REGISTRATION RIGHTS AGREEMENT


     THIS  REGISTRATION  RIGHTS AGREEMENT  ("Agreement") is dated as of June 29,
2001 by and between POSITRON  CORPORATION,  a Texas corporation  ("Company") and
IMATRON  INC.,  a New Jersey  corporation  ("Imatron")  in  connection  with the
issuance of a Warrant to purchase 6,000,000 shares of the Company's Common Stock
("Warrant")  and the  execution of that  certain  Loan  Agreement by and between
Company and Imatron of even date.

     NOW,  THEREFORE,  in  consideration  of the mutual covenants and agreements
contained in the Loan Agreement, the Warrant and herein, the Company and Imatron
hereby agree as follows:

     Capitalized  terms used in this  Agreement but not otherwise  defined shall
have the respective meanings ascribed thereto in the Loan Agreement.

                                   ARTICLE I

                               Registration Rights
                               -------------------

     SECTION 1.01  Definitions. As used in this Article

          (a) The terms "register",  "registered" and "registration"  refer to a
registration  effected  by  preparing  and filing a  registration  statement  in
compliance with the Securities Act (and any  post-effective  amendments filed or
required to be filed) and the declaration or ordering of  effectiveness  of such
registration  statement by the Securities and Exchange Commission  ("SEC");

          (b)  "Registration  Expenses" shall mean all expenses  incurred by the
Company in compliance with Sections 1.02, 1.03, 1.04 and 1.05 hereof, including,
without limitation,  all registration and filing fees,  printing,  messenger and
delivery expenses,  fees and disbursements of counsel for the Company,  blue sky
fees and expenses (including,  without limitation,  fees and expenses of counsel
for  the  underwriters  in  connection  with  blue  sky  qualifications  of  the
Registrable  Securities),  all fees and expenses incurred in connection with the
listing of the  Registrable  Securities  on a national  securities  exchange  or
automated quotation system pursuant to Section 1.06(a)(x) and the expense of any
special audits and/or "cold comfort" letters incident to or required by any such
registration,   liability  insurance  if  the  Company  so  desires  or  if  the
underwriters  so require  and the  reasonable  fees and  expenses of any special
experts  retained  by the  Company  in  connection  with the  registration  (but
excluding the compensation of regular  employees of the Company,  which shall be
paid in any  event  by the  Company);

          (c)  "Selling  Expenses"  shall mean all  underwriting  discounts  and
selling  commissions  applicable to the sale of  Registrable  Securities and all
fees and disbursements of counsel for Imatron; and

          (d)  "Imatron"  shall  mean  IMATRON  INC.  or any  Affiliate  holding
Registrable Securities.

          (e)  "Registrable  Securities"  shall mean (i) shares of Common  Stock
issued or  issuable  pursuant  to the  exercise  of the  Warrant or any  portion
thereof and (ii) any Common  Stock  issued as a dividend  or other  distribution
with respect to or in exchange for and in replacement  of the shares  referenced
in clause (i) above,  provided  however that  Registrable  Securities  shall not
include ay shares of Common Stock which have previously been registered or which
have been sold to the public either pursuant to a registration statement or Rule
144, or which have been sold in a private  transaction in which the transferor's
rights  under  this  Agreement  are  not  assigned.

     SECTION 1.02  Piggy-Back Registration.
                   -----------------------

          (a) Right to Include Registrable  Securities.  If at any time and from
time to time the  Company  proposes  to register  under the  Securities  Act any
shares of capital stock held by shareholders of the Company,  on a form and in a
manner  that  would  permit  registration  of  some  or all  of the  Registrable
Securities  for the sale to the public  under the Act,  the  Company  shall give
prompt written notice to the Holders of Registrable  Securities of its intention
to do so. Upon the written request of any Holder of Registrable Securities given
within ten (10) days after the giving of such notice by the Company, the Company
shall  use  its  reasonable  best  efforts  to  cause  to be  included  in  such
registration  statement  all of the  Registrable  Securities  so  requested  for
inclusion by such Holder. If the registration statement is to cover, in whole or
in part, any underwritten  distribution,  the Company shall use its best efforts
to cause the  Registrable  Securities  requested for inclusion  pursuant to this
Section 1.02 to be included in the underwriting on the same terms and conditions
(including  any  lock-up)  as  the  shares  otherwise  being  sold  through  the
underwriters.

          (b)  Priority  in  Incidental  Registrations.  If,  in the good  faith
judgment of the  lead-managing  underwriter of any  underwritten  offering,  the
inclusion of all of the Registrable  Securities requested for inclusion pursuant
to this  Section  1.02 would  materially  and  adversely  affect the  successful
marketing of the proposed  offering,  then the number of shares of capital stock
and Registrable Securities, if any, to be included in such registration shall be
reduced, such reduction to be applied by excluding (on a pro rata basis) capital
stock  to be sold  by  Persons  other  than  the  Company.  Notwithstanding  the
foregoing  provisions,  the  Company may  withdraw  any  registration  statement
referred to in this Section 1.023 without  incurring any liability to any holder
of Registrable Securities.

     SECTION 1.03  Expenses of Registration.
                   ------------------------

     All  Registration  Expenses  incurred  in  connection  with any Piggy  Back
Registration  Statement,  qualification or compliance pursuant to this Article I
shall  be borne  by the  Company,  and  Selling  Expenses  shall be borne by the
Holders of Registrable Securities included in such registration.

     SECTION 1.04  Registration Procedures.
                   -----------------------

          (a) In the case of each registration  effected by the Company pursuant
to Section 1.02,  the Company will keep each Holder advised in writing as to the
initiation  of  each  registration,  and as to the  completion  thereof.  At its
expense,  the Company  will use its  reasonable  best  efforts to:

               (i) Keep such registration effective for a period of at least one
hundred and eight (180) days or until the Holder has completed the  distribution
described  in the  registration  statement  relating  thereto,  whichever  first
occurs;  provided  however that (i) such 180-day  period shall be extended for a
period  of time  equal to the  period  the  Holder  refrains  from  selling  any
securities  included in such  registration  at the request of an  underwriter of
Common Stock (or other  securities) of the Company;  and (ii) in the case of any
registration  of  Registrable  Securities  on Form S-3 which are  intended to be
offered on a continuous or delayed basis, such 180-day period shall be extended,
if  necessary,  to keep the  registration  statement  effective  until  all such
Registrable  Securities are sold,  however in no event longer than one year from
the effective date of the registration  statement and provided that Rule 145, or
any successor rule under the Securities Act, permits an offering on a continuous
or  delayed  basis,  and  provided  further  that  applicable  rules  under  the
Securities  Act governing  the  obligation  to file a  post-effective  amendment
permit,  in lieu of filing a  post-effective  amendment  that (A)  includes  any
prospectus  required by Section  10(a)(3) of the  Securities Act or (B) reflects
facts or events representing a material or fundamental change in the information
set forth in the  registration  statement,  the  incorporation  by  reference of
information  required  to be included  in (A) and (B) above to be  contained  in
periodic  reports  filed  pursuant to Section 13 or 15(d) of the Exchange Act of
1934 in the registration statement;

               (ii)  Prepare  and  file  with  the  SEC  such   amendments   and
supplements to such Registration Statement and the prospectus used in connection
therewith as may be necessary to keep such Registration  Statement effective for
at least 180 days and to comply with the  provisions of the  Securities Act with
respect to the offer of the Registrable  Securities covered by such Registration
Statement  during  the  period  required  for  distribution  of the  Registrable
Securities;

               (iii)  Furnish such number of  prospectuses  and other  documents
incident thereto, including any amendment of or supplement to the prospectus, as
Holder from time to time may reasonably request;

               (iv) Register or qualify,  not later than the  effective  date of
any filed  Registration  Statement,  the Registrable  Securities covered by such
Registration  Statement  under  the  securities  or  "blue  sky"  laws  of  such
jurisdictions as such holders of Registrable Securities reasonably request;

               (v) Cause all such  Registrable  Securities  registered  pursuant
hereunder to be listed on each securities  exchange on which similar  securities
issued by the Company are then listed;

               (vi) If the Registrable  Securities  covered by the  Registration
Statement are to be sold through one or more underwriters,  make available, upon
reasonable  notice and during business hours, for inspection by such underwriter
or  underwriters  (collectively,  the  "Inspectors"),  all  financial  and other
records, pertinent corporate documents, agreements and properties of the Company
(collectively  the  "Records") as shall be necessary to enable the Inspectors to
conduct due diligence to their reasonable satisfaction,  and cause the Company's
officers, directors and employees to supply all information reasonably requested
by any such Inspector in connection with the Registration Statement;

               (vii)  if  the  Registrable  Securities  covered  by  the  Demand
Registration Statement are to be sold through one or more underwriters, obtain a
comfort letter from the Company's  independent  public  accountants dated within
five  business  days  prior to the  effective  date of the  Demand  Registration
Statement (and as of such other dates as the underwriter or underwriters for the
Registrable  Securities may  reasonably  request) in customary form and covering
such matters of the type  customarily  covered by such  comfort  letters as such
underwriter or underwriters reasonably request;

               (viii)  During the  Registration  Period,  notify the  holders of
Registrable  Securities  of the  happening  of any event  which  results  in the
prospectus included in the Registration Statement containing an untrue statement
of a material  fact or omitting to state any material fact required to be stated
therein  or  necessary  to  make  the  statements   therein,  in  light  of  the
circumstances  under which they were made, not misleading,  and the Company will
forthwith  prepare a  supplement  or amendment to such  prospectus  so that,  as
thereafter  delivered to the shareholders of such Registrable  Securities,  such
prospectus  will not contain an untrue  statement of a material  fact or omit to
state any material fact  required to be stated  therein or necessary to make the
statements  therein,  in light of the circumstances  under which they were made,
not misleading; and

               (ix)  Otherwise  use  reasonable   efforts  to  comply  with  all
applicable  rules and  regulations of the SEC, and make available to the holders
of the Company's  Common Stock, as soon as reasonably  practicable,  an earnings
statement  governing a period of twelve  months,  beginning  within three months
after the effective date of the Registration Statement, which earnings statement
shall satisfy the provisions of Section 11(a) of the Act.

          (b) The holders of Registrable  Securities shall timely furnish to the
Company  such  information   regarding  the  distribution  of  such  Registrable
Securities as the Company may from time to time reasonably request.

          (c) The holders of  Registrable  Securities  shall agree that upon the
receipt of any notice from the Company of the happening of any event of the kind
described in paragraph  (a)(vii) above, such holders will forthwith  discontinue
disposition of Registrable  Securities  pursuant to the  Registration  Statement
covering such  Registrable  Securities until receipt by Imatron of the copies of
the  supplemented  or amended  prospectus  contemplated  by paragraph  (a)(viii)
above.

     SECTION  1.05 .  Indemnification.
                      ---------------

          (a) The Company will  indemnify  the relevant  holders of  Registrable
Securities,  their respective officers,  directors and partners, and each Person
controlling  any of them,  with  respect  to each  registration  which  has been
effected pursuant to this Article I (a "Registration"), and each underwriter, if
any, and each Person who controls any underwriter,  against all claims,  losses,
damages and liabilities (or actions in respect  thereof) arising out of or based
on any untrue  statement  (or  alleged  untrue  statement)  of a  material  fact
contained in any prospectus,  offering circular or other document (including any
related Registration  Statement,  notification or the like) incident to any such
registration,  qualification or compliance, or based on any omission (or alleged
omission)  to state  therein a material  fact  required to be stated  therein or
necessary to make the statements therein not misleading, or any violation by the
Company of the Securities Act or any rule or regulation thereunder applicable to
the  Company  and  relating  to action or  inaction  required  of the Company in
connection with any such  Registration,  qualification  or compliance,  and will
reimburse  the relevant  holders of  Registrable  Securities,  their  respective
officers,  directors and partners, and each Person controlling any of them, each
such  underwriter  and each Person who  controls any such  underwriter,  for any
legal  and  any  other   expenses   reasonably   incurred  in  connection   with
investigating and defending any such claim, loss,  damage,  liability or action,
provided  that the Company  will not be liable in any such case to the  relevant
holders of Registrable  Securities or any underwriter or Person  controlling the
relevant holders of Registrable Securities or any underwriter to the extent that
any such claim, loss, damage,  liability or expense arises out of or is based on
any untrue  statement or omission  based upon written  information  furnished in
writing to the Company by the relevant holders of Registrable Securities or such
underwriter  or  Person  controlling  or the  relevant  holders  of  Registrable
Securities or such underwriter and stated to be specifically for use therein.

          (b) The relevant holders of Registrable Securities,  severally and not
jointly, will indemnify the Company, each of its directors and officers and each
underwriter,  if any, of the  Registrable  Securities  covered by a Registration
Statement,  each Person who controls the Company or such underwriter  within the
meaning of the Securities Act and the rules and regulations thereunder,  against
all claims,  losses,  damages and  liabilities  (or actions in respect  thereof)
arising out of or based on any untrue statement (or alleged untrue statement) of
a  material  fact  contained  in any such  Registration  Statement,  prospectus,
offering  circular or other document made by the relevant holders of Registrable
Securities,  severally and not jointly, or any omission (or alleged omission) to
state therein a material fact required to be stated therein or necessary to make
the  statements by the relevant  holders of Registrable  Securities  therein not
misleading,  and  will  reimburse  the  Company  and  its  directors,  officers,
partners,  underwriters  or control  persons for any legal or any other expenses
reasonably  incurred in  connection  with  investigating  or defending  any such
claim, loss,  damage,  liability or action, in each case to the extent, but only
to the extent,  that such untrue  statement  (or alleged  untrue  statement)  or
omission  (or  alleged  omission)  is  made  in  such  Registration   Statement,
prospectus,  offering  circular  or  other  document  in  reliance  upon  and in
conformity  with  written  information  furnished to the Company by the relevant
holders of Registrable Securities and stated to be specifically for use therein.

          (c) Each party  entitled to  indemnification  under this  Section 1.05
(the  "Indemnified  Party")  shall give notice to the party  required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the  Indemnifying  Party to assume  the  defense of any such claim or any
litigation  resulting  therefrom  provided,  that  counsel for the  Indemnifying
Party,  who shall conduct the defense of such claim or any litigation  resulting
therefrom,  shall be approved by the Indemnified Party (whose approval shall not
unreasonably be withheld ) or delayed) and the Indemnified Party may participate
in such defense at such party's expense (unless (i) the employment of counsel by
such Indemnified  Party has been authorized by the  Indemnifying  Party, or (ii)
the  Indemnified  Party  shall  have  reasonably  concluded  that there may be a
conflict of interest between the Indemnifying Party and the Indemnified Party in
the defense of such action,  in each of which cases the fees and expenses of one
law firm serving as counsel for each  Indemnified  Party shall be at the expense
of the  Indemnifying  Party),  and  provided  further  that the  failure  of any
Indemnified  Party to give  notice as  provided  herein  shall not  relieve  the
Indemnifying  Party of its obligations under this Article II unless such failure
or any delay in providing such notice  results in the loss of material  defenses
or  rights.  No  Indemnifying  Party,  in the  defense  of  any  such  claim  or
litigation,  shall,  except with the consent of each  Indemnified  Party  (which
consent shall not be  unreasonably  withheld ) or delayed),  consent to entry of
any  judgment  or enter  into  any  settlement  which  does  not  include  as an
unconditional  term  thereof  the giving by the  claimant or  plaintiff  to such
Indemnified  Party of a release  from all  liability in respect to such claim or
litigation.  Each  Indemnified  Party shall furnish such  information  regarding
itself or the claim in question as an Indemnifying  Party may reasonably request
in writing and as shall be reasonably required in connection with the defense of
such claim and litigation resulting therefrom.


          (d) If the  indemnification  provided for in this Section 1.05 is held
by a court of competent  jurisdiction to be unavailable to an Indemnified  Party
with  respect  to any loss,  liability,  claim,  damage or expense  referred  to
therein,  then the Indemnifying  Party, in lieu of indemnifying such Indemnified
Party  thereunder,  shall  contribute  to the  amount  paid or  payable  by such
Indemnified Party as a result of such loss, liability,  claim, damage or expense
in such  proportion  as is  appropriate  to reflect  the  relative  fault of the
Indemnifying  Party on the one hand, and of the  Indemnified  Party on the other
hand, in connection  with the  statements  or omissions  which  resulted in such
loss,  liability,  claim,  damage  or  expense  as  well as any  other  relevant
equitable  considerations.  The relative fault of the Indemnifying  Party and of
the  Indemnified  Party shall be determined by reference to, among other things,
whether  the  untrue or  alleged  untrue  statement  of a  material  fact or the
omission  to state a  material  fact  relates  to  information  supplied  by the
Indemnifying Party or by the Indemnified Party and the parties' relative intent,
knowledge,  access to  information  and  opportunity  to correct or prevent such
statement or omission.

          (e) Notwithstanding  the foregoing,  to the extent that the provisions
on  indemnification  and  contribution  contained in a  negotiated  underwriting
agreement entered into in connection with an underwritten public offering are in
conflict  with the foregoing  provisions,  the  provisions  in the  underwriting
agreement shall be controlling.

     SECTION 1.06  Assignability of Registration Rights.
                   ------------------------------------

     The  registration  rights  granted  pursuant  to this  Article  I shall  be
assignable at the option of, in whole or in part,  but in no event in increments
of less  than  25% of the  aggregate  Registrable  Securities  then  held by the
Holder,  provided  that the  Company is given  written  notice at the time of or
within a reasonable  period after said transfer or assignment,  stating the name
and address of the transferee or assignee and  identifying  the securities  with
respect to which such egistration  rights are being transferred or assigned and,
provided  further,  that the  transferee  or assignee of such rights  assumes in
writing the  obligations  of such Holder under this Section I. All references to
Holder shall include any future assignees.

     SECTION 1.07  Termination of Rights.
                   ---------------------

     Notwithstanding  any provisions to the contrary  herein,  the  registration
rights set forth in this  Article I shall  terminate on the earlier of 12 months
from the  effective  date of this  Agreement  or such time as the holders of all
Registrable  Securities  hold  less than 25% of the  aggregate  number of Shares
purchased  pursuant to exercise of the Warrant during the first 12 months of the
Exercise Period.

                                   ARTICLE II

                                  Miscellaneous
                                  -------------

     SECTION 2.01  Notices.
                   -------

     Except in the case of notices and other communications  expressly permitted
to be given by  telephone,  all notices and other  communications  provided  for
herein shall be in writing and shall be  delivered by hand or overnight  courier
service, mailed by certified or registered mail or sent by telecopy, as follows:


          (a) To Company:

                   Positron Corporation.
                   1304 Langham Creek Drive, Suite 310
                   Houston, Texas 77084
                   Attn:  President
                   Telephone:  (281) 492-7199
                   Facsimile: (281) 492.2761

          (b) To Imatron:

                   Imatron Inc.
                   389 Oyster Point Blvd.
                   So. San Francisco, CA 94080
                   Attn: Chief Executive Officer
                   Telephone: 650.583.9964
                   Facsimile: 650.871.0418

          (c) if to a party other than the Company or Imatron,  to such  address
or telecopy number as such party may supply.

Any party hereto may change its address or telecopy number for notices and other
communications  hereunder  by notice to the other  parties  hereto in the manner
provided by this Section 2.01. All notices and other communications given to any
party hereto in accordance with the provisions of this Agreement shall be deemed
to have been given on the date of receipt.

SECTION 2.02      Waivers; Amendments.
                  -------------------

          (a) No failure or delay by Imatron (or its  successors  or assigns) or
the holders of Registrable Securities in exercising any right or power hereunder
or under the other Transaction  Documents shall operate as a waiver thereof, nor
shall  any  single  or  partial  exercise  of any such  right or  power,  or any
abandonment  or  discontinuance  of steps  to  enforce  such a right  or  power,
preclude  any other or further  exercise  thereof or the  exercise  of any other
right  or  power.  The  rights  and  remedies  of  Imatron  and the  holders  of
Registrable  Securities  hereunder  and  under  the  Transaction  Documents  are
cumulative  and are not  exclusive  of any  rights  or  remedies  that it  would
otherwise have. No waiver of any provision of this Agreement or any of the other
Transaction Documents or consent to any departure by the Company therefrom shall
in any event be effective unless the same shall be permitted by paragraph (b) of
this  Section,  and then such waiver or consent  shall be effective  only in the
specific instance and for the purpose for which given.

          (b) Neither this Agreement nor any of the other Transaction Documents,
nor any provision hereof or thereof,  may be waived,  amended or modified except
pursuant to an agreement or  agreements  in writing  entered into by the Company
and Imatron (or the holders of Registrable Securities, as appropriate).

     SECTION 2.03  Successors and Assigns.
                   ----------------------

     The  provisions  of this  Agreement  shall be binding upon and inure to the
benefit  of the  parties  hereto and their  respective  successors  and  assigns
permitted hereby,  except that the Company may not assign or otherwise  transfer
any of its rights or obligations  hereunder without the prior written consent of
Imatron or the  holders  of  Registrable  Securities,  as  appropriate  (and any
attempted  assignment  or transfer by the Company  without such consent shall be
null and void).  Nothing  in this  Agreement,  expressed  or  implied,  shall be
construed  to confer  upon any Person  (other  than the  parties  hereto,  their
respective  successors and assigns permitted hereby and, to the extent expressly
contemplated  hereby,  the Related  Parties of ) any legal or  equitable  right,
remedy or claim under or by reason of this Agreement.

     SECTION 2.04  Counterparts; Integration; Effectiveness.
                   ----------------------------------------

     This Agreement may be executed in  counterparts  (and by the parties hereto
on different counterparts),  each of which shall constitute an original, but all
of which when taken together shall constitute a single contract.  This Agreement
and the other  Transaction  Documents  constitute the entire agreement among the
parties relating to the subject matter hereof and supersede any and all previous
agreements and understandings,  oral or written,  relating to the subject matter
hereof.  This Agreement shall become  effective when the parties hereto exchange
signed  counterparts  and  thereafter  shall be  binding  upon and  inure to the
benefit of the  parties  hereto and their  respective  successors  and  assigns.
Delivery of an executed  counterpart  of a signature  page of this  Agreement by
telecopy  shall be effective as delivery of a manually  executed  counterpart of
this Agreement.

     SECTION 2.05  Severability.
                   ------------

     Any  provision  of  this   Agreement   held  to  be  invalid,   illegal  or
unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective
to the  extent  of  such  invalidity,  illegality  or  unenforceability  without
affecting the validity,  legality and enforceability of the remaining provisions
hereof;   and  the  invalidity  of  a  particular   provision  in  a  particular
jurisdiction shall not invalidate such provision in any other jurisdiction.

     SECTION 2.06  Governing Law.
                   -------------

     This  Agreement  shall be construed in accordance  with and governed by the
law of the State of California.

     SECTION 2.07  WAIVER OF JURY TRIAL.
                   --------------------

     EACH PARTY  HERETO  HEREBY  WAIVES,  TO THE  FULLEST  EXTENT  PERMITTED  BY
APPLICABLE LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY IN ANY LEGAL PROCEEDING
DIRECTLY OR INDIRECTLY  ARISING OUT OF OR RELATING TO THIS AGREEMENT,  ANY OTHER
TRANSACTION DOCUMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY (WHETHER
BASED ON CONTRACT,  TORT OR ANY OTHER  THEORY).  EACH PARTY HERETO (A) CERTIFIES
THAT NO  REPRESENTATIVE,  AGENT OR ATTORNEY OF ANY OTHER PARTY HAS  REPRESENTED,
EXPRESSLY  OR  OTHERWISE,  THAT SUCH  OTHER  PARTY  WOULD  NOT,  IN THE EVENT OF
LITIGATION,  SEEK TO ENFORCE THE FOREGOING WAIVER AND (B)  ACKNOWLEDGES  THAT IT
AND THE OTHER PARTIES  HERETO HAVE BEEN INDUCED TO ENTER INTO THIS AGREEMENT BY,
AMONG OTHER THINGS,  THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION 2.07.
SECTION

     2.08  Headings.
           --------

     Article and Section  headings used herein are for  convenience of reference
only, are not part of this Agreement and shall not affect the  construction  of,
or be taken into consideration in interpreting, this Agreement.

     SECTION 2.09  Directly or Indirectly.
                   ----------------------

     Where any provision in this  Agreement  refers to action to be taken by, or
prohibited  to be taken by,  any  Person,  such  provision  shall be  applicable
whether such action is taken directly or indirectly by such Person.

     IN WITNESS WHEREOF,  the parties execute this Agreement as f the date first
written above.

                                 Company:

                                    Positron Corporation.


                                    By:
                                      ------------------------------------------
                                    Its: President



                                  Purchaser:

                                     Imatron Inc.


                                     By:
                                       -----------------------------------------
                                     Its:
                                        ----------------------------------------