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                                  EXHIBIT 9.1





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                      AMENDED AND RESTATED VOTING AGREEMENT

     This Amended and Restated Voting Agreement ("Agreement") is entered into 
as of the 17th day of June, 1998, by and among Eric A. Wachter, Ph.D. 
("Wachter"), Craig Dees, Ph.D. ("Dees"), Walter G. Fisher, Ph.D. ("Fisher"), 
Tim Scott, Ph.D. (individually and as General Partner of Scott Family 
Investment Limited Partnership, a Delaware limited partnership, "Scott"), 
John Smolik ("Smolik"), and Robert J. Weinstein, M.D. (individually, and as a 
General Partner of W.F. Investments Enterprises, Limited Partnership, a 
Georgia Limited partnership, "Weinstein") (individually, each a "Stockholder" 
and collectively the "Stockholders"), and joined into by Photogen 
Technologies, Inc. for purposes of Sections 1(c) and 1(d) herein. Wachter, 
Dees, Fisher, Scott and Smolik are sometimes collectively referred to herein 
as the "Tennessee Stockholders;" Weinstein is sometimes referred to herein as 
the "Chicago Stockholder;" and the Chicago Stockholder or Tennessee 
Stockholders are each sometimes referred to herein as a "Stockholder."

                                    RECITALS

     The Stockholders collectively own as of the date of this Agreement
approximately 75% of the issued and outstanding shares of common stock, $.001
par value per share (the "Common Stock"), of Photogen Technologies, Inc., a
Nevada corporation (the "Company"). The Company owns all of the issued and
outstanding shares of Photogen, Inc., a Tennessee corporation ("Subsidiary").

     The shares of Common Stock together with all other capital stock or
securities of the Company, whether authorized or outstanding as of the date
hereof or at any time hereafter, are collectively referred to as the "Shares."

     The Stockholders and Theodore Tannebaum ("Tannebaum"), Stuart P. Levine
("Levine") and Thomas B. Rosenberg ("Rosenberg") were parties to that certain
Voting Agreement dated May 16, 1997 (the "Original Agreement"). The parties
desire to amend the Original Agreement to reflect an increase in the number of
directors of the Company, to release the Shares of Tannebaum, Levine and
Rosenberg from the provisions of this Agreement, and to restate the Original
Agreement as set forth herein.

                                    AGREEMENT

     Now, therefore, in consideration of the mutual promises herein and other
consideration, the receipt and adequacy of which is acknowledged, the parties
hereby agree as follows:



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      1. VOTING AGREEMENT

     (a) The agreement in Section 1(b) shall be deemed to constitute a voting 
agreement among the Stockholders pursuant to Section 78.365(3) of the Nevada 
General Corporation Law. The agreement in Section 1(c) shall be deemed to 
constitute an agreement among the parties hereto pursuant to Section 
48-17-302 of the Tennessee Business Corporation Act. As used in this 
Agreement, the definition and determination of a "Beneficial Owner" or 
"Beneficial Ownership" shall be governed by Regulation 13d-3 under the 
Securities Exchange Act of 1934, as amended. All percentages of stock 
ownership in this Agreement shall be calculated on a fully-diluted basis.

     (b) At each annual meeting of the stockholders of the Company, or at each
special meeting of the stockholders of the Company, and at any other time at
which stockholders of the Company will have the right to or will vote for or
render consent in writing, then and in each event, each Stockholder hereby
agrees to vote or cause to be voted all Shares of which he is the Beneficial
Owner in favor of the following actions to the extent any such actions are
subject to such vote or consent:

          (i) To amend, alter, modify or repeal the Articles of Incorporation or
     the By-Laws of the Company only in accordance with the unanimous
     recommendation of all of the Directors of the Company (whether or not any
     Board action is required by law);

          (ii) To fix and maintain the number of directors of the Company at six
     (6); 

          (iii) To cause and maintain the election to the Board of Directors of
     the Company of the following: (A) four (4) persons nominated by the holders
     of 80% of the aggregate Shares Beneficially Owned by the Tennessee
     Stockholders; and (B) one (1) person nominated by the holder(s) of 80% of
     the aggregate Shares Beneficially Owned by the Chicago Stockholder;

          (iv) To remove from the Board of Directors of the Company any director
     nominated by the Tennessee or Chicago Stockholder, as applicable pursuant
     to paragraph 1(b)(iii) at the request of the Stockholder(s) nominating such
     director; and

          (v) To fix and maintain the Executive Committee of the Board of
     Directors of the Company to consist of three (3) directors, two (2) of whom
     shall be selected by the directors nominated by the Tennessee Stockholders
     and one (1) of whom shall be selected by the director nominated by the
     Chicago Stockholder.

     (c) Company is agreeing for the benefit of the other parties hereto to act
in its capacity as stockholder of Subsidiary to the actions set forth in this
paragraph (c). At each annual meeting of the stockholder of the Subsidiary, or
at each special meeting of the stockholder of the Subsidiary, and at any other
time at which stockholder of the Subsidiary will have the right to or will vote
for or render consent in writing, then and in each event, the Company (as the
sole stockholder 

                                      -2-

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of the Subsidiary) hereby agrees to vote or cause to be voted all voting
securities of the Subsidiary of which it is the Beneficial Owner in favor of the
following actions to the extent any such actions are subject to such vote or
consent:

          (i) To amend, alter, modify or repeal the Articles of Incorporation or
     the By- Laws of the Subsidiary only in accordance with the unanimous
     recommendation of all of the Directors of the Subsidiary (whether or not
     any Board action is required by law);

          (ii) To fix and maintain the number of directors of the Subsidiary at
     six (6);

          (iii) To cause and maintain the election to the Board of Directors of
     the Subsidiary of the following: (A) four (4) persons nominated by the
     directors of the Company who were selected by the Tennessee Stockholders;
     and (B) one (1) person nominated by the director of the Company who was
     selected by the Chicago Stockholder;

          (iv) To remove from the Board of Directors of the Subsidiary any
     director nominated by the Tennessee or Chicago Stockholder, as applicable,
     pursuant to paragraph 1(c)(iii) at the request of the Company directors or
     director, as applicable, nominating such Subsidiary director; and

          (v) To fix and maintain the Executive Committee of the Board of
     Directors of the Subsidiary to consist of three (3) directors, two (2) of
     whom shall be selected by the directors nominated by the Tennessee
     Stockholders and one (1) of whom shall be selected by the director
     nominated by the director of the Company who was selected by the Chicago
     Stockholder.

     (d) The Company or Subsidiary, as applicable, shall provide the
Stockholders entitled to nominate directors hereunder prior notice of any
intended mailing of notice to Stockholders for a meeting at which any of the
actions subject to paragraphs 1(b) or 1(c) are to be acted upon. Thereafter,
Stockholders (or Company directors with respect to nominations of Subsidiary
directors) entitled to nominate directors hereunder shall notify the Company or
the Subsidiary (as applicable) in writing, prior to such mailing, of the person
nominated by him or it to be a director; provided, that if such Stockholder (or
Company directors) fails to give notice to the Company or Subsidiary (as
applicable), it shall be deemed that the nominee of such party for such meeting
is the person then serving as director pursuant to such Stockholders' (or
Company directors') previous nomination.

     2. NECESSARY ACTS; ADDITIONAL PARTIES. Each of the parties hereto agrees
that he or it will do (or cause to be done) any act or thing and will execute
(or cause to be executed) any and all instruments necessary and/or proper to
make effective the provisions of this Agreement. Each Stockholder represents and
warrants to, and agrees with, each other party hereto that (a) any transferee
holding Shares over which such Stockholder remains the Beneficial Owner shall
execute 


                                      -3-

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and deliver a counterpart of this Agreement and shall be bound by the provisions
hereof as if such transferee was an original party hereto; and (b) such
Stockholder shall provide each other party hereto true and complete information
concerning the Beneficial Ownership of Shares in the hands of transferees.

     3. LEGEND ON STOCK CERTIFICATE. Each certificate representing Shares
covered by this Agreement is subject to and shall bear the restrictive legend
set forth below:

     The voting of shares of stock evidenced by this certificate is subject to a
     Voting Agreement dated as of May 16, 1997, as amended from time to time.
     Copies of the Agreement may be obtained from the Secretary of the Company
     at no cost by written request of the holder of record of this certificate.

     4. GENERAL PROVISIONS.

     (a) This Agreement shall be binding upon and inure to the benefit of the
parties hereto and their legal representatives, heirs and legatees.

     (b) The section headings in this Agreement are inserted for convenience of
reference only, and shall not affect the construction or interpretation of this
Agreement.

     (c) The failure at any time to enforce any of the provisions of this
Agreement shall not be construed as a waiver of such provisions and shall not
affect the right of any party thereafter to enforce each and every provision of
this Agreement in accordance with its terms.

     (d) This Agreement shall be governed by and construed in accordance with
the laws of the State of Illinois without giving effect to conflict of laws
principles thereof, except to the extent the Nevada General Corporation Law and
the Tennessee Business Corporation Law govern portions hereof.

     (e) This Agreement may be executed in one or more counterparts, each of
which shall be deemed to be an original and shall be enforceable against the
party executing the same, and all of which together shall constitute a single
Agreement. In making proof of this Agreement, it shall not be necessary to
produce or account for more than one such counterpart.

     (f) Whenever possible, each provision of this Agreement shall be
interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this Agreement shall be held to be invalid by a court of
competent jurisdiction, the remaining provisions shall remain in full force and
effect and the provision held invalid shall be modified to the extent necessary
to be valid and shall be enforced as modified.

     (g) Any notice to be served under this Agreement shall be in writing and
shall be deemed to be delivered or given upon receipt if delivered personally,
by overnight courier or by 

                                      -4-

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telecopier, or two days after mailing by registered mail, return receipt
requested, addressed as follows:

          IF TO THE COMPANY:

          Photogen Technologies, Inc.
          To its then current address
          Attention:  John Smolik

          IF TO ANY STOCKHOLDER:

          To such Stockholder's address on file in the
          stock records of the Company

or to such other place as a party may specify in writing, delivered in
accordance with the provisions of this subsection.

     (h) This Agreement constitutes the full and entire understanding and
agreement of the parties with regard to the subject hereof, and supersedes any
prior agreement or understanding, written or oral, with respect to such subject
matter. No party shall be liable or bound by any representations, warranties or
agreements, or any other information or materials previously delivered, whether
written or oral, regarding such subject matter.

     5. AMENDMENT; TERMINATION. This Agreement may be modified or amended in any
respect upon the written approval of the holders of 90% of the Shares, and as so
modified or amended, this shall continue to bind all Stockholders regardless of
whether they consented to such modification or amendment. This Agreement shall
terminate upon the earliest to occur of the following: (i) the written approval
of the termination executed by holders of 90% or more of the Shares; (ii) the
Stockholders collectively cease to own an aggregate of 20% of the issued and
outstanding voting securities of the Company; (iii) the merger of the Company
with another company in which the Company is not the survivor or the sale of all
or substantially all of the Company's assets; or (vii) the 15th anniversary of
the date of this Agreement.

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     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date first written above.

                                       /s/ Eric A. Wachter
                                       -----------------------------------------
                                       Eric A. Wachter, Ph.D.


                                       /s/ Craig Dees
                                       -----------------------------------------
                                       Craig Dees, Ph.D.


                                       /s/ Walter G. Fisher
                                       -----------------------------------------
                                       Walter G. Fisher, Ph.D.


                                       /s/ Tim Scott
                                       -----------------------------------------
                                       Tim Scott, Ph.D., individually and as 
                                       General Partner of the Scott Family 
                                       Investment Limited Partnership, a
                                       Delaware limited partnership


                                       /s/ John Smolik
                                       -----------------------------------------
                                       John Smolik


                                       /s/ Robert J. Weinstein
                                       -----------------------------------------
                                       Robert J. Weinstein, M.D., individually 
                                       and as a General Partner of W.F. 
                                       Investments Enterprises, Limited
                                       Partnership


               Joined into by for purposes of Sections 1(c) and 1(d) herein.


                                       Photogen Technologies, Inc.


                                       By:   /s/ John Smolik
                                           -------------------------------------
                                       Its:  President
                                           -------------------------------------

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