EXHIBIT 3.20


                                     BY-LAWS

                                       OF

                   MAXUM HEALTH SERVICES OF NORTH TEXAS, INC.


                                    ARTICLE I

                                     OFFICES


        Section 1. Registered Office. The registered office of the corporation
in the State of Texas shall be located at 807 Brazos, Austin, Texas 78701. The
name of the corporation's registered agent at such address shall be The
Prentice-Hall Corporation System, Inc.. The registered office and/or registered
agent of the corporation may be changed from time to time by action of the board
of directors.

        Section 2. Other Offices. The corporation may also have offices at such
other places, both within and without the State of Texas, as the board of
directors may from time to time determine or the business of the corporation may
require.


                                   ARTICLE II

                            MEETINGS OF SHAREHOLDERS

        Section 1. Place and Time of Meetings. An annual meeting of the
shareholders shall be held each calendar year on such date and at such time and
place as shall be designated from time to time by the Board of Directors and
stated in the notice of the meeting or in a duly executed waiver of notice of
such meeting. The purpose of the meeting shall be to elect Directors and to
conduct such other proper business as may come before the meeting.

        Section 2. Special Meetings. Special meetings of shareholders may be
called for any purpose and may be held at such time and place, within or without
the State of Texas, as shall be stated in a notice of meeting or in a duly
executed waiver of notice thereof. Such meetings may be called at any time by
the board of directors or the president.

        Section 3. Place of Meetings. The board of directors may designate any
place, either within or without the State of Texas, as the place of meeting for
any annual meeting or for any special meeting called by the board of directors.
If no designation is made, or if a special meeting be otherwise called, the
place of meeting shall be the principal executive office of the corporation.

        Section 4. Notice. Whenever shareholders are required or permitted to
take action at a



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meeting, written or printed notice stating the place, date, time, and, in the
case of special meetings, the purpose or purposes, of such meeting, shall be
given to each shareholder entitled to vote at such meeting not less than 10 nor
more than 60 days before the date of the meeting. All such notices shall be
delivered, either personally or by mail, by or at the direction of the board of
directors, the president or the secretary, and if mailed, such notice shall be
deemed to be delivered when deposited in the United States mail, postage
prepaid, addressed to the shareholder at his, her or its address as the same
appears on the records of the corporation. Attendance of a person at a meeting
shall constitute a waiver of notice of such meeting, except when the person
attends for the express purpose of objecting at the beginning of the meeting to
the transaction of any business because the meeting is not lawfully called or
convened.

        Section 5. Shareholders List. The officer having charge of the stock
ledger of the corporation shall make, at least 10 days before every meeting of
the shareholders, a complete list of the shareholders entitled to vote at such
meeting arranged in alphabetical order, showing the address of each shareholder
and the number of shares registered in the name of each shareholder. Such list
shall be open to the examination of any shareholder, for any purpose germane to
the meeting; during ordinary business hours, for a period of at least 10 days
prior to the meeting, either at a place within the city where the meeting is to
be held, which place shall be specified in the notice of the meeting or, if not
so specified, at the place where the meeting is to be held. The list shall also
be produced and kept at the time and place of the meeting during the whole time
thereof, and may be inspected by any shareholder who is present.

        Section 6. Quorum. The holders of a majority of the outstanding shares
of capital stock, present in person or represented by proxy, shall constitute a
quorum at all meetings of the shareholders, except as otherwise provided by
statute or by the certificate of incorporation. If a quorum is not present, the
holders of a majority of the shares present in person or represented by proxy at
the meeting, and entitled to vote at the meeting, may adjourn the meeting to
another time and/or place.

        Section 7. Adjourned Meetings. When a meeting is adjourned to another
time and place, notice need not be given of the adjourned meeting if the time
and place thereof are announced at the meeting at which the adjournment is
taken. At the adjourned meeting the corporation may transact any business which
might have been transacted at the original meeting. If the adjournment is for
more than thirty days, or if after the adjournment a new record date is fixed
for the adjourned meeting, a notice of the adjourned meeting shall be given to
each shareholder of record entitled to vote at the meeting.

        Section 8. Vote Required. When a quorum is present, the affirmative vote
of the majority of shares present in person or represented by proxy at the
meeting and entitled to vote on the subject matter shall be the act of the
shareholders, unless the question is one upon which by express provisions of an
applicable law or of the certificate of incorporation or of these by-laws a
different vote is required, in which case such express provision shall govern
and control the decision of such question.

        Section 9. Voting Rights. Except as otherwise provided by the General
Corporation Law



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of the State of Texas or by the certificate of incorporation of the corporation
or any amendments thereto and subject to Section 3 of Article VI hereof, every
shareholder shall at every meeting of the shareholders be entitled to one vote
in person or by proxy for each share of common stock held by such shareholder.

        Section 10. Proxies. Each shareholder entitled to vote at a meeting of
shareholders or to express consent or dissent to corporate action in writing
without a meeting may authorize another person or persons to act for him or her
by proxy, but no such proxy shall be voted or acted upon after three years from
its date, unless the proxy provides for a longer period.

        Section 11. Action by Written Consent. Unless otherwise provided in the
certificate of incorporation, any action required to be taken at any annual or
special meeting of shareholders of the corporation, or any action which may be
taken at any annual or special meeting of such shareholders, may be taken
without a meeting, without prior notice and without a vote, if a consent or
consents in writing, setting forth the action so taken and bearing the dates of
signature of the shareholders who signed the consent or consents, shall be
signed by the holders of outstanding stock having not less than the minimum
number of votes that would be necessary to authorize or take such action at a
meeting at which all shares entitled to vote thereon were present and voted and
shall be delivered to the corporation by delivery to its registered office in
the state of Texas, or the corporation's principal place of business, or an
officer or agent of the corporation having custody of the book or books in which
proceedings of meetings of the shareholders are recorded. Delivery made to the
corporation's registered office shall be by hand or by certified or registered
mail, return receipt requested. All consents properly delivered in accordance
with this section shall be deemed to be recorded when so delivered. No written
consent shall be effective to take the corporate action referred to therein
unless, within sixty days of the earliest dated consent delivered to the
corporation as required by this section, written consents signed by the holders
of a sufficient number of shares to take such corporate action are so recorded.
Prompt notice of the taking of the corporate action without a meeting by less
than unanimous written consent shall be given to those shareholders who have not
consented in writing. Any action taken pursuant to such written consent or
consents Of the shareholders shall have the same force and effect as if taken by
the shareholders at a meeting thereof.





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                                   ARTICLE III

                                    DIRECTORS

        Section 1. General Powers. The business and affairs of the corporation
shall be managed by or under the direction of the board of directors.

        Section 2. Number, Election and Term of Office. The number of directors
shall be not less than two (2) nor more than seven (7). The exact number of
directors within the minimum and maximum limitations specified in the preceding
sentence shall be fixed from time to time by the Board of Directors pursuant to
a resolution adopted by a majority of the entire Board of Directors and at least
one director from each class of directors. The directors shall be divided into
three classes as nearly equal in number as possible, with the term of office of
the first class to expire at the first Annual Meeting of Shareholders held after
the initial election of the directors in such class, the term of office of the
second class to expire at the second Annual Meeting of Shareholders held after
the initial election of the directors in such class and the term of office of
the third class to expire at the third Annual Meeting of Shareholders after the
initial election of the directors in such class. At each Annual Meeting of
Shareholders after such initial classification and election, directors elected
to succeed those directors whose terms expire shall be elected for a term of
office to expire at the third succeeding Annual Meeting of Shareholders after
their election. A nominee to be a director of the Corporation may be elected
only by the affirmative vote of more than fifty percent (50%) of the
Corporation's outstanding shares entitled to vote for the election of directors.

        Section 3. Removal and Resignation. Any director or the entire Board of
Directors may be removed only for cause. Any director may resign at any time
upon written notice to the Corporation.

        Section 4. Vacancies. Subject to the rights of the holders of any series
of Preferred Stock then outstanding pursuant to the Corporation's Certificate of
Incorporation, newly created directorships resulting from any increase in the
authorized number of directors or any vacancies in the Board of Directors
resulting from death, resignation, retirement, disqualification, removal from
office or other cause shall be filled by a majority vote of the directors then
in office, although less than a quorum, or by a sole remaining director.
Directors chosen pursuant to any of the foregoing provisions shall hold office
for a term expiring at the Annual Meeting of Shareholders at which the term of
the class to which they have been elected expires and until their successors are
duly elected and have qualified or until their earlier resignation or removal.
Additional directorships resulting from an increase in the number of directors
pursuant to Section 2 of this Article III shall be apportioned among the three
terms of directors as equally as possible. No decrease in the number of
directors constituting the board shall shorten the term of any incumbent
director.


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        Section 5. Annual Meetings. An annual meeting of the Board of Directors
shall be the first scheduled meeting of the Board of Directors following the
annual meeting of the shareholders. The meeting shall be on such date and at
such time and place as shall be designated from time to time by the Board of
Directors and stated in the notice of the meeting or in a duly executed waiver
of notice of such meeting. The purpose of the meeting shall be to conduct such
proper business as may come before the meeting.

        Section 6. Other Meetings and Notice. Regular meetings, other than the
annual meeting, of the board of directors may be held without notice at such
time and at such place as shall from time to time be determined by resolution of
the board. Special meetings of the board of directors may be called by or at the
request of the president on at least 24 hours notice to each director, either
personally, by telephone, by mail, or by telegraph;, in like manner and on like
notice the president must call a special meeting on the written request of at
least a majority of the directors.

        Section 7. Quorum, Required Vote and Adjournment. A majority of the
total number of directors then in office shall constitute a quorum for the
transaction of business, provided, that in no event shall a quorum consist of
less than one third of the total number of directors established by the
shareholders pursuant to Section 2 of this Article III. The vote of a majority
of directors present at a meeting at which a quorum is present shall be the act
of the board of directors, unless the question is one upon which by express
provisions of an applicable law or of the certificate of incorporation or these
by-laws a different vote is required, in which case such express provision shall
govern and control the decision of such question. Any director may authorize
another person or persons to act for him or her by proxy and such proxy shall
count for purposes of determining a quorum and for voting, but no such proxy
shall be voted or acted upon after three years from its date, unless the proxy
provides for a longer period. If a quorum shall not be present at any meeting of
the board of directors, the directors present thereat may adjourn the meeting
from time to time, without notice other than announcement at the meeting, until
a quorum shall be present.

        Section 8. Committees. The board of directors may, by resolution passed
by a majority of the whole board, designate one or more committees, each
committee to consist of one or more of the directors of the corporation, which
to the extent provided in such resolution or these by-laws shall have and may
exercise the powers of the board of directors in the management and affairs of
the corporation except as otherwise limited by law. The board of directors may
designate one or more directors as alternate members of any committee, who may
replace any absent or disqualified member at any meeting of the committee. Such
committee or committees shall have such name or names as may be determined from
time to time by resolution adopted by the board of directors. Each committee
shall keep regular minutes of its meetings and report the same to the board of
directors when required.


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        Section 9. Committee Rules. Each committee of the board of directors may
fix its own rules of procedure and shall hold its meetings as provided by such
rules, except as may otherwise be provided by a resolution of the board of
directors designating such committee. In the event that a member and that
member's alternate, if alternates are designated by the board of directors as
provided in Section 8 of this Article III, of such committee is or are absent or
disqualified, the member or members thereof present at any meeting and not
disqualified from voting, whether or not such member or members constitute a
quorum, may unanimously appoint another member of the board of directors to act
at the meeting in place of any such absent or disqualified member.

        Section 10. Communications Equipment. Members of the board of directors
or any committee thereof may participate in and act at any meeting of such board
or committee through the use of a conference telephone or other communications
equipment by means of which all persons participating in the meeting can hear
each other, and participation in the meeting pursuant to this section shall
constitute presence in person at the meeting.

        Section 11. Waiver of Notice and Presumption of Assent. Any member of
the board of directors or any committee thereof who is present at a meeting
shall be conclusively presumed to have waived notice of such meeting except when
such member attends for the express purpose of objecting at the beginning of the
meeting to the transaction of any business because the meeting is not lawfully
called or convened. Such member shall be conclusively presumed to have assented
to any action taken unless his or her dissent shall be entered in the minutes of
the meeting or unless his or her written dissent to such action shall be filed
with the person acting as the secretary of the meeting before the adjournment
thereof or shall be forwarded by registered mail to the secretary of the
corporation immediately after the adjournment of the meeting. Such right to
dissent shall not apply to any member who voted in favor of such action.

        Section 12. Action by Written Consent. Unless otherwise restricted by
the certificate of incorporation, any action required or permitted to be taken
at any meeting of the board of directors, or of any committee thereof, may be
taken without a meeting if all members of the board or committee, as the case
may be, consent thereto in writing, and the writing or writings are filed with
the minutes of proceedings of the board or committee.

                                   ARTICLE IV

                                    OFFICERS

        Section 1. Number. The officers of the corporation shall be elected by
the board of directors and may consist of a chairman of the board, a president,
one or more vice-presidents, a secretary, a treasurer, and such other officers
and assistant officers as may be deemed necessary or desirable by the board of
directors. Any number of offices may be held by the same person. In its
discretion, the board of directors may choose not to fill any office for any
period as it may deem advisable.





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        Section 2. Election and Term of Office. The officers of the corporation
shall be elected annually by the board of directors at its first meeting held
after each annual meeting of shareholders or as soon thereafter as conveniently
may be. Vacancies may be filled or new offices created and filled at any meeting
of the board of directors. Each officer shall hold office until a successor is
duly elected and qualified or until his or her earlier death, resignation or
removal as hereinafter provided.

        Section 3. Removal. Any officer or agent elected by the board of
directors may be removed by the board of directors whenever in its judgment the
best interests of the corporation would be served thereby, but such removal
shall be without prejudice to the contract rights, if any, of the person so
removed.

        Section 4. Vacancies. Any vacancy occurring in any office because of
death, resignation, removal, disqualification or otherwise, may be filled by the
board of directors for the unexpired portion of the term by the board of
directors then in office.

        Section 5. Compensation. Compensation of all officers shall be fixed by
the board of directors, and no officer shall be prevented from receiving such
compensation by virtue of his or her also being a director of the corporation.

        Section 6. Chairman of the Board and Chief Executive Officer. The
chairman of the board shall be the chief executive officer of the corporation,
and shall have the powers and perform the duties incident to that position.
Subject to the powers of the board of directors, he or she shall be in the
general and active charge of the entire business and affairs of the corporation,
and shall be its chief policy making officer. He or she shall preside at all
meetings of the board of directors and shareholders and shall have such other
powers and perform such other duties as may be prescribed by the board of
directors or provided in these by-laws. Whenever the president is unable to
serve, by reason of sickness, absence or otherwise, the chairman of the board
shall perform all the duties and responsibilities and exercise all the powers of
the president.

        Section 7. The President. The president shall, subject to the powers of
the board of directors and the chairman of the board, have general charge of the
business, affairs and property of the corporation, and control over its
officers, agents and employees; and shall see that all orders and resolutions of
the board of directors are carried into effect. The president shall execute
bonds, mortgages and other contracts requiring a seal, under the seal of the
corporation, except where required or permitted by law to be otherwise signed
and executed and except where the signing and execution thereof shall be
expressly delegated by the board of directors to some other officer or agent of
the corporation. The president shall have such other powers and perform such
other duties as may be prescribed by the chairman of the board or the board of
directors or as may be provided in these by-laws.




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        Section 8. Chief Operating Officer. The chief operating officer of the
corporation, subject to the powers of the board of directors, shall have general
and active management of the business of the corporation; and shall see that all
orders and resolutions of the board of directors are carried into effect. The
chief operating officer shall have such other powers and perform such other
duties as may be prescribed by the chairman of the board., the chief executive
officer or the board of directors or as may be provided in these by-laws.

        Section 9. Vice-presidents. The vice-president, or if there shall be
more than one, the vice-presidents in the order determined by the board of
directors, shall, in the absence or disability of the president, act with all of
the powers and be subject to all the restrictions of the president. The
vice-presidents shall also perform such other duties and have such other powers
as the board of directors, the chairman of the board, the president or these
by-laws may, from time to time, prescribe.

        Section 10. The Secretary and Assistant Secretaries. The secretary shall
attend all meetings of the board of directors, all meetings of the committees
thereof and all meetings of the shareholders and record all the proceedings of
the meetings in a book or books to be kept for that purpose. Under the
president's supervision, the secretary shall give, or cause to be given, all
notices required to be given by these by-laws or by law; shall have such powers
and perform such duties as the board of directors, the chairman of the board,
the president or these by-laws may, from time to time, prescribe; and shall have
custody of the corporate seal of the corporation. The secretary, or an assistant
secretary, shall have authority to affix the corporate seal to any instrument
requiring it and when so affixed, it may be attested by his or her signature or
by the signature of such assistant secretary. The board of directors may give
general authority to any other officer to affix the seal of the corporation and
to attest the affixing by his or her signature. The assistant secretary, or if
there be more than one, the assistant secretaries in the order determined by the
board of directors, shall, in the absence or disability of the secretary,
perform the duties and exercise the powers of the secretary and shall perform
such other duties and have such other powers as the board of directors, the
chairman of the board, the president, or secretary may, from time to time,
prescribe.

        Section 11. The Treasurer and Assistant Treasurer. The treasurer shall
have the custody of the corporate funds and securities; shall keep full and
accurate accounts of receipts and disbursements in books belonging to the
corporation; shall deposit all monies and other valuable effects in the name and
to the credit of the corporation as may be ordered by the board of directors;
shall cause the funds of the corporation to be disbursed when such disbursements
have been duly authorized, taking proper vouchers for such disbursements; and
shall render to the president and the board of directors, at its regular meeting
or when the board of directors so requires, an account of the corporation; shall
have such powers and perform such duties as the board of directors, the chairman
of the board, the president or these by-laws may, from time to time, prescribe.
If required by the board of directors, the treasurer shall give the corporation
a bond (which shall be rendered every six years) in such sums and with such
surety or sureties as shall be satisfactory to the board of directors for the
faithful performance of the duties of the office of treasurer and for the
restoration to the corporation, in case of death, resignation, retirement, or
removal from office, of all books, papers, vouchers, money, and other property


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of whatever kind in the possession or under the control of the treasurer
belonging to the corporation. The assistant treasurer, or if there shall be more
than one, the assistant treasurers in the order determined by the board of
directors, shall in the absence or disability of the treasurer, perform the
duties and exercise the powers of the treasurer. The assistant treasurers shall
perform such other duties and have such other powers as the board of directors,
the chairman of the board, the president or treasurer may, from time to time,
prescribe.

        Section 12. Other Officers. Assistant Officers and Agents. Officers,
assistant officers and agents, if any, other than those whose duties are
provided for in these by-laws, shall have such authority and perform such duties
as may from time to time be prescribed by resolution of the board of directors.

        Section 13. Absence or Disability of Officers. In the case of the
absence or disability of any officer of the corporation and of any person hereby
authorized to act in such officer's place during such officer's absence or
disability, the board of directors may by resolution delegate the powers and
duties of such officer to any other officer or to any director, or to any other
person whom it may select.

                                    ARTICLE V

                INDEMNIFICATION OF OFFICERS, DIRECTORS AND OTHERS

        Section 1. Nature of Indemnity. Each person who was or is made a party
or is threatened to be made a party to or is involved in any action, suit or
proceeding, whether civil, criminal, administrative or investigative
(hereinafter a "proceeding"), by reason of the fact that he or she, or a person
of whom he or she is the legal representative, is or was a director or officer,
of the corporation or is or was serving at the request of the corporation as a
director, officer, employee, fiduciary, or agent of another corporation or of a
partnership, joint venture, trust or other enterprise, shall be indemnified and
held harmless by the corporation to the fullest extent which it is empowered to
do so by the General Corporation Law of the State of Texas, as the same exists
or may hereafter be amended against all expense, liability and loss (including
attorneys' fees actually and reasonably incurred by such person in connection
with such proceeding) and such indemnification shall inure to the benefit of his
or her heirs, executors and administrators; provided, however, that, except as
provided in Section 2 hereof, the corporation shall indemnify any such person
seeking indemnification in connection with a proceeding initiated by such person
only if such proceeding was authorized by the board of directors of the
corporation. The corporation may, by action of its board of directors, provide
indemnification to employees and agents of the corporation with the same scope
and effect as the foregoing indemnification of directors and officers.





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        Section 2. Procedure for Indemnification of Directors and Officers. Any
indemnification of a director or officer of the corporation under Section 1 of
this Article V or advance of expenses under Section 5 of this Article V shall be
made promptly, and in any event within 30 days, upon the written request of the
director or officer. If a determination by the corporation that the director or
officer is entitled to indemnification pursuant to this Article V is required,
and the corporation fails to respond within sixty days to a written request for
indemnity, the corporation shall be deemed to have approved the request. if the
corporation denies a written request for indemnification or advancing of
expenses, in whole or in part, or if payment in full pursuant to such request is
not made within 30 days, the right to indemnification or advances as granted by
this Article V shall be enforceable by the director or officer in any court of
competent jurisdiction. Such person's costs and expenses incurred in connection
with successfully establishing his or her right to indemnification, in whole or
in part, in any such action shall also be indemnified by the corporation. It
shall be a defense to any such action (other than an action brought to enforce a
claim for expenses incurred in defending any proceeding in advance of its final
disposition where the required undertaking, if any, has been tendered to the
corporation) that the claimant has not met the standards of conduct which make
it permissible under the General Corporation Law of the State of Texas for the
corporation to indemnify the claimant for the amount claimed, but the burden of
such defense shall be on the corporation. Neither the failure of the corporation
(including its board of directors, independent legal counsel, or its
shareholders) to have made a determination prior to the commencement of such
action that indemnification of the claimant is proper in the circumstances
because he or she has met the applicable standard of conduct set forth in the
General Corporation Law of the State of Texas, nor an actual determination by
the corporation (including its board of directors, independent legal counsel, or
its shareholders) that the claimant has not met such applicable standard of
conduct, shall be a defense to the action or create a presumption that the
claimant has not met the applicable standard of conduct.

        Section 3. Article Not Exclusive. The rights to indemnification and-the
payment of expenses incurred in defending a proceeding in advance of its final
disposition conferred in this Article V shall not be exclusive of any other
right which any person may have or hereafter acquire under any statute,
provision of the certificate of incorporation, by-law, agreement, vote of
shareholders or disinterested directors or otherwise.

        Section 4. Insurance. The corporation may purchase and maintain
insurance on its own behalf and on behalf of any person who is or was a
director, officer, employee, fiduciary, or agent of the corporation or was
serving at the request of the corporation as a director, officer, employee or
agent of another corporation, partnership, joint venture, trust or other
enterprise against any liability asserted against him or her and incurred by him
or her in any such capacity, whether or not the corporation would have the power
to indemnify such person against such liability under this Article V.





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        Section 5. Expenses. Expenses incurred by any person described in
Section 1 of this Article V in defending a proceeding shall be paid by the
corporation in advance of such proceeding's final disposition upon receipt of an
undertaking by or on behalf of the director or officer to repay such amount if
it shall ultimately be determined that he or she is not entitled to be
indemnified by the corporation. Such expenses incurred by other employees and
agents may be so paid upon such terms and conditions, if any, as the board of
directors deems appropriate.

        Section 6. Employees and Agents. Persons who are not covered by the
foregoing provisions of this Article V and who are or were employees or agents
of the corporation, or who are or were serving at the request of the corporation
as employees or agents of another corporation, partnership, joint venture, trust
or other enterprise, may be indemnified to the extent authorized at any time or
from time to time by the board of directors.

        Section 7. Contract Rights. The provisions of this Article V shall be
deemed to be a contract right between the corporation and each director or
officer who serves in any such capacity at any time while this Article V and the
relevant provisions of the General Corporation Law of the State of Texas or
other applicable law are in effect, and any repeal or modification of this
Article V or any such law shall not affect any rights or obligations then
existing with respect to any state of facts or proceeding then existing.

        Section 8. Merger or Consolidation. For purposes of this Article V,
references to "the corporation" shall include, in addition to the resulting
corporation, any constituent corporation (including any constituent of a
constituent) absorbed in a consolidation or merger which, if its separate
existence had continued, would have had power and authority to indemnify its
directors, officers, and employees or agents, so that any person who is or was a
director, officer, employee or agent of such constituent corporation, or is or
was serving at the request of such constituent corporation as a director,
officer, employee or agent of another corporation, partnership, joint venture,
trust or other enterprise, shall stand in the same position under this Article
V with respect to the resulting or surviving corporation as he or she would have
with respect to such constituent corporation if its separate existence had
continued.

                                   ARTICLE VI

                              CERTIFICATES OF STOCK

        Section 1. Form. Every holder of stock in the corporation shall be
entitled to have a certificate, signed by, or in the name of the corporation by
the chairman of the board, president or a vice-president and the secretary or an
assistant secretary of the corporation, certifying the number of shares owned by
such holder in the corporation. If such a certificate is countersigned (1) by a
transfer agent or an assistant transfer agent other than the corporation or its
employee or (2) by a registrar, other than the corporation or its employee, the
signature of any such chairman of the board, president, vice-president,
secretary, or assistant secretary may be facsimiles. In case any officer or
officers who have signed, or whose facsimile signature or signatures have been
used on, any such certificate or certificates shall cease to be such officer or
officers of the corporation whether because of death, resignation or otherwise
before such certificate or certificates have been


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delivered by the corporation, such certificate or certificates may nevertheless
be issued and delivered as though the person or persons who signed such
certificate or certificates or whose facsimile signature or signatures have been
used thereon had not ceased to be such officer or officers of the corporation.
All certificates for shares shall be consecutively numbered or otherwise
identified. The name of the person to whom the shares represented thereby are
issued, with the number of shares and date of issue, shall be entered on the
books of the corporation. Shares of stock of the corporation shall only be
transferred on the books of the corporation by the holder of record thereof or
by such holder's attorney duly authorized in writing, upon surrender to the
corporation of the certificate or certificates for such shares endorsed by the
appropriate person or persons, with such evidence of the authenticity of such
endorsement, transfer, authorization, and other matters as the corporation may
reasonably require, and accompanied by all necessary stock transfer stamps. In
that event, it shall be the duty of the corporation to issue a new certificate
to the person entitled thereto, cancel the old certificate or certificates, and
record the transaction on its books. The board of directors may appoint a bank
or trust company organized under the laws of the United States or any state
thereof to act as its transfer agent or registrar, or both in connection with
the transfer of any class or series of securities of the corporation.

        Section 2. Lost Certificates. The board of directors may direct a new
certificate or certificates to be issued in place of any certificate or
certificates previously issued by the corporation alleged to have been lost,
stolen, or destroyed, upon the making of an affidavit of that fact by the person
claiming the certificate of stock to be lost, stolen, or destroyed. When
authorizing such issue of a new certificate or certificates, the board of
directors may, in its discretion and as a condition precedent to the issuance
thereof, require the owner of such lost, stolen, or destroyed certificate or
certificates, or his or her legal representative, to give the corporation a bond
sufficient to indemnify the corporation against any claim that may be made
against the corporation on account of the loss, theft or destruction of any such
certificate or the issuance of such new certificate.

        Section 3. Fixing a Record Date for Shareholder Meetings. In order that
the corporation may determine the shareholders entitled to notice of or to vote
at any meeting of shareholders or any adjournment thereof, the board of
directors may fix a record date, which record date shall not precede the date
upon which the resolution fixing the record date is adopted by the board of
directors, and which record date shall not be more than sixty nor less than ten
days before the date of such meeting. If no record date is fixed by the board of
directors, the record date for determining shareholders entitled to notice of or
to vote at a meeting of shareholders shall be the close of business on the next
day preceding the day on which notice is given, or if notice is waived, at the
close of business on the day next preceding the day on which the meeting is
held. A determination of shareholders of record entitled to notice of or to vote
at a meeting of shareholders shall apply to any adjournment of the meeting
provided, however, that the board of directors may fix a new record date for the
adjourned meeting.



                                  Page 12 of 15






        Section 4. Fixing a Record Date for Action by Written Consent. in order
that the corporation may determine the shareholders entitled to consent to
corporate action in writing without a meeting, the board of directors may fix a
record date, which record date shall not precede the date upon which the
resolution fixing the record date is adopted by the board of directors, and
which date shall not be more than ten days after the date upon which the
resolution fixing the record date is adopted by the board of directors. If no
record date has been fixed by the board of directors, the record date for
determining shareholders entitled to consent to corporate action in writing
without a meeting, when no prior action by the board of directors is required by
statute, shall be the first date on which a signed written consent setting forth
the action taken or proposed to be taken is delivered to the corporation by
delivery to its registered office in the State of Texas, its principal place of
business, or an officer or agent of the corporation having custody of the book
in which proceedings of meetings of shareholders are recorded. Delivery made to
the corporation's registered office shall be by hand or by certified or
registered mail, return receipt requested. If no record date has been fixed by
the board of directors and prior action by the board of directors is required by
statute, the record date for determining shareholders entitled to consent to
corporate action in writing without a meeting shall be at the close of business
on the day on which the board of directors adopts the resolution taking such
prior action.

        Section 5. Fixing a Record Date for Other Purposes. In order that the
corporation may determine the shareholders entitled to receive payment of any
dividend or other distribution or allotment or any rights or the shareholders
entitled to exercise any rights in respect of any change, conversion or exchange
of stock, or for the purposes of any other lawful action, the board of directors
may fix a record date, which record date shall not precede the date upon which
the resolution fixing the record date is adopted, and which record date shall be
not more than sixty days prior to such -action. If no record date is fixed, the
record date for determining shareholders for any such purpose shall be at the
close of business on the day on which the board of directors adopts the
resolution relating thereto.

        Section 6. Registered Shareholders. Prior to the surrender to the
corporation of the certificate or certificates for a share or shares of stock
with a request to record the transfer of such share or shares, the corporation
may treat the registered owner as the person entitled to receive dividends, to
vote, to receive notifications, and otherwise to exercise all the rights and
powers of an owner.

        Section 7. Subscriptions for Stock. Unless otherwise provided for in the
subscription agreement, subscriptions for shares shall be paid in full at such
time, or in such installments and at such times, as shall be determined by the
board of directors. Any call made by the board of directors for payment on
subscriptions shall be uniform as to all shares of the same class or as to all
shares of the same series. In case of default in the payment of any installment
or call when such payment is due, the corporation may proceed to collect the
amount due in the same manner as any debt due the corporation.





                                 Page 13 of 15




                                   ARTICLE VII

                               GENERAL PROVISIONS

        Section 1. Dividends. Dividends upon the capital stock of the
corporation, subject to the provisions of the certificate of incorporation, if
any, may be declared by the board of directors at any regular or special
meeting, pursuant to law. Dividends may be paid in cash, in property, or in
shares of the capital stock, subject to the provisions of the certificate of
incorporation. Before payment of any dividend, there may be set aside out of any
funds of the corporation available for dividends such sum or sums as the
directors from time to time, in their absolute discretion, think proper as a
reserve or reserves to meet contingencies, or for equalizing dividends, or for
repairing or maintaining any property of the corporation, or any other purpose
and the directors may modify or abolish any such reserve in the manner in which
it was created.

        Section 2. Checks, Drafts or Orders. All checks, drafts, or other orders
for the payment of money by or to the corporation and all notes and other
evidences of indebtedness issued in the name of the corporation shall be signed
by such officer or officers, agent or agents of the corporation, and in such
manner, as shall be determined by resolution of the board of directors or a duly
authorized committee thereof.

        Section 3. Contracts. The board of directors may authorize any officer
or officers, or any agent or agents, of the corporation to enter into any
contract or to execute and deliver any instrument in the name of and on behalf
of the corporation, and such authority may be general or confined to specific
instances.

        Section 4. Loans. The corporation may lend money to, or guarantee any
obligation of, or otherwise assist any officer or other employee of the
corporation or of its subsidiary, including any officer or employee who is a
director of the corporation or its subsidiary, whenever, in the judgment of the
directors, such loan, guaranty or assistance may reasonably be expected to
benefit the corporation. The loan, guaranty or other assistance may be with or
without interest, and may be unsecured, or secured in such manner as the board
of directors shall approve, including, without limitation, a pledge of shares of
stock of the corporation. Nothing in this section contained shall be deemed to
deny, limit or restrict the powers of guaranty or warranty of the corporation at
common law or under any statute.

        Section 5. Fiscal Year. The fiscal year of the corporation shall be
fixed by resolution of the board of directors.

        Section 6. Corporate Seal. The board of directors shall provide a
corporate seal which shall be in the form of a circle and shall have inscribed
thereon the name of the corporation and the words "Corporate Seal, Texas". The
seal may be used by causing it or a facsimile thereof to be impressed or affixed
or reproduced or otherwise.

                                  Page 14 of 15








        Section 7. Voting Securities Owned By Corporation. Voting securities in
any other corporation held by the corporation shall be voted by the president,
unless the board of directors specifically confers authority to vote with
respect thereto, which authority may be general or confined to specific
instances, upon some other person or officer. Any person authorized to vote
securities shall have the power to appoint proxies, with general power of
substitution.

        Section 8. Inspection of Books and Records. Any shareholder of record,
in person or by attorney or other agent, shall, upon written demand under oath
stating the purpose thereof, have the right during the usual hours for business
to inspect for any proper purpose the corporation's stock ledger, a list of its
shareholders, and its other books and records, and to make copies or extracts
therefrom. A proper purpose shall mean any purpose reasonably related to such
person's interest as a shareholder. In every instance where an attorney or other
agent shall be the person who seeks the right to inspection, the demand under
oath shall be accompanied by a power of attorney or such other writing which
authorizes the attorney or other agent to so act on behalf of the shareholder.
The demand under oath shall be directed to the corporation at its registered
office in the State of Texas or at its principal place of business.

        Section 9. Section Headings. Section headings in these by-laws are for
convenience of reference only and shall not be given any substantive effect in
limiting or otherwise construing any provision herein.

        Section 10. Inconsistent Provisions. In the event that any provision of
these by-laws is or becomes inconsistent with any provision of the certificate
of incorporation, the General Corporation Law of the State of Texas or any other
applicable law, the provision of these by-laws shall not be given any effect to
the extent of such inconsistency but shall otherwise be given full force and
effect.


                                  ARTICLE VIII

                                   AMENDMENTS

        These by-laws may be altered, amended or repealed or new by-laws may be
adopted by the shareholders or by the Board of Directors at any regular meeting
of the shareholders or of the Board of Directors or at any special meeting of
the shareholders or of the Board of Directors if notice of such alteration,
amendment, repeal or adoption of new by-laws be contained in the notice of such
special meeting; provided, however, that such alteration, amendment, repeal or
adoption of new by-laws shall not be effected by the shareholders by less than
the affirmative vote of the holders of at least eighty percent (80%) of the
outstanding shares of the Corporation entitled to vote in the election of
directors, voting as one class, and any required vote of Preferred Stock.

                                  Page 15 of 15




                                 WRITTEN CONSENT
                                     OF THE
                                SOLE STOCKHOLDER
                                       OF
                   MAXUM HEALTH SERVICES OF NORTH TEXAS, INC.
                              (a Texas corporation)
                              IN LIEU OF A MEETING

                                October 16, 2001

        The undersigned, being the sole stockholder of Maxum Health Services
        of North Texas. Inc., a Texas corporation (the "Company"), pursuant to
        the provisions of Article 9.10(A) of the Texas Business Corporation Act,
        hereby consents to the taking of the following actions by written
        consent in lieu of a meeting and hereby consents to, adopts and approves
        the following resolutions and each and every action effected thereby:

        AMENDMENT TO THE BYLAWS

        WHEREAS, the sole stockholder of the Company has deemed it advisable,
        and in the best interests of the Company, to amend (the "Amendment") the
        By-Laws (the "By-Laws") of the Company to change the number of directors
        required to be on the board of directors of the Company;

        NOW, THEREFORE, BE IT RESOLVED, that the By-Laws shall be amended to
        restate, in its entirety, the first sentence of Article III, Section 2
        to state the following: "The number of directors shall be not less than
        one (1) nor more than seven (7)."

        RESOLVED FURTHER, that the proper officers of the Company are and each
        of them hereby is authorized and directed, in the name and on behalf of
        the Company, to execute and deliver the Amendment, with such nonmaterial
        changes or amendments thereto as such officer or officers deem necessary
        or appropriate; and

        RESOLVED FURTHER, that all acts and things heretofore done by any such
        officers, or by any other employees or agents of the Company, on or
        prior to the date hereof, in connection with the transactions
        contemplated by the foregoing resolutions hereby are, in all aspects,
        ratified, confirmed, approved and adopted as acts on behalf of the
        Company.

        IN WITNESS WHEREOF, the undersigned sole stockholder of the Company has
        executed this Written Consent as of the date first above written.



                                        MAXUM HEALTH SERVICES CORP.



                                        By: /s/ MARILYN U. MacNIVEN-YOUNG
                                            ------------------------------------
                                            Mariyln U. MacNiven-Young,
                                            Executive Vice President










                   MAXUM HEALTH SERVICES OF NORTH TEXAS, INC.

                            CERTIFICATE OF SECRETARY



        I, Marilyn U. MacNiven-Young, do hereby certify that: (i) I am the duly
elected and acting Secretary of Maxum Health Services of North Texas, Inc., a
Texas corporation (the "Company"); and (ii) Amendment No. 1 to the Bylaws
("Bylaws") of the Company attached hereto as Exhibit A, constitutes part of the
Bylaws of the Company as duly adopted by the Sole Stockholder of the Company on
October 16, 2001.


        WITNESS my hand this 16th day of October, 2001.



                                       /s/ MARILYN U. MacNIVEN-YOUNG
                                      ------------------------------------------
                                      Marilyn U. MacNiven-Young, Secretary




                                                                       EXHIBIT A


                             AMENDMENT NO. 1 TO THE
                                   BY-LAWS OF
                   MAXUM HEALTH SERVICES OF NORTH TEXAS, INC.
                              A TEXAS CORPORATION

               ADOPTED BY THE SOLE STOCKHOLDER ON OCTOBER 16, 2001






        The first sentence of Article III, Section 2 of the By-laws of Maxum
Health Services of North Texas, Inc. is amended in its entirety as follows:

        "The number of directors shall be not less than one (1) nor more than
seven (7)"