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                                                                   EXHIBIT 10.18

                               MAXUM HEALTH CORP.


                       NONQUALIFIED STOCK OPTION AGREEMENT


     THIS AGREEMENT, entered into as of August 17, 1994, between MAXUM HEALTH
CORP., a Delaware corporation (the "Company"), and Ronald G. Pantello (the
"Optionee").

                                   WITNESSETH:

     WHEREAS, Optionee is a non-employee member of the Board of Directors of the
Company who has rendered valuable services to the Company, and whom the Board of
Directors desires to retain; and

     WHEREAS, the Committee has determined that it would be in the best
interests of the Company and its stockholders to grant the option to purchase
Stock described in this Agreement to Optionee as an inducement to enter into or
remain on the Board of Directors of the Company, and as an incentive for
extraordinary efforts during such service:

     WHEREAS, certain capitalized terms used herein are defined in Section 11
below;

     NOW, THEREFORE, it is agreed as follows:

SECTION 1. GRANT OF OPTION.

     (a)  OPTION.  On the terms and conditions stated below, the Company hereby
grants to Optionee a Nonqualified Stock Option to purchase fifteen thousand
(15,000) Shares of Stock (the "Option Shares") at an Exercise Price equal to
$.0625 per Share.

     (b)  CONTINGENT GRANT.  The Option granted herein is expressly conditioned
on receiving the approval of the majority of Shares of the Company present, or
represented and entitled to vote, at a vote of the stockholders held in
accordance with the Bylaws of the Company by the earlier of (i) the second
anniversary of this Agreement or (ii) the Company's next Annual Meeting of
Stockholders.

SECTION 2. NO TRANSFER OR ASSIGNMENT OF OPTION.

     Except as otherwise provided in this Agreement, this Agreement and the
rights and privileges conferred hereby shall not be transferred, assigned,
pledged or hypothecated in any way (whether by operation of law or otherwise)
and shall not be subject to sale under execution, attachment or similar process.
Upon any attempt to transfer, assign, pledge, hypothecate or otherwise dispose
of this Agreement, or of any right or privilege conferred hereby, contrary

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to the provisions hereof, or upon any attempted sale under any execution, 
attachment or similar process upon the rights and privileges conferred 
hereby, this Agreement and the rights and privileges conferred hereby shall 
immediately become null and void.

     This option may be transferred by Optionee only by will, the laws of
descent and distribution, or by a qualified domestic relations order as defined
in the Code, and during his lifetime, may be exercised only by Optionee, his
guardian or legal representative, or the beneficiaries of such qualified
domestic relations order.

SECTION 3. RIGHT TO EXERCISE; HOLDING PERIOD.

     (a)  VESTING.  Subject to Section 1(b) above, the right of Optionee to
purchase the Option Shares is fully vested at the date of this grant.

     (b)  PARTIAL OR FULL EXERCISE.  Optionee may exercise all or any part this
option for the Option Shares that have not been previously exercised.


SECTION 4. EXERCISE PROCEDURES.

     (a)  NOTICE OF EXERCISE.  The Optionee or the Optionee's representative may
exercise his rights to purchase by giving written notice to the Secretary of the
Company pursuant to Section 10(d).  The notice shall specify the election to
exercise this option, the number of Shares for which it is being exercised and
the form of payment.  The notice shall be signed by the person or persons
exercising this option.  In the event that this option is being exercised by a
representative of Optionee, the notice shall be accompanied by proof
(satisfactory to the Company) of the representative's right to exercise this
option.  The Optionee or Optionee's representative shall deliver to the
Secretary of the Company, at the time of giving the notice, payment in a form
permissible under Section 5 for the full amount of the Purchase Price.  A form
of exercise notice is attached hereto as Exhibit "A".

     (b)  ISSUANCE OF SHARES.  After receiving a proper notice of exercise, the
Company shall cause to be issued a certificate or certificates for the Shares as
to which this option has been exercised, registered in the name of the person
exercising this option (or in the names of such person and his or her spouse as
community property or as joint tenants with right of survivorship) and bearing
the appropriate legends.  The Company shall cause such certificate or
certificates to be delivered to or upon the order of the person exercising the
option.

SECTION 5. PAYMENT FOR STOCK.

     The entire Purchase Price may be paid in lawful money of the United States
of America.  Alternatively, to the extent that applicable law permits and
subject to the sole and absolute discretion of the Committee, all or part of the
Purchase Price may be paid by the surrender of Shares in good form for transfer.
Such Shares must have a fair market value (as determined by


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the Committee) on the date of exercise of this option which, together with any
amount paid in lawful money, is equal to the Purchase Price.

     With the Committee's consent, which may be given or withheld in its sole
and absolute discretion, Optionee may pay some or all of the Purchase Price by
delivery of the Optionee's promissory note (in a form and on terms satisfactory
to the Committee).

SECTION 6. TERM AND EXPIRATION.

     (a)  BASIC TERM.  This option shall in any event expire on the date ten
(10) years after the Date of Grant.

     (b)  TERMINATION OF SERVICE (EXCEPT BY DEATH OR DISABILITY).  If Optionee's
Service terminates for any reason other than death or Disability, then this
Agreement shall expire on the date three (3) months after such termination.
Optionee may exercise all or part of this option at any time before its
expiration under the preceding sentence, but only to the extent that this option
has become vested under Section 3(a) before Optionee's Service terminated.

     (c)  DEATH OR DISABILITY OF OPTIONEE.  If Optionee dies or suffers
Disability while in Service, then this option shall expire on the earlier of the
following dates:

          (1)  The expiration date determined pursuant to Section 6(a) above;

          (2)  The date six (6) months after the Optionee's death; or

          (3)  The date twelve (12) months after Optionee suffers Disability;

     (d)  LEAVES OF ABSENCE.  For purposes of this Section 6, Service shall be
deemed to continue during any period when the Optionee is on military leave,
sick leave, or other bona fide leave of absence (to be determined in the sole
discretion of the Committee).

SECTION 7. LEGALITY OF INITIAL ISSUANCE.

     No Shares shall be issued upon the exercise of this option unless and until
the Company has determined that:

     (a)  It and Optionee have taken any actions the Company decides are
required to register the Shares under the Securities Act or to perfect an
exemption from the registration requirements thereof;

     (b)  Any applicable listing requirement of any stock exchange on which
Stock is listed has been satisfied; and

     (c)  Any other applicable provision of state or federal law has been
satisfied.

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SECTION 8. INVESTMENT INTENT.

     (a)  GENERAL.  Regardless of whether the offering and sale of Shares have
been registered under the Securities Act or have been registered or qualified
under the securities laws of any state, the Company may impose restrictions upon
the sale, pledge or other transfer of such Shares (including the placement of
appropriate legends on stock certificates) if, in the judgment of the Company
and its counsel, such restrictions are necessary or desirable in order to
achieve compliance with the Securities Act, the securities laws of any state,
other applicable law, or with restrictions imposed by the Company's
underwriters.

     (b)  INVESTMENT INTENT AT GRANT.  Optionee represents and agrees that the
Shares to be acquired upon exercising this option will be acquired for
investment, and not with a view to the sale or distribution thereof.

     (c)  INVESTMENT INTENT AT EXERCISE.  In the event that the sale of Shares
is not registered under the Securities Act, but an exemption is available which
requires an investment representation or other representation, the Optionee
shall represent and agree at the time of exercise that the Shares being acquired
upon exercising this option are being acquired for investment, and not with a
view to the sale or distribution thereof, and shall make such other
representations as are deemed necessary or appropriate by the Company and its
counsel.

     (d)  LEGEND.  All certificates evidencing Shares acquired under this
Agreement shall, where applicable and in the discretion of the Committee, have
placed thereon a legend substantially as follows:

          "THE SHARES OF STOCK OF THE CORPORATION REPRESENTED BY THIS
          CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
          AS AMENDED, OR ANY STATE SECURITIES LAWS, AND MAY NOT BE RESOLD IN THE
          ABSENCE OF REGISTRATION THEREUNDER OR THE AVAILABILITY OF AN EXEMPTION
          THEREFROM."

and such other restrictive legends as are required or deemed advisable under the
provisions of any applicable law.

     (e)  REMOVAL OF LEGENDS.  If, in the opinion of the Company and its
counsel, any legend placed on a stock certificate representing Shares sold under
this Agreement is no longer required, the holder of such certificate shall be
entitled to exchange such certificate for a certificate representing the same
number of Shares but lacking such legend.

     (f)  ADMINISTRATION.  Any determination by the Company, the Committee or
their counsel in connection with any of the matters set forth in this Section 8
shall be conclusive and binding on the Optionee and all other persons.


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SECTION 9. SHARES AND ADJUSTMENTS.

     (a)  GENERAL.  In the event of any change in the outstanding Shares that 
occurs by reason of a stock dividend or split, recapitalization, merger, 
consolidation, combination, exchange of shares, or other similar corporate 
change, the aggregate number of Shares subject to this option, and the 
Exercise Price, may (but need not) be adjusted appropriately by the 
Committee, whose determination shall be final and conclusive; provided, 
however, that fractional shares shall be rounded to the nearest whole share.

     (b)  RESERVATION OF RIGHTS.  Except as provided in this Section 9, Optionee
shall have no rights by reason of (i) any subdivision or consolidation of shares
of stock of any class, (ii) the payment of any dividend, or (iii) any other
increase or decrease in the number of shares of stock of any class.  Any issue
by the Company of shares of stock of any class, or securities convertible into
shares of stock of any class, shall not affect, and no adjustment by reason
thereof shall be made with respect to, the number or Exercise Price of the
Shares subject to this option.  The grant of this option shall not affect in any
way the right or power of the Company to make adjustments, reclassifications,
reorganizations or changes of its capital or business structure, to merge or
consolidate or to dissolve, liquidate, sell or transfer all or any part of its
business or assets.

     (c)  DISSOLUTION OR MERGER.  In the event that, prior to the exercise in
full of this option a merger or dissolution in which the Company is not the
surviving business entity shall occur, or a transfer of substantially all the
assets of the Company shall occur:

          (1)  If provision be made in writing in connection with such
     transaction for the assumption and continuance of the option hereby
     granted, or the substitution for such option of a new option covering the
     shares of the successor business entity, with appropriate adjustment as to
     number and kind of shares and prices, this option, or the new option
     substituted therefor, as the case may be, shall continue in the same
     manner and under the terms provided.

          (2)  In the event provision is not made in such transaction for the
     continuance and assumption of this option, or for the substitution of an
     option covering the shares of the successor business entity, the Optionee
     shall be entitled within a reasonable period of time, prior to the
     effective date of any such transaction, to purchase the full number of
     Option Shares.


SECTION 10.  MISCELLANEOUS PROVISIONS.

     (a)  WITHHOLDING TAXES.  In the event that the Company determines that it
is required to withhold foreign, federal, state or local taxes as a result of
the exercise of this option, Optionee, as a condition to the exercise of this
option, shall make arrangements satisfactory to the Company to enable it to
satisfy all withholding requirements.  If agreeable to the Committee and

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the Company's counsel, Optionee shall be allowed to deliver previously owned
Shares, or Shares obtained from the exercise of this option, for the payment of
such withholding tax; provided that Optionee MUST make advance elections, or
otherwise satisfy Rule 16b-3 of the Securities Exchange Act of 1934.

     (b)  RIGHTS AS A STOCKHOLDER.  Neither Optionee nor Optionee's
representative shall have any rights as a stockholder with respect to any Shares
subject to this Agreement until such Shares have been issued in the name of
Optionee or Optionee's representative.

     (c)  NO EMPLOYMENT RIGHTS.  Nothing in this Agreement shall be construed 
as giving Optionee the right to continue Service.  The Company and/or the 
Board reserves the right to terminate Optionee's Service at any time, to the 
fullest extent allowed by the Company's Bylaws.

     (d)  NOTICE.  Any notice required by the terms of this Agreement shall be
given in writing and shall be deemed effective upon personal delivery or upon
deposit with the United States Postal Service, by registered or certified mail
with postage and fees prepaid, by express mail or other overnight delivery
service or by facsimile transmission, receipt confirmed, addressed to the party
entitled to such notice at the address shown below such party's signature on
this Agreement, or at such other address as such party may designate by ten (10)
days' advance written notice to the other party to this Agreement.

     (e)  ENTIRE AGREEMENT.  This Agreement constitutes the entire contract
between the parties hereto with regard to the subject matter hereof.

     (f)  CHOICE OF LAW.  THIS AGREEMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF DELAWARE AS SUCH LAWS ARE APPLIED TO
CONTRACTS ENTERED INTO AND PERFORMED IN SUCH STATE.

     (g)  GENDER AND NUMBER.  Whenever the masculine, feminine or neuter gender,
or the singular or plural number is used herein, the application of one shall
include the application of the other as the context so indicates.

SECTION 11.  DEFINITIONS.

     (a)  "AGREEMENT" shall mean this Nonquafified Stock Option Agreement.

     (b)  "BOARD" shall mean the Board of Directors of the Company, as
constituted from time to time.

     (c)  "CODE" shall mean the Internal Revenue Code of 1986, as amended.

     (d)  "COMMITTEE" shall mean the Compensation Committee of the Board, or, if
none has been appointed, the full Board.

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     (e)  "DATE OF GRANT" shall mean the date first above written, which is the
date the Committee resolved to grant this option.

     (f)  "DISABILITY" shall mean that Optionee is unable to engage in any
Substantial Gainful Activity  by reason of any medically determinable physical
or mental impairment which, in the sole and  final judgment of the Committee,
can be expected to result in death or which has lasted, or can be expected to
last, for a continuous period of not less than 12 months.

     (g)  "EXERCISE PRICE" shall mean the amount for which one Share may be
purchased upon exercise of this option, as specified in Section 1(a).

     (h)  "INCENTIVE STOCK OPTION" shall mean an employee incentive stock option
described in section 422 of the Code.

     (i)  "NONQUALIFIED STOCK OPTION" shall mean a stock option not described in
sections 422, 423(b) or 424(b) of the Code.

     0)   "OPTION SHARES" means the number of shares initially subject to this
option determined pursuant to Section 1(a) hereof.

     (k)  "PURCHASE PRICE" shall mean the Exercise Price multiplied by the
number of Shares with respect to which this option is being exercised.

     (l)  "SECURITIES ACT" shall mean the Securities Act of 1933, as amended.

     (m)  "SERVICE" means the period Optionee is continuously rendering services
for compensation to the Company or a subsidiary whether as a common law
employee, or as an independent contractor, or as a member of the Board.

     (n)  "SHARE" shall mean a share of Stock, as adjusted in accordance with
Section 9 (if applicable).

     (o)  "STOCK" shall mean the Common Stock of the Company, par value of $.01
per share.

     (p)  "SUBSIDIARY" shall mean any corporation, if the Company and/or one or
more other Subsidiaries own not less than 50% of the total combined voting power
of all classes of outstanding stock of such corporation.

     (q)  "SUBSTANTIAL GAINFUL ACTIVITY" means the performance of significant 
duties over a reasonable period of time in work for remuneration or profit 
(or in work of a type generally performed for remuneration or profit), and 
including Service as a member of the Board.

     (r)  "TRANSFEREE" shall mean any person to whom the Optionee has directly
or indirectly transferred any Share acquired under this Agreement.

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     IN WITNESS WHEREOF, the Company has caused this Agreement to be executed on
its behalf by its officer duly authorized to act on behalf of the Committee, and
the Optionee has personally executed this Agreement.



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OPTIONEE                                          MAXUM HEALTH CORP.

/s/ Ronald G. Pantello
-----------------------------------               By: /s/ Glenn P. Cato
          (Signature)                                ---------------------------
                                                  Name: Glenn P. Cato
                                                        ------------------------
                                                  Title: President and CEO
Ronald G. Pantello                                      -----------------------
-----------------------------------
            (Name)


Optionee's Address:                               Company Address:

25 Berkshire Road                                 14850 Quorum Drive, Ste. 400
Woodcliff Lake, NJ 07675                          Dallas, Texas 75240
SSN: ###-##-####

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