EXHIBIT 10.37 AMENDMENT NUMBER 4 TO EMPLOYMENT AGREEMENT THIS AMENDMENT NUMBER 4 TO EMPLOYMENT AGREEMENT, effective as of February 11, 2002, is by and between Radiologix, Inc., a Delaware corporation (the "Company"), and Mark S. Martin ("Martin")....

                                                                   EXHIBIT 10.37



                   AMENDMENT NUMBER 4 TO EMPLOYMENT AGREEMENT


         THIS AMENDMENT NUMBER 4 TO EMPLOYMENT AGREEMENT, effective as of
February 11, 2002, is by and between Radiologix, Inc., a Delaware corporation
(the "Company"), and Xxxx X. Xxxxxx ("Xxxxxx").

         WHEREAS, the Company and Xxxxxx entered into an Employment Agreement
dated as of June 12, 1996, which was amended effective January 1, 1999, February
9, 2000, and July 1, 2000 (as amended, the "Employment Agreement"); and

         WHEREAS, the Company and Xxxxxx desire to further amend the Employment
Agreement to reflect an increase in Xxxxxx'x base salary and to make certain
other amendments;

         NOW, THEREFORE, in consideration of the mutual covenants and conditions
set forth herein, the parties hereby agree as follows:

         1.       Section 3.1 of the Employment Agreement is hereby deleted in
its entirety and replaced with the following new Section 3.1:

                  Section 3.1 SALARY. For the performance of Xxxxxx'x duties
         hereunder, the Company shall pay Xxxxxx an annual salary of $338,000,
         in equal periodic installments (less required withholdings) no less
         frequently than every two weeks.

         2.       The second sentence of Section 4 of the Employment Agreement
is hereby deleted in its entirety and replaced with the following new second
sentence:

         In addition, notwithstanding the provisions of Section 5.2(b), if the
         Company terminates Xxxxxx'x employment hereunder at any time following
         a Change of Control, then immediately upon such termination of
         employment, the Company shall pay Xxxxxx, in addition to the amounts
         required under Section 5.2(a), a lump sum severance payment in an
         amount equal to the sum of (i) the product of Xxxxxx'x then current
         annual salary for one year multiplied by two plus (ii) the product of
         Xxxxxx'x most recent annual bonus payment received for the fiscal year
         immediately preceding the Change of Control multiplied by two. In
         addition, the Company shall continue to provide Xxxxxx with the
         benefits described in Section 3.4 until the earlier of (i) the two-year
         anniversary of the date of Xxxxxx'x termination of employment and (ii)
         the date on which Xxxxxx obtains substantially equivalent benefits from
         another party.

         3.       Section 5.2(b) of the Employment Agreement is hereby deleted
in its entirety and replaced with the following new Section 3.1:

                  (b) In addition, if Xxxxxx'x employment is terminated under
         Sections 5.1(b), (d) or (e), then the Company shall also pay Xxxxxx,
         immediately upon such termination of employment, a lump sum severance
         payment in an amount equal to Xxxxxx'x then current annual salary.



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         IN WITNESS WHEREOF, the parties have executed this Amendment Number 4
to Employment Agreement effective as of the date first written above.



                                  RADIOLOGIX, INC.



                                  By:
                                      ------------------------------------------
                                      Xxxx X. Xxxxx
                                      General Counsel, Executive Vice President,
                                        and Secretary



                                  XXXXXX:



                                  ----------------------------------------------
                                      Xxxx X. Xxxxxx




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