be made by NASI within 30 days 
                  after receipt of invoice(s) submitted by PracSys that shall 
                  be certified by the PracSys chief financial officer to be 
                  true and actual costs.

           9.1.2  NASI will pay to PracSys an amount equal to three (3) 
                  months of service (the "Effective Period") under this 
                  Agreement calculated in accordance with the Reimbursement 
                  Formula for the fixed and semi-variable costs that would be 
                  incurred without production of Product.  The Effective 
                  Period will commence with the last day of actual services 
                  provided by PracSys which is the last day of the six month 
                  notice period proscribed by Section 8.2 above.  Payment is 
                  due within 30 days after receipt of the invoice prepared by 
                  PracSys which will show the calculation of the amount due.

*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.

<PAGE>

10.  Risk of Loss

     Title and risk of loss of the Product pass to NASI FOB the Production 
Center.

11.  Right to Inspect

     NASI at its election and at its own expense may inspect the production 
of the Product at the Production Center, with no less than one business day's 
notice to PracSys, during normal business hours.  Such inspection shall not 
unreasonably interfere with or unreasonably interrupt the service activities. 
NASI representatives must conform to all facility safety instructions and 
license and permit provisions.

12.  Equipment Markings

     During the manufacture of the Systems at the Production Center and upon 
installation of the Systems, the Systems or the work-in-progress thereof 
shall be segregated from the rest of the facility by partitions or prominent 
floor markings.  A name plate with model and serial numbers will be clearly 
affixed to each System identifying NASI ownership.

13.  General Terms and Conditions

     General Terms and Conditions are set forth in Exhibit C.

14.  Indemnification

     PracSys shall indemnify, defend  and hold NASI harmless from and against 
any liability, damage, claims, cost or expense (including reasonable 
attorney's fees) arising out of any claim of infringement by any third party 
of any patents or any claimed violation of any other intellectual property 
right of any third party arising out of the use of the Systems pursuant to 
this Agreement.  NASI shall indemnify, defend  and hold PracSys harmless from 
and against any liability, damage, claims, cost or expense (including 
reasonable attorney's fees) arising out of any claim of infringement by any 
third party of any patents or any claimed violation of any other intellectual 
property right of any third party arising out of the sale by NASI of products 
incorporating the Product to be supplied by PracSys to NASI pursuant to this 
Agreement.  Provided, however, that NASI shall have no such obligation to the 
extent such claim of infringement is based upon the Product incorporated into 
such NASI product.

15.  Confidentiality

     NASI and PracSys shall hold in strict confidence and shall not disclose 
to others or use, either before or after the expiration of termination of 
this Agreement, any technical, financial, or 


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

business information, manufacturing technique, process, trade secret, or 
other confidential information relating to each other's business.  Upon 
expiration or termination of this Agreement, NASI and PracSys shall return to 
each other all documents containing any such information, shall delete and 
purge from any of its electronic or mechanical storage systems all records 
thereof, and shall certify to each other in writing that said steps have been 
taken.

16.  Arbitration

           16.1   If a dispute arises out of or related to this Agreement, or 
                  the breach thereof, and if the dispute cannot be settled 
                  through negotiation, the parties agree first to try in good 
                  faith to settle the dispute by mediation administered by 
                  the American Arbitration Association under its Commercial 
                  Mediation Rules before resorting to arbitration, litigation 
                  or some other dispute resolution procedure.

           16.2   All disputes, controversies or differences which may arise 
                  between the parties, out of or in relation to or in 
                  connection with this Agreement, or for the breach thereof, 
                  shall be finally settled by arbitration proceedings held in 
                  Boston, Massachusetts, and conducted in accordance with the 
                  rules and procedures of the American Arbitration 
                  Association.  The award shall be final and binding on all 
                  parties hereto.  Judgment upon the award rendered may be 
                  entered in any court having jurisdiction, or application 
                  may be made to such court for judicial acceptance of the 
                  award or order of enforcement as the case may be.

17.  Construction

     This Agreement shall be construed, and all rights, powers, and 
liabilities of the parties hereunder shall be determined, in accordance with 
the laws of The Commonwealth of Massachusetts.  All amounts mentioned in this 
Agreement are in the currency of the United States of America at exchange 
rates in effect on the date when such payments shall become due and payable.

18.  Waiver

     No omission or delay of either party hereto in requiring due and 
punctual fulfillment by the other party of the obligations of such other 
party hereunder shall be deemed to constitute a waiver of its rights to 
require such due and punctual fulfillment or of any of its remedies hereunder.

19.  Notices

     Any notice given by either party hereto to the other party shall be 
deemed to have been sufficiently given if sent by the mailing thereof by 
certified or registered mail, or by a recognized national overnight delivery 
service, to the signatories herein to the address of such other party herein 


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

set forth, unless and until another addressee and or address shall have been 
designated in writing by such other party for the purpose.

20.  Agency

     It is understood and agreed that the parties hereto are independent 
contractors and are engaged in the operation their own respective businesses 
and neither NASI nor PracSys shall be considered the agent of the other party 
hereto for any purposes whatsoever, and neither NASI nor PracSys has the 
authority to enter into any contracts or assume any obligation for the other 
party hereto, and nothing in this Agreement shall be construed to establish a 
relationship of partners or joint ventures between the parties hereto.

21.  Captions

     The captions and section numbers appearing in this Agreement are 
inserted only as a matter of convenience and in no way define, limit or 
construe the scope and intent of such sections nor in any way affect this 
Agreement.

22.  Assignment

     Neither NASI nor PracSys may assign or license any of its rights or 
obligations under this Agreement without the prior written consent of the 
other party. 


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

      IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be 
executed in duplicate, upon the date hereinabove set forth.

PracSys Corp.                          North American Scientific, Inc.

By: /s/ Wayne E. Webster               By:/s/ L. Michael Cutrer
    --------------------------            -----------------------------
        Wayne E. Webster                       L. Michael Cutrer
        President & CEO                        President & CEO





*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>


                                EXHIBIT A

                          PRODUCT SPECIFICATION

                                   ***










*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

                                 EXHIBIT B

                           REIMBURSEMENT FORMULA

                                    ***









*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

                                  EXHIBIT C

                         GENERAL TERMS AND CONDITIONS

1.   PracSys ("Seller") warrants that at the time of shipment, the Products 
     produced by it pursuant to this Agreement are free from defects in 
     material and workmanship and conform to the specification set out in 
     Exhibit A.  SELLER MAKES NO OTHER WARRANTY, EXPRESS OR IMPLIED, WITH 
     RESPECT TO THE PRODUCTS INCLUDING ANY WARRANTY OF MERCHANTABILITY OR 
     FITNESS FOR ANY PARTICULAR PURPOSE. Notification of any breach of 
     warranty must be made within the half-life of the radioisotope contained 
     in the product, unless otherwise provided in writing by the Seller.  No 
     claim shall be honored if NASI (the "Buyer") fails to notify the Seller 
     within the period specified.  THE SOLE AND EXCLUSIVE REMEDY OF THE BUYER 
     FOR ANY LIABILITY OF SELLER OF ANY KIND INCLUDING LIABILITY BASED UPON 
     WARRANTY (EXPRESS OR IMPLIED WHETHER CONTAINED HEREIN OR ELSEWHERE), 
     STRICT LIABILITY, CONTRACT, OR OTHERWISE IS LIMITED TO THE REPLACEMENT 
     OF THE GOODS.  SELLER SHALL NOT IN ANY CASE BE LIABLE FOR SPECIAL, 
     INCIDENTAL, OR CONSEQUENTIAL DAMAGES OF ANY KIND.

2.   Seller shall not be responsible for any failure or delay in delivery of 
     services or goods because of any cause beyond Seller's reasonable 
     control.  The Seller reserves the right to ship in one or more shipments.

3.   The price of services and payment schedules are set forth in the 
     Agreement.

4.   Any tax or governmental charge imposed upon the sale of services or 
     goods shall be paid by the Buyer, and the Buyer's failure to do so, 
     unless cured within 60 days after notice of such failure, shall be a 
     breach of this entire agreement. Prices on the specified services and 
     products are exclusive of all city, state and federal excise taxes, 
     including without limitation, taxes on manufacture, sales, receipts, 
     gross income, occupation, use and similar taxes.

5.   No right to the use of any trade name or trademark of the Seller or 
     Buyer passes to the other party  under this Agreement and the Buyer and 
     Seller agrees to refrain from using, either directly or indirectly, any 
     of the other parties trade names or trademarks unless specifically 
     authorized to do so in writing. Except as otherwise specifically agreed 
     in writing, all drawings, and specification produced by Seller and Buyer 
     pursuant to this Agreement, and all patent, copyright and other 
     intellectual property rights with respect to the goods sold hereunder, 
     shall be the sole and exclusive property of the originator and holder of 
     such rights.


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>

6.   No modification of this Agreement shall be binding unless in writing and 
     signed by Buyer and Seller.

7.   Waiver by Seller or Buyer of a breach by the other party  of any 
     provision of this Agreement shall not be deemed a waiver of future 
     compliance therewith, and such provision, as well as all other 
     provisions hereunder, shall remain in full force and effect.

8.   If any provision of this Agreement is or becomes, at any time and under 
     any law, rule or regulation, unenforceable or invalid, no other 
     provision of this Agreement shall be affected thereby, and the remaining 
     provisions of this Agreement shall continue with the same effect as if 
     such unenforceable or invalid provisions shall not have been inserted in 
     this Agreement.

9.   Each party agrees to pay for all costs and expenses including attorney's 
     fees, incurred in the enforcement of this Agreement and the collection 
     of any amounts due the other party hereunder.

10.  Each party hereby represents that such party is solvent and has the 
     financial resources sufficient to perform its obligations under this 
     Agreement, and that on each delivery this representation shall be deemed 
     renewed unless notice to the contrary is given in writing by such party 
     to the other party at or before delivery of the goods.


*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
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<PAGE>
                                                                          10.3
                                          
                                          
                                          
                         EXCLUSIVITY AND PURCHASE AGREEMENT

     EXCLUSIVITY AGREEMENT, dated as of December 31, 1997 by and between PracSys
Corp., a Massachusetts corporation (the "Company") and North American
Scientific, Inc. a Delaware California corporation, ("NASI").

     WHEREAS, NASI wishes to purchase from the Company two of its proprietary
integrated NHVG-TM- isotope production systems (the "Systems") at a fixed price
(the "Fixed Price") for installation and operation by the Company in its
production center, and

     WHEREAS, NASI wishes to obtain from the Company certain market exclusivity
in the use of the Systems within the Market (as described hereinafter), and

     WHEREAS, NASI wishes to obtain from the Company an option to acquire the
exclusive rights to acquire the Company's proprietary NHVG-TM- isotope
production systems for use in other markets (the "Option"), and

     WHEREAS, NASI wishes to have an equity interest in the Company, and

     WHEREAS, the Company is willing, in return for certain consideration and
under certain terms and conditions, to provide to NASI the Service Contract (as
described in Section 3. below), the Fixed Price purchase of Systems, the Market
exclusivity, the Option for additional exclusive rights, and an equity interest
in the Company.

     NOW THEREFORE,  the parties agree as follows:

     1. During the Term of this Agreement (as defined in Section 9. below), the
Company (i) will produce the Product (as described in Section 4. below),
exclusively for NASI pursuant to the Service Contract, (ii) will not knowingly
sell the System to third parties' for the purpose of the third parties'
production of the Product, and as expanded to include other isotopes pursuant to
Section 6. below, and (iii) will use its best efforts to limit the purchase and
adaptation of the Company's proprietary technology by third parties for the
production of the Product, and as expanded to include other isotopes pursuant to
Section 6. below.

     2. In consideration for the exclusivity, NASI will pay to the Company 
$ ***  (the "Exclusivity Consideration") by wire transfer to the Company's 
account upon the Closing (as described in Section 8. below).

     3. At the Closing, NASI and the Company shall enter into a renewable 
Service Contract for a two (2) year term commencing with the installation of 
System #1 ready for the production of the Product, generally in accordance 
with the Company's proposal to NASI dated December 12, 1997, which is hereby 
incorporated by reference, made a part hereof and is attached hereto as 
Exhibit A.  The Service Contract will provide for monthly reimbursement, in 
advance, based on volume estimates from NASI in advance, subject to quarterly 
adjustment retrospectively to reflect volume of Product 

*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


<PAGE>

delivered to NASI and pricing adjustment factors to be defined in the Service 
Contract.  The Service Contract will be a rolling two year agreement extended 
by one year annually subject to negotiation, based on actual cost, as defined 
in the Service Contract, incurred by the Company in producing the Product, 90 
days prior to the expiration of the annual period.  The Company shall 
negotiate the annual extension in good faith and shall have a right of 
termination only in the event of default by NASI of the provisions of the 
Service Contract or this Agreement after a 60 day cure period.  NASI may, 
upon written notice six (6) months in advance of the expiration of any annual 
period, elect not to extend the term of the Service Contract. Additionally, 
as provided in the Service Contract, NASI may upon six (6) months notice 
elect to relocate or sell the Systems and terminate the Service Contract.  In 
event of System relocation or sale, the equipment, facility and organization 
decommissioning charge set forth in the Service Contract would be paid to the 
Company.

     4. At the Closing, (also the "Order Date") NASI agrees to place with the 
Company a purchase order in form and substance to be agreed upon by both 
parties, providing for the purchase by NASI of two Systems each consisting of 
a Nested High Voltage Generator (NHVG-TM-) linear accelerator, target end 
station, and processing equipment for the production of *** processed targets 
(the "Product"), with such Systems to be delivered to and installed in the 
Production Center (the "Purchase Order").

     a. The Purchase Order will be issued with a *** lead time to delivery 
from the Order Date for System #1 and a *** lead time to delivery from the 
Order Date for System #2.

     b. The Fixed Price Systems purchase price, which includes installation 
at the Production Center, is $ ***    and includes the following:

     - NHVG-TM- accelerator complete with operating system, shielding and stand.
     - *** target end station, shielding and processing equipment.
     - Facilities modification, utility hook-ups and installation.

     c. Payments will be made to the Company according to the following 
schedule:
- -------------------------------------------------------------------------------
   MILE-
  STONES                      DESCRIPTION                          AMOUNT
- -------------------------------------------------------------------------------
     1     Execution of Purchase Order                             $ ***
- -------------------------------------------------------------------------------
     2     Receipt of Long Lead Items for System #1 & #2           $ ***
- -------------------------------------------------------------------------------
     3     Start of Accelerator Assembly System #1 & #2            $ ***
- -------------------------------------------------------------------------------
     4     System #1 Proton Beam Demonstration                     $ ***
- -------------------------------------------------------------------------------
     5     System #2 Proton Beam Demonstration                     $ ***
- -------------------------------------------------------------------------------
     6     Acceptance of System #1                                 $ ***
- -------------------------------------------------------------------------------
     7     Acceptance of System #2                                 $ ***
- -------------------------------------------------------------------------------



*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


                                       2
<PAGE>


     d. The Purchase Order will also include a provision whereby the Company, 
at the request of NASI, will use its best efforts to sell the System(s) as a 
non-commissioned agent of NASI.

     5. Commencing with the delivery of Product to NASI, and thereafter 
during the Term of the Agreement as it may be extended, NASI shall pay to the 
Company, quarterly in arrears, an amount ("Revenue Participation") equal to a 
percentage of its gross revenues ("Market Revenue") for Market sales of 
brachytherapy seeds that incorporate Product in accordance with the following 
sliding scale.  Such Market Revenues shall be defined as collected sales 
revenues at the end user price.

QUARTERLY NASI MARKET REVENUES                       REVENUE PARTICIPATION %
- ------------------------------                       -----------------------

     first $1 million ....................................  *** % then
                                                            -----
     for sales from $1 million to 3 million ..............  *** % then
                                                            -----
     for sales from $3 million to $6 million .............  *** % then
                                                            -----
     for all sales over $6 million .......................  *** %
                                                            -----
     For example, the Revenue Participation for quarterly seed sales of $4
million would be $***:
                 -----

     for first $1 million ................................  $ ***   
                                                              ----
     for the sales between $1 million to $3 million ......  $ ***   
                                                              ----
     for sales between $3 million to $4 million ..........  $ ***   
                                                              ----
     The quarterly Revenue Participation for $4 million in seed sales would 
     be $ ***.
          ----

     6. The Company at the Closing grants to NASI a first Option to acquire 
during the Term of this Agreement, the exclusive or, at NASI's option, 
non-exclusive rights to acquire proprietary equipment or services for the 
production of other isotopes (excluding positron emitting isotopes used in 
Positron Emission Tomography) and for other markets at a mutually acceptable 
price and terms to be negotiated in good faith.  Also, during the Term of 
this Agreement, NASI is granted 30 calendar days to match any third party 
offers received by the Company for the equipment or services referred to in 
the preceding sentence.  If NASI chooses not to make a matching offer, the 
Company may proceed to sell rights, equipment, and or services to the third 
party on the terms set forth in such offer.  Such rights do not include the 
use of NASI owned equipment or other rights previously granted to NASI for 
such third party agreements.

     7. Upon the Closing, the Company will issue to NASI a certificate for 
140,150 shares of its common stock representing a 5% fully diluted interest 
in the Company's currently issued and outstanding common stock and assuming 
conversions of the currently issued and outstanding preferred stock (the 
"Securities").  THE SECURITIES REPRESENTED BY SUCH CERTIFICATE WILL NOT HAVE 
BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 AND, ACCORDINGLY, MAY NOT BE 
OFFERED FOR SALE, SOLD OR OTHERWISE TRANSFERRED EXCEPT (i) UPON EFFECTIVE 
REGISTRATION  OF THE SECURITIES REPRESENTED BY SUCH CERTIFICATE UNDER THE 
SECURITIES ACT OF 1933, OR (ii) UPON ACCEPTANCE BY THE COMPANY OF AN OPINION 
OF COUNSEL IN SUCH FORM 

*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


                                      3
<PAGE>


AND BY SUCH COUNSEL, OR OTHER DOCUMENTATION, AS IS SATISFACTORY TO COUNSEL 
FOR THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.  By accepting the 
Securities, NASI agrees, in the event of a public offering of the Company's 
common stock, not to sell any of its Securities (in any manner, including 
pursuant to Rule 144 under the Act and however acquired) for a period 
established by the Underwriter (the "Lockup Period") that is equally applied 
to the Company's officers, private investors, directors and shareholders 
including those that own five (5%) or more of the outstanding shares of the 
Company.

     8. NASI and the Company shall use reasonable efforts to negotiate and 
prepare the Purchase Order and the Service Contract on or before January 15, 
1998.  NASI will proceed with its due diligence during that period.  NASI's 
obligation shall be subject to its reasonable satisfaction with the results 
of its due diligence, agreement upon the Purchase Order and Service Contract, 
and approval thereof of its Board of Directors.  A closing is scheduled on or 
before January 15, 1998 (the "Closing").  At the Closing, (i) the Exclusivity 
Consideration (see Section 2. above) shall be wire transferred to the 
Company, (ii) the Company will issue the Securities (see Section 7. above), 
(iii) the parties shall execute the Purchase Order (see Section 4. above) and 
the Milestone 1 payment shall be wire transferred to the Company (see Section 
4. c. above), and (iv) the parties shall execute the Service Contract (see 
Section 3. above). 

     9. This Agreement shall be in effect for a period ending with the later 
of (i) the expiration of the term, as extended, of the Service Contract or 
(ii) the cessation of use of the Systems by NASI, its affiliates or 
successors to produce the Product (the "Term").

     10. This Agreement shall be binding upon and inure to the benefit of the 
parties hereto and their respective successors and assigns.  This Agreement 
may not be amended, except by a written instrument duly executed by the 
parities hereto, and it sets forth the entire agreement and understanding 
between the parties as to the subject matter hereof.

     11. This Agreement shall be governed by and construed under 
Massachusetts law not giving effect to its internal conflicts of laws 
provisions and the parties hereby agree to submit themselves to the 
jurisdiction of the courts thereof.

     12. Neither the Company nor NASI shall make any public disclosure 
whether in a news release, securities offering documents or otherwise with 
respect to this Agreement, or the subject matter thereof, without the prior 
written consent of the other party, except where public disclosure may be 
required by law (in which event the disclosing party shall give the other 
party prior written notification of such disclosure along with the legal 
basis therefor).



*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


                                       4
<PAGE>


     IN WITNESS WHEREOF  the parties have caused this Agreement to be 
executed as of the date set forth above.

PracSys Corp.                        North American Scientific, Inc.


By: /S/ WAYNE E. WEBSTER             By: /S/ L. MICHAEL CUTRER
   -----------------------------        ------------------------------
        Wayne E. Webster                        Michael Cutrer 
        President & CEO                         President & CEO



*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


                                         5
<PAGE>



                         EXCLUSIVITY AND PURCHASE AGREEMENT

                                  AMENDMENT NO. 1
                                          
     AMENDMENT NO. 1, dated as of February 6, 1998 by and between PracSys 
Corp., a Massachusetts corporation (the "Company") and North American 
Scientific, Inc. a Delaware corporation, ("NASI").

     WHEREAS, NASI and the Company entered into the Exclusivity and Purchase 
Agreement (the "Agreement") dated as of December 31, 1997; and

     WHEREAS, the Agreement provides that the Agreement may not be amended, 
except by a written instrument duly executed by the parties, and

     WHEREAS, NASI and the Company wish to amend the Agreement.

     NOW THEREFORE, in consideration of the premises and of mutual promises 
and undertakings hereinafter set forth, as well as other good and valuable 
consideration, the receipt and sufficiency of which is hereby acknowledged by 
the parties hereto, it is agreed that the Agreement is amended as follows:

     Section 2 of the Agreement is amended to read in its entirety as follows:

     "2.  IN CONSIDERATION FOR THE EXCLUSIVITY, NASI WILL PAY TO THE
     COMPANY $ ***  BY WIRE TRANSFER TO THE COMPANY'S ACCOUNT UPON THE
     CLOSING (AS DESCRIBED IN SECTION 8 BELOW) AND WILL, SUBJECT TO THE
     PROVISIONS OF THIS AGREEMENT, ENTER INTO THE SERVICE CONTRACT AND
     PURCHASE ORDER, AS DEFINED HEREIN (COLLECTIVELY, THE "EXCLUSIVITY
     CONSIDERATION")."

     Section 7 of the Agreement is revised to include the following
     provisions after the existing paragraph:

          "THE COMPANY SHALL PRIOR TO THE ISSUANCE BY THE COMPANY OF ANY OF
     ITS EQUITY SECURITIES,  OFFER NASI BY WRITTEN NOTICE THE RIGHT, FOR A
     PERIOD OF THIRTY (30) DAYS, TO PURCHASE UP TO THE NUMBER OF SHARES OF
     SUCH SECURITIES THAT WOULD PRESERVE THE NASI PERCENT OWNERSHIP IN THE
     EQUITY OF THE COMPANY, FOR CASH AT AN AMOUNT EQUAL TO THE PRICE OR
     OTHER CONSIDERATION FOR WHICH SUCH SECURITIES ARE TO BE ISSUED;
     PROVIDED, 

*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


<PAGE>




     HOWEVER, THAT THESE FIRST REFUSAL RIGHTS OF NASI SHALL NOT APPLY TO 
     SECURITIES ISSUED (A) UPON THE CONVERSION OF ANY OF THE PREFERRED STOCK 
     OF THE COMPANY, (B) AS A STOCK DIVIDEND OR UPON ANY SUBDIVISION OF 
     SHARES OF COMMON STOCK, PROVIDED THAT THE SECURITIES ISSUED PURSUANT TO 
     SUCH STOCK DIVIDEND OR SUBDIVISION ARE LIMITED TO ADDITIONAL SHARES OF 
     COMMON STOCK, (C) PURSUANT TO SUBSCRIPTIONS, WARRANTS, OPTIONS, OR 
     CONVERTIBLE SECURITIES, (D) SOLELY IN CONSIDERATION FOR THE ACQUISITION 
     (WHETHER BY MERGER OR OTHERWISE) BY THE COMPANY OR ANY OF ITS 
     SUBSIDIARIES OF ALL OR SUBSTANTIALLY ALL OF THE STOCK OR ASSETS OF ANY 
     OTHER ENTITY, (E) PURSUANT TO THE EXERCISE OF OPTIONS TO PURCHASE COMMON 
     STOCK GRANTED TO DIRECTORS, OFFICERS, EMPLOYEES OR CONSULTANTS OF THE 
     COMPANY, (F) PURSUANT TO A PUBLIC OFFERING (G) TO EQUIPMENT LEASING 
     COMPANIES IN CONNECTION WITH ANY LEASING ARRANGEMENTS TO WHICH THE 
     COMPANY IS A PARTY AND WHICH HAVE BEEN APPROVED BY THE COMPANY'S BOARD 
     OF DIRECTORS, AND (H) UPON THE EXERCISE OF ANY RIGHT WHICH WAS NOT 
     ITSELF IN VIOLATION OF THE TERMS OF THIS FIRST RIGHT OF REFUSAL.  THE 
     COMPANY'S WRITTEN NOTICE TO NASI SHALL DESCRIBE THE SECURITIES PROPOSED 
     TO BE ISSUED BY THE COMPANY AND SPECIFY THE NUMBER, PRICE AND PAYMENT 
     TERMS.  NASI MAY ACCEPT THE COMPANY'S OFFER AS TO THE FULL NUMBER OF 
     SECURITIES OFFERED TO IT OR ANY LESSER NUMBER, BY WRITTEN NOTICE THEREOF 
     GIVEN BY IT TO THE COMPANY PRIOR TO THE EXPIRATION OF THE AFORESAID 
     THIRTY (30) DAY PERIOD, IN WHICH EVENT THE COMPANY SHALL PROMPTLY SELL 
     AND NASI SHALL BUY, UPON THE TERMS SPECIFIED, THE NUMBER OF SECURITIES 
     AGREED TO BE PURCHASED BY NASI.  THE COMPANY SHALL BE FREE AFTER THE 
     DATE OF ITS NOTICE TO NASI, TO OFFER AND SELL TO ANY THIRD PARTY OR 
     PARTIES THE NUMBER OF SUCH SECURITIES NOT AGREED BY NASI TO BE PURCHASED 
     BY THEM AND THE NUMBER OF SUCH SECURITIES NOT OFFERED TO NASI, AT A 
     PRICE AND ON PAYMENT TERMS NO LESS FAVORABLE TO THE COMPANY THAN THOSE 
     SPECIFIED IN SUCH NOTICE OF OFFER TO NASI.  HOWEVER, IF SUCH THIRD PARTY 
     SALE OR SALES ARE NOT CONSUMMATED AT A PRICE AND ON PAYMENT TERMS NO 
     LESS FAVORABLE TO THE COMPANY THAN THOSE SPECIFIED IN SUCH NOTICE OF 
     OFFER TO NASI, THE COMPANY SHALL NOT SELL SUCH SECURITIES WITHOUT AGAIN 
     COMPLYING WITH THIS FIRST REFUSAL RIGHT PROVISION. THE RIGHT OF FIRST 
     REFUSAL PROVIDED IN THIS PARAGRAPH SHALL EXPIRE ON THE EARLIER OF (I) 
     DECEMBER 31, 2000 OR (II) THE EFFECTIVE DATE OF THE INITIAL PUBLIC 
     OFFERING OF THE COMPANY'S COMMON STOCK) PROVIDING NO LESS THAN 
     $3,000,000 GROSS PROCEEDS TO THE COMPANY ("IPO").

     NASI IS GRANTED A COMMON STOCK WARRANT (THE "NASI WARRANT") TO
     PURCHASE A NUMBER OF COMMON STOCK THAT WILL BE EQUAL TO 5% OF THE

*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


                                      2
<PAGE>

     NUMBER OF IPO COMMON STOCK OFFERED TO THE PUBLIC IN AN IPO AT A PER
     SHARE PURCHASE PRICE EQUAL TO 80% OF THE IPO PER SHARE PRICE TO THE
     PUBLIC.  THE WARRANT MUST BE EXERCISED IN WHOLE OR IN PART WITHIN 60
     DAYS AFTER THE IPO OFFERING DATE.  THE WARRANT EXPIRES ON THE EARLIER
     OF THREE (3) YEARS OR 61 DAYS AFTER THE IPO OFFERING DATE. THE
     CALCULATION OF THE NUMBER OF SHARES PURCHASABLE BY NASI IS BASED ON
     THE NUMBER OF COMMON STOCK INITIALLY OFFERED TO THE PUBLIC AND NOT ANY
     UNDERWRITER OVER-ALLOTMENT SHARES SHOULD THEY BE ISSUED.  THE NASI
     WARRANT DOES NOT INCLUDE THE RIGHT TO PURCHASE COMMON STOCK WARRANTS
     SHOULD THEY BE SOLD TO THE PUBLIC AS PART OF AN IPO.

     ANY SECURITIES, INCLUDING THE NASI WARRANT, ISSUED PURSUANT TO THIS
     SECTION 7 SHALL BE SUBJECT TO THE PROVISIONS OF THE FIRST PARAGRAPH
     HEREOF."

     Section 8 of the Agreement is amended to restate the last sentence
     thereof to read in its entirety as follows:

     "AT THE CLOSING, (i) THE EXCLUSIVITY CONSIDERATION (SEE SECTION 2.
     ABOVE) SHALL BE WIRE TRANSFERRED TO THE COMPANY, (ii) THE COMPANY WILL
     ISSUE THE SECURITIES (SEE SECTION 7. ABOVE), (iii) THE PARTIES SHALL
     EXECUTE THE PURCHASE ORDER (SEE SECTION 4. ABOVE), AND THE
     PREPRODUCTION ENGINEERING PRICE OF $ ***  AND THE MILESTONE 1 PAYMENT
     (SEE SECTION 4. c. ABOVE) SHALL BE WIRE TRANSFERRED TO THE COMPANY,
     AND (iv) THE PARTIES SHALL EXECUTE THE SERVICE CONTRACT (SEE SECTION
     3. ABOVE)." 





*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


                                         3
<PAGE>


     IN WITNESS WHEREOF  the parties have caused this Agreement to be executed
as of the date set forth above.

PracSys Corp.                              North American Scientific, Inc.


By:/s/ Wayne E. Webster                    By:/s/ L. Michael Cutrer      
   ---------------------------                -----------------------------
     Wayne E. Webster                                L. Michael Cutrer 
      President & CEO                                 President & CEO         
                                                                       
                                                                    





*** REDACTED PORTION.  CONFIDENTIAL TREATMENT REQUESTED.  THE REDACTED MATERIAL
HAS BEEN SEPARATELY FILED WITH THE COMMISSION.


                                       4



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