EXHIBIT 3.23

ARTICLES OF INCORPORATION

NDDC, INC.

I, the undersigned natural person of the age of eighteen (18) years or
more, acting as incorporator under the Texas Business Corporation Act, do hereby
adopt the following Articles of Incorporation for such corporation.

ARTICLE I

The name of the corporation is NDDC, Inc.

ARTICLE II

The period of duration of the corporation is perpetual.

ARTICLE III

The corporation is organized for the purpose of transacting any and all
lawful business for which corporations may be organized under the Texas Business
Corporation Act.

ARTICLE IV

The aggregate number of shares which the corporation shall have
authority to issue is 1,000 shares of common stock of the par value of $.01
each.

ARTICLE V

No shareholder of the corporation shall have the right of cumulative
voting at any election of directors or upon any other matter.

ARTICLE VI

Shareholders of the corporation shall have no preemptive right to
acquire additional, unissued, or treasury shares of the corporation.

ARTICLE VII

The following provisions are inserted herein for the purpose of
defining, limiting, and regulating the powers of the corporation and of the
directors and of the shareholders, provided, however, that said provisions shall
not be deemed exclusive of any rights or liabilities otherwise granted or
imposed by the laws of the State of Texas:

1. The liability of the directors of the corporation is eliminated to
the fullest extent permitted by the provisions of the Texas Business Corporation
Act and by the provisions of the Texas Miscellaneous Corporation Laws Act, as
the same may be amended and supplemented.

2. The corporation shall, to the fullest extent permitted by the
provisions of the Texas Business Corporation Act, as the same may be amended and
supplemented, indemnify any and all persons whom it shall have power to
indemnify under said Article from and against any and all of the expenses,
liabilities, or other matters referred to or covered by said Article.

3. With respect to any matter for which the affirmative vote of the
holders of at least a two-thirds portion of the shares entitled to vote is
otherwise required by the Texas Business Corporation Act, the act of the
shareholders on that matter shall be the affirmative vote of the holders of at
least a majority of the shares entitled to vote on that matter, rather than the
affirmative vote otherwise required by the Texas Business Corporation Act. With
respect to any matter for which the affirmative vote of the holders of at least
two-thirds portion of the shares of any class is otherwise required by the Texas
Business Corporation Act, the act of the holders of shares of that class on that
matter shall be the affirmative vote of the holders of at least a majority of
the shares of that class, rather than the affirmative vote of the holders of
shares of that class otherwise required by the Texas Business Corporation Act.

4. Any action required by the Texas Business Corporation Act to be taken
at an annual or special meeting of shareholders, or any action which may be
taken at an annual or special meeting of 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, shall be signed by the holder or
holders of shares having not less than the minimum number of votes that would be
necessary to take such action at a meeting at which the holders of all shares
entitled to vote on the action were present and voted.

ARTICLE VIII

The corporation will not commence business until it has received from
the issuance of its shares consideration of the value of One Thousand Dollars
($1,000), consisting of money, labor done, or property actually received.

ARTICLE IX

The address of the registered office of the corporation is 807 Brazos,
Austin, Texas 78701, and the name of its initial registered agent at such
address is The Prentice-Hall Corporation System, Inc.

Page - 2

ARTICLE X

The business and affairs of the corporation shall be managed by a board
of directors (the "board of directors") composed of such number of persons as
may be filed by the bylaws of the corporation. Until changed by the bylaws, the
number of directors constituting the board of directors shall be three (3). The
name and address of each person who shall serve as initial directors of the
corporation as follows:

William L. MacKnight 14850 Quorum Drive, Suite 400
Dallas, Texas 75240

Mark A. Solls 14850 Quorum Drive, Suite 400
Dallas, Texas 75240

Glenn P. Cato 14850 Quorum Drive, Suite 400
Dallas, Texas 75240

ARTICLE XI

The initial bylaws of the corporation shall be adopted by the board of
directors and the power to alter, amend or repeal the bylaws or adopt new
bylaws, subject to repeal or change by action of the shareholders, shall be
vested in the board of directors.

ARTICLE XII

The name and address of the incorporator is Mark A. Solls, 14850 Quorum
Drive, Suite 400, Dallas, Texas 75240.

ARTICLE XIII

From time to time any of the provisions of these Articles of
Incorporation may be amended, altered, or repealed, and other provisions
authorized by the laws of the State of Texas at the time in force may be added
or inserted in the manner and at the time prescribed by said laws, and all
contracts and rights at any time conferred upon the shareholders of the
corporation by these Articles of Incorporation are granted subject to the
provisions of this Article.

Page - 3

IN WITNESS WHEREOF, I have hereunto set my hand this 16th day of
December, 1991.

/s/ MARK A. SOLLS
-----------------------------------
Mark A. Solls, Incorporator

THE STATE OF TEXAS )(
)(
COUNTY OF DALLAS )(

I, the undersigned, a Notary Public, do hereby certify that on this 16th
day of December, 1991, personally appeared before me Mark A. Solls, who,
being by me first duly sworn, declared that he is the person who signed the
foregoing document as incorporator, and that the statements contained therein
are true.

/s/ JANET L. IOTT
-----------------------------------
Janet L. Iott, Notary Public

ooooooooooooooooooooooooooooooooooooooooooooooooooo
o NOTARY PUBLIC JANET L. IOTT o
o [STAR] Notary Public, State of Texas o
o STATE OF TEXAS My Commission Expires 8-21-93 o
ooooooooooooooooooooooooooooooooooooooooooooooooooo

Page - 4

FILED
In the Office of the
Secretary of State of Texas

JAN 13 1992

Corporations Section

ASSUMED NAME CERTIFICATE
FOR
NDDC, INC.

1. The name of the incorporated business as stated in its Articles of
Incorporation or comparable document is NDDC, Inc.

2. The assumed name under which the business or professional service is to
be conducted or rendered is North Dallas Diagnostic Center.

3. The state under the laws of which it was incorporated is Texas and the
address of its registered or similar office in that jurisdiction is c/o
The Prentice-Hall Corporation System, Inc., 807 Brazos, Austin, Texas
78701.

4. The period, not to exceed ten years, during which the assumed name will
be used is ten years.

5. The corporation is a business corporation.

6. The address of the registered office of the Corporation is 807 Brazos,
Austin, Texas 78701 and the name of its registered agent at such
address is The Prentice-Hall Corporation System, Inc.

7. The county where the business or professional service is being or is to
be conducted or rendered under such assumed name is all counties.

NDDC, INC.

By: /s/ MARK A. SOLLS
------------------------------------
Name: MARK A. SOLLS
----------------------------------
Title: SENIOR VICE PRESIDENT
---------------------------------

STATE OF TEXAS SS.
SS.
COUNTY OF DALLAS SS.

Before me on this 31st day of December, 1991, personally appeared Mark
A. Solls and acknowledged to me that he executed the foregoing certificate for
the purposes therein expressed.

[SEAL]

/s/ VICKI BATES
---------------------------------
Notary Public in and for
the State of Texas

My Commission Expires:

4/24/93
- ----------------------------

FILED
In the Office of the
Secretary of State of Texas

SEP 16 1992

Corporations Section

ASSUMED NAME CERTIFICATE
FOR AN INCORPORATED BUSINESS OR PROFESSION

1. The name of the incorporated business or profession as stated in its
Articles of Incorporation or comparable document is NDDC, Inc. .
-------------------

2. The assumed name under which the business or professional service is to
be conducted or rendered is Maxum Diagnostic Center .
-------------------------------------------

3 The state, country, or other jurisdiction under the laws of which it was
incorporated or associated is Texas , and the address of
---------------------
its registered or similar office in that jurisdiction is
807 Brazos, Austin, Texas 78701 .
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4. The period, not to exceed 10 years, during which the assumed name will
be used is 10 years
--------------------

5. The corporation is a (circle one) business corporation, non-profit
corporation, professional corporation, professional association or some
other type of incorporated business, professional or other association
(specify)

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6 If the corporation is required to maintain a registered office in Texas,
the address of the registered office is 807 Brazos, Austin, Texas 78701
-------------------------------
and the name of its registered agent at such address is
The Prentice-Hall Corporation System, Inc.
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7 If the corporation is not required to or does not maintain a registered
office in Texas, the office address in Texas is N/A
-----------------------
and its office address elsewhere is
------------------------------------

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8 The county or counties where business or professional services are being
or are to be conducted or rendered under such assumed name are [if
applicable, use the designation "ALL"]:
Dallas
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NDDC, INC.

By: /s/ MARK A. SOLLS
--------------------------------------------
Signature of officer, representative or
attorney-in-fact of the corporation
Mark A. Solls, Senior Vice President

Before me on this 11th day of September , 19 92 , personally appeared Mark A.
------- ----------- ---- ---------
Solls and acknowledged to me that he executed the foregoing certificate
- ---------- ----
for the purposes therein expressed.

- ---------------------------------------
JANET L IOTT
[SEAL] Notary Public State of Texas
My Commission Expires 8 21 93 /s/ JANET L IOTT
- --------------------------------------- ------------------------------------
(Notary seal) Notary Public Dallas County
---------------

NOTE: A certificate executed and acknowledged by an attorney-in-fact shall
include a statement that the attorney-in-fact has been duly authorized in
writing by his or her principal to execute and acknowledge the same.

FILED
In the Office of the
Secretary of State of Texas

OCT 19 1992

Corporations Section

STATEMENT OF CHANGE OF REGISTERED

OFFICE BY REGISTERED AGENT

To Secretary of State
State of Texas:

Pursuant to the provisions of Article 2.10-1 of the Texas Business Corporation
Act, the undersigned registered agent, for the domestic and foreign corporations
named on the attached list submits the following statement for the purpose of
changing the registered office for such corporations in the State of Texas:

1. The names of the corporations, (hereinafter called the "corporations")
to be represented by the said registered agent are

See attached list
-----------------

2. The post office address at which the said registered agent has
maintained the registered office for the corporations is

c/o The Prentice-Hall Corporation System, Inc.
807 Brazos, Austin, Texas 78701.

3. The new post office address at which the said registered agent will
hereafter maintain the registered office for the corporations is

c/o The Prentice-Hall Corporation System, Inc.
400 N. St. Paul, Dallas, Texas 75201.

4. Notice of this change of address has been given in writing to each
corporation named on the attached list at least 10 days prior to the
date of filing of this Statement.

Dated: October 19, 1992

THE PRENTICE-HALL CORPORATION SYSTEM, INC.

/s/ RICHARD L. KUSHAY
----------------------------------------------
Richard L. Kushay, Assistant Vice President

FILED
In the Office of the
Secretary of State of Texas

OCT 09 1995

Corporations Section

ASSUMED NAME CERTIFICATE

1. The name of the corporation as stated in its articles of incorporation
is NDDC, Inc.

2. The assumed name under which the business or professional service is or
is to be conducted or rendered is Maxum Diagnostic Center - Forest Lane.

3. The state under the laws of which it was incorporated is Texas, and the
address of its registered or similar office in that jurisdiction is 807
Brazos, Austin, Texas 78701.

4. The period, not to exceed 10 years, during which the assumed name will
be used is October 1, 1995 until September 30, 2004.

5. The entity is a business corporation.

6. The entity's registered office in Texas is 807 Brazos, Austin, Texas
78701 and the name of its registered agent at such address is
CSC/Prentice Hall Corporation System, Inc. The address of the principal
office is 14850 Quorum Drive, Suite 400, Dallas, Texas 75240.

7. The county where business or professional services are being or are to
be conducted or rendered under such assumed name is Dallas.

/s/ DON G. HICKS
---------------------------------------
Don G. Hicks, Chief Accounting Officer

Before me on this 5th day of October, 1995, personally appeared Don G.
---
Hicks, an Officer of NDDC, Inc., and acknowledged to me that he executed the
foregoing certificate for the purposes therein expressed.

- ---------------------------------
KIMBERLY BERTRAND
[SEAL] MY COMMISSION EXPIRES
DECEMBER 1, 1997
- ---------------------------------
(Notary Seal) /s/ KIMBERLY BERTRAND
--------------------------------
Notary Public, State of Texas

STATEMENT OF CHANGE OF REGISTERED OFFICE
BY ---------------------------
REGISTERED AGENT FILED
In the Office of the
Secretary of State of Texas

To the Secretary of State JUL 14 1997
State of Texas
Corporations Section
---------------------------
Pursuant to the provisions of Article 2.10.1 of the Texas Business Corporation
Act, the undersigned registered agent, for the corporation named below submits
the following statement for the purpose of changing the registered office
address for such corporation in the State of Texas:

Charter No. See attached list

1. The name of the corporation (hereinafter called the "Corporation")
represented by the said registered agent is:

See attached list

2. The address at which the said registered agent has maintained the
registered office for the corporation is

400 N. St. Paul
Dallas, Texas 75201

3. The new address at which the said registered agent will hereafter
maintain the registered office for the corporation is

800 Brazos
Austin, Texas 78701

4. Notice of this change of address has been given in writing to the above
corporation at least 10 days prior to the date of filing of this
Statement.

Dated: July 11, 1997

THE PRENTICE-HALL CORPORATION SYSTEM, INC.

/s/ JOHN H. PELLETIER
-------------------------------------------------
John H. Pelletier, Assistant Vice President

OFFICE OF THE Corporations Section
SECRETARY OF STATE [THE STATE OF TEXAS SEAL] P.O. Box 13697
Austin, Texas 78711-3697

STATEMENT OF CHANGE OF REGISTERED OFFICE OR
REGISTERED AGENT OR BOTH BY A CORPORATION,
LIMITED LIABILITY COMPANY OR LIMITED PARTNERSHIP

FILED
In the Office of the
Secretary of State of Texas

APR 15 1998

Corporations Section

1. The name of the entity is NDDC, INC.
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The entity's charter/certificate of authority/file number is 1215244 .
-----------------------------

2. The registered office address as PRESENTLY shown in the records of the
Texas secretary of state is: 800 Brazos Street, Austin, TX 78701 .
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3. A.__ The address of the NEW registered office is: (Please provide street
address, city, state and zip code. THE ADDRESS MUST BE IN TEXAS.)

c/o C T CORPORATION SYSTEM, 350 N. St. Paul Street, Dallas, TX 75201 .
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OR B.__ The registered office address will not change.

4. The name of the registered agent as PRESENTLY shown in the records of
the Texas secretary of state is The Prentice-Hall Corporation System, Inc. .
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5. A.__ The name of the NEW registered agent is C T CORPORATION SYSTEM .
--------------------------------------------

OR B.__ The registered agent will not change.

6. Following the changes shown above, the address of the registered office
and the address of the office of the registered agent will continue to
be identical, as required by law.

7. The changes shown above were authorized by
Business Corporations may select A or B Limited Liability Companies may select D or E
Non-Profit Corporations may select A, B, or C Limited Partnerships select F

A X The board of directors; OR
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B. An officer of the corporation so authorized by the board of directors, OR
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C. The members of the corporation in whom management of the corporation is vested
------ pursuant to article 2.14C of the Texas Non-Profit Corporation Act

D. Its members
------
E. Its managers
------
F. The limited partnership
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/s/ BGD 4/2/98
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(Authorized Officer of Corporation)
(Authorized Member of Manager of LLC)
(General Partner of Limited Partnership)
BRIAN G. DRAZBA
S.V.P. OF FINANCE & CONTROLLER

(TEXAS -- 2231 -- 12/28/95)