<PAGE>

FINOVA
FINANCIAL INNOVATORS

FINOVA CAPITAL CORPORATION                  EQUIPMENT LEASE
HEALTHCARE FINANCE
311 S. WACKER DRIVE, SUITE 4400             NO.            4125
CHICAGO, IL 60606                              ------------------------------

                                            ---------------------------------
                                                 Lessee's Tax ID Number

                              TERMS AND CONDITIONS

FINOVA CAPITAL CORPORATION ("Lessor") agrees to lease to Lessee, and Lessee
agrees to lease from Lessor, the personal property, together with all
attachments, replacements, parts, additions, and accessories ("Equipment")
listed on any Lease Schedule. The words YOU, YOUR, and YOURS mean the Lessee
indicated below. The words WE, US, and OUR refer to the Lessor indicated above.

         1. TERM. The term of this lease will start on the date we sign this
lease ("Lease Commencement Date"). The payments of rent are payable periodically
in advance as stated on any Lease Schedule. You promise to pay the total amount
of all rent payments stated in any Lease Schedule, plus any other amounts
provided for in this lease. This lease cannot be canceled by you.

         2. RENT

             (A) You will pay for use of the Equipment all rent payments and
other amounts provided for in this lease. Consecutive periodic rent payments
will be due on the first day of the month following the Acceptance Date (see
Section 3. Acceptance) of the Equipment (the "Payment Date"). You agree to pay
one prorate rent payment from the Acceptance Date to the first Payment Date. You
will pay all rent payments even if you do not receive a notice that the payments
are due. All rent payments and other amounts due will be made to us at the
address on this lease, or to any other address we designate in writing.

             (B) You will pay a late charge of five percent (5%) on any part of
a rent payment or other amount payable not made by you within five (5) days of
the due date, but only to the extent permitted by law.

             (C) The rent payment on the Lease Schedule shall be raised or
lowered, in a proportionate manner, if there is an adjustment to the equipment
cost, or if a tax is required on the purchase of the Equipment or the rent. We
are authorized by you to insert the amount of the adjusted rent on the
appropriate Lease Schedule.

         3. ACCEPTANCE. On the date the Equipment is available for first use
(the "Acceptance Date"), you will sign and deliver to us an acceptance
certificate in a form satisfactory to us. We may terminate this lease without
cause for any Equipment you have not accepted within six (6) months of our
issuing a purchase order for the Equipment.

         4. NET LEASE. This is a net lease. You promise to pay when due all
taxes, licenses, fines, penalties, and other charges (including but not limited
to personal property, sales, state, Federal, and local taxes) relating to this
lease or the Equipment. Any taxes due will be based on the full amount of the
tax, regardless of any discounts we may receive.

         5. END OF LEASE OPTION; REDELIVERY OF EQUIPMENT; LEASE EXTENSION.

             (A) END OF LEASE OPTION. Provided you are not in default, at the
expiration of the lease term of any Lease Schedule, you have the option to: (i)
renew this lease with respect to all the Equipment on that Lease Schedule for a
term agreeable to us and at a rent equal to the then fair market rental for the
renewal term, payable in advance, or (ii) purchase all, but not less than all,
of the Equipment provided on that Lease Schedule for the then fair market value,
or (iii) return the Equipment to us. You will give us ninety (90) days prior
written notice of the option you choose.

             (B) REDELIVERY OF EQUIPMENT. If you decide not to renew or purchase
all the Equipment, then when the term of that Lease Schedule expires, at your
own risk and expense, you will disconnect, properly package for transportation,
and return the Equipment to us, freight prepaid, to a location designated by us
within the continental United States. You agree to include all


<PAGE>

instruction and service manuals, software documentation, service records, and a
certificate from the manufacturer of the Equipment or other service organization
reasonably acceptable to us that (i) at the time of shipment to us, the
Equipment is in good condition and contains all software and (ii) the
manufacturer will provide an extended maintenance contract to a new user at a
new location to perform the same or similar procedures as performed by you,
without additional costs for repair, refurbishment or software.

      (C) LEASE EXTENSION. If you do not renew, purchase or return the Equipment
as provided above, then this lease shall be extended on a month-to-month basis
for a minimum of six (6) months and you agree to pay us the same rent as stated
on the Lease Schedule. During the month-to-month period, at our option, we may
terminate this lease at any time by giving you ten (10) days notice.

     6. OWNERSHIP; IDENTIFICATION. We are the owner of the Equipment and have
title to the Equipment. If any other person attempts to claim ownership of
the Equipment by asserting that claim against you or through you, you agree,
at your expense, to protect and defend our title to the Equipment. Further,
you agree that you will at all times, and at your expense, keep the Equipment
free from any legal process or lien, and you will give us immediate notice if
any legal process or lien is asserted or made against the Equipment. So long
as you are not in default under any of the terms of this lease, we agree that
you shall quietly use and enjoy the Equipment. We may require plates or
markings be placed on the Equipment indicating our ownership. You represent
that the Equipment shall always remain personal property, even though the
Equipment may become attached to real estate.

     7. COMPLIANCE WITH LAW; INDEMNIFICATION. You will use the Equipment for
business purposes only in compliance with all applicable laws and regulations.
You agree that we are not responsible for any injuries or losses to you or any
other person caused by the installation or use of the Equipment. EXCEPT FOR ACTS
BY US THAT ARE IN VIOLATION OF OUR OBLIGATIONS UNDER THIS LEASE, YOU AGREE TO
INDEMNIFY, HOLD HARMLESS AND DEFEND US FROM AND AGAINST ANY AND ALL CLAIMS,
COSTS, ATTORNEYS' FEES, EXPENSES, DAMAGES AND LIABILITIES ARISING FROM OR
RELATING TO THE POSSESSION, OPERATION, USE, OWNERSHIP, SELECTION, LEASING,
MAINTENANCE, DELIVERY OR RETURN OF ANY OF THE EQUIPMENT.

     You agree that we shall be entitled to deductions and other benefits
provided to an owner of property by federal and state income tax laws,
including deductions for cost recovery and depreciation on the Equipment over
the shortest period available. If we lose the right to claim any benefits, or
any portion of the benefits are disallowed or recaptured as a result of any
omissions, acts, or failures to act by you, you shall pay us an amount, after
deduction of any taxes we must pay on said amount, that allows us to receive
(on an after-tax basis over the full term of the lease) the same rate of
return had there not been a loss or disallowance of benefits. You agree to
pay any interest or penalties due in connection with such loss or
disallowance.

     The indemnities in this section shall continue even after the term of the
lease has expired.

     8. MAINTENANCE. You agree that at your expense you will provide for all
maintenance, service, and repairs necessary to keep all Equipment in good
condition, working order and repair so that it meets or exceeds the
manufacturer's original performance specifications. You may not alter or
modify the Equipment without our prior written permission, which we will not
unreasonably withhold. You agree that all parts, modifications, alterations,
and additions are part of the Equipment and become our property.

     9. DISCLAIMER OF WARRANTIES; LIMITATION OF LIABILITY. WE ARE LEASING THE
EQUIPMENT TO YOU "AS IS", WE MAKE NO WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
PARTICULAR PURPOSE OR ORDINARY USE IN CONNECTION WITH THIS LEASE. If the
seller or anyone else has made a representation or warranty to you as to the
Equipment or any other matter, you agree that such representation or warranty
shall not obligate us, nor shall the breach of such relieve you of, or in any
way affect, any of your obligations to us any this lease. If the Equipment is
not satisfactory for any reason, you shall make your claim only against the
seller and you shall nevertheless pay us all rent payable under this lease.
So long as you are not in default under any of the terms of this lease, we
transfer to you any warranties made to us by the manufacturer or seller. You
understand and agree that the seller, its agents and employees are not agents
of ours, nor are they authorized to waive or change any term or condition of
this lease. YOU AGREE, THAT REGARDLESS OF CAUSE, YOU WILL NOT ASSERT ANY
CLAIM WHATSOEVER AGAINST US FOR LOSS OF PROFITS YOU EXPECTED TO MAKE OR ANY
OTHER DIRECT, SPECIAL OR INDIRECT DAMAGES.

     10. ASSIGNMENT. YOU MAY NOT SELL, TRANSFER, ASSIGN, OR SUBLEASE THE
EQUIPMENT. We may, without notifying you, sell, assign or transfer this lease
and ownership of the Equipment; and you agree that if we do so, the new
lessor will have the same rights and benefits that we now have, and the new
lessor will not have to perform any of our obligations. You agree that the
rights of the new lessor will not be subject to any claims, defenses or
set-offs that you may have against us. However, any such assignment, sale, or
transfer of this lease or the Equipment will not relieve us of our


<PAGE>

obligations to you under this lease. You agree to pay all rent payments and
other amounts due directly to our assignee if we notify you to do so.

     11. INSURANCE; LOSS OR DAMAGE.

      (A) INSURANCE. You agree to maintain liability insurance and keep the
Equipment fully insured against loss until you have met all of your obligations
under this Lease. You agree to provide and maintain, at your expense, insurance
against fire, theft, and all other risks of loss customarily insured against on
the Equipment by businesses like yours, for the greater of the full replacement
value or the Stipulated Loss Value reflected on the attached Exhibit A. Prior to
the Equipment being delivered to you, you agree to provide us with certificates
or other evidence of insurance in a form acceptable to us, from insurers
acceptable to us, that name us as additional insured for liability insurance and
loss payee for property damage insurance, and provide us with at least thirty
(30) days prior written notice if the policy is changed or canceled.

      (B) LOSS OR DAMAGE. You will bear the entire risk of loss and damage
from any cause whatsoever ("Loss"). If a Loss occurs, you shall promptly
notify us and, at our option, either (i) place the Equipment in good
condition and repair; or (ii) replace the Equipment with equipment having the
same value and function which is acceptable to us; or (iii) pay us the fair
value of the Equipment on the date of the Loss, which you agree will be the
sum of (a) the total rent due and owing at the time of such payment, and (b)
the amount arrived at by multiplying the equipment cost by the Stipulated
Loss Value opposite the rent payment number preceding the date of Loss.

     12. USE; LOCATION.

      (A) USE. You shall cause the Equipment to be operated by qualified
personnel only, within its normal capacity, and in accordance with applicable
manufacturers' instructions and governmental regulations. YOU AND YOUR AGENTS
AND EMPLOYEES ASSUME RESPONSIBILITY FOR ANY CLAIMS OR DAMAGES ARISING FROM
SUCH USE. You are responsible for all licenses, permits and consents required
by law or any government body in connection with the Equipment.

      (B) LOCATION. You agree that you will not remove the Equipment from its
place of installation unless you get our written permission in advance.

     13. EVENT OF DEFAULT. You will be default if you (a) do not pay rent or any
other amount payable within ten (10) days of the due date; or (b) break any of
your promises or fail to perform any obligation under this lease and your
failure continues for more than ten (10) days after we send you written notice;
or (c) attempt to remove, sell, or lease any of the Equipment without our
written permission; or (d) are unable to pay your debts as they become due,
assign your assets for the benefit of your creditors, or enter (voluntarily or
involuntarily) a bankruptcy proceeding; or (e) make any representation or
warranties in this lease or the credit information that is misleading or false
in any material respect; or (f) are in default under any material obligation; or
(g) are in default under any other agreement with us or our affiliates.

     14. REMEDIES. If you are in default, we can do any one or more of the
following: (a) require you to pay us the remaining balance of all the rent
payments due under this lease, present valued using a six percent (6%) per year
discount rate; (b) require you to pay us one hundred twenty five percent (125%)
of the then applicable Stipulated Loss Value as liquidated damages; (c) remove
the Equipment from its location; (d) sell or lease any or all of the Equipment
to others or dispose of it; (e) use any of the remedies available to us under
the Uniform Commercial Code or any other law. If we take any action to enforce
this lease or protect our interest in the Equipment, you will pay our actual
costs, including reasonable attorneys' fees. You agree that any delay or failure
to enforce our rights under this lease does not prevent us from enforcing any
rights at a later time.

     15. REPRESENTATIONS AND WARRANTIES OF LESSEE. You represent and warrant
that: (a) you are in good standing under the laws of the jurisdiction under
which you are organized and are fully qualified to do business in each
jurisdiction where your activities require such qualification; (b) you have the
authority and legal right to enter into and perform your obligations under this
lease and any Lease Schedule; (c) the lease and all Lease Schedules are your
valid and binding obligations and are enforceable by us; (d) any approval,
notice, registration, or other action required by your organizational documents,
or any order of any court or other governmental agency in connection with your
signing, delivery, and performance of this lease has been given or obtained; (e)
except as you have disclosed to us in writing prior to our entering into this
lease with you, there are no actions, suits or proceedings pending or, to your
knowledge, threatened against you or your property which, if decided against
you, would have a material unfavorable effect on your financial condition or
your ability to pay us under this lease; (f) the balance sheet and related
statement of income and statement of changes in financial position of Lessee
delivered to us were prepared in conformity with generally accepted accounting
principles and fairly represent your position as of the date of such
statements; (g) you have the right, title or interest in or to the Equipment,
except that given by this lease; (h) as of the Acceptance Date, the Equipment
will be new and unused; and (i) you will not use the Equipment outside the
United States.
<PAGE>

     16. LESSOR'S RIGHT TO PERFORM FOR LESSEE. In the event you fail to comply
with any part of this lease, we can, but we do not have to, take any action
necessary to cause your compliance, without waiving any event of default. If we
are required to pay any amount to obtain your compliance, the amount we pay plus
all of our expenses, including reasonable attorneys' fees, in causing your
compliance, shall become additional rent and shall be paid by you at the time of
the next rental payment due.

     17. REPORTS; INSPECTION.

       (A) REPORTS. Within ninety (90) days after the close of each fiscal
quarter and year, you will provide us with a balance sheet, statement of income,
and statement of changes in your financial position as of the end of such fiscal
quarter and year, in each case audited by independent public accountants if such
audited financial statements are otherwise available. Additionally, you will
provide us such other information we may reasonably request from time to time.

       (B) INSPECTION. Upon our request, you will confirm the location of any
Equipment for us and, at any reasonable time, allow us to inspect and observe
the use and condition of the Equipment and copy your operating and maintenance
records relating to the Equipment.

     18. NOTICE. If any notices or demands are required under this lease, they
shall be sufficient if given in writing either personally or by first-class
mail, postage prepaid, to the addresses in the Lease Schedules, or to any other
address either party may designate in writing. Such notice shall be effective
when deposited in the United States mail.

     19. JURISDICTION. THIS LEASE SHALL BE GOVERNED BY THE LAWS OF THE STATE OF
ARIZONA, THE STATE IN WHICH LESSOR'S PRINCIPAL PLACE OF BUSINESS IS LOCATED. YOU
AGREE THAT THE COURT OF THE STATE OF ARIZONA FOR MARICOPA COUNTY OR ANY OTHER
FEDERAL DISTRICT COURT HAVING THE JURISDICTION IN THAT COUNTY SHALL HAVE
NON-EXCLUSIVE JURISDICTION FOR DETERMINING ALL DISPUTES ARISING UNDER THIS
LEASE. HOWEVER, LESSOR MAY BRING ANY ACTION OR CLAIM TO ENFORCE THE PROVISIONS
OF THIS LEASE IN ANY OTHER APPROPRIATE STATE OR FORUM. YOU WAIVE TRIAL BY JURY
IN ANY ACTION BETWEEN US.

     20. FINANCING STATEMENTS. You give us the right to immediately file any
financing statements and other documents we may require with respect to the
lease and the Equipment, as well as the right to sign any such financing
statements as your attorney-in-fact.

     21. UCC-ARTICLE 2A PROVISIONS. You agree that this lease is a "Finance
Lease" under Article 2A of the Uniform Commercial Code; that is you acknowledge
that (a) we did not select, manufacture or supply the Equipment, but we did
purchase the Equipment for lease to you; and (b) we have given you the name of
the seller of the Equipment you are leasing from us in the Lease Schedule.  You
may have rights under the supply contracts and may contact the seller for a
description of those rights or warranties. To the extent permitted by applicable
law, you waive any and all rights and remedies given to you under UCC Sections
2A-303 and 2A-508 through 522.

     22. PUBLICITY. You authorize us to issue, at our sole option, appropriate
press releases and to cause a tombstone to be published announcing the
completion of this transaction and the total amount of the lease.

     23. MISCELLANEOUS. This lease contains the entire agreement between Lessee
and Lessor and it may not be altered, amended, modified, terminated or
otherwise changed except in writing and signed by both parties. This lease is
for the benefit of and obligates you and your personal representatives,
successors and assigns.  The captions used in this lease are for convenience
only and shall not define or limit any of the terms of this lease.  If more than
one Lessee is named in the lease and any Lease Schedule, the liability of each
Lessee shall be joint and several.


     The parties here to have executed this lease dated as of the ___ day of
_________________ , 19__.


  FINOVA CAPITAL CORPORATION                 MOBILE PET SYSTEMS, INC.
-------------------------------------      -------------------------------------
  Lessor                                     Lessee


  By:                                        By:
     --------------------------------           --------------------------------
                          Title                                      Title

<PAGE>

                                                                          [LOGO]
                                                            FINANCIAL INNOVATORS

LEASE SCHEDULE                                       FINOVA CAPITAL CORPORATION
NO. 4125.01                                          311 SOUTH WACKER DRIVE
                                                     SUITE 4400
                                                     CHICAGO, ILLINOIS 60606


     The following described equipment and accessories are leased by Lessor to
     Lessee, on the terms specified in this Lease Schedule, subject to the terms
     and conditions of the Equipment Lease Number 4125 dated ___________ , 1999.



1.   DESCRIPTION OF EQUIPMENT: One (1) Calumet Coach Company Model MMS-381P
     Mobile Unit with One (1) Siemens ECAT EXACT P.E.T. Scanner System as
     further itemized on the Equipment Schedule Addendum No. One attached
     hereto and made a part hereof.


2.       SELLER:                 See Addendum No. One attached hereto and made
                                 a part hereof.
                 ---------------------------------------------------------------


         SELLER'S ADDRESS:       See Addendum No. One attached hereto and made
                                 a part hereof.
                          ------------------------------------------------------


--------------------------------------------------------------------------------
3.   TERM:      60 MONTHS                   4. SECURITY DEPOSIT:        N/A
           --------------------                                  ---------------

5. RENTAL PAYMENTS: $16,000.00 per period for the three (3) consecutive monthly
rental periods; 22,000.00 per period for the next three (3) consecutive monthly
rental periods; and $34,8885.28 per period for the remaining fifty four (54)
consecutive rental periods.

         To each rental payment, when paid, shall be added the amount of any
applicable sales or use tax.

6.   ADVANCE RENTALS: $  16,000.00     to be applied to the       FIRST
                     ------------------                     --------------------
rental payments.
--------------------------------------------------------------------------------


7.   EQUIPMENT LOCATION:   2240 Shelter Island Drive, Suite 110      San Diego
                        --------------------------------------------------------
                           (Street)                                   (City)

                         San Diego                                     CA
                        --------------------------------------------------------
                           (County)                                   (State)

8.   LESSEE'S ADDRESS ( if different than paragraph 7 above):

--------------------------------------------------------------------------------
  (Street)                (City)                 (State)          (Zip Code)


9.   Other Provisions
     -    Addendum No. One, Two and Three attached hereto and made a part
          hereof.
     -    "Notwithstanding anything to the contrary in Equipment lease F4125 and
          provided Lessee is not in default thereunder, Lessee, upon giving
          Lessor ninety (90) days prior written notice, shall have a one time
          Option to Purchase not less than all the Equipment under this Lease at
          maturity of the base lease term for the then fair market value not to
          exceed twelve percent (12.00%) of the original equipment cost a paid
          by Lessor the Equipment and any other items or charges included in the
          Lease plus applicable sales taxes."
     -    FINOVA has the option to adjust its monthly payment consistent with
          increases in the five-year, fixed-rate cost of financing from the date
          of this Lease Schedule to delivery and acceptance of the Equipment.
          Upon acceptance of the Equipment, the monthly payment will become
          fixed for the entire term.

The parties hereto have executed this Lease Schedule as of the_____________ day
of___________ , 19________.


FINOVA CAPITAL CORPORATION                   MOBILE PET SYSTEMS, INC.
---------------------------------            -----------------------------------
Lessor                                       Lessee

By:                                          By:
   ------------------------------               --------------------------------
                       Title                                       Title


<PAGE>

                                ADDENDUM NO. ONE
                                       TO
                           LEASE SCHEDULE NO. 4125.01
                                     BETWEEN
                       FINOVA CAPITAL CORPORATION (LESSOR)
                                       AND
                        MOBILE PET SYSTEMS, INC. (LESSEE)

          Dated the _______________day of__________________, 19_______

                               EQUIPMENT SCHEDULE

Equipment provide by: Siemens Medical Systems, Inc., 186 Wood Avenue South
Iselin, NH 08830-0401

-    One (1) Siemens ECAT EXACT P.E.T. Scanner System


               The ECAT EXACT is a high-resolution positron emission tomography
               system for imaging biochemical processes and metabolism for whole
               body applications. The multi-detector ring system provide 3D
               aquisition and reconstruction in the static and dynamic modes.

               The ECAT EXACT consist of a 47 image plane system with a 16.2 cm
               (6.4 in ) field of view.

               -    High spatial slice resolution in transaxial and axial
                    dimensions
               -    Three-dimensional display of organs with a large axial view
               -    Excellent volume sensitivity
               -    Fast aquisition and reconstruction of 64 X 64 and 128 X 128
                    matrixes
               -    High-resolution, flicker free, color display monitor
               -    Unique block detector technology provides excellent temporal
                    and energy resolution response
               -    Simultaneous data aquisition and image reconstruction for
                    high patient throughput
               -    Retractable rotating rod source holders for quick and
                    accurate attenuation correction. (Ge-68 is available in
                    safe, solid form from recommended vendors).
               -    Water-cooled gantry for quiet operation.
               -    Window-oriented operating software.

               The system consists of:

               Whole Body Ring Detector Gantry:

               -    824 mm detector ring diameter.

               -    56.2 cm gantry aperture

               -    16.2 cm (6.4 inch) axial field of view

               -    Nine laser lines for precise, reproducible patient
                    positioning

               -    Dual operator controls on gantry for positioning from either
                    side of patient

               -    Count rate monitor on gantry control panels


                                       1
<PAGE>

                                ADDENDUM NO. ONE
                                       TO
                            LEASE SCHEDULE NO. 4125.01
                                     BETWEEN
                        FINOVA CAPITAL CORPORATION (LESSOR)
                                       AND
                         MOBILE PET SYSTEMS, INC. (LESSEE)

    Dated the ________________ day of _________________________, 19_______

                                EQUIPMENT SCHEDULE


      *  Three integrated retractable transmission rod source holders which
         extend/retract from a lead housing under computer control for enhanced
         patient throughout and reduced radiation exposure.


      Patient Handling System:
      *  Low attenuation foam core carbon fiber pellet
      *  57 to 93 cm (22 to 36 inch) vertical motion range
      *  195 cm (77 inch) horizontal scan range
      *  Low attenuation head holder
      *  Maximum patient weight of 159 kg (350 lbs.).

      Data Acquisition/Processing and Storage Electronics:
      *  Image plane coincidence processor
      *  Real-time sorter (RTS) with 64 MB memory
      *  VME Bus acquisition controller
      *  1 Quad i660 array processor
      *  SCSI (small computer system interface) adapter to the VME Bus
      *  2.0 GB acquisition disk
      *  Ethernet interface to operator's console
      *  Sparc processor

      Operator's Console for Image Display and Analysis:
      *  UltraSPARC 60 1300 Workstation with 20 inch, high resolution monitor
      *  256 MB main memory
      *  1 x 4.2, 1 x 9.0 GB internal disk storage
      *  2.6 GB erasable optical storage system for archiving image data
      *  CD ROM drive (mounted in desktop storage unit)
      *  600 dpi laser printer
      *  Ethernet connection to data acquisition/processing and storage
         electronics.
      *  4mm DAT (digital audio tape) archive system, mounted in desktop
         storage unit.
      *  UNIX operating system and utilities
      *  TCP/IP and network file system communication software.
      *  Floppy drive
      *  ECAT Software version 7.1 features, including interactive
         reconstruction, segmented attenuation correction, and the whole body
         protocol.


                                       2
<PAGE>

      ECAT STANDARD SOFTWARE
      Image Acquisition:
      *  Transmission scan allows accurate measurement of tissue attenuation
         correction coefficients
      *  Static emission scan
      *  Dynamic emission scan
      *  Acquisition protocols
      *  Image reconstruction and processing
      *  Wide variety of reconstruction filters
      *  Image size and displacement parameters
      *  Calculated or measured attenuation correction.

      Display Software:
      *  Window-oriented to allow simultaneous acquisition, reconstruction,
         data processing and image display
      *  image zoom and magnification
      *  Multi-image static display
      *  Any oblique data re-orientation
      *  Cine mode display
      *  Multiple plane dynamic displays
      *  Region of interest and image profiles
      *  Image filtering, summing and arithmetic
      *  Regions of interest and image statistics
      *  Screen save/restore operations
      *  Image labeling with variable fonts and graphics
      *  Interactive color translation table operations
      *  Three-dimensional volume interactive data reveiw (transverse, sagital
         and coronal displays).

      Utilities Software:
      *  Patient database
      *  Patient data archive
      *  Motion control
      *  System calibration
      *  System normalization
      *  Performance tests
      *  System diagnostics.

      Educational Software:
      *  Multi-media educational package LPP (Let's Play PET) for use on
         separate Macintosh) or ICON (not provided with system).


                                       3

<PAGE>

                             ADDENDUM NO. ONE
                                     TO
                        LEASE SCHEDULE NO. 4125.01
                                  BETWEEN
                    FINOVA CAPITAL CORPORATION (LESSOR)
                                    AND
                      MOBILE PET SYSTEMS, INC. (LESSEE)

Dated the __________________ day of ________________________________, 19______

                             EQUIPMENT SCHEDULE


               Systems Documentation (1 set):
               -  ECAT scanner software manual
               -  ECAT scanner hardware manual.

               -  Water-cooled, whole-body gantry
               -  D216 Bismuth germanate (BGO) crystals
               -  18.2 cm (6.4 inch) axial field of view
               -  Simultaneous acquisition of up to 47 contiguous slices
               -  23 interplane retractable septs for high axial resolution,
                  high sensitivity, and minimum scatter to permit 3-D
                  acquisition.
               -  Full-body patient couch and head holder
               -  Data acquisition and electronics
               -  ECAT Software
               -  Operators console and peripherals

         2       1782188      PRE-INSTALL KIT EXACT 31/47

         2       3549560      ISOLATION TRANSFORMER (US)

               Transformer for isolating ECAT power from line power

         2       3552948      GANTRY AIR/WATER CHILLER (60HZ)

               Closed system air/water chiller. Requires onsite chilled
               water. Requires siting in well-ventilated utility room.

         2       2964901      ECAT EXACT INSTALLATION #USA

               Installation by the SMS PET Group is available.

000700  10       5220228      PET APPLICATIONS TRAINING (PER DAY)

               Operator's training for ECAT Scanners performed by
               applications specialist. Scheduling for training is available
               upon request. Standard 7.1 software training consists of 5
               working days. New scanner installation training consists of
               five to ten working days.

                                       4

<PAGE>

                             ADDENDUM NO. ONE
                                     TO
                        LEASE SCHEDULE NO. 4125.01
                                  BETWEEN
                    FINOVA CAPITAL CORPORATION (LESSOR)
                                    AND
                      MOBILE PET SYSTEMS, INC. (LESSEE)

Dated the __________________ day of ________________________________, 19______

                             EQUIPMENT SCHEDULE


Equipment provided by: Calumet Coach Company, 2150 East Dolton Road,
Calumet City, IL 60409-1411

One (1) Calumet Coach Model MMS-381P 8' x 40' Self-Propelled Mobile Unit for
the Siemens ECAT P.E.T. Scanner described above.

VEHICLE IDENTIFICATION NUMBER:  _________________________________










FINOVA CAPITAL CORPORATION             MOBILE PET SYSTEMS, INC.
----------------------------------     -----------------------------------
Lessor                                 Lessee

By:                                    By:
   -------------------------------        --------------------------------
                       Title                                  Title

(720/R0195)

                                       5


<PAGE>

                                ADDENDUM NO. TWO
                                      TO
                           LEASE SCHEDULE NO. 4125.01
                                    BETWEEN
                      FINOVA CAPITAL CORPORATION (LESSOR)
                                      AND
                       MOBILE PET SYSTEMS, INC. (LESSEE)

INTERIM RENT:

Notwithstanding anything to the contrary in the Lease, Lessor and Lessee hereby
agree that COMPUTERS UNLIMITED ("Seller") is providing Equipment under the Lease
and requires that advance monies be paid by Lessor prior to delivery and
acceptance by Lessee. The advance required by Seller is TWENTY PERCENT (20%) of
the purchase price to be paid by customer upon issuance of the purchase order to
Seller; Fifty Percent (50%) of the purchase price upon the completion, and
THIRTY PERCENT (30%) of the purchase price plus applicable sales tax upon
Lessor's receipt of Lessee's written acceptance of the Equipment.

To compensate Lessor for performing as described above, Lessee agrees to pay
Lessor rental(s), monthly in arrears, computed at two percent (2%) over the
prime rate as quoted in the Wall Street Journal, which rate shall be adjusted
accordingly as such prime rate changes from time to time during the term of
this Interim Rent Agreement, from the day said advance monies are paid by
Lessor for the actual number of days such advances are outstanding ("Interim
Rent").

The Interim Rent chargeable to the Lessee shall terminate upon Lessor's receipt
of Lessee's written acceptance of the equipment for the purpose of the Lease and
the commencement of the basic lease term, in accordance with the terms of the
Lease, at which time the full lease rental under the Lease ("Basic Rental") will
commence.

The monies advanced by Lessor to Seller as aforesaid are in any and all
events an obligation of Lessee. Lessee agrees to promptly reimburse Lessor in
the event, and for any reason whatsoever, Lessee does not accept the
Equipment. In addition, Lessee agrees to hold Lessor harmless from any and
all claims by the Seller arising out of Lessee's failure or refusal to accept
the Equipment.

The undersigned agree to all the terms and conditions set forth above and IN
WITNESS WHEREOF, Lessor and Lessee hereby execute this Addendum this _____ day
of _________, 19__.

FINOVA CAPITAL CORPORATION          MOBILE PET SYSTEMS, INC.
--------------------------          ------------------------
Lessor                              Lessee

By:                                 By:
   -----------------------          ------------------------
                    Title                             Title

<PAGE>

                                                      FINOVA CAPITAL CORPORATION
                                              311 SOUTH WACKER DRIVE, SUITE 4400
                                                           CHICAGO IL 60606-6618

                            DELIVERY AND ACCEPTANCE

                                                      LEASE SCHEDULE NO. 4125.01

                        DESCRIPTION OF LEASED EQUIPMENT

One (1) Calumet Coach Company Model MMS-381P Mobile Unit with one (1) Siemens
ECAT EXACT P.E.T. System as further itemized on the Equipment Schedule Addendum
No. One attached hereto and made a part hereof.

TO LESSEE:       PLEASE SIGN THIS ACCEPTANCE WHEN YOU HAVE RECEIVED THE ABOVE
                 DESCRIBED PROPERTY.

         The undersigned acknowledges that: (1) the undersigned has fully
inspected the Equipment that has heretofore been delivered to the undersigned
(2) said Equipment is in full compliance with the terms of the Lease pertaining
thereto; (3) said Equipment has not been delivered to the undersigned, nor
installed, on a trial basis; (4) said Equipment is in good condition (operating
and otherwise) and repair; (5) the undersigned accepts said Equipment, as is and
where is; and (6) the Lease is a net lease, with personal property tax, public
liability insurance and insurance for damage and theft to be for Lessee's
account. The undersigned confirms that FINOVA Capital Corporation ("FINOVA") has
made no warranty or representation, express or implied, of the merchantability,
fitness, design, condition, workmanship or otherwise of the Equipment.

         It is further understood that FINOVA shall not be responsible for
any third-party contracts or other agreements other than FINOVA's obligation
to pay the purchase price for the Equipment, pursuant to the terms and
conditions set forth in the Purchase Order issued by FINOVA to the Seller of
the Equipment unless specifically included in the Lease; that default of such
agreements, if any, shall in no way affect the responsibility of the
undersigned for payment of the Lease in accordance with its terms.

                                    MOBILE PET SYSTEMS, INC.

                                    -------------------------------------------
                                    Lessee

                                    By:
                                      -----------------------------------------
                                                                         Title
                                    Date:
                                         --------------------------------------


<PAGE>

                              LOSS PAYABLE CLAUSE
                                      AND
                            ADDITIONAL NAMED INSURED
                                                               Lease No. 4125.01
To: FINOVA Capital Corporation
    311 South Wacker Drive, Suite 4400
    Chicago, IL  60606-6618

THIS IS TO CERTIFY THAT COVERAGES ARE PROVIDED UNDER THE POLICY NUMBERS BELOW
FOR THE FOLLOWING INSURED:

NAME OF INSURED:    MOBILE PET SYSTEMS, INC.

EQUIPMENT COST:     $1,577,500.00

EQUIPMENT LOCATION: 2240 SHELTER ISLAND DRIVE, SUITE 110, SAN DIEGO, CA 92106

EQUIPMENT DESCRIPTION: One (1) Calumet Coach Company Model MMS-381P Mobile Unit
with one (1) Siemens ECAT EXACT P.E.T. System as further itemized on the
Equipment Schedule Addendum No. One attached hereto and made a part hereof.

I.    ALL RISK PHYSICAL DAMAGE COVERAGE
      A.   Insurance Company: _________________________________
      B.   Policy Number: _________________________
      C.   Expiration Date of Policy: _____________
      D.   FINOVA CAPITAL CORPORATION IS NAMED AS LOSS PAYEE AS ITS INTEREST
           MAY APPEAR.

II.   COMPREHENSIVE GENERAL LIABILITY COVERAGE:
      A.   Insurance Company: _________________________________
      B.   Policy Number: _________________________
      C.   Expiration Date of Policy: _____________
      D.   Limits:
                    Bodily Injury (each occurrence): ___________________
                    Property Damage (each occurrence): _________________
      E.   FINOVA CAPITAL CORPORATION IS NAMED AS ADDITIONAL INSURED.

Coverage may be canceled by the company by mailing to FINOVA Capital
Corporation, at the address shown below, written notice stating when, not less
than (30) days thereafter, such cancellation shall be effective.  SUBSEQUENT
RENEWALS, CANCELLATIONS, ETC. SHOULD BE SENT TO FINOVA CAPITAL CORPORATION,
DIAL TOWER, 1850 NORTH CENTRAL AVENUE, PHOENIX, ARIZONA 85002-2209.

Dated:________________________                 _________________________________
                                                 (INSURANCE AGENCY OR COMPANY)

                                                By:_____________________________
                                                       (ORIGINAL AUTHORIZED
                                                          SIGNATURE/STAMP)

Agents Phone #:_______________                  Address:________________________

Fax #:_________________________                         ________________________

<PAGE>

                                     INVOICE
                                   F I N O V A
                           FINOVA CAPITAL CORPORATION
                               HEALTHCARE FINANCE
             311 SOUTH WACKER DRIVE, SUITE 4400, CHICAGO, IL 60606
                                 (800)662-6268


--------------------------------------------------------------------------------
MOBILE PET SYSTEMS, INC.



--------------------------------------------------------------------------------
2240 SHELTER ISLAND DRIVE, SUITE 110
--------------------------------------------------------------------------------
SAN DIEGO, CA 92106
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
4125.01                                                             3/15/99
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
         FIRST MONTHLY ADVANCE RENTAL DUE                           $16,000.00
--------------------------------------------------------------------------------
         RENTAL TAX @ 7.75%                                           1,240.00
--------------------------------------------------------------------------------
         UCC/TITLE FEE                                                  125.00
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
         TOTAL AMOUNT DUE                                           $17,365.00
--------------------------------------------------------------------------------

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

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

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

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

<PAGE>

                                            THIS SPACE FOR USE OF FILING OFFICER
--------------------------------------------

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

--------------------------------------------
0090893000279001

FINANCING STATEMENT - FOLLOW INSTRUCTIONS CAREFULLY

THIS FINANCING STATEMENT IS PRESENTED FOR FILING PURSUANT TO THE UNIFORM
COMMERCIAL CODE AND WILL REMAIN EFFECTIVE, WITH CERTAIN EXCEPTIONS, FOR 5 YEARS
FROM DATE OF FILING.

<TABLE>
<S><C>
--------------------------------------------------------------------------------------------------
A.  NAME & TEL # OF CONTACT AT FILER (OPTIONAL)                B. FILING OFFICE ACCT # (OPTIONAL)

--------------------------------------------------------------------------------------------------
C.  RETURN COPY TO: (NAME AND MAILING ADDRESS)

         UCC PROCESSING CENTER

         P.O. BOX 239

         VAN NUYS, CA 91408-0239
------------------------------------------------------------------------------------------------------------------------------------
         [ILLEGIBLE]
------------------------------------------------------------------------------------------------------------------------------------
1.  DEBTOR'S EXACT FULL LEGAL NAME - INSERT ONLY ONE DEBTOR NAME (1a OR 1b)     FILED WITH       CALIFORNIA
    --------------------------------------------------------------------------------------------------------------------------------
     1a.  ENTITY'S NAME
      MOBILE PET SYSTEMS, INC.

    --------------------------------------------------------------------------------------------------------------------------------
OR
     1b.  INDIVIDUAL'S LAST NAME                               FIRST NAME             MIDDLE NAME                      SUFFIX

------------------------------------------------------------------------------------------------------------------------------------
1c.  MAILING ADDRESS                                           CITY                   STATE        COUNTRY      POSTAL CODE
         2240 SHELTER ISLAND DRIVE, SUITE 11                   SAN DIEGO              CA                        92106

------------------------------------------------------------------------------------------------------------------------------------
1d.   S.S. OR TAX I.D.#       OPTIONAL    1e. TYPE OF ENTITY   1f. ENTITY'S STATE     1g. ENTITY'S ORGANIZATIONAL I.D. # IF ANY
                          ADD'NL INFO RE                           OR COUNTRY OF
                           ENTITY DEBTOR                           ORGANIZATION                                         / / NONE
------------------------------------------------------------------------------------------------------------------------------------
2.  ADDITIONAL DEBTOR'S EXACT FULL LEGAL NAME - INSERT ONLY ONE DEBTOR NAME (2a OR 2b)
    --------------------------------------------------------------------------------------------------------------------------------
     2a.  ENTITY'S NAME

OR
    --------------------------------------------------------------------------------------------------------------------------------
     2b.  INDIVIDUAL'S LAST NAME                               FIRST NAME             MIDDLE NAME                      SUFFIX

------------------------------------------------------------------------------------------------------------------------------------
2c.  MAILING ADDRESS                                           CITY                   STATE        COUNTRY      POSTAL CODE

------------------------------------------------------------------------------------------------------------------------------------
2d.   S.S. OR TAX I.D.#       OPTIONAL    2e. TYPE OF ENTITY   2f. ENTITY'S STATE     2g. ENTITY'S ORGANIZATIONAL I.D. # IF ANY
                          ADD'NL INFO RE                           OR COUNTRY OF
                           ENTITY DEBTOR                           ORGANIZATION                                         / / NONE
------------------------------------------------------------------------------------------------------------------------------------
3.  SECURED PARTY'S (ORIGINAL S/P OR ITS TOTAL ASSIGNEE) EXACT FULL LEGAL NAME - INSERT ONLY ONE SECURED PARTY NAME (3a OR 3b)
------------------------------------------------------------------------------------------------------------------------------------
     3a.  ENTITY'S NAME
      FINOVA CAPITAL CORPORATION
OR
    --------------------------------------------------------------------------------------------------------------------------------
     3b.  INDIVIDUAL'S LAST NAME                               FIRST NAME             MIDDLE NAME                      SUFFIX

------------------------------------------------------------------------------------------------------------------------------------
3c.  MAILING ADDRESS                                           CITY                   STATE        COUNTRY      POSTAL CODE
         3200 PARK CENTER DRIVE                                COSTA MESA             CA                        92626
         FIFTH FLOOR

------------------------------------------------------------------------------------------------------------------------------------
4.  THE FINANCING STATEMENT COVERS THE FOLLOWING TYPES OR ITEMS OF PROPERTY

ONE (1) SIEMENS ECAT EXACT MOBILE P.E.T. SCANNER SYSTEM FURTHER ITEMIZED ON THE EQUIPMENT SCHEDULE ADDENDUM NO.
ONE ATTACHED HERETO AND MADE A PART HEREOF, TOGETHER WITH ACCESSIONS, APPURTENANCES, ACCESSORIES THERETO ALL AS
DESCRIBED IN LEASE SCHEUDLE NO. 4125.01 BETWEEN SECURED PARTY AS LESSOR AND DEBTOR AS LESSEE.  NEITHER THE
EXECUTION NOR FILING OF THIS FINANCING STATEMENT SHALL IN ANY MANNER IMPLY THAT THE RELATIONSHIP BETWEEN THE
SECURED PARTY AND DEBTOR IS OTHER THAN LESSOR AND LESSEE RESPECTIVELY.  THIS FINANCING STATEMENT IS FILED SOLELY
TO PROTECT THE INTEREST

OF THE PARTIES IN THE EVENT OF UNWARRANTED ASSERTIONS BY ANY THIRD PARTY.  PROCEEDS OF THE COLLATERAL ARE ALSO
COVERED.


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</TABLE>


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