Document:

<PAGE>
                                                                Exhibit 10.19(b)
                                  AMENDMENT ONE
                                       TO
                                LIMITED EXCLUSIVE
                              PATENT, COPYRIGHT AND
                           TRADEMARK LICENSE AGREEMENT

                                       FOR

                      PEREGRINE(TM) DOSE CALCULATION SYSTEM
                        FOR RADIATION TREATMENT PLANNING

                                     BETWEEN

                   THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

                                       AND

                                NOMOS CORPORATION

                            LLNL Case No. TL-1613-99

                     Lawrence Livermore National Laboratory
                            University of California
                    P.O. Box 808, L-795, Livermore, CA 94551
                  Industrial Partnerships and Commercialization

                                    June 2000

<PAGE>

                                  AMENDMENT ONE
                                       TO
                        LICENSE AGREEMENT NO. TL-1613-99

                                     BETWEEN

                   THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

                                       AND

                                NOMOS CORPORATION

                                       FOR

                      PEREGRINE(TM) DOSE CALCULATION SYSTEM
                        FOR RADIATION TREATMENT PLANNING

INTRODUCTION
This Amendment One to License Agreement No. TL-1613-99, for the "PEREGRINE(TM)
Dose Calculation System For Radiation Treatment Planning," (the "License") is
entered into by and between The Regents of the University of California ("THE
REGENTS") and NOMOS Corporation ("LICENSEE"). This Amendment One, and the
associated License Agreement, are subject to overriding obligations to the
Federal Government pursuant to the provisions of THE REGENTS' Contract No.
W-7405-ENG-48 with the United States Department of Energy ("DOE") for the
operation of the Lawrence Livermore National Laboratory ("LLNL").

PURPOSE
The purpose of this Amendment One is to reflect a change in the scope of the
original License Agreement to include the licensing of certain trademarks owned
by THE REGENTS, as provided for in Attachment 1 (entitled "Limited Exclusive
Patent, Copyright and Trademark License Agreement") to this Amendment One which
is incorporated in its entirety by this reference.

<PAGE>

AGREEMENT
NOW, THEREFORE, THE REGENTS and LICENSEE mutually agree to replace the original
License Agreement having an effective date of July 20, 1999, with Amendment One
to the License Agreement having an effective date of July 20, 1999.

THE REGENTS and LICENSEE hereby execute this Amendment One, in duplicate
originals, by their respective duly authorized officers.

NOMOS CORPORATION                    THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

                                     LAWRENCE LIVERMORE NATIONAL LABORATORY

By: /s/ John W. Manzetti             By: /s/ Karena McKinley
    -------------------------------     -------------------------------------

             John W. Manzetti
Name:  Executive Vice President and  Name:   Karena McKinley
     -------------------------------      -----------------------------------
          Chief Financial Officer
Title:        Nomos Corporation      Title:      Director, IPAC
      ------------------------------       ----------------------------------

Date Signed:  June 23, 2000          Date Signed:     7/11/2000
            ------------------------             ----------------------------

<PAGE>

                                  ATTACHMENT 1

                                LIMITED EXCLUSIVE
                              PATENT, COPYRIGHT AND
                           TRADEMARK LICENSE AGREEMENT

                                       FOR

                      PEREGRINE(TM) DOSE CALCULATION SYSTEM
                        FOR RADIATION TREATMENT PLANNING

                                     BETWEEN

                   THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

                                       AND

                                NOMOS CORPORATION

                            LLNL Case No. TL-1613-99

                     Lawrence Livermore National Laboratory
                            University of California
                    P.O. Box 808, L-795, Livermore, CA 94551
                  Industrial Partnerships and Commercialization

                                    June 2000

<PAGE>

                                  ATTACHMENT 1

                                TABLE OF CONTENTS

                                                                         Page
                                                                         ----

INTRODUCTION..............................................................i

PURPOSE...................................................................i

AGREEMENT................................................................ii

1.    BACKGROUND..........................................................1

2.    DEFINITIONS.........................................................3

3.    LICENSE GRANT.......................................................8

4.    SUBLICENSING RIGHTS AND OBLIGATIONS.................................9

5.    FEES, ROYALTIES AND PAYMENTS........................................9

6.    PERFORMANCE OBLIGATIONS............................................10

7.    PROGRESS AND ROYALTY REPORTS.......................................12

8.    BOOKS AND RECORDS..................................................16

9.    TERM...............................................................17

10.   TERMINATION AND DISPOSITION OF LICENSED PRODUCTS...................18

11.   PATENT PROSECUTION AND MAINTENANCE.................................19

12.   PATENT, COPYRIGHT, AND TRADEMARK INFRINGEMENT......................20

13.   USE OF NAMES AND TRADEMARKS........................................22

14.   LIMITED WARRANTY...................................................23

15.   INDEMNIFICATION....................................................24

16.   INSURANCE..........................................................24

17.   WAIVER.............................................................26

18.   ASSIGNABILITY......................................................27

19.   LATE PAYMENTS......................................................27

20.   NOTICES............................................................27

21.   DISPUTES AND GOVERNING LAWS........................................28

22.   PATENT MARKING.....................................................29

23.   COPYRIGHT MARKING..................................................29

24.   GOVERNMENT APPROVAL OR REGISTRATION................................30

                                      -i-
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25.   EXPORT CONTROL LAWS................................................30

26.   FORCE MAJEURE......................................................30

27.   UNITED STATES PREFERENCE...........................................31

28.   PROPRIETARY INFORMATION............................................31

29.   MISCELLANEOUS......................................................31

30.   QUALITY CONTROL....................................................32

31.   TRADEMARK USE AND OWNERSHIP........................................33

EXHIBIT A - LICENSED PATENTS AND LICENSED COPYRIGHTS
EXHIBIT B - RIGHTS GRANTED AND PERFORMANCE OBLIGATIONS
EXHIBIT C - FEES AND ROYALTIES
EXHIBIT D - MUTUAL NONDISCLOSURE AGREEMENT
EXHIBIT E - LICENSED TRADEMARKS

                                      -ii-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
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                     LIMITED EXCLUSIVE PATENT, COPYRIGHT AND
                           TRADEMARK LICENSE AGREEMENT
                    FOR PEREGRINE(TM) DOSE CALCULATION SYSTEM
                        FOR RADIATION TREATMENT PLANNING

This Agreement is effective on the Effective Date by and between The Regents of
the University of California ("THE REGENTS"), under its U.S. Department of
Energy Contract No. W-7405-ENG-48 to manage and operate Lawrence Livermore
National Laboratory ("LLNL"), and NOMOS Corporation, a Delaware corporation
having its principal place of business at 2591 Wexford-Bayne Road, Sewickley, PA
15143. THE REGENTS is a corporation organized and existing under the laws of the
State of California, with its principal office at 1111 Franklin Street, 12th
Floor, Oakland, CA 94607-5200. THE REGENTS and NOMOS Corporation are referred to
jointly as "Parties."

1.       BACKGROUND
1.1      Certain inventions characterized as the PEREGRINE(TM) Dose Calculation
         System ("Inventions") and certain copyrightable workS characterized as
         the computer program PEREGRINE(TM) version 1.1 ("Software"), described
         in LLNL patents, patent applicationS and copyrights listed in Exhibit A
         (LICENSED PATENTS AND LICENSED COPYRIGHTS), which may be useful for
         various radiation therapy applications, were made at LLNL and are
         covered by THE REGENTS' Patent Rights and THE REGENTS' Copyright Rights
         as defined in Article 2 (DEFINITIONS).

1.2      LLNL published a Commerce Business Daily announcement in which it
         sought one or more industrial partners to commercialize the
         PEREGRINE(TM) Dose Calculation System as a means of achieving LLNL's
         objective of ubiquitous, rapid distribution of

                                      -1-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

         PEREGRINE(TM) to radiation therapy clinics. NOMOS Corporation responded
         to LLNL's announcement and shares LLNL's objective IN commercializing
         the PEREGRINE(TM) Dose Calculation System.

1.3      NOMOS Corporation entered into a Mutual Nondisclosure Agreement
         provided in Exhibit D (MUTUAL NONDISCLOSURE AGREEMENT), which is
         incorporated herein, that allowed it to evaluate its interest in taking
         a license to the Inventions and Software.

1.4      NOMOS Corporation is interested in acquiring certain rights to the
         Inventions and Software for the development, manufacture, and sale of
         products and services based on the Inventions and Software. In addition
         to selling directly to its customers, NOMOS Corporation is willing to
         sell such products on an OEM basis or to sublicense Inventions and
         Software to other companies, including NOMOS Corporation's competitors,
         to facilitate ubiquitous, rapid distribution of the PEREGRINE(TM) Dose
         Calculation System.

1.5      THE REGENTS is willing to grant such rights so that the Inventions and
         Software may be developed and used to the fullest extent for the
         benefit of the Unites States' economy and the general public.

1.6      NOMOS Corporation recognizes that royalties due under this Agreement
         will be paid on licensed patent applications, issued patents, and
         copyrights.

1.7      The Parties have entered into a Work for Others agreement to facilitate
         transfer of the PEREGRINE(TM) Dose Calculation System to NOMOS
         Corporation for commercial development and to further develop the
         Inventions and Software.

                                      -2-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
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1.8      NOMOS Corporation is a "small entity" as defined in 37 CFRss.1.9.

1.9      NOMOS Corporation is a "small business firm" as defined at section 2 of
         Pub. L. 85-536 (15 U.S.C.ss.632).

1.10     THE REGENTS has established and desires to preserve, protect, enhance
         and promote the international reputation and prestige of PEREGRINE
         technology and its derivatives including products and services
         incorporating or based on PEREGRINE technology, and NOMOS Corporation
         acknowledges and recognizes this reputation and prestige.

1.11     THE REGENTS owns and uses certain trademarks and service marks
         associated with PEREGRINE technology.

1.12     NOMOS Corporation desires a license to use certain of THE REGENTS'
         trademarks and service marks on, or in connection with, products and
         services based on or using PEREGRINE technology and THE REGENTS is
         willing, subject to the terms and conditions recited herein, to grant
         such a license.

THEREFORE, the Parties agree as follows:

2.       DEFINITIONS

2.1      "Effective Date" means July 20, 1999.

2.2      "Field of Use" is the application or use defined in Exhibit B (RIGHTS
         GRANTED AND PERFORMANCE OBLIGATIONS).

2.3      "Government" means the United States Government.

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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
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2.4      "Lease Price" means gross income from a contract by which LICENSEE or
         its sublicensees conveys Licensed Products for a specified term at a
         specified fee.

2.5      "Licensed Methods" are any methods, procedures, processes, or other
         subject matter whose use or practice would constitute an infringement
         of THE REGENTS' Patent Rights but for the license granted to LICENSEE
         under this Agreement.

2.6      "Licensed Patents" are:

         2.6.1    U.S. patents and U.S. patent applications specified in Exhibit
                  A (LICENSED PATENTS AND LICENSED COPYRIGHTS), and U.S. patents
                  AMENDMENT ONE resulting from these applications and
                  continuations of these applications, including divisionals
                  resulting from these applications, but not including
                  continuation-in-part applications resulting from these
                  applications;

         2.6.2    reissues of 2.6.1;

         2.6.3    foreign patent applications filed under Article 11 (PATENT
                  PROSECUTION AND MAINTENANCE) and patents resulting from these
                  applications; and,

         2.6.4    Licensable WFO Subject Inventions.

2.7      "Licensed Products" are products that 1) incorporate or are produced by
         the practice of subject matter claimed in Licensed Patents, and whose
         manufacture, use, sale, import, or offer for sale would constitute an
         infringement of THE REGENTS' Patent Rights, or 2) duplicate, display,
         perform, or are Derivative Works of the subject matter of Licensed
         Copyrights and whose duplication, distribution, display, or performance
         would constitute

                                      -4-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

         an infringement of Licensed Copyrights, but for the license granted to
         LICENSEE under this Agreement.

2.8      "LICENSEE" means NOMOS Corporation.

2.9      Net Sales," as used in this Agreement to compute royalties, means the
         aggregate Sale Price, Lease Price, and Service Price of Licensed
         Products and Licensed Methods by LICENSEE and any sublicensees in
         transactions throughout the world with independent third parties for
         cash, or other consideration as mutually agreed by the Parties, using
         generally accepted accounting principles.

         No deductions will be made from Net Sales for commissions paid to
         individuals whether they are with independent sales agencies or
         regularly employed by LICENSEE and on its payroll, or for cost of
         collections.

2.10     "Sale Price" means the gross invoice selling price after deducting:

         2.10.1   Discounts allowed in amounts customary in the trade;

         2.10.2   Sales, tariff duties or use taxes directly imposed and with
                  reference to particular sales;

         2.10.3   Actually paid and limited to rejections, returns, and prompt
                  payment and volume discounts granted to customers of Licensed
                  Products, whether in cash or Licensed Products in lieu of
                  cash;

         2.10.4   Freight, transport packing, insurance charges associated with
                  transportation; and

                                      -5-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
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         2.10.5   Taxes, tariff, or import/export duties based on sales when
                  included in gross sales, but not value-added taxes or taxes
                  assessed on income derived from such sales.

         The Sale Price of Licensed Products and Licensed Methods that are
         disposed of other than by sale or lease is LICENSEE'S gross invoice
         selling price for products of similar kind and quality, sold in similar
         quantities provided that the Sale Price shall not be less than the
         minimum value established in section C.2 of Exhibit C (FEES AND
         ROYALTIES). If LICENSEE is not currently offering comparable products
         for sale, then the Sale Price is the average gross invoice selling
         price at which products of similar kind and quality, sold in similar
         quantities, are currently offered for sale by other manufacturers. If
         comparable products are not currently sold or offered for sale by
         others, then the Sale Price will be LICENSEE'S cost of manufacture,
         determined by LICENSEE'S customary accounting procedures, plus
         LICENSEE'S standard markup.

2.11     "Sales of Licensed Products" means sale or lease of Licensed Products
         or performance of services using Licensed Products, Licensed Methods or
         Licensed Copyrights.

2.12     "Service Price" means gross income from services performed by LICENSEE
         or its sublicensees using Licensed Products, Licensed Methods, or
         Licensed Copyrights, including gross income for support, maintenance,
         and repair services.

2.13     "THE REGENTS' Patent Rights" are THE REGENTS' rights in Licensed
         Patents under applicable patent laws.

2.14     "THE REGENTS' Copyright Rights" means THE REGENTS' rights in Licensed
         Copyrights under applicable copyright laws.

                                      -6-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

2.15     "Licensed Copyrights" means the copyrighted works listed in Exhibit A
         (LICENSED PATENTS AND LICENSED COPYRIGHTS) and Licensable WFO Computer
         Software.

2.16     "Derivative Work" means a work that is based on one or more
         pre-existing works and that, if reproduced, distributed to the public,
         or displayed publicly or performed publicly without permission of the
         owner of the pre-existing work, would constitute copyright
         infringement.

2.17     "Licensable WFO Subject Inventions" means Contractor's Subject
         Inventions arising from the WFO to which rights have been waived to THE
         REGENTS by DOE for licensing in accordance with THE REGENTS' Contract
         No. W-7405-ENG-48 with DOE.

2.18     "WFO" means Work for Others Agreement No. L-8788 by and between the
         Parties.

2.19     Licensable WFO Computer Software" means Contractor's Computer Software
         arising from the WFO in which the Contractor has been given permission
         to assert copyright in accordance with its prime contract with DOE.

2.20     "Use Sublicense" means any agreement by LICENSEE or a sublicensee which
         grants to end users, only the right to use, on a single computer or
         compute server, object code versions of Licensed Products.

2.21     "THE REGENTS' Trademarks" means any trademark, service mark, logo,
         insignia, seal, design or other symbol/device used by THE REGENTS and
         associated with or referring to PEREGRINE technology, and its
         derivatives, and products and services based on PEREGRINE technology.

                                      -7-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

2.22     "Licensed Trademarks" means THE REGENTS' Trademarks listed in the
         attached Exhibit E (LICENSED TRADEMARKS), incorporated herein by this
         reference.

2.23     "Territory" means the countries listed in Exhibit E.

3.       LICENSE GRANT

3.1      The license rights granted to LICENSEE by THE REGENTS are set forth in
         Exhibit B (RIGHTS GRANTED AND PERFORMANCE OBLIGATIONS).

3.2      The Government retains a paid-up, royalty-free, nontransferable,
         worldwide, irrevocable license to practice Licensed Patents by or on
         behalf of the Government. The Government has certain other rights under
         35 U.S.C.ss.ss.200-212 and applicable regulations.

3.3      The Government retains for itself and others acting on its behalf a
         paid-up, royalty-free, worldwide, irrevocable license in Licensed
         Copyrights to reproduce, prepare Derivative Works, and perform publicly
         and display publicly. Beginning ten (10) years after January 14, 1999,
         subject to possible five-year renewals, the Government is granted for
         itself and others acting on its behalf a paid-up, nonexclusive,
         irrevocable worldwide license in Licensed Copyrights to reproduce,
         prepares, distribute copies to the public, perform publicly and display
         publicly, and to permit others to do so.

3.4      The Government retains for itself the right to indicate on any similar
         goods or services produced by or for the Government that such goods
         were derived from and are a DOE version of the goods or services
         protected by Licensed Trademarks, with the trademark and the owner
         thereof being specifically identified. In addition, the Government
         shall have the right to use Licensed Trademarks in print or
         communications media.

                                      -8-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

3.5      THE REGENTS reserves all rights not otherwise granted in this Agreement
         and the right to use THE REGENTS' Patent Rights, THE REGENTS' Copyright
         Rights, and THE REGENTS' Trademark Rights for educational and research
         purposes.

4.       SUBLICENSING RIGHTS AND OBLIGATIONS

4.1      The sublicensing rights granted to LICENSEE by THE REGENTS are set
         forth in Exhibit B (RIGHTS GRANTED AND PERFORMANCE OBLIGATIONS),
         Paragraph B.2.

4.2      LICENSEE will provide THE REGENTS with an executed copy of each
         sublicense within thirty (30) days of execution of the agreement.

4.3      LICENSEE must include in any sublicense all the rights and obligations
         due THE REGENTS and the Government set forth in this Agreement.

4.4      LICENSEE will promptly forward to THE REGENTS any reports and
         statements it receives from sublicensees under Article 4.3.

4.5      LICENSEE must include in all sublicenses the notice that upon
         termination of this Agreement for any reason, THE REGENTS will
         automatically succeed to all rights of LICENSEE arising from
         sublicenses granted under this Agreement.

5.       FEES, ROYALTIES AND PAYMENTS

5.1      As partial consideration for rights granted to LICENSEE, LICENSEE will
         pay to THE REGENTS a license issue fee and maintenance fees as set
         forth in Exhibit C (FEES AND ROYALTIES).

                                      -9-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

5.2      As further consideration for rights granted to LICENSEE, LICENSEE will
         pay to THE REGENTS a minimum annual royalty and an earned royalty based
         on Net Sales as set forth in Exhibit C (FEES AND ROYALTIES).

5.3      LICENSEE will pay royalties to THE REGENTS according to the schedule
         specified in Article 7 (PROGRESS AND ROYALTY REPORTS).

5.4      LICENSEE will pay all fees and royalties in U.S. dollars collectible at
         par in San Francisco, California. When Licensed Products are sold for
         currencies other than U.S. dollars, earned royalties will first be
         determined in the foreign currency of the country in which the Licensed
         Products were sold and then converted into equivalent U.S. dollars. The
         exchange rate is that rate quoted in the Wall Street journal on the
         last business day of the reporting period and is quoted as local
         currency per U.S. dollar. LICENSEE will be responsible for all bank
         transfer charges.

5.5      Notwithstanding the provisions of Article 26 (FORCE MAJEURE), if at any
         time legal restrictions would prevent LICENSEE from making payment of
         part or all of any royalties in any country outside the U.S. from
         LICENSEE'S source of funds outside the U.S., LICENSEE will convert the
         amount owed to THE REGENTS into U.S. funds and pay THE REGENTS directly
         from LICENSEE'S U.S. source of funds.

5.6      No royalties are due on Net Sales to the Government. LICENSEE will
         reduce the amount charged for such sales by an amount equal to the
         royalty otherwise due THE REGENTS.

6.       PERFORMANCE OBLIGATIONS

                                      -10-
<PAGE>

6.1      LICENSEE, upon execution of this Agreement, will diligently proceed
         with development, regulatory approvals, manufacture, and sale of
         Licensed Products and use of Licensed Methods, and earnestly and
         diligently endeavor to market the same as specified in Exhibit B
         (RIGHTS GRANTED AND PERFORMANCE OBLIGATIONS).

6.2      During the term of this Agreement, LICENSEE will demonstrate a
         continuing effort to commercialize and sell Licensed Products and use
         Licensed Methods to meet market demand.

6.3      If LICENSEE does not meet the performance obligations specified in
         Exhibit B (RIGHTS GRANTED AND PERFORMANCE OBLIGATIONS), THE REGENTS may
         at its sole option: (a) convert the limited exclusive license for
         Licensed Patents, Licensed Copyrights(and Licensed Trademark to a
         nonexclusive license; (b) negotiate with LICENSEE a new schedule and
         conditions for continuation of a limited exclusive license; or (c)
         terminate this Agreement.

6.4      THE REGENTS will notify LICENSEE if THE REGENTS is approached by a
         third party seeking a license to make, use, or sell Licensed Products
         in LICENSEE'S Field of Use. LICENSEE will negotiate in good faith with
         that third party to grant a sublicense for any Licensed Patents or
         Licensed Copyrights ~r Licensed Trademarks in the market for which
         LICENSEE and existing sublicensees are not meeting commercial demand.
         The determination to grant a sublicense may be based on LICENSEE'S
         business interests. LICENSEE will provide THE REGENTS with
         justification for denying any such sublicense.

                                      -11-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

6.5      During the term of this Agreement, LICENSEE will conduct normal,
         continuous business operations. If LICENSEE seeks protection under any
         United States bankruptcy proceedings during the term of this Agreement,
         LICENSEE will notify THE REGENTS in writing no later than seventy-two
         (72) hours after the bankruptcy filing. THE REGENTS has the option to
         terminate this Agreement upon a bankruptcy filing by the LICENSEE.

7.       PROGRESS AND ROYALTY REPORTS

7.1      SEMI-ANNUAL PROGRESS REPORT: LICENSEE will submit to THE REGENTS
         semi-annual progress reports according to the following schedule:

                           DUE DATE                  FOR PREVIOUS PERIOD
                           February 28               July 1 - December 31
                           August 31                 January 1 - June 30

         The progress report must cover LICENSEE'S activities in meeting the
         performance obligations set forth in Article 6 (PERFORMANCE
         OBLIGATIONS) and Exhibit B (RIGHTS GRANTED AND PERFORMANCE
         OBLIGATIONS), and must include at a minimum the following information:

         Name of LICENSEE

         License Number

         Date of Report

         Reporting period

         Summary of work completed

         Summary of work in progress

         Current schedule of anticipated events or milestones

                                      -12-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
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         Description of Licensed Products or Licensed Methods under development

         Licensed Patents, Licensed Copyrights, and Licensed Trademarks
         practiced or incorporated into each Licensed Product and Licensed
         Method under development

         Anticipated market introduction date of Licensed Products/ Methods

         Commercial name of Licensed Products/ Methods

         A summary of resources (dollar value) spent in the reporting period on
         commercialization efforts

         Name and summary of activities of sublicensees, if any

         Changes in corporate ownership (see Article 18, ASSIGNABILITY)

         Change in small entity status (see Article 1, BACKGROUND)

         Addition of and/or participation in an affiliate

         Existence of and/or participation in a joint venture

7.2      FIRST COMMERCIAL SALE: Within thirty (30) days following the first
         commercial sale of each type of Licensed Product in the U.S. and each
         country outside the U.S. by LICENSEE, LICENSEE will report to THE
         REGENTS, at a minimum, the following information:

         License Number

         Name of LICENSEE

         Date of Report

         Date of First Commercial Sale or Lease

         Place of First Commercial Sale or Lease

         Description of Licensed Products /Methods sold or leased

         Licensed Patents, Licensed Copyrights, and Licensed Trademarks
         practiced or incorporated

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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
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7.3      QUARTERLY WRITTEN ROYALTY REPORTS: After the First Commercial Sale of
         Licensed Products or Licensed Methods anywhere in the world by
         LICENSEE, LICENSEE will submit quarterly written royalty reports to THE
         REGENTS as follows:

                           Due date     For previous period
                           February 28  October 1 - December 31
                           May 31       January 1 - March 31
                           August 31    April 1 - June 30
                           November 30  July 1 - September 30

         If LICENSEE has not sold or used any Licensed Products or Licensed
         Methods during the reporting period, LICENSEE will so state in the
         royalty report.

         The quarterly royalty report must include at a minimum the following
         information:

         License Number

         Name of LICENSEE

         Date of Report

         Reporting period

         Report of sales:

         For each type of Licensed Products /Methods:

         Name/ description of each type of product or process

                  A.       Domestic sales:

                           1.       Description of Licensed Products/ Methods

                           2.       Unit price (sale, lease, and/or use)

                           3.       Units sold in U.S.

                           4.       Units leased in U.S.

                           5.       Gross sales in U.S.

                           6.       Net Sales in U.S.

                           7.       Accrued royalties

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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
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                           8.       If Government approval requirements apply to
                                    sale/use of the Licensed Product/Method (see
                                    Article 24, GOVERNMENT APPROVAL OR
                                    REGISTRATION), provide details.

                  B.       Foreign sales:

                           1.       Country of sales

                           2.       Description of Licensed Products/ Methods

                           3.       Unit price (sale, lease, and/or use)

                           4.       Units sold in each country

                           5.       Units leased in each country

                           6.       Gross sales in each country

                           7.       Net Sales in each country

                           8.       Monetary exchange rate

                           9.       Accrued royalties in $U.S.

                           10.      If foreign government approval/ registration
                                    requirements apply to sale/use of the
                                    Licensed Product/Method (see Article 24,
                                    GOVERNMENT APPROVAL OR REGISTRATION),
                                    provide details.

                  C.       Government Sales:

                           1.       Description of Licensed Products /Methods

                           2.       Unit price (sale, lease, and/or use)

                           3.       Units sold

                           4.       Units leased

                           5.       Gross sales

                           6.       Net Sales to the Government

         Provide information A-C for each type of product or process sold

                  D.       Royalties Due THE REGENTS

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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
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         Minimum Royalty paid    Total accrued royalties to date   Royalties Due
         for this calendar year  for this calendar year

7.4      LICENSEE will provide THE REGENTS with an annual audited statement of
         royalty accounts within sixty (60) days after the end of each calendar
         year. THE REGENTS will protect such statements as Proprietary
         Information and not disseminate them unless required by law.

7.5      LICENSEE will report in writing to THE REGENTS, within ten (10) days of
         their occurrence, dates of the following events pertaining to
         performance obligations specified in Exhibit B (RIGHTS GRANTED AND
         PERFORMANCE OBLIGATIONS):

         7.5.1    LICENSEE'S filings of relevant regulatory applications
                  pertaining to Licensed Products in accordance with B.5.1.

         7.5.2    Each grant of clearance by the FDA for Licensed Products.

         7.5.3    LICENSEE'S compliance with performance obligations specified
                  in B.5.2, B.5.4, B.5.5, B.5.6, and B.5.7.

8.       BOOKS AND RECORDS

8.1      LICENSEE will keep books and records accurately showing the
         manufacture, use, sale, and lease of Licensed Products, Licensed
         Methods and Licensed Copyrights, and Sales of Licensed Products under
         this Agreement. LICENSEE will preserve such books and records for at
         least five (5) years after the date of the royalty payment to which
         they

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         apply. Such books and records will be open for inspection by
         representatives or agents of THE REGENTS at all reasonable times, with
         reasonable notice given.

8.2      THE REGENTS will pay the costs incurred by its representatives or
         agents to examine LICENSEE'S books and records. If there is an error
         adverse to THE REGENTS in LICENSEE'S royalty accounting, then LICENSEE
         will pay THE REGENTS within ten (10) days the amount necessary to
         correct such error. If there is an error adverse to THE REGENTS in
         LICENSEE'S royalty accounting of more than ten percent (10%) of the
         total royalties due for any year, then LICENSEE will pay the costs
         incurred by THE REGENTS' representatives and agents for such
         examination.

8.3      LICENSEE will provide THE REGENTS with an annual audited financial
         statement of LICENSEE, including at a minimum a balance sheet and
         operating statement or LICENSEE'S annual report. Such statement will be
         due to THE REGENTS within one hundred twenty (120) days following the
         close of LICENSEE'S fiscal year to which such statement relates.

9.       TERM

9.1      The term of this Agreement is the longer of either the term of the
         license to Licensed Patents or the term of the license to Licensed
         Copyrights.

9.2      The term of the license to Licensed Patents will commence on the
         Effective Date and, unless terminated by operation of law or by acts of
         the Parties under this Agreement, will remain in effect until the
         expiration or abandonment of all Licensed Patents.

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9.3      The term of the license to Licensed Copyrights will commence on the
         Effective Date and, unless terminated by operation of law or by acts of
         the Parties under this Agreement, will remain in effect for ten (10)
         years from January 14, 1999, the date on which THE REGENTS received
         permission to assert copyright. The term of the license to Licensed
         Copyrights may be renewed for additional five-year periods for the life
         of the copyright upon mutual written agreement of the Parties.

10.      TERMINATION AND DISPOSITION OF LICENSED PRODUCTS

10.1     If LICENSEE fails to perform any material term or covenant of this
         Agreement, THE REGENTS may give written notice to LICENSEE that if
         LICENSEE has not cured such failure within sixty (60) days after the
         effective date of receipt of the notice, this Agreement will terminate
         at the end of such sixty- (60) day period or at the end of such longer
         period as may be set forth in THE REGENTS' notice.

10.2     LICENSEE may terminate this Agreement by giving at least thirty (30)
         days prior written notice to THE REGENTS.

10.3     Termination of this Agreement will not relieve LICENSEE of any
         obligation or liability accrued hereunder prior to such termination,
         nor rescind any payments due or paid to THE REGENTS prior to the time
         such termination becomes effective. Such termination will not affect,
         in any manner, any rights of THE REGENTS arising under this Agreement
         prior to such termination. Any and all obligations of the Parties under
         this Agreement will remain in effect until properly fulfilled or
         otherwise discharged, notwithstanding the completion or early
         termination of this Agreement.

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10.4     Within thirty (30) days after termination of this Agreement by either
         Party, LICENSEE will provide THE REGENTS with a written inventory of
         all Licensed Products in process of manufacture or in stock on the date
         of termination. LICENSEE may complete Licensed Products in the process
         of manufacture at the time of termination, and may dispose of Licensed
         Products for sixty (60) days after the date of termination provided
         that LICENSEE pays royalties to THE REGENTS on such dispositions. At
         the conclusion of the sixty (60) day period, LICENSEE will destroy any
         remaining Licensed Products in stock or in process of manufacture and
         certify such destruction to THE REGENTS.

10.5     LICENSEE may not practice Licensed Patents or use Licensed Copyrights
         or Licensed Trademarks after the date of termination of this Agreement
         except as necessary to complete the manufacture of Licensed Products as
         permitted under Article 10.4.

10.6     LICENSEE agrees that all legal rights and goodwill associated with THE
         REGENTS' Trademarks shall remain the property of THE REGENTS and
         LICENSEE shall make no claim thereto.

10.7     This Agreement will terminate, effective thirty (30) days after the
         effective date of notice by THE REGENTS, if LICENSEE ceases to carry on
         its business.

11.      PATENT PROSECUTION AND MAINTENANCE

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11.1     THE REGENTS will prosecute U.S. patent applications and maintain U.S.
         patents licensed under this Agreement at THE REGENTS' expense, unless
         otherwise agreed by the Parties.

11.2     LICENSEE may request foreign rights in Licensed Patents, if such rights
         are available. Unless requested herein, LICENSEE must request in
         writing such rights, and specify the countries in which it wants
         rights, within seven (7) months after the filing date of the U.S.
         applications. Failure to request such rights will be considered an
         election not to seek foreign rights. THE REGENTS may file patent
         applications at its own expense in any country in which LICENSEE has
         not elected to secure foreign rights, and LICENSEE has no rights to any
         such foreign applications and resultant patents.

11.3     LICENSEE will pay all costs, including those incurred by THE REGENTS
         prior to the Effective Date, associated with preparation, filing,
         prosecution, and maintenance of Licensed Patents in foreign countries
         in which LICENSEE obtains rights under this Agreement. All Licensed
         Patents will be held in the name of THE REGENTS and obtained using
         counsel selected by THE REGENTS.

11.4     LICENSEE may terminate its license to foreign patent applications or
         patents, and its obligation to pay any further costs for those foreign
         rights, upon ninety (90) days written notice to THE REGENTS. THE
         REGENTS or the Government may, at its sole discretion and expense,
         continue prosecution and/or maintenance of any patents or applications
         for which LICENSEE has relinquished rights.

12.      PATENT, COPYRIGHT, AND TRADEMARK INFRINGEMENT

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12.1     If LICENSEE learns of the possible infringement by a third party of any
         Licensed Patents, Licensed Copyrights, or Licensed Trademarks, LICENSEE
         will inform THE REGENTS in writing within thirty (30) days and provide
         all known evidence of the infringement. LICENSEE will not contact such
         third party concerning the infringement without prior written approval
         of THE REGENTS. The Parties will use their best efforts to terminate
         such infringement without litigation.

12.2     LICENSEE may request in writing that THE REGENTS take legal action
         against an infringer of any Licensed Patents, Licensed Copyrights, or
         Licensed Trademarks, which request must include reasonable evidence of
         the infringement and of potential damages to LICENSEE. Within one
         hundred (100) days after the date of receipt by THE REGENTS of
         LICENSEE'S request, if the infringement continues, THE REGENTS will
         notify LICENSEE in writing that THE REGENTS will either:

12.2.    Commence suit on its own account; or

         12.2.2   Refuse to participate in such suit. LICENSEE may thereafter
                  bring suit for infringement at its own expense if, and only
                  if, THE REGENTS elects not to commence suit and if the
                  infringement occurred during the period and in a jurisdiction
                  where LICENSEE has exclusive rights under this Agreement.
                  However, in the event LICENSEE elects to bring suit in
                  accordance with this Article, THE REGENTS may thereafter join
                  such suit at its own expense. If THE REGENTS elects to not
                  participate in such suit, LICENSEE may join THE REGENTS in any
                  suit in which THE REGENTS is a necessary party for the suit

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                  to proceed, and if so joined the LICENSEE will pay all
                  reasonable costs of THE REGENTS associated with joining the
                  suit as a necessary party to the litigation.

12.3     Any legal or equitable action brought under this Article 12 will be at
         the expense of the Party bringing such legal or equitable action and
         all recoveries will belong to such Party. Legal or equitable action
         brought jointly by THE REGENTS and LICENSEE and participated in by both
         will be at the joint expense of the Parties in such proportions as are
         agreed to in writing, and all recoveries will be shared by them in
         proportion to the expense paid by each Party, or otherwise as they may
         agree in writing.

12.4     The Parties will cooperate with each other in legal and equitable
         proceedings instituted against an infringing third party, but such
         cooperation by a Party will be at the expense of the Party bringing
         such legal or equitable action; if both Parties bring the action, the
         principles of Article 12.3 will apply. Such legal or equitable action
         will be controlled by the Party bringing the legal or equitable action,
         except that THE REGENTS may be represented by counsel of its choice in
         any action brought by LICENSEE.

13.      USE OF NAMES AND TRADEMARKS
         Except for the use of Licensed Trademarks as authorized herein, neither
         Party has any right to use any name, trade name, trademark, or other
         designation of the other Party (including any contraction,
         abbreviation, or simulation) in advertising, publicity, or other
         promotional activities. Unless required by law, the use of the name
         "Lawrence Livermore National Laboratory," or "The Regents of the
         University of California," or the name of any University of California
         campus by LICENSEE is expressly prohibited under California Education
         Code ss.92000. Upon request of THE REGENTS,

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         LICENSEE will issue express disclaimers of any support, endorsement, or
         sponsorship by THE REGENTS of LICENSEE or LICENSEE'S activities.

14.      LIMITED WARRANTY

14.1     THE REGENTS has the right to grant the license granted in this
         Agreement.

14.2     THIS LICENSE AND THE ASSOCIATED INVENTIONS AND SOFTWARE ARE PROVIDED
         WITHOUT WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
         OR ANY OTHER WARRANTY, EXPRESS OR IMPLIED. THE REGENTS AND DOE MAKE NO
         REPRESENTATION OR WARRANTY THAT LICENSED PRODUCTS OR LICENSED METHODS
         WILL NOT INFRINGE ANY PATENT, COPYRIGHT, TRADEMARK OR OTHER PROPRIETARY
         RIGHT.

14.3     IN NO EVENT WILL THE REGENTS OR DOE BE LIABLE FOR ANY INCIDENTAL,
         SPECIAL, OR CONSEQUENTIAL DAMAGES RESULTING FROM EXERCISE OF THIS
         LICENSE OR THE USE OF THE SOFTWARE, INVENTIONS, LICENSED METHODS, OR
         LICENSED PRODUCTS, OR LICENSED TRADEMARKS.

14.4     Nothing in this Agreement will be interpreted as:

         14.4.1   A warranty or representation by THE REGENTS as to the validity
                  or scope of Licensed Patents, Licensed Copyrights, or Licensed
                  Trademarks; or

         14.4.2   A warranty or representation that anything made, used,
                  duplicated, displayed, performed, sold, or otherwise disposed
                  of under the license granted in this

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                  Agreement is or will be free from infringement of
                  intellectual property rights of third parties; or

         14.4.3   Any obligation to bring suit against a third party for
                  patent, copyright, or trademark infringement; or

         14.4.4   Conferring by implication, estoppel, or otherwise any license
                  or rights under 1) any patents of THE REGENTS other than
                  Licensed Patents, regardless of whether such patents are
                  dominant or subordinate to Licensed Patents or 2) any
                  copyrights of THE REGENTS other than Licensed Copyrights as
                  defined in this Agreement or 3) any trademarks or service
                  marks of THE REGENTS other than Licensed Trademarks as defined
                  in this Agreement; or

         14.4.5   An obligation to furnish to LICENSEE or any third party any
                  know-how, improvements, or Derivative Works not specifically
                  provided in this Agreement.

15.      INDEMNIFICATION

         LICENSEE will, and will require its sublicensees to, indemnify, hold
         harmless, and defend THE REGENTS, DOE, their officers, employees, and
         agents; the sponsors of the research that led to the Inventions,
         Software, and Trademarks; and the inventors and authors against any
         claims, suits, losses, liabilities, damages, costs, fees, and expenses
         resulting from or arising out of exercise of this license or any
         sublicense. LICENSEE will pay any and all costs, including reasonable
         attorney fees, incurred by THE REGENTS in enforcing this
         indemnification.

16.      INSURANCE

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16.1     LICENSEE will insure its activities relating to this Agreement at its
         own cost with an insurance company acceptable to THE REGENTS. LICENSEE
         will obtain, keep in force, and maintain insurance as follows with an
         insurance company acceptable to THE REGENTS or an equivalent program of
         self-insurance: Comprehensive or Commercial Form General Liability
         Insurance, including contractual liability and product liability, with
         coverage as follows:

         16.1.1   Each occurrence coverage of not less than One Million Dollars
                  ($1,000,000.00); and

         16.1.2   Product Liability Insurance: completed operations aggregate
                  coverage of not less than Ten Million Dollars
                  ($10,000,000.00); and

         16.1.3   Personal and Advertising Injury: coverage of not less than One
                  Million Dollars ($1,000,000.00); and

         16.1.4   General Aggregate (Commercial Form Only): coverage of not less
                  than Five Million Dollars ($5,000,000.00).

         These coverages do not limit the liability of LICENSEE to THE REGENTS
         in any way. LICENSEE will provide THE REGENTS, upon request, with
         certificates of insurance or self-insurance, including renewals that
         show compliance with these requirements. LICENSEE'S failure to maintain
         such required insurance will be considered a material breach of this
         Agreement.

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16.2     If the required insurance is written on a claims-made form, coverage
         must provide a retroactive date of placement before or coinciding with
         the Effective Date of this Agreement.

16.3     LICENSEE will maintain the general liability insurance specified in
         this Article 16 during the period that the Licensed Patents, Licensed
         Copyrights, or Licensed Trademarks are being used and/or Licensed
         Products are being sold or otherwise commercially distributed by
         LICENSEE, and for a period of not less than five (5) years thereafter.

16.4     LICENSEE'S insurance coverage must:

         16.4.1   Provide for at least thirty (30) days advance written notice
                  to THE REGENTS of cancellation or any modification; 16.4.2
                  Indicate that DOE, THE REGENTS, and their respective officers,
                  employees, students, and agents, are endorsed on the policy as
                  additional named insureds; and

         16.4.3   Include a provision that the coverage is primary and does not
                  participate with, or is in excess of, any valid and
                  collectible insurance, program, or self-insurance carried or
                  maintained by THE REGENTS.

17.      WAIVER

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17.1     No provision of this Agreement is deemed waived and no breach excused
         unless such waiver or consent is made in writing and signed by the
         Party to have waived or consented.

17.2     Failure on the part of either Party to exercise or enforce any right of
         such Party under this Agreement will not be a waiver by such Party of
         any right, or operate to bar the enforcement or exercise of the right
         at any time thereafter.

18.      ASSIGNABILITY
         This Agreement is binding on and inures to the benefit of THE REGENTS,
         its successors and assigns, but is personal to LICENSEE. Any assignment
         or bankruptcy assumption of this Agreement requires prior written
         consent of THE REGENTS which consent shall not be unreasonably
         withheld.

19.      LATE PAYMENTS
         If THE REGENTS does not receive payments or fees due from LICENSEE
         hereunder when due, LICENSEE must pay such payments or fees within
         sixty (60) days plus interest charges at the rate of ten percent (10%)
         simple interest per annum from the date on which the payment was
         originally due, or THE REGENTS may terminate this Agreement in
         accordance with its terms.

20.      NOTICES
         Any report, payment, notice, or other communication that either Party
         receives under this Agreement must be in writing and will be properly
         given and effective on the date of delivery if delivered in person
         (including delivery by courier service), or the fifth (5th)

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         day after mailing if mailed by first-class certified mail, postage
         paid, to the addresses given below (or to an address designated by
         written notice to the other Party), or the date of facsimile with
         confirmed receipt.

        In the case of LICENSEE:              NOMOS Corporation
                                              2591 Wexford-Bayne Road
                                              Sewickley, PA  15143
                                              Attention:  President
                                              Phone:  724-934-8200
                                              Fax:  724-934-5488

        In the case of THE REGENTS:

        All correspondence, original progress Lawrence Livermore National
        reports, and royalty reports:         Laboratory Industrial Partnerships
                                              and Commercialization P.O. Box
                                              808, L-795, 7000 East Avenue,
                                              L-795Livermore, CA  94550
                                              Attention:  Director, IPAC
                                              Fax:  925-423-8988

        Payments and copies of corresponding  Lawrence Livermore National
        royalty reports:                      Laboratory P.O. Box 5517
                                              Livermore, CA  945551

21.      DISPUTES AND GOVERNING LAWS

         The Parties will attempt to jointly and promptly resolve any disputes
         arising from this Agreement. If the Parties are unable to resolve a
         dispute within a reasonable time from one Party's written notice to the
         other that dispute resolution has begun, then either Party may commence
         proceedings in a court of competent jurisdiction. This Agreement will
         be governed by the laws of the State of California, U.S.A., without
         regard to such State's conflict of laws provisions.

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22.      PATENT MARKING
         LICENSEE will mark all Licensed Products and their containers that are
         made, used, sold, or otherwise disposed of under this Agreement in
         accordance with applicable patent marking laws.

23.      COPYRIGHT MARKING
         For all Licensed Products that incorporate Licensed Copyrights,
         LICENSEE will affix to all copies of such Licensed Products and their
         containers that are made, used, or sold or otherwise distributed under
         this Agreement:

         a)       the proper copyright notice in accordance with applicable
                  copyright marking laws; and

         b)       the following notice:

         "NOTICE: The Government is granted for itself and others acting on its
         behalf a paid-up, nonexclusive, irrevocable, worldwide license in this
         data to reproduce, prepare Derivative Works, and perform publicly and
         display publicly. Beginning ten (10) years after January 14, 1999, and
         subject to any subsequent five (5) year renewals, the Government is
         granted for itself and others acting on its behalf a paid-up,
         nonexclusive, irrevocable, worldwide license in this data to reproduce,
         prepare Derivative Works, distribute copies to the public, perform
         publicly and display publicly, and to permit others to do so. NEITHER
         THE UNITED STATES NOR THE UNITED STATES DEPARTMENT OF ENERGY, NOR THE
         REGENTS OF THE UNIVERSITY OF CALIFORNIA, NOR ANY OF THEIR EMPLOYEES,
         MAKES ANY WARRANTY,

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         EXPRESS OR IMPLIED, OR ASSUMES ANY LEGAL LIABILITY OR RESPONSIBILITY
         FOR THE ACCURACY, COMPLETENESS, OR USEFULNESS OF ANY INFORMATION,
         APPARATUS, PRODUCT, OR PROCESS DISCLOSED, OR REPRESENTS THAT ITS USE
         WOULD NOT INFRINGE PRIVATELY OWNED RIGHTS."

24.      GOVERNMENT APPROVAL OR REGISTRATION
         If this Agreement or any associated transaction is required by the law
         of any jurisdiction to be approved, permitted, or registered with any
         governmental agency, LICENSEE assumes all obligations to do so.
         LICENSEE will notify THE REGENTS if LICENSEE becomes aware that this
         Agreement is subject to a United States or foreign government
         reporting, permitting, or approval requirement. LICENSEE will make all
         necessary filings and pay all costs including fees, penalties, and all
         other out-of-pocket costs associated with such reporting, permitting,
         or approval process.

25.      EXPORT CONTROL LAWS
         LICENSEE will comply with all applicable United States and foreign laws
         and regulations concerning the transfer of Licensed Products and
         related technical data, including but not limited to International
         Traffic in Arms Regulations (ITAR) and Export Administration
         Regulations (EAR).

26.      FORCE MAJEURE
         The Parties will be excused from any performance required hereunder if
         such performance is rendered impossible or unfeasible due to any Acts
         of God, catastrophes, or other major events beyond their reasonable
         control, including, without limitation, war,

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         riot, and insurrection; laws, proclamations, edicts, ordinances, or
         regulations; strikes, lock-outs, or other serious labor disputes; and
         floods, fires, explosions, or other natural disasters. However, either
         Party will have the right to terminate this Agreement pursuant to this
         Article upon sixty (60) days prior written notice if either Party is
         unable to fulfill its obligations under this Agreement due to any of
         the causes mentioned above and such inability continues for a period of
         one (1) year.

27.      UNITED STATES PREFERENCE
         LICENSEE agrees that any Licensed Products and Licensed Methods for
         applications, use, or sale shall be manufactured substantially in the
         United States.

28.      PROPRIETARY INFORMATION
         The term of the Mutual Nondisclosure Agreement (MNDA) between the
         Parties, attached as Exhibit D (MUTUAL NONDISCLOSURE AGREEMENT), is
         hereby extended for the term of this Agreement. The confidentiality
         obligation of the MNDA will also apply to any other Proprietary
         Information provided in connection with this Agreement that is clearly
         marked in accordance with the MNDA, such as patent prosecution,
         engineering drawings, process and technical information, and other
         related information not contemplated when the MNDA was executed.

29.      MISCELLANEOUS

29.1     The headings of the Articles of this Agreement are for reference only
         and do not affect the interpretation of this Agreement.

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29.2     Any amendment or modification of this Agreement must be in writing and
         signed by each Party.

29.3     This Agreement, with the attached Exhibits A, B, C, D, and E embodies
         the entire understanding of the Parties with respect to the subject
         matter of this Agreement, and supersedes all other communications,
         representations, or understandings, either oral or written, between the
         Parties with respect to such subject matter.

29.4     If any provision of this Agreement is held to be invalid, illegal, or
         unenforceable in any respect, such provision will be enforced to the
         extent legally permissible and such invalidity, illegality, or
         unenforceability will not affect any other provisions of the Agreement,
         and this Agreement will be construed as if the invalid, illegal, or
         unenforceable provision, or relevant portion, were never in this
         Agreement.

29.5     Except as specifically provided in Exhibit B, Paragraph B.5.1, neither
         Party is an agent of the other and neither will have any power to
         contract for or bind the other Party for any purpose.

30.      QUALITY CONTROL
30.1     LICENSEE acknowledges that maintenance of high quality of the Licensed
         Products, and LICENSEE'S certification of such quality to THE REGENTS
         as provided for in this Article 30, are material conditions for
         LICENSEE'S use of Licensed Trademarks on Licensed Products or for
         Licensed Methods.

30.2     LICENSEE will request in writing THE REGENTS' approval to use Licensed
         Trademarks on each of its Licensed Products and for each of its
         Licensed Methods.

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         LICENSEE will include in such requests, a written certification to THE
         REGENTS that Licensed Products manufactured by LICENSEE and its
         sublicensees meet the performance and quality specifications of
         sections 3.1 (Dose Calculation), 4.0 (Performance), and 6.0 (Quality)
         of System Requirements Specifications (SRS) Document PG-0060v1.1, which
         specifications may be adjusted by THE REGENTS from time to time.
         LICENSEE'S initial certification will occur prior to first Sales of
         Licensed Products and thereafter prior to first Sales of Licensed
         Products, which Licensed Products embody changes of sufficient
         magnitude to require, in accordance with LICENSEE'S normal practices,
         an Engineering Change Order for product release.

30.3     All matters concerning quality control requiring the approval of THE
         REGENTS or the exercise of its discretion shall be the sole subjective
         discretion of THE REGENTS. A submission for approval shall be deemed
         disapproved unless THE REGENTS provides LICENSEE a written notice of
         approval within ten (10) days after receipt by THE REGENTS.

30.4     If at any time THE REGENTS denies or withdraws its approval of the use
         of Licensed Trademarks on a Licensed Product or for a Licensed Method,
         LICENSEE shall immediately cease all use of the Licensed Trademarks on
         such Licensed Products and shall remove such from public sale or
         distribution. In such event, THE REGENTS shall not be liable to
         LICENSEE for any costs or expenses incurred by LICENSEE in the design,
         manufacture, distribution, advertising, promotion, or sale of Licensed
         Products for which THE REGENTS has withdrawn its approval.

31.      TRADEMARK USE AND OWNERSHIP

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31.1     LICENSEE agrees to use the Licensed Trademarks only in the form and
         manner and with appropriate legends, as prescribed from time to time by
         THE REGENTS, and not to use any other trademark combination with any
         said Licensed Trademarks without the prior written approval of THE
         REGENTS. LICENSEE agrees it will not alter, modify or otherwise misuse
         the Licensed Trademarks.

31.2     LICENSEE agrees that, upon request by THE REGENTS, it shall cause to
         appear on or within each Licensed Product, by means of tag, label,
         imprint, or other appropriate device, such trademark or [service mark]
         notices as THE REGENTS may from time to time, upon reasonable notice,
         designate. Failure to include such notices or use of improper notices,
         shall constitute grounds for termination by THE REGENTS of the grant of
         rights to Licensed Trademarks to LICENSEE and shall preclude LICENSEE
         from disposal of Licensed Products after such termination, as provided
         in Article 10 (TERMINATION AND DISPOSITION OF LICENSED PRODUCTS).

31.3     LICENSEE acknowledges the ownership of THE REGENTS' Trademarks
         including Licensed Trademarks in THE REGENTS, and LICENSEE agrees that
         it will do nothing inconsistent with such ownership, and that use of
         the Licensed Trademarks by LICENSEE shall inure to the benefit of THE
         REGENTS. LICENSEE agrees that it shall not apply for registration or
         seek to obtain ownership of any of THE REGENTS' Trademarks in any
         nation.

31.4     LICENSEE agrees that it will use the Licensed Trademarks only in the
         manner authorized by this Agreement and will comply with all applicable
         local, State of California, Federal, and International laws.

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31.5     LICENSEE shall cooperate with THE REGENTS in the registration of
         Licensed Trademarks. LICENSEE shall supply samples of such Licensed
         Products or invoices or other documents relating to the sale of
         Licensed Products to THE REGENTS for use in filing and prosecution of
         such applications and/or registrations. LICENSEE shall cooperate with
         THE REGENTS in making and terminating registered user entries. These
         obligations shall survive termination of this Agreement.

31.6     LICENSEE acknowledges THE REGENTS' exclusive rights in THE REGENTS'
         Trademarks and, further, acknowledges that the Licensed Trademarks are
         unique and original to THE REGENTS and that THE REGENTS is the owner
         thereof. LICENSEE shall not, at any time during or after the effective
         term of this Agreement dispute or contest, directly or indirectly, THE
         REGENTS' exclusive right and title to the Licensed Trademarks or the
         validity thereof.

31.7     All rights with respect to any designs, logos or artwork that LICENSEE
         may incorporate or use in conjunction with the Licensed Trademarks
         shall be deemed the sole and exclusive property of THE REGENTS. In this
         regard, if necessary, LICENSEE agrees to assign to THE REGENTS all
         right, title and interest to and in such designs, logos and/or artwork
         including all copyright and trademark rights associated therewith.
         LICENSEE is not permitted to make any copyright claims to any designs
         or graphics that include the Licensed Trademarks.

31.8     LICENSEE recognizes the goodwill associated with the Licensed
         Trademarks and acknowledges that said goodwill belongs to THE REGENTS.

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--------------------------------------------------------------------------------

31.9     THE REGENTS will prosecute U.S. trademark registrations and maintain
         U.S. trademarks licensed under this Agreement at THE REGENTS' expense,
         unless otherwise agreed by the Parties.

31.10    LICENSEE may request foreign rights in Licensed Trademarks, if such
         rights are available. Unless requested herein, LICENSEE must request in
         writing such rights, and specify the countries in which it wants
         rights, within eighteen (18) months of the Effective Date. Failure to
         request such rights will be considered an election not to seek foreign
         trademark rights. THE REGENTS may register trademarks at its own
         expense in any country in which LICENSEE has not elected to secure
         foreign trademark rights, and LICENSEE has no rights to any such
         foreign trademarks.

31.11    LICENSEE will pay all costs incurred by THE REGENTS on or after June 1,
         2000, associated with preparation, registration, prosecution, and
         maintenance of Licensed Trademarks in foreign countries in which
         LICENSEE obtains rights under this Agreement. All Licensed Trademarks
         will be held in the name of THE REGENTS and obtained using counsel
         selected by THE REGENTS.

31.12    LICENSEE may terminate its license to foreign trademarks and its
         obligation to pay any further costs for those trademark rights, upon
         ninety (90) days written notice to THE REGENTS. THE REGENTS or the
         Government may, at its sole discretion and expense, continue
         prosecution and/or maintenance of any trademarks for which LICENSEE has
         relinquished rights.

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                                                                   Amendment One
--------------------------------------------------------------------------------

              EXHIBIT A - LICENSED PATENTS AND LICENSED COPYRIGHTS

A.1      THE LICENSED PATENTS ARE AS FOLLOWS:

UNITED STATES PATENTS GRANTED:

<TABLE>
<CAPTION>
------------------- -------------------- ------------------------------- -------------------------- ------------------
    Invention
Disclosure Number      Patent Number                 Title                       Inventors             Issue Date
------------------- -------------------- ------------------------------- -------------------------- ------------------
<S>                 <C>                  <C>                             <C>                        <C>
IL-9839             5,870,697            Calculation of Radiation        William P. Chandler,       2/9/99
                                         Therapy Dose Using all          Christine L.
                                         Particle Monte Carlo Transport  Hartmann-Siantar, James
                                                                         A. Rathkopf
------------------- -------------------- ------------------------------- -------------------------- ------------------
IL-10165            6,029,079            Evaluated Teletherapy Source    Lawrence J. Cox, Alexis    2/22/00
                                         Library (ETSL)                  E. Schach von Wittenau
------------------- -------------------- ------------------------------- -------------------------- ------------------
</TABLE>

UNITED STATES PATENT APPLICATIONS:

<TABLE>
<CAPTION>
------------------- ---------------- ----------------------- -------------------------- --------------- --------------
    Invention           Patent               Title                   Inventors           Filing Date    Priority Date
Disclosure Number     Application
                        Number
------------------- ---------------- ----------------------- -------------------------- --------------- --------------
<S>                 <C>              <C>                    <C>                        <C>            <C>
IL-10350            09/238297        System and Method for   Paul M. Bergstrom,         1/28/99         11/12/98
                                     Radiation Dose          Thomas Daly, Edward I.
                                     Calculation Within      Moses, Ralph Patteson,
                                     sub-Volumes of a        Dewey Garret, Ronald
                                     Monte Carlo Based       House, Christine
                                     Particle Transport      Hartmann-Siantar,
                                     Grid                    Lawrence J. Cox, Donald
                                                             H. Fujino, Alexis E.
                                                             Schach Von Wittenau
------------------- ---------------- ----------------------- -------------------------- --------------- --------------
IL-10351            09/247653        FALCON:  Automated      Tser-Yuan Yang, Edward     2/9/99          9/10/98
                                     Optimization for        I. Moses, Christine L.
                                     Arbitrary Criteria      Hartmann-Siantar
------------------- ---------------- ----------------------- -------------------------- --------------- --------------
IL-10472            09520287         Correlated Histogram    Alexis E. Schach von       3/7/00          3/8/00
                                     Representation of       Wittenau
                                     Monte Carlo Derived
                                     Medical Accelerator
                                     Photon-Output Phase
                                     Spaces
------------------- ---------------- ----------------------- -------------------------- --------------- --------------
</TABLE>

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--------------------------------------------------------------------------------

FOREIGN PATENTS GRANTED:  None

FOREIGN PATENT APPLICATIONS:

<TABLE>
<CAPTION>
------------------- -------------------- ------------------------------- -------------------------- ------------------
    Invention          International
Disclosure Number      Serial Number                 Title                       Inventors             Filing Date
------------------- -------------------- ------------------------------- -------------------------- ------------------
<S>                 <C>                  <C>                             <C>                        <C>
IL-9839             97915859.9-EP All    Calculation of Radiation        William P. Chandler,       2/28/97
                    EP Countries         Therapy Dose Using All          Christine L.
                                         Particle Monte Carlo Transport  Hartmann-Siantar, James
                                                                         A. Rathkopf
------------------- -------------------- ------------------------------- -------------------------- ------------------
IL-9839             521883/1977-JP       Calculation of Radiation        William P Chandler,        2/28/97
                                         Therapy Dose Using All          Christine L.
                                         Particle Monte Carlo Transport  Hartmann-Siantar, James
                                                                         A. Rathkopf
------------------- -------------------- ------------------------------- -------------------------- ------------------
IL-9839             2248862-CA           Calculation of Radiation        William P. Chandler,       2/28/97
                                         Therapy Dose Using All          Christine L.
                                         Particle Monte Carlo Transport  Hartmann-Siantar, James
                                                                         a. Rathkopf
------------------- -------------------- ------------------------------- -------------------------- ------------------
</TABLE>

FUTURE PATENT RIGHTS

Licensable WFO Subject Inventions will be added by amendment.

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--------------------------------------------------------------------------------

A.2      THE LICENSED COPYRIGHTS ARE AS FOLLOWS:

COPYRIGHT ASSERTION

PEREGRINE(TM), Version 1.1
1a.      Software Acronym:
         PEREGRINE.

1b.      Short Title:
         3D All Particle Monte Carlo code to calculate radiation dose delivered
         to cancer patients.

2.       Authors Names and Affiliations:
         Paul M. Bergstrom, William P. Chandler, Lila Chase, Larry J. Cox, Tom
         P. Daly, Don H. Fujino, Dewey N. Garrett, Brian L. Guidry, Ron K.
         House, Don Y. Jong, Dave A. Knapp, Sarita S. May, Edward I. Moses,
         Clark, L. Powell, James A. Rathkopf, Christine L. Hartmann Siantar,
         Alexis E. Schach von Wittenau, Rosemary S. Walling, Steve I. Warshaw,
         Jody A White, (LLNL).

3.       Software Completion Date: July 1999.

4.       Brief Description:
         PEREGRINE is a 3D All Particle Monte Carlo Code that calculates the
         dose to cancer patients from a variety of clinical radiation sources.
         PEREGRINE utilizes large nuclear, atomic, and electron databases, the
         patient CT scan data, and the Monte Carlo method to accurately
         calculate the dose delivered to a patient for photon teletherapy
         sources. The results of the dose calculation are then written to a file
         for graphical display over the CT scan data.

5.       Method of Solution:
         PEREGRINE uses conventional analog and condensed history Monte Carlo
         radiation transport methods to calculate dose three-dimensional dose
         distributions in the body. It reads input from standard treatment
         planning exchange files.

6.       Computer(s) for which software is written:  UNIX workstation.

7.       Operating System:
         UNIX, Solaris.

8.       Programming Language(s) Used:
         Fortran (physical transport), C (I/O), Perl (scripting language used to
         run PEREGRINE), Tcl/Tk (scripting and control).

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--------------------------------------------------------------------------------

9.       Software Limitations:
         Must run on a UNIX workstation with >128MB RAM/CPU.

10.      Unique Features of the Software:
         PEREGRINE package includes a PEREGRINE Monte Carlo transport software,
         LLNL generated atomic data.

11.      Related and Auxiliary Software:
         None.

12.      Other Programming or Operating Information or Restrictions:
         None.

13.      Hardware Requirements:
         UNIX workstation with >128MB RAM/CPU.

14.      Time Requirements:
         Time requirements vary substantially with the complexity of the problem
         addressed.

TECHNICAL DESCRIPTION OF LICENSED COPYRIGHTS

The files are:

libpg - PEREGRINE Monte Carlo library source files:

alias_sampling.F
alias_sampling_choice.F
check.F
direction_cosines.F
dose_mesh_data.F
electron_data.F
electron_physics.F
elpo_distribution.h
energy_groups.F
energy_groups.h
epsilon.h file_io.F
form_factors.F
material_data.F
mesh_data.F
particle_attributes.h
particle_bank.F
particle_bank.h

                                      -40-
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NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

particle_intercepts.F
pg.F pg_instantiate_device.F
pg_transport.F photon_data.F
photort._physics.F
place_deposit.F
radial_function.F
random_numbers.F
random_numbers.h
source_data.F
source_electron_Physics.F
source_geometry.F
source_particle.F
source_photori.physics.F
source_rejection.F
source_transport.F
timer.F
track_particle.F
transform_coordinates.
F transform_coordinates.h
versim-pglib.h

libtpi - Treatment Planning Interface source files:

beam_geometry.c
ct_scan.c
dose.c
dose-array.c
f77_wrapper.c
inst_log_file.c
log_msg.c
runtime_diagnostics.c
scanner_data.c
structurex
tpi_Support.c
tpi_Support.h
version.h

libtsl - Teletherapy Source Library source files:
beam_device_compare.c
crc_checksurn.c
device_data.c
f77_wrapper.c

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                                                                   Amendment One
--------------------------------------------------------------------------------

fit_data.c
fit_data.h
instantiate_device.c
modify_one_device.c
pdt_data.c
runtime_options.c
transform._one_device.c
tsl_support.c
tsl-support.h

include - source files:

case_data.h
distributed_data.h
histo.h
material_data.h
pdt_data.h pg.h
pg_constants.h
pg_exec.h
pg_types.h
physics_constants.h
runtime_options.h
timer.h
tpi.h
tsl.h
tuning_parameters.h

Single-Threaded test executive and utilities source files

Master Slave executive source files

FUTURE COPYRIGHT RIGHTS:
------------------------

Licensable WFO Computer Software will be added by amendment.

                                      -42-
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--------------------------------------------------------------------------------

EXHIBIT B - RIGHTS GRANTED AND PERFORMANCE OBLIGATIONS

                                     NOTICE
                                     ------

       LICENSEE CONSIDERS INFORMATION IN THIS EXHIBIT B TO BE PROPRIETARY.

B.1      RIGHTS GRANTED

         B.1.1    Rights to Licensed Patents
                  Subject to the limitations set forth in this Agreement, THE
                  REGENTS hereby grants to LICENSEE an exclusive,
                  nontransferable, royalty-bearing license to: a) make, have
                  made, use, sell, offer for sale, and import Licensed Products
                  in the Field of Use, and b) practice Licensed Methods in the
                  Field of Use.

         B.1.2    Rights to Licensed Copyrights
                  Subject to the terms and conditions of this Agreement, THE
                  REGENTS grants to LICENSEE an exclusive, nontransferable,
                  royalty-bearing license to duplicate, display, perform, make
                  Derivative Works, distribute and have distributed, and sell
                  Licensed Products covered by Licensed Copyrights in the Field
                  of Use.

         B.1.3    Rights to Licensed Trademarks
                  Subject to the terms and conditions of this Agreement, THE
                  REGENTS hereby grants LICENSEE an exclusive license to use
                  Licensed Trademarks, in corresponding Territories, as
                  specified in Exhibit E (LICENSED TRADEMARKS), on Licensed
                  Products or for Licensed Methods in the Field of Use.

         B.1.4    "Field of Use" means planning human and animal cancer
                  therapies based on tumor irradiation with photons or electrons
                  that are generated either by a radiation

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--------------------------------------------------------------------------------

                  source external to the patient (teletherapy) or by a radiation
                  source internal to the patient (brachytherapy).

B.2      SUBLICENSING RIGHTS

         THE REGENTS also grants to LICENSEE the right to issue royalty-bearing
         sublicenses to third parties in the Field of Use, having rights no
         greater than those granted to LICENSEE, provided that LICENSEE has
         exclusive rights in such Licensed Patents, Licensed Copyrights, and
         Licensed Trademarks in the Field of Use at the time of sublicensing.
         LICENSEE may issue sublicenses to Licensed Trademarks only in
         conjunction with LICENSEE'S sublicensing of Licensed Patents and
         Licensed Copyrights.
         A Use Sublicense is considered to be a Licensed Product and not a
         sublicense as contemplated in this B.2.

B.3      RIGHTS EXCLUDED

         Rights that are not specifically granted in this Exhibit B or elsewhere
         in this Agreement are specifically excluded from the license. In
         particular, no license, express or implied, is granted to LICENSEE to
         Licensed Trademarks outside the corresponding Territory as specified in
         Exhibit E (LICENSED TRADEMARKS).

B.4.     FUTURE RIGHTS
         Licensable WFO Subject Inventions and Licensable WFO Computer Software
         will be added to Exhibit A by amendment.

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--------------------------------------------------------------------------------

B.5      PERFORMANCE OBLIGATIONS

         B.5.1    LICENSEE will proceed diligently to develop, file relevant
                  regulatory applications for and attempt to obtain relevant
                  regulatory commercialization approvals with respect to the
                  manufacturing, marketing, and sale of Licensed Products for
                  all uses in the Field of Use. LICENSEE will file with the U.S.
                  Food and Drug Administration at least one 510k Application or
                  PMA (Pre-Market Approval) for clearance of Licensed Products
                  for at least teletherapy uses within one (1) year of the
                  Effective Date.

                  Notwithstanding any other term of this Agreement, for the
                  purposes of (a) invoking/ complying with the Hatch-Waxman Act
                  (35 U.S.C. ss.156) and any corresponding rules and regulations
                  of the U.S. Patent & Trademark Office regarding patent term
                  extension, and (b) seeking regulatory approval of LICENSEE'S
                  Licensed Products and Licensed Methods, LICENSEE shall act as
                  THE REGENTS' agent. To the extent deemed necessary by
                  LICENSEE, in good faith, the Parties will cooperate to secure
                  regulatory approval of LICENSEE'S Licensed Products and
                  Licensed Methods.

         B.5.2    LICENSEE will release for distribution and offer Sales of
                  Licensed Products by the later date of either October 1, 2000,
                  or within sixty (60) days after the date of FDA clearance for
                  teletherapy uses of Licensed Products.

         B.5.3    LICENSEE will have gross revenues from Sales of Licensed
                  Products or use of Licensed Methods of at least Three Million
                  Dollars ($3,000,000.00) per calendar year, as measured at the
                  dose of LICENSEE'S business on December 31 of the

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                  relevant calendar year, commencing with the later of calendar
                  year 2001, or the first full calendar year after a Licensed
                  Product has been released for distribution and offered for
                  sale in accordance with paragraph B.5.2.

         B.5.4    LICENSEE will release for distribution and offer first OEM
                  sale of Licensed Products that interface with radiation
                  treatment planning systems that are manufactured and sold, or
                  otherwise distributed to third parties, by entities other than
                  LICENSEE by the later date of either October 1, 2001, or one
                  year after initial release for distribution and offer of Sales
                  of Licensed Products as defined in B.5.2. To the extent that
                  some commercial entities may prefer to sublicense Licensed
                  Patents and Licensed Copyrights rather than to purchase
                  Licensed Products on an OEM basis, LICENSEE'S sublicenses may
                  satisfy this OEM performance obligation.

         B.5.5    LICENSEE will release for distribution and offer first sale of
                  Licensed Products in the Field of Use for brachytherapy by the
                  later date of either October 1, 2002, or within sixty (60)
                  days after the date of FDA clearance for brachytherapy uses of
                  Licensed Products.

         B.5.6    LICENSEE will release for distribution and offer first sale of
                  Licensed Products in the Field of Use for inverse treatment
                  planning by the later date of either October 1, 2002, or
                  within sixty (60) days after the date of FDA clearance for
                  inverse treatment planning uses of Licensed Products.

         B.5.7    LICENSEE will release for distribution and offer first sale of
                  Licensed Products in the Field of Use for electron
                  radiotherapy by the later date of either October 1,

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                  2002, or within sixty (60) days after the date of FDA
                  clearance for electron radiotherapy uses of Licensed Products.

         B.5.8    The sales and other performance requirements specified above
                  may, by mutual written consent of LICENSEE and THE REGENTS, be
                  amended and/or extended at the written request of LICENSEE to
                  THE REGENTS, based upon legitimate business or technical
                  reasons specified in reasonable detail in such written
                  request. THE REGENTS will not unreasonably withhold its
                  consent to requests made in accordance with this paragraph.

         B.5.9 The first progress report will be due on February 28, 2000.

B.6      OPTION RIGHT

         THE REGENTS also grants to LICENSEE an option to negotiate terms under
         which THE REGENTS will add protons, neutrons or both particles to the
         Field of Use as otherwise defined in B.1.3 above (Option). The term of
         the Option will be eighteen (18) months from the Effective Date.
         LICENSEE may exercise this Option by providing THE REGENTS a written
         plan (Plan) for the development and commercialization of Licensed
         Products in the expanded Field of Use (Expanded FOU) which Plan is
         acceptable to THE REGENTS. LICENSEE will provide the Plan as soon as
         practical, but in no case later than fifteen (15) months after the
         Effective Date. Upon exercise of the Option, and acceptance of the Plan
         by THE REGENTS, THE REGENTS will negotiate in good faith terms for the
         Expanded FOU. Terms will include, but not be limited by, specific
         performance obligations of LICENSEE pertaining to regulatory

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--------------------------------------------------------------------------------

         approvals and sales of Licensed Products in the Expanded FOU and
         additional fees, royalties, or other compensation for the rights
         obtained by LICENSEE under the Option.

                                      -48-
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--------------------------------------------------------------------------------

                         EXHIBIT C - FEES AND ROYALTIES

                                     NOTICE
                                     ------

       LICENSEE CONSIDERS INFORMATION IN THIS EXHIBIT C TO BE PROPRIETARY.

C.1      LICENSE ISSUE FEE

         C.1.1    As partial consideration for this Agreement, LICENSEE will pay
                  to THE REGENTS a nonrefundable issue fee of Three Hundred
                  Thousand Dollars ($300,000.00) (License Issue Fee) as follows:

                  C.1.1.1  Fifty Thousand Dollars ($50,000.00) to be paid when
                           LICENSEE executes the Agreement.

                  C.1.1.2  Fifty Thousand Dollars ($50,000.00) to be paid no
                           later than October 1, 1999.

                  C.1.1.3  Fifty Thousand Dollars ($50,000.00) to be paid no
                           later than November 1, 1999.

                  C.1.1.4  Fifty Thousand Dollars ($50,000.00) to be paid no
                           later than December 1, 1999.

                  C.1.1.5  Fifty Thousand Dollars ($50,000.00) to be paid no
                           later than January 1, 2000.

                  C.1.1.6  Fifty Thousand Dollars ($50,000.00) to be paid no
                           later than February 1, 2000.

         C.1.2    THE REGENTS will execute the Agreement after receipt of
                  LICENSEE'S executed copies of the Agreement and payment of the
                  first installment of the License Issue Fee specified in
                  C.1.1.1 above.

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--------------------------------------------------------------------------------

         C.1.3    The License Issue Fee will not be credited against any other
                  royalty or fee due from LICENSEE to THE REGENTS.

         C.1.4    In the event that LICENSEE grants sublicenses, LICENSEE will
                  collect an issue fee equal to or greater than the License
                  Issue Fee. LICENSEE will pay to THE REGENTS fifty percent
                  (50%) of any issue fee from sublicensing.

C.2      EARNED ROYALTIES

         In addition to the License Issue Fee, LICENSEE will pay THE REGENTS an
         earned royalty equal to eight percent (8%) of Net Sales by LICENSEE and
         any sublicensees. The earned royalty on sales of any Licensed Product
         that is sold as part of a larger product system, shall be based on the
         average Net Sales of that Licensed Product sold separately on a non-OEM
         basis over the relevant royalty reporting period. For the purposes of
         calculating earned royalties, the minimum value of any License Product
         shall be Fifty Thousand Dollars ($50,000.00) for the first two (2) full
         years after the date of initial release for distribution and offer of
         Sales of Licensed Products as specified in B.5.2. The minimum value
         shall be Thirty-Five Thousand Dollars ($35,000.00) for the next two (2)
         full years, and Twenty-Five Thousand Dollars ($25,000.00) thereafter.
         In the event that LICENSEE terminates the WFO without cause and without
         funding sufficient to complete the tasks and deliverables specified in
         Phase 1 (Technology Transfer and Clinical Implementation) of Attachment
         A to the WFO, the royalty rate specified above will be ten percent
         (10%).

         Payments of earned royalties will be in accordance with the
         requirements of Article 4.2 (SUBLICENSING RIGHTS AND OBLIGATIONS),
         Article 5 (FEES, ROYALTIES

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         AND PAYMENTS) and Article 7 (PROGRESS AND ROYALTY REPORTS) of this
         Agreement.

C.3      MAINTENANCE FEES

         Beginning in calendar year 2000, LICENSEE will pay THE REGENTS a
         license maintenance fee of Thirty Five Thousand Dollars ($35,000.00)
         per calendar year, which will be due according to the schedule in CA.
         The maintenance fee in any calendar year will be creditable against the
         minimum annual royalty due in the same calendar year.

C.4      MINIMUM ANNUAL ROYALTIES

         LICENSEE will pay to THE REGENTS a minimum annual royalty according to
         the requirements of Article 5 (FEES, ROYALTIES AND PAYMENTS) and the
         schedule below. Earned royalties paid to THE REGENTS for Net Sales
         during a calendar year will be accrued and credited against the minimum
         annual royalty paid for that same calendar year.

<TABLE>
<CAPTION>
         ------------------------------------- ---------------------------------- -----------------------------------
                    Calendar Year              Minimum Annual Royalty             Due Date in Calendar Year
         ------------------------------------- ---------------------------------- -----------------------------------
<S>                      <C>                              <C>                               <C>
                         2000                             $35,000.00                         February 28
         ------------------------------------- ---------------------------------- -----------------------------------
                         2001                            $135,000.00                         February 28
         ------------------------------------- ---------------------------------- -----------------------------------
                         2002                            $200,000.00                         February 28
         ------------------------------------- ---------------------------------- -----------------------------------
                         2003                            $250,000.00                         February 28
         ------------------------------------- ---------------------------------- -----------------------------------
                         2004                            $325,000.00                         February 28
         ------------------------------------- ---------------------------------- -----------------------------------
         2005 and thereafter for the life of             $400,000.00                         February 28
         this Agreement
         ------------------------------------- ---------------------------------- -----------------------------------
</TABLE>

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--------------------------------------------------------------------------------

                   EXHIBIT D - MUTUAL NONDISCLOSURE AGREEMENT

           MUTUAL NONDISCLOSURE AGREEMENT FOR EXCHANGE OF INFORMATION
                   WITH LAWRENCE LIVERMORE NATIONAL LABORATORY

         This Agreement, effective on the date the last party signs, is made by
and between NOMOS CORPORATION located at 2591 Wexford Bayne Road, Sewickley, PA
15143 and THE REGENTS OF THE UNIVERSITY OF CALIFORNIA, located at 1111 Franklin
Street, Oakland, CA 94607 ("THE REGENTS"), under its Contract No. W-7405-ENG-48
with the U.S. DEPARTMENT OF ENERGY ("DOE"), as operators of the LAWRENCE
LIVERMORE NATIONAL LABORATORY, located at 7000 East Avenue, Livermore, CA 94550
("LLNL").

         WHEREAS, THE REGENTS, as operators of LLNL, and NOMOS CORPORATION
(hereinafter individually referred to as the "PARTY" or collectively as the
"PARTIES") wish to exchange certain confidential and propriety information
relating to applications of Monte Carlo technologies for radiation therapy
("PROPRIETARY INFORMATION"), this Agreement will govern the conditions of mutual
disclosure of PROPRIETARY INFORMATION by the PARTIES.

The PARTIES hereby agree:

         (1)      To perform all terms of this Agreement and to maintain the
                  PROPRIETARY INFORMATION in confidence, giving it the same
                  degree of care, but no less than a reasonable degree of care,
                  as the receiving PARTY exercises with its own proprietary
                  information to prevent its unauthorized disclosure;

         (2)      To exchange and use the PROPRIETARY INFORMATION solely for the
                  purpose of evaluation, testing, and development of potential
                  collaborations, joint ventures, and/or license of the
                  technology;

         (3)      That neither PARTY, without the prior written consent of the
                  other, will disclose any portion of the PROPRIETARY
                  INFORMATION to others except to their employees, agents,
                  consultants, subcontractors or Government personnel having a
                  need to know in order to accomplish the sole purpose stated
                  above, and who are bound by a like obligation of
                  confidentiality under this Agreement;

         (4)      That neither PARTY will have any obligation, nor will the DOE,
                  assume any liability with respect to any portion of the
                  PROPRIETARY INFORMATION that:

                  (a)      the receiving PARTIES can demonstrate by written
                           record was previously known to them;

                  (b)      is, or becomes, available to the public through no
                           fault of the PARTIES;

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                  (c)      is lawfully obtained by the PARTIES from a third
                           party and is not subject to an obligation of
                           confidentiality owed to the third party; or

                  (d)      is independently developed by or for the PARTIES
                           Independent of any disclosure hereunder.

         (5)      That PROPRIETARY INFORMATION disclosed by the PARTIES Will be
                  in writing and clearly marked "PROPRIETARY INFORMATION" or its
                  equivalent. If such PROPRIETARY INFORMATION is initially
                  disclosed orally or by demonstration, it will be identified as
                  PROPRIETARY INFORMATION or us equivalent at the time of
                  disclosure. The disclosing PARTY will, within thirty (30) days
                  thereafter (a) reduce such PROPRIETARY INFORMATION to writing
                  or other tangible form, referencing the date and type of
                  PROPRIETARY INFORMATION disclosed, and mark it as PROPRIETARY
                  INFORMATION or its equivalent; and (b) deliver a copy to the
                  receiving PARTY. All protections and restrictions as to use
                  and disclosure will apply during such thirty (30) day period.

         (6)      That all rights and title to the PROPRIETARY INFORMATION
                  disclosed under this Agreement Will remain the property of
                  disclosing PARTY unless otherwise agreed to in writing by the
                  PARTIES.

         (7)      That PROPRIETARY INFORMATION provided by any disclosing PARTY
                  to any receiving PARTY shall be returned to the disclosing
                  PARTY within five (5) days of written request for such return
                  by the disclosing PARTY.

         (8)      That no copies shall be made by a receiving PARTY of any
                  PROPRIETARY INFORMATION without the express written consent of
                  the disclosing PARTY. Any copies so authorized shall be
                  returned to the disclosing PARTY or destroyed in accordance
                  with the term and demand provisions of this Agreement.

         (9)      That the receiving PARTY agrees that with regard to any
                  pattern application provided as PROPRIETARY INFORMATION under
                  this Agreement that no protest, public use proceeding, copied
                  claims for provoking interference, or other action impeding
                  Issuance of any patent based on the disclosed application
                  shall be filed by the receiving PARTY prior to issuance of
                  such patent.

         (10)     The PARTIES agree that any photocopy or facsimile copy of this
                  fully-executed agreement shall have the same legal force and
                  effect as any copy bearing original signatures of the PARTIES.

                                      -53-
<PAGE>

NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

         TECHNICAL CONTACT FOR COMPANY:        TECHNICAL CONTACT FOR LLNL:

         Name:    Robert Otes                  Name:      Ralph Patterson
         Company: NOMOS Corporation            Company:   Lawrence Livermore
         Address: 2591 Wexford Bayne Road                 National Laboratory
                  Sewickley, PA  15143         Address:   7000 East Avenue
         Phone:   (724) 934-8200                          P.O. Box 808, L-051
         Fax:     (724) 934-5488                          Livermore, CA  94550
                                               Phone:     (925) 423-5723
                                               Fax:       (925) 422-9523

It is further agreed that the furnishing of PROPRIETARY INFORMATION does not
constitute any grant or license to the other PARTY for any legal rights now or
hereinafter held by either PARTY.

This Agreement will be subject to, and interpreted in accordance with, the laws
of the State of California.

Unless terminated earlier by thirty (30) days written notice by either PARTY to
the other, this Agreement will remain in effect for two (2) year(s) from the
effective date first written above, at which time the receiving PARTY will
return or destroy the PROPRIETARY INFORMATION within thirty (30) days of the
termination of this Agreement. If the PROPRIETARY INFORMATION is destroyed, a
certificate of destruction must be furnished to the disclosing PARTY within the
thirty (30) days. The secrecy and non-use obligations of the receiving PARTY set
forth above will remain in effect for five (5) years from the effective date.

The receiving PARTY acknowledges its obligations to control access to technical
data under the U.S. Export Laws and Regulations and agrees to adhere to such
Laws and Regulations with regard to any technical data received under this
Agreement.

                                      -54-
<PAGE>

NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

Any modification to this Agreement must be in writing and signed by the duly
authorized representative of each PARTY.

NOMOS CORPORATION                   THE REGENTS OF THE UNIVERSITY OF CALIFORNIA,
                                    LAWRENCE LIVERMORE NATIONAL LABORATORY

By: /s/ Anil Rastogi                By:  /s/ Kathy Kaufman
   -------------------------------     -------------------------------------

Name:  A. K. Rastogi                Name: for Karena McKinley
     -----------------------------       -----------------------------------

Title: President & CEO              Title: Director
      ----------------------------        -----------------------------------
                                          Industrial Partnerships and
                                          Commercialization

Date: 12/11/98                      Date:12/8/98
      ---------------------------        ----------------------------------

RETURN TO:            Lawrence Livermore National Laboratory
                      ATTN:  Linda Lerner
                      7000 East Avenue
                      P.O. Box 808, L-795
                      Livermore, CA  94551

cc:      James Somercom, L-795

                                      -55-
<PAGE>

NOMOS CORPORATION             ATTACHMENT 1          Radiation Treatment Planning
                                                                   Amendment One
--------------------------------------------------------------------------------

                         EXHIBIT E - LICENSED TRADEMARKS

----------------------------------------- ------------------------------------
LICENSED TRADEMARK                        TERRITORY
----------------------------------------- ------------------------------------
"PEREGRINE"                               United States of America
                                          Europe
                                          Canada
                                          Japan
----------------------------------------- ------------------------------------
"PEREGRINE Dose Calculation Engine"       United States of America
----------------------------------------- ------------------------------------
"PEREGRINE 3d Monte Carlo"                United States of America
----------------------------------------- ------------------------------------

                                      -56-<PAGE>

                                                                   Exhibit 10.20

[Logo of National Research Council of Canada]

                                                     Date drafted: 27 March 2000
                                                              Case Number: 11104

GIVEN BY NATIONAL RESEARCH COUNCIL OF CANADA                  (called "NRC")
      Head     {1200 Montreal Road,        Participating  Institute for National
      Office   {Ottawa, Ontario KIA OR6    Institute      Measurement Standards

TO       NOMOS Corporation (called the "User")
         whose address is:
                  2591 Wexford Bayne Road
                  Sewickley, PA 15143
                  U.S.A.

PREAMBLE

The User desires to use computer software created by NRC and identified as BEAM
99 (called herein the "Software").

IN CONSIDERATION of the preamble and the terms below, the Parties agree as
follows:

SL-1     TITLE AND GRANT

         NRC grants to the User, and User accepts, a non-transferable,
         non-exclusive licence to use the Software only in the manner described
         under the heading "USAGE". All proprietary interest, right, title, and
         copyright in the Software remain with NRC.

SL-2     TERM

         This Licence is in effect until 31 December, 2000 ("Initial Term").
         Thereafter, the User will have the right to continue this licence for
         one year periods upon payment of the annual licence fee, which is due
         on the expiration of the Initial Term and each anniversary thereof.

SL-3     PAYMENTS BY THE USER

         The User must pay an initial licence fee of Thirty thousand U.S.
         Dollars ($ 30,000.00) upon execution of this agreement. Thereafter, to
         continue this licence, the User must pay an annual licence fee of
         Thirty thousand United States Dollars ($30,000.00) as set out in SL-2.
         Neither the initial licence fee or the annual licence fees are
         refundable.

         Invoices will not be sent. The User must remit payment with the
         executed agreement. Cheques are to be made out to "Receiver General -
         National Research Council". Customs duties, if applicable, will be paid
         by the User.

<PAGE>

Cheques must be addressed to:

         Finance and Information Management Services
         National Research Council
         1200 Montreal Road, Ottawa, Ontario, KIA OR6

The case number 11104 should be noted on the check.

SL-4     USAGE

         4.1      The User may install the software on an unlimited number of
                  workstations located solely at the Users address at 2591
                  Wexford Bayne Road, Sewickley, PA 15143, U.S.A.. NRC agrees
                  that the software may also be installed on the workstations of
                  the Users contractor, Lawrence Livermore National Laboratory
                  (LLNL) located solely at 7000 East Avenue, Livermore CA
                  945550, USA provided that LLNL certifies in writing that it
                  agrees to be bound by the terms and conditions of this
                  licence. (letter attached)

         4.2      Subject to clause 4.3, the User may not lease, sublicense,
                  sell or transfer the Software or create and lease, sublicense,
                  sell or transfer any derivative programs that incorporate,
                  embody or are derived in any way from the Software.

         4.3      The User may only use the software for internal work to
                  develop beam characterization models for generic accelerators
                  which it may incorporate into its Peregfine related treatment
                  planning software and provide to third parties. The User
                  agrees not to use the Software to provide services or data to
                  third parties which are in any way based on modelling any
                  third party's individual accelerator.

         4.4      The Software constitutes valuable trade secrets which are
                  provided to the User for the sole internal use of the User and
                  which must not be made available to any other person.

         4.5      NRC agrees to provide, when available, any corrections, bug
                  fixes and updates of the Software to the User under this
                  licence. However, access to a new version of the Software (for
                  example BEAMOO) is not included and shall be the subject of a
                  separate licence.

         4.6      This licence does not include the fight to use the EGS4
                  Software and the User is responsible for independently
                  obtaining all necessary authorizations for such use.

                                      -2-
<PAGE>

SL-5.    TERMINATION PROCEDURE

         5.1      The User may terminate this licence at any time, by notifying
                  NRC in writing. NRC may terminate this licence by notifying
                  the User if the User violates any term of this Agreement and
                  the violation is not corrected to the satisfaction of NRC
                  within thirty (30) days after NRC gives the User notice in
                  writing of the allegation of a violation.

         5.2      Immediately upon notice of termination by either the User or
                  NRC, the User must certify that no copies, portions, modified
                  versions, or translations of the Software remain accessible to
                  the User, and that none have been passed from the User to
                  third parties.

         5.3      Termination by either the User or NRC does not erase any debt
                  already due pursuant to this Agreement.

SL-6     LIMITED WARRANTY AND REMEDIES

         6.1      NRC makes no warranty with respect to the accuracy of the
                  software code. NRC will use its best efforts to attempt to
                  correct any minor defects reported by the User to NRC. NRC
                  will not provide any technical assistance or support under
                  this licence but, at its discretion, will respond to minor
                  requests from the User. The provision of any other support or
                  technical services will be the subject of a separate agreement
                  between the parties.

         6.2      NRC warrants that the Software does not infringe any copyright
                  or violate any obligation of confidentiality. NRG also
                  warrants that NRC is not actually aware of any patent which
                  may be infringed by the Software. If a breach of a warranty
                  mentioned in this paragraph is proved in a court, NRC will
                  cancel all debts owing and refund all payments made pursuant
                  to this Agreement within the three (3) years preceding the
                  commencement of the court action.

         6.3      EXCEPT AS EXPRESSLY STATED HEREIN, NRG DISCLAIMS ANY
                  WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, OF ANY KIND OR
                  NATURE WITH RESPECT TO THE SOFTWARE, INCLUDING WITHOUT
                  LIMITATION ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A
                  PARTICULAR PURPOSE. NRC SHALL NOT BE LIABLE IN ANY EVENT FOR
                  ANY DAMAGES, WHETHER DIRECT OR INDIRECT, SPECIAL OR GENERAL,
                  CONSEQUENTIAL OR INCIDENTAL, ARISING FROM THE USE OF THE
                  SOFTWARE.

                                      -3-
<PAGE>

SL-7     GENERAL

         7.1      This Agreement supersedes all prior communications,
                  negotiations and agreements, written or oral, concerning the
                  Software. No amendment or waiver of terms is effective unless
                  it is in writing, signed by both Parties, and specifically
                  states the intention to affect this Agreement.

SIGNED by the User in duplicate at .....Sewickley, PA..........................

NOMOS CORPORATION

                                    Date:            3-28-00
                                            -----------------------------------

                                            John W. Manzetti
                                            Executive Vice President and
                                            Chief Financail Officer
                                            NOMOS Corporation
                                    per:                   /s/ John W. Manzetti
                                            -----------------------------------
                                            Print name and title

SIGNED by NRC in duplicate at Ottawa, Ontario, Canada:

NATIONAL RESEARCH COUNCIL OF CANADA

                                    Date:
                                            -----------------------------------

                                    per:
                                            -----------------------------------
                                            Print name and title

                                       -4-
<PAGE>

Letter to be signed by NOMOS and LLNL. Copy to be returned to NRC with the
executed agreement.

Date:

Mr. Ralph Patterson
Lawrence Livermore National Laboratory
7000 East Avenue, L-051
Livermore, California  94550

Dear Mr. Patterson:

As our contractor for the PEREGRINE project under the terms of Work for others
Agreement L-8788, NOMOS is furnishing you a copy of BEAM99 for use in performing
the required tasks of this agreement. BEAM99 is owned by the National Research
Council of Canada, and licensed by NOMOS for the purposes of developing beam
characterization models for generic accelerators. The license specifically
excludes providing services or data to third parties which are in any way based
on modeling any third party's individual accelerator.

By cosigning this letter, Lawrence Livermore National Laboratory agrees to use
this software solely in accordance with the terms of the National Research
Council licence in performing agreement L-8788, and that it will return the
software when requested by NOMOS.

Signed,

Robert M. Oates, Vice President Engineering
NOMOS Corporation

Agreed,

Ralph W. Patterson, Product Manager
Lawrence Livermore National Laboratory

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