Copyright Security Agreement

                     GUARANTOR COPYRIGHT SECURITY AGREEMENT

         THIS GUARANTOR  COPYRIGHT SECURITY AGREEMENT (the "Agreement") dated as
of January 31,  2000,  is  executed by  LITHOTRIPTERS,  INC.,  a North  Carolina
corporation (the "Debtor"), for the benefit of BANK OF AMERICA, N.A., a national
banking  association  ("B of A"), not in its  individual  capacity but solely as
administrative  agent  for  itself  and  each  of the  other  banks  or  lending
institutions (each, a "Lender" and collectively,  the "Lenders") which is or may
from time to time become a party to the Loan Agreement (as hereinbelow  defined)
(in  such  capacity,   together  with  its  successors  in  such  capacity,  the
"Administrative Agent").

                                R E C I T A L S:

     A. Prime Medical Services,  Inc., a Delaware corporation (the "Borrower"),
B of A as administrative  agent,  BankBoston,  N.A., as documentation agent, and
the Lenders  have entered into that  certain  Fourth  Amended and Restated  Loan
Agreement  dated as of the date hereof,  (as the same may be amended,  restated,
extended,  supplemented  or modified from time to time,  the "Loan  Agreement"),
pursuant to which the Lenders have agreed to make a revolving credit loan to the
Borrower with advances thereunder not to exceed an aggregate principal amount of
Eighty-Six Million and 00/100 Dollars ($86,000,000.00) at any time outstanding.

         B. The Debtor and certain other  guarantors  have executed that certain
Guaranty  Agreement  of  even  date  herewith  (as  the  same  may  be  amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
the Debtor has  guaranteed to the Agents (as defined in the Loan  Agreement) and
the Lenders the full and complete payment and performance of the Obligations (as
defined in the Loan Agreement).

         C. The Debtor has executed that certain Guarantor Security Agreement of
even date  herewith (as the same may be amended,  supplemented  or modified from
time to time, the "Security Agreement") pursuant to which the Debtor has granted
to the Administrative Agent for the benefit of the Lenders a continuing security
interest in certain personal property of the Debtor.

     D. The Agents and the Lenders have conditioned  their obligations under the
Loan Agreement upon the execution and delivery of this Agreement by the Debtor.

         NOW,  THEREFORE,  in  consideration  of the premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

         SECTION 1.1 Terms Defined in Loan Agreement. Capitalized terms used and
not  otherwise  defined  herein shall have the same meanings as set forth in the
Loan Agreement.

         SECTION 1.2 Terms Defined in Uniform Commercial Code. Terms used herein
which are  defined  in the  Uniform  Commercial  Code as adopted by the State of
Texas,  unless  otherwise  defined herein or in the Loan  Agreement,  shall have
their  meanings  as set forth in the Uniform  Commercial  Code as adopted by the
State of Texas.


<PAGE>





D-737397.1

                                      - 3 -

                                                    Copyright Security Agreement

         SECTION 2. Grant of Security  Interest.  The Debtor hereby  pledges and
grants to the  Administrative  Agent,  for the benefit of the  Lenders,  a first
priority lien on and security interest in all of the Debtor's right,  title, and
interest in and to the following property (the "Copyright Collateral"),  whether
now owned or hereafter arising or acquired,  being all copyrights of the Debtor,
whether statutory or common law, registered or unregistered, now or hereafter in
force throughout the world including,  without  limitation,  all of the Debtor's
right,  title and  interest in and to all  copyrights  registered  in the United
States  Copyright  Office or  anywhere  else in the  world  and also  including,
without limitation,  the copyrights referred to in Item A of Schedule 1 attached
hereto,  and all applications for  registration  thereof,  whether pending or in
preparation,  all copyright licenses,  including each copyright license referred
to in Item B of Schedule 1 attached hereto,  the right to sue for past,  present
and future  infringements  of any of the  foregoing,  all  rights  corresponding
thereto  throughout  the  world,  all  extensions  and  renewals  of  any of the
foregoing,  and all proceeds of the foregoing,  including,  without  limitation,
licenses, royalties, income, payments, claims, damages and proceeds of suit.

         SECTION 3. Secured Indebtedness.  The Copyright Collateral shall secure
the following  obligations,  indebtedness,  and  liabilities  (whether at stated
maturity, by acceleration or otherwise) (all such obligations, indebtedness, and
liabilities being hereinafter sometimes called the "Secured Indebtedness"):

     (a) the Obligations and the  obligations,  liabilities and  indebtedness of
the Debtor to the Agents and the Lenders under the Guaranty;

                  (b) all  reasonable  costs and  expenses,  including,  without
limitation,  all reasonable attorneys' fees and legal expenses,  incurred by any
of the Agents or any Lender to preserve and maintain the  Collateral (as defined
in the Security Agreement),  collect the obligations described herein and in the
Security Agreement, and enforce this Agreement and the Security Agreement; and

     (c) all extensions, renewals, and modifications of any of the foregoing.

         SECTION 4.  Security  Agreement.  This  Agreement has been executed and
delivered by the Debtor for the purpose of registering the security  interest of
Administrative  Agent  in  the  Copyright  Collateral  with  the  United  States
Copyright Office and corresponding  offices in other countries of the world. The
security interest granted hereby has been granted as a supplement to, and not in
limitation of, the security  interest  granted to  Administrative  Agent for its
benefit  and the  benefit  of the  Lenders  under the  Security  Agreement.  The
Security Agreement (and all rights and remedies of Administrative  Agent and the
Lenders thereunder) shall remain in full force and effect in accordance with its
terms.

         SECTION 5. Termination.  If all of the Secured  Indebtedness shall have
been paid and  performed  in full and the  Commitments  shall  have  expired  or
terminated,  the  Administrative  Agent shall,  upon the written  request of the
Debtor and in  accordance  with  applicable  provisions  of the Loan  Agreement,
promptly  execute and deliver to the Debtor a proper  instrument or  instruments
acknowledging  the release and termination of the security  interests created by
this  Agreement as the Debtor may reasonably  deem  necessary or desirable,  and
shall duly assign and deliver to the Debtor  (without  recourse  and without any
representation  or warranty)  such of the Copyright  Collateral as may be in the
possession  of the  Administrative  Agent  and has not  previously  been sold or
otherwise applied pursuant to this Agreement.


<PAGE>


         SECTION 6.  Acknowledgment.  The Debtor does hereby further acknowledge
and affirm that the rights and remedies of Administrative  Agent with respect to
the security interest in the Copyright  Collateral granted hereby are more fully
set  forth  in the  Security  Agreement,  the  terms  and  provisions  of  which
(including  the remedies  provided for  therein) are  incorporated  by reference
herein as if fully set forth herein.

         SECTION  7. Loan  Document,  etc.  This  Agreement  is a Loan  Document
executed  pursuant to the Loan Agreement and shall (unless  otherwise  expressly
indicated herein) be construed,  administered and applied in accordance with the
terms and provisions of the Loan Agreement.

     SECTION 8.  Counterparts.  This Agreement may be executed by parties hereto
in several counterparts, each of which shall be deemed to be an original and all
of which shall constitute together but one and the same agreement.


                     REMAINDER OF PAGE INTENTIONALLY BLANK.

                            SIGNATURE PAGE TO FOLLOW.


<PAGE>





                                                    Copyright Security Agreement

         IN WITNESS  WHEREOF,  the Debtor has duly executed this Agreement as of
the day and year first written above.

                                                     LITHOTRIPTERS, INC.



                                                 By: /s/ Teena E. Belcik
                                                           Teena E. Belcik
                                                           Treasurer

                                             Address: 2008 Litho Place
                                                      Fayetteville, NC 28304
                                                      Attention: Treasurer


<PAGE>





                          Copyright Security Agreement

         IN WITNESS  WHEREOF,  B of A has duly executed this Agreement as of the
day and year first written above.

                                                     BANK OF AMERICA, N.A.,
                                                       as Administrative Agent

                                                     By: /s/ Daniel H. Penkar
                                                           Daniel H. Penkar
                                                           Senior Vice President

                                  Address:       515 Congress Avenue, 11th Floor
                                                 Austin, Texas 78701
                                                 Attention:     Wade Morgan


<PAGE>







                                                    Copyright Security Agreement

                                   SCHEDULE 1

Item A:  Registered Copyrights

Title                                                         Registration No.
-----                                                         ---------------

Generic Quality Assurance Plan: Lithotripsy Unit              TX 3124352

Generic Hospital Lithostar Service Quality Assessment Plan    TX 3124351

Lithotripters, Inc., Quality Assurance Plan                   TX 2792856

Introduction to the Lithostar and Guide to its Use            TX 2670895





Item B: Copyright License Rights

Title                                                      Licensor

Scheduling, Billing and Accounts
         Receivable Computer System                  Omni-Medical Systems, Inc.

QA Outcome Analysis Computer System                  MEDformatics, Inc.

<PAGE>


                          Copyright Security Agreement

                     GUARANTOR COPYRIGHT SECURITY AGREEMENT

         THIS GUARANTOR  COPYRIGHT SECURITY AGREEMENT (the "Agreement") dated as
of January 31,  2000,  is  executed by  LITHOTRIPTERS,  INC.,  a North  Carolina
corporation (the "Debtor"), for the benefit of BANK OF AMERICA, N.A., a national
banking  association  ("B of A"), not in its  individual  capacity but solely as
administrative  agent  for  itself  and  each  of the  other  banks  or  lending
institutions (each, a "Lender" and collectively,  the "Lenders") which is or may
from time to time become a party to the Loan Agreement (as hereinbelow  defined)
(in  such  capacity,   together  with  its  successors  in  such  capacity,  the
"Administrative Agent").

                                R E C I T A L S:
                                 - - - - - - - -

         A.. Prime Refractive  Management,  L.L.C., a Delaware limited liability
company (the "Borrower"), B of A, as administrative agent, BankBoston,  N.A., as
documentation  agent,  and the  Lenders  have  entered  into that  certain  Loan
Agreement  dated as of the date hereof,  (as the same may be amended,  restated,
extended,  supplemented  or modified from time to time,  the "Loan  Agreement"),
pursuant to which the Lenders have agreed to make an advancing  term loan to the
Borrower with advances thereunder not to exceed an aggregate principal amount of
Fourteen Million and 00/100 Dollars ($14,000,000.00).

         B. The Debtor and certain other  guarantors  have executed that certain
Guaranty  Agreement  of  even  date  herewith  (as  the  same  may  be  amended,
supplemented or modified from time to time, the  "Guaranty"),  pursuant to which
the Debtor has  guaranteed to the Agents (as defined in the Loan  Agreement) and
the Lenders the full and complete payment and performance of the Obligations (as
defined in the Loan Agreement).

         C. The Debtor has executed that certain Guarantor Security Agreement of
even date  herewith (as the same may be amended,  supplemented  or modified from
time to time, the "Security Agreement") pursuant to which the Debtor has granted
to the Administrative Agent for the benefit of the Lenders a continuing security
interest in certain personal property of the Debtor.

     D. The Agents and the Lenders have conditioned  their obligations under the
Loan Agreement upon the execution and delivery of this Agreement by the Debtor.

         NOW,  THEREFORE,  in  consideration  of the premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
acknowledged, the parties hereto agree as follows:

         SECTION 1.1 Terms Defined in Loan Agreement. Capitalized terms used and
not  otherwise  defined  herein shall have the same meanings as set forth in the
Loan Agreement.

         SECTION 1.2 Terms Defined in Uniform Commercial Code. Terms used herein
which are  defined  in the  Uniform  Commercial  Code as adopted by the State of
Texas,  unless  otherwise  defined herein or in the Loan  Agreement,  shall have
their  meanings  as set forth in the Uniform  Commercial  Code as adopted by the
State of Texas.


<PAGE>






                                      - 3 -

                          Copyright Security Agreement


<PAGE>


         SECTION 2. Grant of Security  Interest.  The Debtor hereby  pledges and
grants to the  Administrative  Agent, for the benefit of the Lenders,  a lien on
and security  interest in all of the Debtor's right,  title, and interest in and
to the following  property (the  "Copyright  Collateral"),  whether now owned or
hereafter  arising or  acquired,  being all  copyrights  of the Debtor,  whether
statutory or common law,  registered or unregistered,  now or hereafter in force
throughout the world including,  without limitation,  all of the Debtor's right,
title and  interest in and to all  copyrights  registered  in the United  States
Copyright  Office or  anywhere  else in the world  and also  including,  without
limitation,  the copyrights referred to in Item A of Schedule 1 attached hereto,
and  all  applications  for   registration   thereof,   whether  pending  or  in
preparation,  all copyright licenses,  including each copyright license referred
to in Item B of Schedule 1 attached hereto,  the right to sue for past,  present
and future  infringements  of any of the  foregoing,  all  rights  corresponding
thereto  throughout  the  world,  all  extensions  and  renewals  of  any of the
foregoing,  and all proceeds of the foregoing,  including,  without  limitation,
licenses,  royalties,  income,  payments,  claims, damages and proceeds of suit.
Such  lien  and  security  interest  shall be  subordinate  only to the lien and
security  interest granted in favor of Bank of America,  N.A., as Administrative
Agent ("Prime  Administrative Agent") under the Fourth Amended and Restated Loan
Agreement dated as of the date hereof among Prime Medical  Services,  Inc., Bank
of America,  N.A., as administrative agent,  BankBoston,  N.A., as documentation
agent, and the lenders from time to time thereunder.

         SECTION 3. Secured Indebtedness.  The Copyright Collateral shall secure
the following  obligations,  indebtedness,  and  liabilities  (whether at stated
maturity, by acceleration or otherwise) (all such obligations, indebtedness, and
liabilities being hereinafter sometimes called the "Secured Indebtedness"):

     (a) the Obligations and the  obligations,  liabilities and  indebtedness of
the Debtor to the Agents and the Lenders under the Guaranty;

                  (b) all  reasonable  costs and  expenses,  including,  without
limitation,  all reasonable attorneys' fees and legal expenses,  incurred by any
of the Agents or any Lender to preserve and maintain the  Collateral (as defined
in the Security Agreement),  collect the obligations described herein and in the
Security Agreement, and enforce this Agreement and the Security Agreement; and

     (c) all extensions, renewals, and modifications of any of the foregoing.

         SECTION 4.  Security  Agreement.  This  Agreement has been executed and
delivered by the Debtor for the purpose of registering the security  interest of
Administrative  Agent  in  the  Copyright  Collateral  with  the  United  States
Copyright Office and corresponding  offices in other countries of the world. The
security interest granted hereby has been granted as a supplement to, and not in
limitation of, the security  interest  granted to  Administrative  Agent for its
benefit  and the  benefit  of the  Lenders  under the  Security  Agreement.  The
Security Agreement (and all rights and remedies of Administrative  Agent and the
Lenders thereunder) shall remain in full force and effect in accordance with its
terms.

         SECTION 5. Termination.  If all of the Secured  Indebtedness shall have
been paid and  performed  in full and the  Commitments  shall  have  expired  or
terminated,  the  Administrative  Agent shall,  upon the written  request of the
Debtor and in  accordance  with  applicable  provisions  of the Loan  Agreement,
promptly  execute and deliver to the Debtor a proper  instrument or  instruments
acknowledging  the release and termination of the security  interests created by
this  Agreement as the Debtor may reasonably  deem  necessary or desirable,  and
shall duly assign and deliver to the Debtor  (without  recourse  and without any
representation  or warranty)  such of the Copyright  Collateral as may be in the
possession  of the  Administrative  Agent  and has not  previously  been sold or
otherwise applied pursuant to this Agreement.


<PAGE>


         SECTION 6.  Acknowledgment.  The Debtor does hereby further acknowledge
and affirm that the rights and remedies of Administrative  Agent with respect to
the security interest in the Copyright  Collateral granted hereby are more fully
set  forth  in the  Security  Agreement,  the  terms  and  provisions  of  which
(including  the remedies  provided for  therein) are  incorporated  by reference
herein as if fully set forth herein.

         SECTION  7. Loan  Document,  etc.  This  Agreement  is a Loan  Document
executed  pursuant to the Loan Agreement and shall (unless  otherwise  expressly
indicated herein) be construed,  administered and applied in accordance with the
terms and provisions of the Loan Agreement.

     SECTION 8.  Counterparts.  This Agreement may be executed by parties hereto
in several counterparts, each of which shall be deemed to be an original and all
of which shall constitute together but one and the same agreement.


                     REMAINDER OF PAGE INTENTIONALLY BLANK.
                            SIGNATURE PAGE TO FOLLOW.


<PAGE>





                          Copyright Security Agreement

         IN WITNESS  WHEREOF,  the Debtor has duly executed this Agreement as of
the day and year first written above.

                           LITHOTRIPTERS, INC.



                           By: /s/ Teena E. Belcik
                                 Teena E. Belcik

                                 Treasurer

                                 Address:       2008 Litho Place
                                                Fayetteville, NC 28304
                                                Attention:     Treasurer


<PAGE>





                          Copyright Security Agreement

         IN WITNESS  WHEREOF,  B of A has duly executed this Agreement as of the
day and year first written above.

                             BANK OF AMERICA, N.A.,
                             as Administrative Agent

                             By:/s/ Daniel H. Penkar
                                 Daniel H. Penkar

                                 Senior Vice President

                                 Address:       515 Congress Avenue, 11th Floor
                                                Austin, Texas 78701
                                                Attention:     Wade Morgan


<PAGE>







                          Copyright Security Agreement

                                                     SCHEDULE 1

Item A:  Registered Copyrights

Title                                                       Registration No.
-----                                                      ----------------

Generic Quality Assurance Plan: Lithotripsy Unit              TX 3124352

Generic Hospital Lithostar Service Quality Assessment Plan    TX 3124351

Lithotripters, Inc., Quality Assurance Plan                   TX 2792856

Introduction to the Lithostar and Guide to its Use            TX 2670895





Item B: Copyright License Rights

Title                                                         Licensor

Scheduling, Billing and Accounts Receivable
         Computer System                              Omni-Medical Systems, Inc.

QA Outcome Analysis Computer System                   MEDformatics, Inc.