EXHIBIT 10.4


                        [FORM OF] SECURED PROMISSORY NOTE
                               Due October 1, 2002
                                     Note 1

                  FOR VALUE RECEIVED, MEDICAL DIAGNOSTICS, INC., a Delaware
corporation ("MAKER") hereby promises to pay to DVI FINANCIAL SERVICES INC. or
its assignee ("HOLDER"), or order, principal in the sum of ________________
MILLION Dollars ($___________), and interest thereon at the rate of 10.00 % per
annum computed on the basis of a 360-day year and actual days elapsed (the
"STATED RATE"). Principal and interest is payable, in sixty (60) consecutive
monthly installments of __________________ Dollars ($________) on November 1,
1997 and on the first day of each calendar month thereafter, with all unpaid
principal and interest due and payable in full on October 1, 2002.

         1. Principal and interest are payable to Holder at DVI Financial
Services Inc., 500 Hyde Park, Doylestown, Pennsylvania 18901, or such other
place as the Holder may, from time to time in writing to Maker, designate.

         2. This Note is made pursuant to, and secured by that certain Loan and
Security Agreement dated as of September 29, 1997 among Holder as Lender, Maker
as Borrower and U.S. Diagnostic Inc. as Guarantor (the "AGREEMENT"). All
capitalized terms used but not defined herein have the meanings ascribed to them
in the Agreement, the terms of which are incorporated herein by reference
thereto. This Note is also secured by the Security Documents referred to in the
Agreement. The Agreement and the Security Documents create a lien on and
security interest in, the personal property described therein ("COLLATERAL").
The Agreement and the Security Documents are collectively referred to as the
"LOAN AND SECURITY DOCUMENTS" and are hereby incorporated herein by reference
thereto and made a part of this Note.

         3. If any part of the principal or interest of the Note is not paid
within five (5) days after notice from Holder that such payment is due, it
thereafter bears interest at the rate of eighteen percent (18%) per annum from
and as of the date of delinquency until paid; provided, however that any amount
due pursuant to paragraph 7 hereof must be deducted from the amount due pursuant
to this paragraph 3. If the specified interest rate at any time exceeds the
maximum rate allowed by law, then the applicable interest rate is reduced to the
maximum rate allowed by law. This Note may be prepaid pursuant to Section 2.3 of
the Agreement.

         4. The occurrence of an Event of Default under the Agreement, after
notice is give pursuant to the Agreement, may, at the election of the Holder,
make the entire unpaid balance of the principal amount of this Note and accrued
interest thereon immediately due and payable with out notice of default,
presentment or demand for payment, protest or notice of nonpayment or dishonor,
or other notices or demands of any kind or character.



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         5. Failure of the Holder to exercise the acceleration option of
paragraph 4 of this Note on the occurrence of an Event of Default does not
constitute a waiver of the right to exercise such option on the subsequent
occurrence of an Event of Default.

         6. Principal and interest are payable in lawful money of the United
States of America which is legal tender in payment of all debts and dues, public
and private, at the time of payment. If any payment of principal or interest
under this Note becomes due on a Saturday, Sunday or legal or banking holiday,
such payment is due on the next succeeding business day. Maker waives
presentment, demand for payment, notice of nonpayment, protest, and notice of
protest, and all other notices and demands in connection with the delivery,
acceptance, performance, default, or enforcement of this Note, except as
specifically provided in the Agreement. Maker consents to any and all
assignments of this Note, extensions of time, renewals, and waivers that may be
made or granted by the Holder. Maker expressly agrees that such assignments,
extensions of time, renewals, or waivers do not affect Maker's liability
hereunder. Maker agrees that Holder may, without notice to Maker and without
affecting the liability of Maker, accept additional or substitute security for
this Note, or release any security or any party liable for this Note, or extend
or renew this Note.

         7. If Maker fails to make any payment of interest or principal under
this Note, including the payment due upon maturity, when the same is due and
payable and such failure continues for five (5) days after notice from Holder of
such nonpayment, a late charge by way of damages to the extent provided in this
paragraph is immediately due and payable. Maker recognizes that default by Maker
in making the payments herein agreed to be paid when due will result in the
Holder incurring additional expenses, in loss to the Holder of the use of the
money due and in frustration to the Holder in meeting its other commitments.
Maker agrees that, if for any reason Maker fails to pay any amount due under
this Note when due, the Holder is entitled to damages for the detriment caused
thereby, but that it is extremely difficult and impractical to ascertain the
extent of such damages. Maker therefore agrees that a sum equal to five cents
($.05) for each one dollar ($1.00) of each payment which is not received within
five (5) days after notice that such payment it is due and payable is a
reasonable estimate of the damages to the Holder, which sum Maker agrees to pay
on demand.

         8. If action is instituted on this Note (including without limitation,
any proceedings for collection hereof in any bankruptcy or probate matter or
case), or if proceedings are commenced on or under any of the Loan and Security
Documents, and Holder prevails in such proceedings Maker promises to pay the
Holder all costs of collection and enforcement including, without limitation,
reasonable attorneys' fees plus interest on any defaulted amount at the rate of
eighteen percent (18%) per annum.

         9. Any and all notices or other communications or payments required or
permitted to be given hereunder are effective when received or refused if given
or rendered in writing, in the manner provided in the Agreement.



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         10. This Note inures to the benefit of and is binding upon the Holder's
successors and assigns. References to the "Holder" are deemed to refer to the
holders of this Note at the time such reference becomes relevant.

         11. If any term, provision, covenant, or condition of this Note is held
by a court of competent jurisdiction to be invalid, void, or unenforceable, the
rest of this Note remains in full force and effect to the greatest extent
permitted by law and is in no other way affected, impaired or invalidated.

         12. Nothing contained herein or in the Loan and Security Documents may
be deemed to prevent recourse to and the enforcement against Maker and the
Collateral of all liabilities, obligations and undertakings contained herein and
in the Loan and Security Documents.

         13. THIS NOTE IS GOVERNED BY AND MUST BE CONSTRUED UNDER THE LAWS OF
THE STATE OF PENNSYLVANIA WITHOUT RESORT TO PRINCIPLES OF CONFLICTS OF LAW AND
MAKER AGREES TO SUBMIT TO THE JURISDICTION OF THE STATE OR FEDERAL COURTS IN THE
STATE OF PENNSYLVANIA.


Dated:  September 29, 1997

MEDICAL DIAGNOSTICS, INC.


By:      /S/ ALAN WINAKOR
         ---------------------------------
         Name: Alan Winakor
         Title: Executive Vice President




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