<PAGE>
                                                                   Exhibit 10.2

                         CONFIDENTIAL TREATMENT HAS BEEN [???????????????????]
                         PORTIONS OF THIS EXHIBIT PURSUANT TO RULE [?????????]
                         UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED


                              EMPLOYMENT AGREEMENT

         THIS EMPLOYMENT AGREEMENT ("AGREEMENT") is made effective as of the
1st day of July, 1999, by and between Photogen, Inc., a Tennessee corporation
("COMPANY"), and Gerald L. Wolf, Ph.D., M.D. ("EMPLOYEE").

                                    RECITALS

         A.       Employee has substantial experience in development of medical
devices, therapeutic procedures, and medical diagnostics; and

         B.       Employee is the owner/inventor of certain intellectual
properties; and

         C.       The Company desires to retain Employee and Employee hereby
agrees to serve in such capacity to assist it in various research projects,
developing product inventions and related matters, as hereinafter provided;
subject to the terms of this Agreement.

                                    AGREEMENT

         NOW, THEREFORE, in consideration of the mutual promises herein and for
other good and valuable consideration, the receipt and adequacy of which are
hereby acknowledged, the parties agree as follows:

         1.       Definitions.  The following terms have the meanings set forth
below:

                  (a) "COMPETITIVE BUSINESS" means engaging in the research,
development, sale, lease, marketing, financing or distribution of technology,
products or services similar to or competitive with the Company's products or
services in the Field anywhere in the world.

                  (b) "CONFIDENTIAL INFORMATION" means any and all
information that has or could have value or utility to the Company or any of
its affiliates, whether or not reduced to written or other tangible form and
all copies thereof, relating to the Company's or its affiliates' private or
proprietary matters, confidential matters or trade secrets (including
information developed by or at the direction of Employee). For purposes of
illustration, Confidential Information may be contained in various media,
including, without limitation, records of research data and observations,
records and results of preclinical and clinical trials, patent applications,
regulatory filings, computer programs, manuals, plans, drawings, designs,
specifications, supply and customer lists, internal financial data and other
documents and records of the Company or its affiliates, whether or not
labeled or identified as "Confidential," or information prepared in full or
in part by Employee.

                  (i) Confidential Information includes, but is not limited
to, the following: (A) the Company's Technical Information; (B) except to the
extent publicly disclosed by the Company without any fault by Employee or any
other person or entity, information relating to


<PAGE>

the Company's Patents; (C) business information, such as information
concerning any products, customers, suppliers, production, developments,
costs, purchasing, pricing, profits, markets, sales, accounts, customers,
financing, acquisitions, strategic alliances or collaborations, expansions;
and (D) other information relating to the Company's or any of its affiliates'
business practices, strategies or policies.

                  (ii) Confidential Information does not include information
that is or becomes generally known to the public or in the industry without
any fault by Employee or any other person or entity, or if the Company ceases
to have a legally protectable interest in it.

                  (c) "DEVELOPMENTS" means any and all Patents and Technical
Information that during the Term of this Agreement and for twelve (12) months
after termination (regardless of the reason for termination), Employee
conceives, reduces to practice, discovers or makes, alone or with others (i)
by use of the Company's equipment, facilities, Confidential Information,
Technical Information, Research Materials or other intellectual property,
through a Research Project sponsored or funded by the Company or otherwise at
Company's expense; or (ii) which are directly or indirectly related to or
result from the Employment Services.

                  (d) "FIELD" means the use of electromagnetic energy
(including light generated by ultra fast lasers or other sources, x-rays and
other sources of radiation), alone or in combination with photoactive
compounds or targeting agents, to treat, diagnose or image human or animal
tissue and/or disease.

                  (e) "PATENTS" means patents, patent applications, and
patent disclosures, together with all reissuances, continuations,
continuations-in-part, revisions, extensions, and reexaminations thereof, and
all improvements and inventions related thereto.

                  (f) "RESEARCH MATERIALS" means and includes, without
limitation, photoactive compounds, targeting agents, lasers, software and
other materials provided to the Employee by the Company or used by the
Employee in providing his Employment Services.

                  (g) "TECHNICAL INFORMATION" means technical information or
other intellectual property (whether or not subject to patent or other
registration with any governmental office), including research and
development, methods, trade secrets, know-how, formulas, compositions,
protocols, processes and techniques, discoveries, machines, inventions,
ideas, computer programs (including software and data used in all such
programs), drawings, and specifications, including information relating to
Patents.

         2.       EMPLOYMENT SERVICES.

                  (a) During the Term of this Agreement, Employee shall use
his best efforts to and shall devote a minimum of 75% of his working time to
competently and faithfully promote the Company's interests, develop the
Company's products and to perform the following services (collectively, the
"EMPLOYMENT SERVICES"):


<PAGE>

                  (i) direct the scientific and medical activities for
specific research projects mutually agreed to between the Company and
Employee, including but not limited to the following: (A) sentinel lymph node
mapping, (B) enhanced radiation therapy through the use of radiosensitizers,
(C) photodynamic therapy of deep tissue cancer, and (D) other research
projects assigned by the Company (individually and collectively, "RESEARCH
PROJECTS");

                  (ii)  design, implement and complete certain experiments
related to the Company's Research Projects;

                  (iii) develop new product inventions for the Company;

                  (iv)  design and assist in human clinical trials undertaken
by the Company;

                  (v)   assist the Company in obtaining patent or other
protection for any technologies developed by Employee and arising out of his
Employment Services;

                  (vi) assist the Company in obtaining licenses to
technologies developed by third parties;

                  (vii) assist Company in working with outside preclinical
and clinical researchers and research organizations; and

                  (viii) perform such other duties assigned to Employee from
time to time by the Company's Chief Executive Officer and/or Board of
Directors.

                  (b) Employee will perform the Employment Services
substantially in the Boston, Massachusetts area. Employee may also be
required to travel from time to time to Knoxville, Tennessee and elsewhere as
reasonably necessary to perform the Employment Services.

         3.       COMPENSATION.

                  (a) Company shall pay Employee an annual base gross salary
as set forth in Exhibit A, payable in accordance with normal Company payroll
procedures and subject to deductions and withholdings required by law or by
agreement with Employee. Company will reimburse Employee for reasonable and
necessary business expenses in accordance with Company's policies.

                  (b) Concurrently with the execution of this Agreement,
Company and Employee will execute an Incentive Stock Option Award Agreement
("Award Agreement") providing for the Company to grant Employee a total of
750,000 options to acquire Company common stock, pursuant to Company's 1998
Long Term Incentive Compensation Plan. The options will vest in accordance
with and in all other respects be subject to the provisions of the


<PAGE>

Award Agreement.

                  (c) Employee will be eligible to participate in and receive
benefits provided under Company's insurance and benefit plans as set forth on
Exhibit A, in accordance with their respective provisions. Company reserves
the right to amend all insurance and benefit plans at any time as necessary
to accomplish Company's business objectives.

         4.       COVENANTS AND REPRESENTATIONS. Employee represents and
warrants to, and covenants with, the Company as follows:

                  (a) During the Term, Employee will render services (similar
to the Employment Services or otherwise) in the Field only to the Company and
will not enter into any other agreement, arrangement, understanding, or other
relationship pursuant to which Employee is obligated to render advice and
services in the Field to any third party, except to the extent set forth in
paragraph 4(b), below.

                  (b) Employee is under no contractual or other obligation or
restriction which is inconsistent with Employee's obligations under this
Agreement or the performance of the Employment Services. Employee's
pre-existing relationships with commercial, educational or other research
institutions are listed in Exhibit B. Except for professorships at
Massachusetts General Hospital/Harvard Medical School and Tufts University
Veterinary School and affiliations as a consultant with Biovector
Technologies, Inc., Employee will terminate all employment, consulting and
similar affiliations with commercial entities in the Field. Employee may act
as a consultant or member of a scientific advisory board working outside the
Field. Employee will arrange to perform any responsibilities to third parties
in a manner that will not conflict with Employee's responsibilities under
this Agreement. Employee agrees to indemnify, defend and hold Company and its
affiliates, directors, officers, employees and independent contractors
harmless from all claim, allegation, loss, liability (including settlement
payments), expenses (including reasonable attorneys' fees and expenses) any
of them incurs that arise out of or relate to (i) any wrongful act or
omission of Employee while he is engaged in such activities with third
parties, or (ii) the acts or omissions of those third parties.

                  (c) The performance of the Employment Services does not and
will not breach any agreement which obligates Employee to keep in confidence
any confidential or proprietary information of any third party or to refrain
from competing, directly or indirectly, with the business of any third party.
Employee shall not disclose to Company or use in providing Employment
Services hereunder any confidential or proprietary information of any third
party.

                  (d) In performing the Employment Services, Employee shall
comply with all legal and regulatory requirements established by the Food &
Drug Administration and other applicable governmental authorities.

         5.       ROYALTIES.


<PAGE>

                  (a) Exhibit C hereto is a correct and complete list of all
royalties, development payments or similar compensation right to which
Employee is entitled relating to any existing Patents and Technical
Information in the Field of which the Employee is the joint or sole inventor,
any licenses with respect to inventions in the Field to which Employee is a
party (whether as licensee or licensor), and any agreements granting Employee
development or similar rights with respect to Patents or Technical
Information in the Field (collectively, the "ROYALTIES"). Employee represents
and warrants to Company that he is the lawful owner of the Royalties listed
on Exhibit C, free and clear of any liens, claims, security interests,
restrictions, options or similar rights, or any other encumbrance, except as
stated in Exhibit C.

                  (b) Employee agrees to use all of the Royalties (on an
after-tax basis) to fund his purchase of common stock from Photogen
Technologies, Inc. upon exercise of options granted pursuant to the Award
Agreement. Employee will use all such Royalties for the purpose of effecting
such exercises and purchases as soon as practicable after any part of such
options vest in accordance with the Award Agreement.

         6.       OWNERSHIP OF DEVELOPMENTS

                  (a) Employee hereby assigns and transfers to the Company
all of Employee's right, title and interest in and to all Developments for
the Company's ownership and use without restriction or additional
compensation. Employee agrees to sign and deliver to the Company (during and
after the Term) other documents the Company considers necessary or desirable
to evidence its ownership of Developments. All copyrightable works that are
Developments, whether or not works made for hire (as defined in 17 U.S.C.
Section 101), shall be owned by the Company and it may file and own the same
as the author throughout the world. If the Company is unable for any reason
to secure Employee's signature on any document necessary or desirable to
apply for, prosecute, obtain, or enforce any patent, trademark, service mark,
copyright, or other right or protection relating to any Development, Employee
hereby irrevocably designates and appoints the Company and each of its duly
authorized officers and agents, as Employee's agent and attorney-in-fact to
act for and in Employee's behalf, name and stead to execute and file any such
document and to do all other lawfully permitted acts to further the
prosecution, issuance, and enforcement of patents, trademarks, service marks,
copyrights, or other rights or protections with the same force and effect as
if personally executed and delivered by Employee. Employee agrees that this
power of attorney is irrevocable and is coupled with an interest and thereby
survives Employee's death or disability.

                  (b) Employee shall keep and maintain complete written
records of all Developments, Technical Information and of all work or
investigations done or carried out by Employee. Employee agrees to promptly
and fully disclose in writing to the Company's President, all Developments
and Technical Information. These records shall be works made for hire, and
shall remain the exclusive property of Company. Employee may keep one copy of
these records in Employee's files during the Term of this Agreement solely
for reference purposes; however, all originals of such records shall be
turned over to the Company promptly and regularly and no less frequently than
monthly.

<PAGE>

         7.       CONFIDENTIALITY.

                  (a) The Company has developed and will develop Confidential
Information over a substantial period of time and at substantial expense. The
Confidential Information is of great importance to the Company's business.
During the Term, Employee may develop, become aware of, or have access to the
Confidential Information. Employee acknowledges the Company is and shall at
all times remain the sole owner of the Confidential Information.

                  (b) During the Term and at all times thereafter, Employee
will hold in trust, keep confidential and not disclose, directly or
indirectly, to any third parties or make any use of Confidential Information
for any purpose except for the benefit of the Company in the performance of
the Employment Services, and then only in a manner consistent with the
Company's instructions. Upon termination of the Term (regardless of the
reason for termination), Employee will immediately return to the Company all
tangible Confidential Information and any other material made or derived from
Confidential Information, including information stored in electronic format
and handwritten notes, which is in Employee's possession or control or which
Employee delivered to others. Employee may disclose the Confidential
Information to a governmental authority if required by law to do so or by
order of a court of competent jurisdiction, provided that in either case such
disclosure is subject to all applicable governmental or judicial protection
available for like material, reasonable advance notice is given to the
Company before any such disclosure is made and Employee cooperates with the
Company to obtain such confidential protection.

                  (c) During the Term and thereafter, Employee shall exercise
all commercially reasonable precautions to physically protect the integrity
and confidentiality of the Confidential Information. Employee will not remove
any Confidential Information or copies thereof from the Company's premises or
the other places Employee is authorized to perform the Employment Services to
the extent necessary to perform such Employment Services, and then only with
the Company's prior written consent.

                  (d) Employee will comply with Company's policies concerning
publication with respect to his work for the Company.

         8.       NONCOMPETITION; NONSOLICITATION.

                  (a) During the Term, and for 24 months after termination of
the Term, the Employee agrees not to, directly or indirectly, (i) own,
manage, control, participate in, consult with, be employed by, render
services for, any person or entity engaged in a Competitive Business or in
any manner or in any capacity (except as owner of 2% or less of stock of a
publicly registered and traded entity) engage in any Competitive Business,
(ii) solicit, induce or attempt to influence any other person or entity to
engage in any Competitive Business or to curtail or cease any business or
business relationship with the Company, its affiliates, employees or
independent contractors, (iii) solicit any other employee or independent
contractor to

<PAGE>

terminate any employment or engagement with the Company and engage in a
Competitive Business, or (iv) disparage the Company, its affiliates,
employees, independent contractors or their services or products.

                  (b) The Company consents to Employee performing services
for the entities listed in paragraph 4(b), provided that (i) Employee keeps
the Company advised on a current basis of his activities for such other
entities (or, to the extent Employee is unable to keep the Company advised
because of a confidentiality agreement with such other entity, Employee will
disclose as much information as possible without breaching the
confidentiality agreement and seek the other entity's permission to make
further limited disclosure to the Company), (ii) Employee strictly observes
the confidentiality obligations in paragraph 7, above, and (iii) Employee
uses his best efforts to assure that those other entities do not obtain any
interest in Developments or the Company's Patents. Upon written notice by one
party hereto to the other of a conflict situation, Employee and the Company
will negotiate in good faith for a period of 30 days (or longer by mutual
agreement) to modify Employee's responsibilities under this Agreement or to
develop other protections and procedures to minimize the possibility of
competitive conflict, the disclosure of Confidential Information and
uncertainty as to the Company's ownership of Developments or the Company's
Patents. If Employee and the Company are unable to agree on such
modifications, either of them may terminate this Agreement upon written
notice to the other.

         9.       TERM AND TERMINATION.

                  (a) Unless terminated earlier pursuant to paragraph 9(b)
below, this Agreement shall be in effect for an initial term of three years
beginning on the effective date hereof (the "INITIAL TERM"). This Agreement
will be renewed for successive renewal terms lasting for one year (the
"RENEWAL TERMS") unless one party notifies the other in writing at least
fifteen (15) days prior to the beginning of any Renewal Term of its or his
intention not to renew this Agreement. The Initial Term and any Subsequent
Renewal Terms are collectively referred to as the "TERM."

                  (b) This Agreement and Employee's employment by the Company
may be terminated before the expiration of any Term as follows:

                  (i)      By the Company in the event:

                           (1)      Employee commits a material breach of this
                                    Agreement where such breach, if curable, is
                                    not remedied to the Company's reasonable
                                    satisfaction within thirty (30) days after
                                    written notice to Employee (and termination
                                    shall be effective as of the end of such
                                    30-day period); or

                           (2)      Employee is convicted for committing an act
                                    of fraud, embezzlement, theft or another
                                    act constituting a felony (and


<PAGE>


                                    termination shall be effective upon written
                                    notice to Employee); or

                           (3)      Employee dies or becomes mentally or
                                    physically disabled such that the Employee
                                    cannot, in the opinion of an independent
                                    physician selected by the Company, perform
                                    the Employment Services (with reasonable
                                    accommodation to the extent required by
                                    law) for a period of 12 months (and
                                    termination shall be effective on the date
                                    Employee dies or upon written notice the
                                    Company has determined he is disabled under
                                    the foregoing criteria);

                           in which case: (A) the Company shall pay Employee
                           his base salary and any other amounts required by
                           applicable law to be paid through the effective date
                           of termination but the Company shall have no other
                           obligations under this Agreement as of the effective
                           date of the termination, and (B) the Company shall
                           permit the Employee or his beneficiary to exercise
                           vested options to acquire Company stock in
                           accordance with and subject to the Award Agreement.

                  (ii)     By the Company in the event the Company is
dissatisfied in its reasonable judgment with the Employee's performance of the
Employment Services or the results thereof which, if curable, are not remedied
to the Company's reasonable satisfaction within sixty (60) days after specific
written notice thereof has been delivered to the Employee (and termination
shall be effective as of the end of such 60-day period); in which case the
Company shall:

                           (1)      Pay the Employee a severance payment in 12
                                    monthly installments equal to the amount of
                                    gross salary the Employee would have
                                    received for 12 months following
                                    termination if Employee remained employed
                                    by the Company,

                           (2)      Continue (or pay the cost of premiums to
                                    continue) for 12 months the Employee's
                                    coverage under the medical and dental
                                    insurance programs Employee participated in
                                    immediately prior to termination,

                           (3)      Permit the Employee or his beneficiary to
                                    exercise vested options to acquire Company
                                    stock in accordance with and subject to the
                                    Award Agreement, and

                           (4)      Pay Employee a royalty of [****] of the
                                    Company's Net Sales Price on U.S. Patent
                                    Nos. [****] and [****] and related
                                    foreign patents pursuant to the terms of
                                    Exhibit D hereto.

                  (iii)    By the Employee, provided the Employee shall give the
Company at least 60 days prior written notice thereof (and termination shall be
effective as of the end of such 60-

-----------------------
[****] REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST FOR
       CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE SECURITIES ACT
       OF 1934, AS AMENDED.

<PAGE>


day or longer period); in which case (A) the Company shall pay Employee his
base salary and any other amounts required by applicable law to be paid
through the effective date of termination but the Company shall have no other
obligations under this Agreement as of the effective date of the termination,
and (B) the Company shall permit the Employee to exercise vested options to
acquire Company stock in accordance with and subject to the Award Agreement.

                  (c)      The Company's President shall have the authority
to exercise the Company's right to terminate the Employee's employment
pursuant to paragraphs 1(b)(i) and 1(b)(ii), above. If the Employee disagrees
with the President's decision, the Employee shall notify the Company's
Chairman of the Board in writing (a "NOTICE OF OBJECTION") within 10 days of
the effective date of termination. Promptly upon receipt of the Employee's
Notice of Objection, the Chairman shall convene a special meeting of the
Board of Directors to be held within 20 days of the Chairman's receipt of the
Notice of Objection, for the purpose of reviewing the decision of the
President. In connection with the special Board meeting, the Employee may
submit a reasonable amount of written materials and may make an oral
presentation to the directors lasting not more than three hours (which can be
extended by the Board for good cause). Promptly after the Employee's
presentation, the Board will meet in executive session. With the approval of
the Board (other than the President) the President may participate in
discussions during the executive session and may be counted to determine the
presence of a quorum, but he may not vote. Unless the Board ratifies and
confirms the President's decision concerning the Employee's termination by a
vote of two-thirds of the directors present, excluding the President, the
termination shall not be effective and the Employee shall be reinstated as an
employee under this Agreement. If the President's decision is ratified by
such two-thirds vote, the termination shall be final and shall be effective
as of the date originally determined by the President (and no options shall
vest nor salary or benefits accrue during the notice and hearing procedures
described in this paragraph 9(c)). The Board shall not issue findings of fact
or an opinion in connection with its decision, and it shall be entitled to
all of the rights and protections afforded directors acting in their
capacities as such under the Nevada General Corporation Law.

                  (d)      Notwithstanding anything to the contrary, the
obligations under this Agreement which by their terms survive termination,
including, without limitation, the applicable Royalties, Developments,
Confidentiality, Noncompetition, and Nonsolicitation provisions of this
Agreement as set forth in paragraphs 5, 6, 7 and 8 hereof, shall survive
termination; and the representations and warranties, including without
limitation the provisions of paragraph 4 hereof, shall survive termination.
Upon termination, and in any case upon the Company's request, Employee shall
return immediately to the Company all Confidential Information and copies
thereof and not retain any copies thereof.

         10.      MISCELLANEOUS.

                  (a) This Agreement and the rights and obligations hereunder
may not be assigned, delegated or transferred by Employee without the prior
written consent of the Company. The Company may assign this Agreement to an
affiliate of the Company or to an acquirer or successor in connection with
the merger, consolidation, or sale of all or substantially

<PAGE>

all of its assets, and this Agreement shall inure to the benefit of the
Company's assignee.

                  (b) This Agreement may not be amended or modified, or any
provision hereof waived, except by a written instrument duly signed by both
parties contemporaneously or after the date of this Agreement. This Agreement
(together with the Award Agreement and the Agreement regarding certain
conditions) constitutes the entire agreement between the parties concerning
the subject matter hereof and thereof, and supersedes all prior written or
oral negotiations, representations and agreements.

                  (c) The Employee acknowledges that a breach of paragraphs
5, 6, 7 or 8 would cause the Company and its affiliates irreparable harm.
Accordingly, in the event of a breach or threatened breach by the Employee of
any of the provisions of paragraphs 5, 6, 7 or 8, the Employee agrees that
the Company shall be entitled to injunctive relief restraining the Employee
and any individual or entity from participating in such breach or threatened
breach. The Employee waives any provision of law requiring the Company to
post a bond for any such injunctive relief. Nothing herein shall be construed
as prohibiting the Company from pursuing any other remedies available at law
or in equity for any breach or threatened breach of this Agreement.

                  (d) Any waiver of a breach of any provision of this
Agreement shall not operate as a waiver of any other breach of such provision
or any other provision, nor shall any failure to enforce any provision hereof
operate as a waiver of such provision or of any other provision.

                  (e) If any provision of this Agreement is deemed in a final
order by a court of competent jurisdiction to be unenforceable or invalid,
the enforceability and validity of all other provisions shall not be affected
and that court shall modify the unenforceable or invalid provision to the
extent necessary to render it enforceable and valid and that provision shall
be enforced as modified. Employee agrees that the time period and scope of
the covenants in paragraphs 6, 7 and 8 of this Agreement are reasonable and
appropriate under the circumstances of the Company's business.

                  IN WITNESS WHEREOF, Employee and the President of the Company
have signed this Agreement as of the Effective Date.


COMPANY                                       Address: 7327 Oak Ridge Highway
                                                       Suite B
Photogen, Inc.                                         Knoxville, TN  37931
                                                       Telephone: 423/769-4011
                                                       Telecopier: 423/769-4013
By: /S/John T. Smolik                                  E-mail:
   ---------------------------------                   smolik@photogen.com
       John T. Smolik, President

<PAGE>

EMPLOYEE




By: /s/Gerald L. Wolf
   -----------------------------
      Gerald L. Wolf, Ph.D, M.D.

Address:     3 Gable Ridge Road
             Westborough, MA 01581-2216

             Telephone:_______________
             Telecopier:______________
             E-mail: _________________


<PAGE>

                                    EXHIBIT A

                             TITLE AND COMPENSATION

Title:                     Medical Director

Gross Salary:              Starting salary of $190,000 per year.  Salary
                           subject to periodic review.

Bonus/Options:             Bonus will be available and paid at the discretion
                           of the Board or its Compensation Committee.

Benefits:                  Medical/Dental/Term Life Insurance
                           Long term disability insurance
                           Paid vacation (3 weeks)
                           Benefit programs will be developed and implemented
                           as approved by the Board 401(k) salary deferral plan
                           (non-contributory by Company


<PAGE>

                                    EXHIBIT B

                      EMPLOYEE'S PREEXISTING RELATIONSHIPS

<TABLE>
<CAPTION>
                                                                                                        SUBJECT TO WRITTEN
                                                                                                             AGREEMENT
                                                                                                              (Y OR N)
                                                                                                         IF "YES" ATTACH A
                ENTITY                                  SUMMARY OF RELATIONSHIP                          COPY OF AGREEMENT
                                                                                                            (REDACTED AS
                                                                                                             NECESSARY)
<S>                                    <C>                                                              <C>
[****]
























</TABLE>
-----------------------
[****] REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST FOR
       CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE SECURITIES ACT
       OF 1934, AS AMENDED.

<PAGE>

                                    EXHIBIT C

                        EMPLOYEE'S INTELLECTUAL PROPERTY

<TABLE>
<CAPTION>

                   DESCRIPTION                                              STATUS
<S>                                                <C>
[****]
















































</TABLE>
-----------------------
[****] REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST FOR
       CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE SECURITIES ACT
       OF 1934, AS AMENDED.


<PAGE>

                                    EXHIBIT D

                              ROYALTY CALCULATIONS


                       TERMS OF [****] ROYALTY TO EMPLOYEE

                                 1. DEFINITIONS

                  1.1 The term "Accounting Period" shall mean each six month
period ending June 30 and December 31 of each year.

                  1.2 The term "Affiliate" shall mean any corporation or
other legal entity controlling, controlled by or under common control with,
Company. The term "Control" means possession, direct or indirect, of the
power to direct or cause the direction of the management and policies of an
entity, whether through the ownership of voting securities, by contract or
otherwise.

                  1.3 The term "First Commercial Sale" shall mean in each
country the first sale of a Product by Company, its Affiliates or
Sublicensees to a final customer who will be the end user of the Product.

                  1.4 The term "Net Sales Price" shall mean the Gross Sales
Price as defined in (b) below actually received in cash by Company or any of
its Affiliates or Sublicensees ("Sellers") for the sale or distribution of a
Product to a final customer who will be the end user of the Product and is
not an Affiliate or Sublicensee ("Customer"), less (to the extent
appropriately documented) the following amounts actually paid out by Company,
its Affiliate or Sublicensee or credited against the amounts received by them
from the sale or distribution of a Product:

                  (a) credits and allowances for price adjustment, rejection,
or return of Products previously sold;

                  (b) rebates, customary trade, quantity and cash discounts
to purchasers and non-affiliated brokers' or agents' for commissions allowed
and taken; provided, however, that such broker's or agent's commissions not
to exceed 10%; and further, provided, that the term "non-affiliated brokers'
or agents'" does not include distributors;

                  (c) amounts for transportation, insurance, handling or
shipping charges to purchasers;

                  (d) taxes, duties and other governmental charges levied on
or measured by the sale of Products, whether absorbed by a Seller or paid by
the purchaser so long as a Seller's price

-----------------------
[****] REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST FOR
       CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE SECURITIES ACT
       OF 1934, AS AMENDED.

<PAGE>

                                                            EXHIBIT D CONTINUES

is reduced thereby, but not franchise or income taxes of any kind whatsoever;

                  (e) for any sale in which the United States government on
the basis of its royalty-free license pursuant to 35 U.S.C. Section 202(c) to
any Patent Rights requires that the Gross Sales Price of any Product subject
to such Patent Rights, be reduced by the amount of such royalty owed Employee
pursuant to paragraph 2.1, the amount of such royalty;

                  (f) the "Gross Sales Price" shall be the gross billing
price of any Product sold in a bona fide sale to a bona fide Customer by a
Seller. None of the Sellers shall sell any Product for consideration other
than cash or a receivable payable in cash. Transfer of a Product within
Company or between Company and an Affiliate or Sublicensee for sale by the
transferee shall not be considered a sale, commercial use or disposition for
the purpose of this Exhibit D; in the case of such transfer the Gross Sales
Price shall be based on sale of the Product by the transferee.

                  1.5 The term "Patent Rights" shall mean U.S. Patent Nos.
5,114,703 and 5,496,536 relating to percutaneous lymphography, or the
equivalent of such patents issued in any foreign jurisdiction, together with
the inventions described and or claimed therein. The term shall include any
division or continuation or the equivalent thereof issuing thereon or
reissue, reexamination or extension thereof. Patent Rights shall also include
those claims in any continuation-in-part of the aforementioned patents which
claim an invention described or claimed in said patents.

                  1.6 The term "Product" shall mean any article, device,
composition, method or service, the manufacture, use, or sale of which,
absent the licenses granted herein, would infringe a Valid Claim of any
Patent Right.

                  1.7 The term "Sublicensee" shall mean any non-Affiliate
third party licensed by Company or by an Affiliate to make, have made, use or
sell any Product. As used in this Agreement, "Sublicensee" shall include any
third party to whom Company has granted, directly or indirectly, the right to
distribute a Product, provided that such third party has the responsibility
in whole or in part for marketing and/or promotion of the Product within the
territory for which such distribution rights are granted.

                  1.8 The term "Valid Claim" shall mean any claim of any
Patent Right (i) that has not been finally rejected, (ii) that has not been
declared invalid by a patent office or court of competent jurisdiction in any
unappealed and unappealable decision or (iii) as to which patent protection
has not expired.

                                   2. ROYALTY

                  2.1 Upon the occurrence of the condition specified in Section
9(b)(ii) of the Employment Agreement, Company shall pay Employee a royalty as
follows: Beginning with the


<PAGE>

                                                            EXHIBIT D CONTINUES

First Commercial Sale in any country, Company shall pay Employee a royalty of
[****] of the Net Sales Price on all sales of Products by a Seller anywhere in
the world so long as the Product, its manufacture, use or sale is covered by
a Valid Claim of any Patent Right owned by or licensed exclusively to Company.

                  2.2 If a Seller sells any Product in a bona fide sale as a
component of a combination of active functional elements, the Gross Sales
Price of the Product shall be determined by multiplying the Gross Sales Price
of the combination by the fraction A over A + B, in which "A" is the Gross
Sales Price of the Product portion of the combination when sold separately
during the Accounting Period in the country in which the sale was made, and
"B" is the Gross Sales Price of the other active elements of the combination
sold separately during said Accounting Period in said country. In the event
that no separate sale of either such Product or active elements of the
combination is made during said Accounting Period in said country, the Gross
Sales Price of the Product shall be determined by multiplying the Gross Sales
Price of such combination by the fraction C over C + D, in which "C" is the
standard fully-absorbed cost of the Product portion of such combination, and
"D" is the sum of the standard fully-absorbed costs of the other active
elements component(s), such costs being arrived at using the standard
accounting procedures of Company which will be in accord with United States
generally accepted accounting principles.

                  2.3 If a Seller commercially uses or disposes of any
Product by itself (as opposed to a use or disposition of the Product as a
component of a combination of active functional elements) other than in a
bona fide sale to a bona fide Customer, the Gross Sales Price hereunder shall
be the price which would be then payable in an arm's length transaction with
such a Customer. If a Seller commercially uses or disposes of any Product as
a component of a combination of active functional elements other than in a
bona fide sale to a bona fide Customer, the Gross Sales Price of the Product
shall be determined in accordance with paragraph (c) above, using as the
Gross Sales Price of the combination that price which would be then payable
in an arm's length transaction. A "commercial use or disposition" of a
Product does not include (i) the use of a Product for research, clinical
testing or educational purposes for which no payment is made to or received
by the Company or (ii) a disposition of a Product which, in the opinion of
the Company, is damaged, obsolete or not usable for the purposes intended and
for which no payment is made to or received by the Company.

                  2.4 In the event that the royalty paid to Employee is a
significant factor in the return realized by Company so as to diminish
Company's capability to respond to competitive pressures in the market,
Employee agrees to consider a reasonable reduction in the royalty paid to
Employee as to each such Product for the period during which such market
condition exists. Factors determining the size of the reduction will include
profit margin on Product and on analogous or competitive products, prices of
competitive products, total prior sales by Company, and Company's
expenditures in Product development.

-----------------------
[****] REPRESENTS MATERIAL WHICH HAS BEEN REDACTED PURSUANT TO A REQUEST FOR
       CONFIDENTIAL TREATMENT PURSUANT TO RULE 24B-2 UNDER THE SECURITIES ACT
       OF 1934, AS AMENDED.


<PAGE>

                                                            EXHIBIT D CONTINUES

                  2.5 The payments due under this Exhibit D shall, if overdue,
bear interest until payment at a per annum rate equal to one percent (1%) above
the prime rate in effect at the Bank of Boston on the due date, not to exceed
the maximum permitted by law. The payment of such interest shall not preclude
Employee from exercising any other rights it may have as a consequence of the
lateness of any payment.

                             3. REPORTS AND PAYMENTS

                  3.1 Company shall keep, and shall cause each of its
Affiliates and Sublicensees, if any, to keep full and accurate books of
accounts on both the cash and accrual basis, containing all particulars that
may be necessary for the purpose of calculating all royalties payable to
Employee. Such books of account shall be kept at their principal place of
business and, with all necessary supporting data shall, during all reasonable
times for the three (3) years next following the end of the calendar year to
which each shall pertain be open for inspection at reasonable times upon
reasonable prior notice by Employee or its designee at Employee's expense for
the purpose of verifying royalty statements or compliance with this Exhibit D.

                  3.2 In each year the amount of royalty due shall be
calculated semiannually as of the end of each Accounting Period and shall be
paid semiannually within the sixty (60) days next following such date, every
such payment to be supported by the accounting prescribed in paragraph 6.3
and to be made in United States currency. Whenever conversion from any
foreign currency shall be required, such conversion shall be at the rate of
exchange thereafter published in The Wall Street Journal for the business day
closest to the end of the applicable Accounting Period.

                  3.3 With each semiannual payment, Company shall deliver to
Employee a full and accurate accounting to include the following information
and such other reasonable additional information relevant to the calculation
of royalty payments as may be requested by Employee from time to time:

                  (a) Quantity of each Product sold or leased (by country) by
Company, and its Affiliates or Sublicensees;

                  (b) Total billings for each Product (by country);

                  (c) Names and addresses of all Sublicensees of Company; and

                  (d) Total royalties payable to Employee.