<PAGE>
                                                                  EXHIBIT 10.16

                EXCLUSIVE PATENT AND TECHNOLOGY LICENSE AGREEMENT


THIS EXCLUSIVE PATENT AND TECHNOLOGY LICENSE AGREEMENT, having an effective date
of February 1st, 1995, (hereinafter "Effective Date") by and between
Schlumberger Technology Corporation (hereinafter "STC"), having a place of
business at Schlumberger-Doll Research, Old Quarry Road, Ridgefield, Connecticut
06877-4108 and CTI, Inc. (hereinafter "CTI"), having a place of business at 810
Innovation Drive, Knoxville, Tennessee 37933. Either STC or CTI may hereinafter
be individually referred to as a "Party" or collectively as the "Parties"; and

         WHEREAS, STC represents that it has invented and developed certain
intellectual property hereinafter referred to as "LSO Patent Rights" and
"Lutetium Oxyorthosilicate Technology" ("LSO Technology"), each hereinafter
defined, useful in detecting and measuring gamma ray spectra; and

         WHEREAS, CTI desires to obtain from STC, and STC is willing to grant
CTI certain exclusive patent and technology license rights with respect to the
LSO Patent Rights and the LSO Technology.

         NOW, THEREFORE, in consideration of the terms, conditions and
provisions hereinafter set forth, the sufficiency and adequacy of which are
hereby acknowledged, the Parties hereby agree as follows:


1.0 Definitions

1.1 LSO means crystalline cerium-doped lutetium oxyorthosilicate as described in
US Patent No. 4,958,080 and in US Patent Application Serial No. 08/330,051.

1.2 LSO PATENTS means the patents and applications listed in Schedule A.

1.3 LSO TECHNOLOGY means the reports, documents and papers listed in Schedule B.

1.4 AFFILIATE means any business entity that is owned or controlled by, or owns
or controls a Party to this Agreement, or that is owned or controlled by the
business entity which owns or controls a Party. Ownership, direct or indirect,
of at least fifty percent of the voting stock ordinarily entitled to vote in the
election of directors of a business entity or, if no such stock is issued, of at
least fifty percent of the ownership interest in the business entity, shall
constitute ownership thereof. An Affiliate shall not be considered to be a third
party under this Agreement.

1.5 STC RETAINED USE means any and all uses of LSO, LSO Patents and LSO
Technology in the fields of oil well logging, logging-while-drilling or
formation evaluation, either in the form of apparatus or tools offered for sale
or lease to third parties or as a service performed on behalf of third parties.




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<PAGE>

1.6 SUB-LICENSEE means any party other than STC, CTI and their Affiliates which
is licensed by CTI to make use of the LSO Patents and LSO Technology outside the
STC Retained Use.

1.7 LICENSED SALES means sales of LSO not incorporated into any form of device
or apparatus to third parties for use other than the STC Retained Use.

1.8 LICENSED USE means any use of LSO in a device or apparatus which is to be
sold or leased to a third party or operated for a third party for money or
money's worth.

1.9 GROSS VOLUME means the volume of LSO manufactured by or for CTI, its
Affiliates or Sub-Licensees for further processing thereby prior to
incorporation into devices or apparatus within the scope of the Licensed Use. It
is recognized that in the process of preparing LSO to be incorporated into a
device or apparatus within the scope of Licensed Use, scrappage will be
generated. Such scrappage will not be included in the Gross Volume.

1.10 MANUFACTURING COST means the actual or deemed cost per unit volume of LSO
comprising the Gross Volume. An example of an actual cost is the cost invoiced
by a manufacturer. An example of a deemed cost is the calculated cost when a
party manufactures on its own behalf.

2.0 License Grants

2.1 Subject to the terms of this Agreement, and subject to the terms and
conditions contained herein, STC hereby grants to CTI and its Affiliates an
exclusive and non-transferable (except as otherwise provided herein) right and
license under the LSO Patents to make and have made and use world-wide materials
and methods covered by such LSO Patents. CTI and its Affiliates are further
granted the right to sell world-wide such material and apparatus containing such
material subject to the restrictions contained herein.

2.2 Subject to the terms of this Agreement and subject to the terms and
conditions contained herein, STC hereby grants to CTI and its Affiliates an
exclusive and non-transferable (except as otherwise provided herein) right and
license under the LSO Technology to make and have made and use world-wide
materials and methods covered by such LSO Technology. CTI and its Affiliates are
further granted the right to sell world-wide such material and apparatus
containing such material subject to the restrictions contained herein.

2.3 During the term of this Agreement, CTI may extend license rights as defined
in this Section 2.0 to any Affiliate or Sub-Licensee. Grants made to Affiliates
or Sub-Licensees and extensions made to Affiliates or Sub-Licensees are made
effective when any such Affiliate or Sub-Licensee shall agree in writing to be
bound by the terms hereof as if such Affiliate or Sub-Licensee had entered into
this Agreement with STC effective as of the Effective Date of this Agreement.
Such extension may not be made at any time that CTI is in default with respect
to any of its obligations to STC under this Agreement. The extension shall be on
such forms as may be provided or approved by STC which approval shall not be
unreasonably withheld. A





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<PAGE>

true copy of the executed extension agreement to any such Affiliate or
Sub-Licensee shall be furnished promptly to STC.

2.4 The Parties agree that the STC Retained Uses are excluded from the license
rights as defined in this Section 2.0.

2.5 The Parties agree that CTI and its Affiliates are granted only the rights
defined in the Agreement herein, and unless explicitly otherwise mutually agreed
to by Parties, CTI is not granted any additional rights by STC.

2.6 Upon finalization and execution of this Agreement, STC agrees to promptly
disclose the details of all LSO Technology to CTI including the transfer to CTI,
at no cost to CTI, of reports, data, specifications, drawings and other
documents listed in Schedule B entirely owned by STC at the time of the
Effective Date and to cooperate with and assist CTI, including allowing
inspection of equipment and making available key STC technical personnel to
consult with CTI subject to the following conditions for the orderly transfer of
such LSO Technology to CTI for enabling CTI to use the LSO Technology and LSO
Patent Rights as contemplated under this Agreement. Under the terms of this
agreement, STC shall provide at no additional cost to CTI, other than relevant
travel expenses and related miscellaneous expenses, key STC technical personnel
for the time duration defined in Schedule D, to facilitate the integration of
LSO Technology into the operations of CTI as specified in Schedule D. Beyond
that time duration and the tasks noted in Schedule D, CTI may request further
assistance from STC, and any such assistance will be subject to mutually
agreeable reasonable terms and billing rates and subject to a separate and
mutually agreeable Consulting Agreement. CTI is not obliged to request any
further assistance from STC nor is STC obliged to provide any further assistance
above and beyond its obligations set forth in Schedule D.

2.7 In the event that CTI transfers the LSO Technology to a third party
manufacturer, the manufacturer shall be required to maintain such LSO Technology
confidential according to the terms outlined in Section 5.0 of this Agreement;
will be required to sign a Confidentiality Agreement of a form approved by STC;
and will be required to allow the examination of its records as provided in
Paragraph 4.4.

3.0 License Fee and Royalties

3.1 CTI, on its behalf and on behalf of its Affiliates or Sub-Licensee shall pay
an annual exclusive license fee of * Dollars ($*) to STC no later than December
15th of each year following execution of this Agreement for a fully paid-up
worldwide exclusive license to the LSO Technology and LSO Patent Rights.

3.2 CTI shall make payments ("Royalty Payments") to STC based on a royalty rate
dependent on the Manufacturing Cost as set forth in Schedule C in respect of
Licensed Sales and Licensed Use made by CTI and its Affiliates or Sub-Licensees
to whom this Agreement is extended as provided herein during each twelve month
period from October 1st to September 30th of the following year, which royalty
rate is subject to the provisions of Paragraphs 9.1.


* Omitted information is the subject of a request for confidential treatment
  pursuant to Rule 406 under the Securities Act of 1933 and has been filed
  separately with the Securities and Exchange Commission.


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<PAGE>

3.3 An amount of * Dollars ($*) corresponding to the annual exclusive license
fee shall be deducted from the Royalty Payments prior to CTI making the payment
as set forth in 3.2 above. In the event that the Royalty Payments for a given
twelve month period are less than * Dollars ($*), no payment other than the
yearly license fee shall be made by CTI to STC.

3.4 In the event that a non-exclusive license is imposed on CTI in accordance
with the provisions of Paragraph 11.4 or in the event that CTI elects to revert
to a non-exclusive license in accordance with the provisions of Paragraph 11.6,
the * Dollar ($*) annual exclusive license fee will not apply.

4.0 Accounting

4.1 On or before November 1st of each year following the Effective Date, CTI
shall submit to STC a "Statement" in writing, showing in respect of operations
of CTI and its Affiliates or Sub-Licensees for the preceding twelve month period
ending September 30th showing:

         (a) the Gross Volume of LSO purchased by CTI or its Affiliates or
Sub-Licensees;

         (b) a computation of the average Manufacturing cost;

         (c) a computation of the Royalty Payment payable hereunder for the
Gross Volume of LSO consumed and the total volume sold.

4.2 Payment in full of, the amounts determined in Paragraph 4.1 above shall be
made by CTI to STC in United States Dollars no later than December 15th
following the submission of the Statement.

4.3 CTI and its Affiliates or Sub-Licensees shall keep records adequate to
support the Statements required to be submitted to STC pursuant to Paragraph
4.1.

4.4 At any time during regular business hours, STC, or its independent auditor,
at its expense may, having given CTI reasonable notice, make an examination, not
more frequently than once each calendar year, of the records of CTI and/or its
Affiliates or Sub-Licensees relevant to the licensed Sales to verify such
reports-and payments provided for in Paragraphs 4.1 and 4.2. CTI and/or its
Affiliates or Sub-Licensees must maintain such records for a period of three (3)
years following the applicable reporting period.

5.0 Confidentiality

5.1 CTI hereby agrees that all LSO Technology disclosed by STC, including verbal
information confirmed within thirty (30) days after disclosure by STC in writing
to be Confidential Information shall be maintained by CTI in confidence and
shall be used by CTI solely under the terms, conditions, and provisions of this
Agreement, and shall not be disclosed to any third party except such third
parties who have entered into appropriate secrecy agreements with CTI concerning
such LSO Technology. CTI's obligation of


* Omitted information is the subject of a request for confidential treatment
  pursuant to Rule 406 under the Securities Act of 1933 and has been filed
  separately with the Securities and Exchange Commission.


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<PAGE>

confidentiality shall not extend to any portion of such LSO Technology, to the
extent that the identical information:

                  (a) is now or hereafter becomes a part of the public domain,
other than by act or omission to act on the part of CTI; or

                  (b) was developed by CTI or its Affiliates and in its
possession prior to disclosure by or on behalf of STC as evidenced by CTI's or
its Affiliates' written records; or

                  (c) is hereafter furnished to CTI by a third Party as a matter
of right and without restriction on use or disclosure, who lawfully possesses
such information and did not acquire the same directly or indirectly from STC;
or

                  (d) is disclosed in any U.S. or foreign patent or foreign
published patent application whether owned by STC or any third party; or

                  (e) was independently developed by CTI or its Affiliates
without reference to the STC Confidential Information as evidenced by CTI's or
its Affiliates' records; or

                  (f) is disclosed to a government agency or pursuant to a
judicial proceeding.

5.2 As and to the extent that STC may first approve in writing (which approval
shall not unreasonably be withheld), limited but necessary disclosure of the LSO
technology may be made by CTI to those manufacturing the LSO for or on behalf of
CTI or its Affiliates per the license granted herein, provided that such
Manufacturers shall agree in writing to be bound by the terms and conditions of
Paragraph 3.5 above.

5.3 All information obtained by STC from CTI or its Affiliates shall be
maintained confidential but subject to the same exceptions as listed in
Paragraph 5.1.

6.0 Protection of Patent Rights

6.1 STC, at its expense, agrees to exercise reasonable diligence in seeking,
obtaining and maintaining patent protection in the United States and in those
foreign countries deemed appropriate and by STC for LSO Technology, as apart of
the LSO Patent Rights, and to retain patent counsel for this purpose. In the
case that STC does not seek patent protection, CTI will have the right to
pursue, at its expense, such protection in the United States and those foreign
countries deemed appropriate by CTI. Such patents shall be assigned to STC and
shall be subject to all the terms and conditions of the Agreement.

6.2 Any inventions or improvements relating to LSO Technology made jointly by
employees or consultants of STC and CTI and its Affiliates after the Effective
Date of this Agreement shall be considered the joint property of STC and CTI and
shall not be subject to the Royalty Payments set forth above.

6.3 Any inventions or improvements relating to the LSO Technology made
separately by employees or consultants of STC or CTI and its Affiliates-during
the term of this Agreement shall be considered the separate property of the
Party whose employees or consultants made the invention or improvement. Any
patent applications filed on such inventions or improvements made separately by
STC shall be added to the list of the LSO Patent Rights as specified in Schedule
A and shall thereafter be subject to all of the terms and conditions of this
Agreement at no additional consideration. Any patent issued on such inventions
or


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<PAGE>

improvements made separately by CTI shall be subject to a grant to STC of a
royalty-free, non-transferable right (without right to sub license other then to
Affiliates) for STC to use any such inventions and improvements made by CTI in
the business of STC. CTI has no obligation to grant licenses to inventions or
improvements constituting its own property to any third party.

6.4 Any patents for inventions or improvements relating to LSO Technology made,
separately by employees or consultants of STC and actually conceived prior to
the Effective Date of this Agreement and for which invention disclosures have
been prepared and documented within thirty (30) days after the Effective Date of
this Agreement shall be considered to be the separate property of STC and shall
be added to the list of LSO Patent Rights as specified in Schedule A and shall
thereafter be subject to all of the terms and conditions of this Agreement at no
additional consideration.

6.5 In those countries foreign to the United States which require working of
patents to prevent lapsing of same, CTI shall prepare proofs of steps taken in
or for commercial exploitation of the pertinent patents, as requested by STC,
and shall forward the same in timely manner to STC, provided that STC agrees
that any such information shall be treated as confidential information that is
not to be provided to any real or potential competitor of CTI except as the
unavoidable result of filing and prosecuting the necessary patent documentation;
and provided, further, that STC shall reimburse CTI for any reasonable expense
CTI incurs, with the prior approval of STC, in connection with the preparation
of such proofs.

6.6. CTI agrees to affix a patent notice or notices as STC may reasonably
request, to any documentation relating to LSO or devices containing LSO
materials sold by CTI under this Agreement. Each sale of LSO or devices
containing LSO materials by CTI and its Affiliates or Sub-Licensees under this
Agreement shall be accompanied by the following notice.

THE LUTETIUM OXYORTHOSILICATE (LSO) SCINITLLATOR MATERIAL IS MANUFACTURED AND
SOLD SUBJECT TO A LICENSE UNDER US PATENT NO. 4,958,080 (AND EQUIVALENTS) FROM
SCHLUMBERGER TECHNOLOGY CORPORATION. IT IS A CONDITION OF THIS SALE, WHICH THE
BUYER ACCEPTS, THAT THE LSO CANNOT BE USED FOR THE MANUFACTURE OF TOOLS OR
APPARATUS FOR OIL WELL LOGGING, LOGGING-WHILE-DRILLING OR FORMATION EVALUATION,
OR SOLD ON FOR SUCH USE.

7.0 Indemnification for Intellectual Property Rights

7.1 STC agrees to defend, indemnify, and hold harmless CTI from and against any
claim, suit, demand, or action alleging that LSO, and/or the use of LSO and/or
any use of the LSO Technology when used in accordance with the terms hereof
infringes any patent, copyright,



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trade secret, or other proprietary right of any third party under the laws of
any country, and STC shall indemnify CTI against all costs, expenses and damages
arising from any such claim, suit, demand, or action; provided, that

                (a) CTI shall have given STC prompt written notice of such
claim, suit, demand, or action; and

                (b) CTI shall cooperate with STC in the defense and settlement
thereof; and

                (c) STC shall have control of the defense of such claim, suit,
demand or action and the settlement or compromise thereof.

7.2 If conditions of legal interference ("Legal Interference") including but not
limited to, litigation filed by a third party, or an injunction, temporary or
final, is threatened or obtained by a third party in any particular country
against CTI's sale or use of LSO and/or the LSO Technology by reason of
infringement of a patent, copyright trade secret, or other proprietary right of
any third party within that particular country, then STC may, at its option and
expense:

                (a) procure for CTI the right to continue sale or use of LSO
and/or the LSO Technology in the particular country; or

                (b) in the particular country, replace or modify the LSO and/or
the LSO Technology for CTI, or such infringing portion thereof, in order that it
no longer infringes such patent, copyright, trade secret, or other proprietary
right in that particular country, provided that the utility or performance is
not adversely affected by such replacement or modification in that particular
country; or

                (c) authorize CTI, at the expense of STC and through written
instructions from STC, to pursue legal action in the name of CTI and to join STC
as a voluntary party plaintiff in order to procure continued use by CTI of LSO
and/or the LSO Technology.

7.3 STC shall have no liability to CTI for any infringement action or claim that
is based upon or arises out of the use by CTI of LSO and/or the LSO Technology,
or any portion thereof, in combination with any other system, equipment, or
apparatus not furnished by STC, in the event that, but for such use in
combination, the claim of infringement would not have been made.

7.4 This Section 7.0 sets forth the exclusive remedy of CTI against STC with
respect to any action or claim for any alleged patent, copyright, trade secret
or other proprietary right infringement by LSO and/or the LSO Technology, or any
component or any portion thereof, and with respect to any claim for lost
business or consequential business damages due to CTI's inability to conduct
business or meet any contractual business obligations incurred by CTI and this
Section 7.0 shall survive any termination of this Agreement.




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8.0 Warranty and Limitation, of Liability

8.1 IT IS UNDERSTOOD AND AGREED THAT NO WARRANTY, EXPRESS OR IMPLIED, INCLUDING
WITHOUT LIMITATION ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE, IS EXTENDED BY STC UNDER THIS AGREEMENT.

8.2 EXCEPT FOR THE INDEMNIFICATION BY STC TO CTI FOR INTELLECTUAL PROPERTY
RIGHTS IN ACCORDANCE WITH SECTION 7.0, STC WILL NOT BE LIABLE FOR ANY DIRECT,
INDIRECT, ACTUAL, SPECIAL OR CONSEQUENTIAL DAMAGES OF ANY KIND OR NATURE
WHATSOEVER, INCLUDING, WITHOUT LIMITATION, LOST PROFITS, BUSINESS INTERRUPTIONS,
OR OTHER ECONOMIC LOSS ARISING OUT OF CTI AND/OR USE OF LSO UNDER THE LSO PATENT
RIGHTS, OR THE USE OF THE LSO TECHNOLOGY, OR THE MANUFACTURING OF LSO. IF FOR
ANY REASON BY OPERATION OF LAW OR OTHERWISE, ANY SUCH LIMITATIONS OF LIABILITY
SHALL BE INEFFECTIVE, THEN, IN SUCH EVENT CTI AGREES THAT STC'S ENTIRE LIABILITY
FOR BREACH OF WARRANTY OR FOR THE USE OF LSO AS COVERED BY THE LSO PATENT
RIGHTS, OR USE OF THE LSO TECHNOLOGY, IF ANY, SHALL NOT EXCEED THE TOTAL OF THE
LICENSE FEE AND ANY AND ALL ROYALTY PAYMENTS PREVIOUSLY MADE TO STC UNDER THIS
AGREEMENT.

8.3 STC WARRANTS THAT IT OWNS THE PATENT RIGHTS AND TECHNOLOGY LICENSED UNDER
THIS AGREEMENT. STC AGREES TO DEFEND INDEMNIFY, AND HOLD HARMLESS CTI FROM AND
AGAINST ANY CLAIM, SUIT, DEMAND, OR ACTION ARISING FROM A CHALLENGE BY A THIRD
PARTY TO STC'S CLAIMS TO OWNERSHIP OR RIGHT TO LICENSE THE LSO PATENTS AND LSO
TECHNOLOGY AND STC SHALL INDEMNIFY CTI AGAINST ALL COSTS, EXPENSES AND DAMAGES
ARISING FROM ANY SUCH CLAIM, SUIT, DEMAND, OR ACTION.

8.4 CTI agrees to protect, defend, indemnify and hold harmless STC, its
officers, employees, agents, representatives and subcontractors from any and all
claims, liability, damages, losses, costs and expenses sustained by STC, its
officers, employees, agents, representatives and subcontractors for the

                (a) death of or injury to officers, employees, agents,
representatives and subcontractors of CTI, even though CTI may be protected from
direct suit by any workers' compensation laws, or

                (b) loss of, or damage to or destruction of property or
equipment of CTI, its officers, employees, agents, representatives and
subcontractors, in connection with the manufacturing of LSO by CTI or the use by
CTI of LSO in the Licensed Use.

8.5 STC agrees to protect, defend, indemnify and hold harmless CTI, its
officers, employees, agents, representatives and subcontractors from any and all
claims, liability, damages, losses, costs and expenses sustained by CTI, its
officers, employees agents, representatives and subcontractors for the



                                       8
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                (a) death of or injury to officers, employees, agents,
representatives and subcontractors of STC, even though STC may be protected from
direct suit by any workers' compensation laws, or

                (b) loss of, damage to or destruction of property or equipment
of STC, its officers employees, agents, representatives and subcontractors in
connection with STCs development of LSO, or STC's manufacture or use of LSO in
connection with STC's Retained use.

8.6 CTI agrees to protect, defend, indemnify and hold STC harmless from and
against any and all claims, demands, liabilities and causes of action brought or
presented by third parties for personal injury or death, or property or
equipment damage which is attributable to CTI's negligence in connection with
use of LSO.

9.0 Unlicensed Competition

9.1 STC and CTI agree to notify the other, where one or both of them have
knowledge, of a third party infringing one or more of the patents specified in
the LSO Patent Rights in any particular country where CTI or its Affiliates are
conducting Licensed Use under this Agreement. If STC has not caused such
infringement to cease, or if an infringement suit has not been filed against
such identified infringer by STC within a first three (3) month period after
having received notice, which date of receipt of notice will be provided in
writing to CTI by STC, CTI at its option, may:

                (a) have the Royalty Payments due hereunder to STC discontinued
for that. particular country while the infringement continues unchallenged,
and/or

                (b) file a lawsuit against the infringer and control the lawsuit
at its own expense and risk. In such case, and in that particular country only,
CTI or its Affiliates shall continue or resume to pay to STC the Royalty
Payments and STC agrees to join CTI as a plaintiff if required by the law of
that country and to assist in the prosecution of the lawsuit.

10.0 Sales from CTI to STC.

10.1 STC agrees that in the event that it requires LSO for its own uses which it
does not wish to manufacture itself, it shall first offer CTI the opportunity to
meet such requirement before any third party. CTI agrees to meet such a request
for a cost comparable to that charged to third parties less the amount
attributable to royalty payments.

10.2 * will be due in respect of sales of LSO made by CTI to STC.

11.0 Term and Termination

11.1 Unless sooner terminated in accordance with the provisions as herein
provided, this Agreement shall remain in full force and effect for a period of
ten years from the Effective Date or for the term of any Patent included in the
STC Patent Rights, whichever is the longer.

*Omitted information is the subject of a request for confidential treatment
pursuant to Rule 406 under the Securities Act of 1933 and has been filed
separately with the Securities and Exchange Commission.

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<PAGE>

11.2 If CTI shall be in default in making any payments hereunder at the times
and in the manner herein provided, or if CTI shall be in default in observing or
performing any other terms, conditions, or provisions of this Agreement, STC may
give written notice to CTI specifying the particulars of such default and, in
the event CTI shall not remedy such default within thirty (30) days after such
notice, STC may at its option terminate this Agreement by giving thirty (30)
days' prior written notice to CTI to that effect and or proceed to enforce the
defaulted obligation of-CTI by any available means. Any indulgence on the part
of STC in respect to a default by CTI shall not be construed as a waiver of
STC's right to proceed under this Article either with aspect to such default or
to similar subsequent defaults,

11.3 The exclusive license granted under this Agreement is conditional on the
prompt and continuous commercialization of the LSO Technology and Patents. The
following situations shall be considered as failure to meet this condition:

                (a) If two consecutive Statements required by paragraph 4.1 show
no Licensed Sales or Licensed Use have been made during the respective twelve
month periods, or

                (b) If three consecutive Statements required by paragraph 4.1
show that Royalty Payments do not exceed * dollars ($*) for the respective
twelve month periods.

None of the Statements required by paragraph 4.1 which relate to periods prior
to 1997 shall be considered when determining failure under (a) or (b) above.

11.4 After the first instance of failure asset forth in 11.3(a) or (b), STC may
impose upon CTI a non-exclusive license of substantially similar terms by giving
ninety (90) days written notice. After the second instance of failure as set
forth in 11.3(a) or (b), STC may terminate this Agreement by giving ninety (90)
days written notice.

11.5 After an initial term of two years from the Effective Date, the Parties
agree that thereafter CTI or its Affiliates may terminate this Agreement if CTI
has invested a minimum of $* in development of the LSO Technology and elects not
to proceed further in making this a commercial product.

11.6 After an initial term of five years, the Parties agree that thereafter CTI
or its Affiliates may terminate this Agreement, or elect to have a non-exclusive
license on substantially similar terms at any time by giving ninety (90) days
prior notice in writing of such termination to STC.

11.7 From and after the effective date of termination of this Agreement under
this Section 11.0, the license grants under the STC Patent Rights all other
rights and privileges of CTI hereunder shall cease and terminate. However, CTI
shall not thereby be relieved of its obligations under Paragraph 5.1 or for
unpaid payments to STC of any type which have accrued or for any other
obligation or liability accrued hereunder prior to the effective date of such
termination.

11.8 Termination of this Agreement shall operate coextensively as to any CTI
Affiliate or Sub-Licensee.

*Omitted information is the subject of a request for confidential treatment
pursuant to Rule 406 under the Securities Act of 1933 and has been filed
separately with the Securities and Exchange Commission.



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<PAGE>

11.9 Regardless of the basis for any lawful termination of this Agreement,
Paragraph 2.2 (except insofar as any such LSO Technology is the subject of any
of the LSO Patents) and Sections 5.0, 7.0, and 8.0 shall survive any such
termination.

12.0 Disputes

12.1 If a dispute arises out of or relates to this Agreement, or the breach
thereof, the Parties agree that in the first instance they shall enter into good
faith negotiations to resolve such dispute by mutual agreement.

13.0 General

13.1 This Agreement shall not be assignable by either Party without the prior
written consent of the other Party hereto, except that it may be assigned
without such consent to the successor of either Party or to a person, firm or
corporation acquiring all or substantially all of the business assets of such
Party; provided further, STC may, without the consent of CTI, assign this
Agreement to any person, firm or corporation which shall acquire all or
substantially all of the LSO Patent Rights and LSO Technology relating to this
Agreement. No assignment of this Agreement shall be valid until and unless this
Agreement shall have been assumed by the assignee in writing. When assigned in
accordance with the foregoing, this Agreement shall be binding upon and shall
enure to the benefit of the assignee. Any assignment of this Agreement shall not
relieve CTI of its obligations provided for in Paragraph 5.1 hereof, nor shall
it relieve CTI of any other obligation or liability incurred prior to the
effective date of such assignment.

13.2 No modification of this Agreement shall be effective unless in writing and
signed by the Parties hereto.

13.3 Any article or technical publication (or news release) relating to this
Agreement, to LSO and/or the LSO Patent Rights and/or to any LSO Technology
shall acknowledge that the technology has been licensed from STC.

13.4 Any notice to be served by one Party on the other Party may be served by
mailing the same, certified mail, postpaid, or hand delivered by commercial air
courier to the following addresses, respectively, as follows:

         For CTI:
         CTI, Inc.
         810 Innovation Drive
         Knoxville, Tennessee 37933
         Attn:    Dr. Ronald Nutt
                  Vice President and Technology Director



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<PAGE>



         For STC:
         Schlumberger Technology Corporation
         Schlumberger-Doll Research
         Old Quarry Road
         Ridgefield, Connecticut 06877
         Attn:    Patent Counsel

or to such other address as to which either Party shall give due written notice
from time to time.

13.5 This Agreement shall be construed and the legal relations between the
parties determined in accordance with the laws of the State of Tennessee.

13.6 CTI and STC agree that their performance under this Agreement is subject to
compliance with the laws and regulations of the Government of the United States
of America for the export and re-export of LSO Technology (including classified
information) and equipment based thereon, comprising where required validated
export licenses, and the Parties agree that they shall be bound by the terms
thereof.

13.7 If any provisions of this Agreement shall be held unenforceable, such
holding shall not affect the enforceability of any other provisions herein as
long as the unenforceable provision(s) does not materially affect the rights
granted in this Agreement.

13.8 Neither CTI nor STC shall be responsible for delays or failures in
performance resulting from acts beyond their control. Such acts shall include,
but not be limited to, acts of God, strikes, riots, acts of war, epidemics,
fire, communication line failures, earthquakes, floods, or other disasters.

13.9 Failure of either Party to seek a remedy for the breach of any portion of
this Agreement by the other Party shall not constitute a waiver of its rights
with respect to the same or any subsequent breach.

13.10 This Agreement, including Schedules A, B, C and D, states the entire
agreement between CTI and STC and supersedes all prior proposals, oral or
written, and all, other prior communications between CTI and STC relating to the
subject matter of this Agreement.

13.11 All dollar amounts in this Agreement are in United States Dollars.




                                       12
<PAGE>



IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be executed
by their duly authorized officers as of the dates shown proximate the execution
signatures but which shall have the Effective Date shown above.


SCHLUMBERGER TECHNOLOGY                    CTI, INC.
CORPORATION


By:      /s/ Brian Clark                   By: /s/ Ronald Nutt
   --------------------------------            ---------------------------------

Name:  Brian Clark                         Name:  Ronald Nutt

Title:  Vice President                     Title: Vice President & Technical
        Director, Schlumberger-Doll               Director
        Research

Date:   2/7/95                             Date:  2/13/95




                                       13
<PAGE>



                  SCHEDULE A

                  LICENSED PATENTS AND PATENT APPLICATIONS


                  US Patent No. 4,958,080
                  European Patent No. 0373970 (designating GB, France, Germany)
                  Norwegian Pawn Application No. 893973
                  Japanese Patent Application No. 1-260313

                  US Pawn Application Serial No. 08/330,051





                                       14
<PAGE>






SCHEDULE B


Internal publications:

R. A. Manente, C. L. Melcher, C. A. Peterson, J. S. Schweitzer, Crystal growth
      parameters for lutetium oxyorthosilicate scintillator crystals, gamma-ray
      and Neutron Sensor Research program, October, 1994.

R. A. Manente, C. L. Melcher, J. S. Schweitzer, Progress in the growth of single
      crystals at SDR, Nuclear Spectroscopy Program, January 1990.

C. L. Melcher, R A. Manente, J. S. Schweitzer, crystal growth and scintillation
      performance of yttrium oxyorthosilicate, Nuclear Spectroscopy Program,
      September 1989.

C. L. Melcher, Synthesis of a new inorganic scintillator Cerium-activated
      lutetium oxyorthosilicate, Nuclear Spectroscopy Program, May 1987.

External publications:

W. W. Moses, S. E. Derenzo, C. L. Melcher, and R. A. Manente, A room temperature
      LSO/PIN photodiode PET detector module that measures depth of interaction,
      submitted to IEEE Trans. Nucl. Sci. (1994).

F. Daghighian, D. M. Lovelock, B. Eshaghian, P. Shenderov, C. L. Melcher, J. S.
      Schweitzer, R. A. Manente, and C A. Peterson, Design considerations of an
      animal PET scanner utilizing LSO scintillators and position sensitive PMT,
      submitted to IEEE Trans. Nucl. Sci. (1994).

W. W. Moses, S. E. Derenzo, C. L. Melcher, and R. A. Manente, Gamma-ray
      spectroscopy and timing using LSO and PIN photodiodes, submitted to IEEE1
      Trans. Nucl. Sci. (1994).

R. Visser, C. L. Melcher, J. S. Scgweitzer, H. Suzuki, and T. A. Tombrello,
      Photostimulated luminescence and thermoluminescence of LSO scintillators,
      IEEE Trans. Nucl. Sci. NS-41(4), 689-693 (1994).

P. Dorenbos, J. S. M. de Haas, C. W. E. van Eijk, C. L. Melcher, and J. S.
      Schweitzer, Non-linear response in the scintillation yield of
      Lu2(SiO4)O:Ce3+, IEEE Trans. Nucl Sci. NS-41(4),735-737 (1994).

P. Dorenbos, C. W. E. van Eijk, A. J. J. Bos, and C. L. Melcher, Afterglow and
      thermoluminescence properties of Lu2SiO5:Ce scintillation crystals, J. of
      Phys.: Condens. Matter 6(22) 4167-80 (1994).




                                       15
<PAGE>
P. Dorenbos, C. W. E. van  Eijk,. A. J. J.  Bos, and C. L. Melcher, Study of the
      scintillation and thermoluminescence properties of Lu2SiO5 fast
      scintillation crystals, J. Luminescence 60 & 61, 979-982 (1994).

H. Suzuki, T. A. Tombrello, C. L. Melcher, and J. S. Schweitzer, UV and
      gamma-ray excited luminescence of ce-doped rare earth oxyorthosilicates,
      Nucl. Instr. and Meth. A320, 263-272 (1992).

C. L.  Melcher, R A. Manente, C. A. Peterson, and J. S. Schweitzer, Czochralski
      growth of rare earth oxyorthosilicate single crystals, J. Crystal Growth
      128, 1001-1005 (1993).

H. Suzuki, T. A. Tombrello, C. L. Melcher, and J. S. Schweitzer, Light emission
      mechanism of cerium doped lutetium oxyorthosilicate, IEEE Trans. Nucl Sci.
      NS-40(4) 380-383 (1992)

F. Daghighian, P. Shenderov, K. S. Pentlow; M. C. Graham, C. L. Melcher, and
      J. S. Schweitzer, Evaluation of cerium-doped lutetium oxyorthosilicate
      (LSO) as scintillation crystal for PET, IEEE Trans. Nucl. Sci. NS-40(4),
      1045-1047 (1993).

M. Kobayashi, M. Ishii, C. L. Melcher, Radiation damage-of a cerium-doped
      lutetium oxyorthosilicate single crystal, Nucl. Instr. and Meth. A335,
      509-512 (1993).

R. A. Manente, C. L. Melcher, C. A. Peterson, J. S. Schweitzer, M. A.
      Singelenberg, and F. J. Bruni, A Macintosh-based system for Czochralski
      crystal growth, Scientific Computing and Automation, 39-45; January, 1994.

C. L. Melcher and J. S. Schweitzer, A promising new scintillator: ceriun-doped
      lutetium oxyorthosilicate, Nuc. Instr. Meth. A314, 212-214 (1992).

C. L. Melcher and J. S. Schweitzer; Cerium-doped lutetium oxyorthosilicate:  A
      fast, efficient new scintillator, IEEE Trans. Nucl. Sci. NS-39(4), 502-505
      (1992).

C. L. Melcher, Progress in the development. of LSO scintillators, in Crystal
      2000 Conference Proceedings 1992.

C. L. Melcher, LSO/Photodiode and LSO/Avalanche photodiode detectors, in IEEE
      Nucl Sci. Sym. Conference Record 1992.

M. Kobayashi, M. Ishii, C. L. Melcher, Radiation Hardness of LSO:Ce, in IEEE
      Nucl. Sci. Sym. Conference Record 1993.



                                       16
<PAGE>



SCHEDULE D

The objective of Schedule D is to enable STC to transfer the LSO Technology to
CTI for the commercialization of LSO pursuant to this Agreement. To fulfill its
obligations in this respect, STC will make available personnel from
Schlumberger-Doll Research (SDR) until December 31st, 1995 for meetings and
technical support as detailed below. The combined total length of time for this
SDR personnel will be available to CTI is two man months.


Meetings:

SDR and CTI personnel will meet at mutually agreeable locations to:

         (a)   observe and discuss crystal growth equipment;

         (b)   discuss LSO crystal growth parameters and procedures; and

         (c)   observe and verify that the LSO crystal growth protocol has been
         properly implemented.


Technical Support:

If deemed necessary to ensure the success of this Agreement, SDR will, upon
request from CTI:

         (a)   provide seeds and/or boules from which seeds can be cut;

         (b)   provide some parts for seed holder;

         (c)   analyze samples from initial boules grown at CREOL and/or CTI to
         determine crystal quality and scintillation properties;

         (d)   grow at least one boule from standard 4N Lu2O3 supplied by CTI
         for comparison with boules grown at CREOL and/or CTI;

         (e)   grow at least one boule from Lu2O3 purified by CCTI; and

         (f)   analyze and compare properties of crystals grown by CTI and SDR
         from the same raw material.





                                       17
<PAGE>

SCHEDULE C


<Table>
<Caption>

             LSO Manufacturing Cost                       Royalty Rate
               $/cc (Gross Volume)                             %
<S>                                                     <C>
                 10.00 and above                              *
                  9.90-9.99                                   *
                  9.80-9.89                                   *
                  9.70-9.79                                   *
                  9.60-9.69                                   *
                  9.50-9.59                                   *
                  9.40-9.49                                   *
                  9.30-9.39                                   *
                  9.20-9.29                                   *
                  9.10-9.19                                   *
                  9.00-9.09                                   *
                 less than 9.00                               *
</Table>


*Omitted information is the subject of a request for confidential treatment
pursuant to Rule 406 under the Securities Act of 1933 and has been filed
separately with the Securities and Exchange Commission.




<PAGE>




                                 ADDENDUM NO. 1

                                       TO
                EXCLUSIVE PATENT AND TECHNOLOGY LICENSE AGREEMENT



         This ADDENDUM NO. 1 to Exclusive Patent and Technology License
Agreement is made and entered into this 5th day of December, 1995, effective as
of February 1, 1995, by and between Schlumberger Technology Corporation
(hereinafter "STC") and CTI, Inc. (hereinafter "CTI").

         WHEREAS, STC and CTI made and entered into an Exclusive Patent and
Technology License Agreement effective February 1, 1995 (the "License
Agreement") pursuant to which STC granted to CTI certain rights with respect to
Lutetium Oxyorthosilicate Patent Rights and Technology ("LSO Patent Rights" and
"LSO Technology", respectively); and

         WHEREAS, STC and CTI wish to clarify their intention and agreement with
respect to certain provisions of the License Agreement and the meaning of such
provisions.

         NOW, THEREFORE, in consideration of the terms, conditions and
provisions of the License Agreement and the terms, conditions and provisions
hereinafter set forth, the sufficiency and adequacy of which are hereby
acknowledged, STC and CTI hereby agree as follows:

         A. At the time of the execution of the License Agreement, it was the
intention of STC and CTI, and STC and CTI hereby confirm and agree, that the
License Grants Section of the License Agreement, Section 2.0 thereof, and in
particular paragraphs 2.1, 2.2 and 2.3 thereof, do not grant to any Affiliates
of CTI any rights in the LSO Patents and LSO Technology unless and until CTI
shall extend the rights under the LSO Patents and LSO Technology to an Affiliate
and such Affiliate shall execute an agreement in writing on a form to be
provided or approved by STC, to be bound by the terms of the License Agreement
as if such Affiliate had entered into the License Agreement with STC, and a copy
of such agreement shall be furnished to STC.

         B. As clarified by this Addendum No. 1, the License Agreement shall
remain in full force and effect.