Exhibit 4.6

       

THESE  SECURITIES  HAVE NOT BEEN  REGISTERED  WITH THE  SECURITIES  AND EXCHANGE
COMMISSION UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND ANY SALE, TRANSFER,
PLEDGE OR OTHER DISPOSITION THEREOF MAY BE MADE ONLY (i) IN A REGISTRATION UNDER
SAID ACT OR (ii) IF AN EXEMPTION FROM  REGISTRATION  UNDER SAID ACT IS AVAILABLE
AND THE  COMPANY HAS  RECEIVED  AN OPINION OF COUNSEL TO THAT EFFECT  REASONABLY
SATISFACTORY TO IT

                                  IMATRON INC.

                          COMMON STOCK PURCHASE WARRANT

                      This Warrant Expires October 21, 2001

                      Warrant No. 97-TR2 Shares: 2,000,000

THIS  CERTIFIES  that,  subject  to the terms and  conditions  herein set forth,
TeraRecon  Inc. (the  "Holder") is entitled to purchase from Imatron Inc., a New
Jersey corporation (the "Company"),  at any time or from time to time during the
Exercise Period (as hereinafter  defined) the number of shares of fully paid and
non-assessable  shares of Common Stock of the Company (the "Shares") as provided
herein upon surrender hereof at the principal office of the Company, and, at the
election of the holder hereof, upon payment of the purchase price at said office
in cash or by  cashier's  check  or by the  wire  transfer  of funds in a dollar
amount equal to the purchase price of the Shares for which the  consideration is
being given.

This Warrant shall be exercisable for that number of Shares as set forth above.

1. Purchase Price. Subject to adjustment as hereinafter  provided,  the purchase
price of one share of Common Stock (or such securities as may be substituted for
one share of Common  Stock  pursuant to the  provisions  hereinafter  set forth)
shall be Four Dollars and Fifty Cents ($4.50) per share.  The purchase  price of
one share of Common Stock is referred to herein as the "Warrant Price".

2. Exercise Period.  The exercise Period shall mean the period commencing on the
date hereof and ending four years thereafter.

3.  Adjustment  of Warrant  Price and  Number of Shares.  The number and kind of
securities  issuable  upon the  exercise  of this  Warrant  shall be  subject to
adjustment from time to time upon the happening of certain events as follows:

(a) Adjustment of Warrant Price and Number of Shares.  The Warrant Price and the
number of shares  purchasable upon the exercise of this Warrant shall be subject
to adjustment from time to time upon the occurrence of certain events  described
in this Section 3. Upon each adjustment of the Warrant Price, the Holder of this
Warrant shall thereafter be entitled to purchase, at the Warrant Price resulting
from such  adjustment,  the number of shares obtained by multiplying the Warrant
Price in effect  immediately  prior to such  adjustment  by the number of shares
purchasable  pursuant hereto immediately prior to such adjustment,  and dividing
the product thereof by the Warrant Price resulting from such adjustment. In case
the Company shall at any time subdivide its  outstanding  shares of Common Stock
into a greater number of shares,  the Warrant Price in effect  immediately prior
to such subdivision shall be proportionately  reduced,  and conversely,  in case
the  outstanding  shares of Common Stock of the Company shall be combined into a
smaller number of shares,  the Warrant Price in effect immediately prior to such
combination shall be proportionately increased.

(b) Adjustment for Dividends in Stock.  In case at any time or from time to time
on or after the date hereof the  holders of the Common  Stock of the Company (or
any shares of stock or other securities at the time receivable upon the exercise
of this Warrant) shall have received,  or, on or after the record date fixed for
the  determination  of  eligible  stockholders,  shall have  become  entitled to
receive,  without payment therefor,  other or additional stock of the Company by
way of dividend (other than as provided for in Paragraph 2(b) herein),  then and
in each such case, the holder of this Warrant shall,  upon the exercise  hereof,
be  entitled to  receive,  in addition to the number of shares of Common  shall,
upon the exercise hereof,  be entitled to receive,  in addition to the number of
shares  of  Common  Stock  receivable  thereupon,  and  without  payment  of any
additional  consideration therefor, the amount of such other or additional stock
of the Company  which such holder would hold on the date of such exercise had it
been the  holder of  record  of such  Common  Stock on the date  hereof  and had
thereafter,  during the period from the date hereof to and including the date of
such exercise, retained such shares and/or all other additional stock receivable
by it as aforesaid  during such period,  given effect to all adjustments  called
for during such period by this  Paragraph  3. The Company  shall give the Holder
thirty (30) days advance  written  notice of any dividend  causing an adjustment
pursuant to this subsection.

(c)  Adjustment  for  Changes  in  Common  Stock.  In the event  changes  in the
outstanding   Common   Stock   of  the   Company   by   reason   of   split-ups,
recapitalizations,  reclassifications,  mergers, consolidations, combinations or
exchanges of shares, separations,  reorganizations,  liquidations,  or the like,
are  effected  in such a way that  holders of Common  Stock shall be entitled to
receive stock,  securities,  or other assets or property (an "Organic  Change"),
then,  as a condition of such  Organic  Change,  lawful and adequate  provisions
shall be made by the Company whereby the Holder hereof shall thereafter have the
right to purchase  and receive (in lieu of the shares of the Common Stock of the
Company  immediately  therefore  purchasable and receivable upon the exercise of
the rights represented hereby) such shares of stock,  securities or other assets
or property  as may be issued or payable  with  respect to or in exchange  for a
number of outstanding  shares of such Common Stock equal to the number of shares
of such  stock  immediately  theretofore  purchasable  and  receivable  upon the
exercise of the rights represented hereby; provided,  however, that in the event
the value of the stock,  securities or other assets or property  (determined  in
good faith by the Board of Directors  of the  Company)  issuable or payable with
respect to one share of the Common Stock of the Company immediately  theretofore
purchasable and receivable upon the exercise of the rights represented hereby is
in excess of the  Warrant  Price  hereof  effective  at the time of a merger and
securities  received in such  reorganization,  if any, are publicly traded, then
this Warrant shall expire unless exercised prior to such Organic Change.  In the
event of any Organic Change,  appropriate provision shall be made by the Company
with  respect to the rights and  interests  of the Holder of this Warrant to the
end that the provisions hereof (including,  without  limitation,  provisions for
adjustments  of the Warrant  Price and of the number of shares  purchasable  and
receivable upon the exercise of this Warrant) shall thereafter be applicable, in
relation to any shares of stock,  securities  or assets  thereafter  deliverable
upon the exercise hereof.

(d) Certain Events. If any change in the outstanding Common Stock of the Company
or any other event occurs as to which the other provisions of this Section 3 are
not strictly  applicable or if strictly  applicable would not fairly protect the
purchase rights of the Holder of the Warrant in accordance with such provisions,
then the Board of  Directors  of the  Company  shall make an  adjustment  in the
number and class of shares available under the Warrant, the Warrant Price or the
application  of such  provisions,  so as to  protect  such  purchase  rights  as
aforesaid.  The adjustment  shall be such as will give the Holder of the Warrant
upon exercise for the same aggregate  Warrant Price the total number,  class and
kind of shares as he would have owned had the Warrant  been  exercised  prior to
the  event  and had he  continued  to hold  such  shares  until  after the event
requiring adjustment.

4. No Fractional  Shares. No fractional shares of Common Stock will be issued in
connection with any  subscription  hereunder.  In lieu of any fractional  shares
which would  otherwise  be  issuable,  the  Company  shall pay cash equal to the
product of such  fraction  multiplied  by the fair market  value of one share of
Common Stock on the date of exercise,  as determined by the fair market value of
one share of the Company's Common Stock on the date of exercise as determined by
the average of the closing or last reported  sale prices on the NASDAQ  National
Market  over  the  5-day  period  ending  five  days  prior  to the time of such
exercise.

5. No  Stockholder  Rights.  This Warrant shall not entitle its holder to any of
the rights of a stockholder of the Company prior to exercise thereof.

6.  Representations,  Warranties  and  Covenants.  This  Warrant  is issued  and
delivered  by the  Company  and  accepted  by each  Holder  on the  basis of the
following representations, warranties and covenants made by the Company:

(a) The Company has all necessary  authority to issue,  execute and deliver this
Warrant and to perform its  obligations  hereunder.  This  Warrant has been duly
authorized,  issued,  executed and delivered by the Company and is the valid and
binding obligation of the Company, enforceable in accordance with its terms.

(b) The share of the Common  Stock  issuable  upon the  exercise of this Warrant
have been duly  authorized  and reserved  for issuance by the Company and,  when
issued in accordance with the terms hereof,  will be validly issued,  fully paid
and  nonassessable.  The Company  further  covenants that during the period this
Warrant is  exercisable,  the  Company  will  reserve  from its  authorized  and
unissued Common Stock a sufficient  number of shares to provide for the issuance
of Common Stock upon the exercise of this Warrant.

(c) The  issuance,  execution  and  delivery  of this  Warrant  do not,  and the
issuance  of the share of Common  Stock  upon the  exercise  of this  Warrant in
accordance  with the terms  hereof  will not,  
(i)  violate  or  contravene  the Company's Articles or by-laws, or any law, 
statute,  regulation,  rule, judgment or order  applicable  to the Company,  
(ii)  violate,  contravene or result in a breach or default under any material 
contract,  agreement or instrument to which the Company is a party or by which 
the  Company or any of its assets are bound, or 
(iii)  require  the  consent  of  approval  of or the filing of any notice or
registration  with any person or entity except for the filing of notice pursuant
to federal and state securities laws which, if required,  the Company  covenants
and agrees to file within the prescribed period.

(d) The Company agrees that its issuance of this Warrant shall  constitute  full
authority  to its  officers  who are charged  with the duty of  executing  stock
certificates to execute and issue the necessary certificate for shares of Common
Stock upon the exercise of this Warrant.

7. Exercise of Warrant.  This Warrant may be exercised by the registered  holder
or its registered assigns, in whole or in part, by the surrender of this Warrant
at the principal  office of the Company,  together with the form of subscription
hereof  duly  executed,  accompanied  by  payment  in full of the  amount of the
Warrant  Price in the form  described in this  Warrant.  Upon  partial  exercise
hereof,  a new warrant or warrants  containing  the same date and  provisions as
this  Warrant  shall be issued by the Company to the  registered  holder for the
number of shares of Common Stock with  respect to which this  Warrant  shall not
have  been  exercised.  A  Warrant  shall  be  deemed  to  have  been  exercised
immediately  prior to the close of  business  on the date of its  surrender  for
exercise as  provided  above,  and the person  entitled to receive the shares of
Common Stock  issuable upon such  exercise  shall be treated for all purposes as
the holder of such shares of record as of the close of business on such date. As
promptly  as  practicable  on or after such date,  the  Company  shall issue and
deliver to the person or persons  entitled to receive the same, a certificate or
certificates  for the number of full shares of Common Stock  issuable  upon such
exercise,  together  with cash in lieu of any  fraction  of a share as  provided
above.

8.  Certificate of Adjustment.  Whenever the Warrant Price is adjusted as herein
provided,  the  Company  shall  promptly  deliver to the  record  holder of this
Warrant a  certificate  of an officer of the Company  setting forth the relevant
Warrant  Price or number of shares  after such  adjustment  and setting  forth a
brief statement of the facts requiring such adjustment.

9. Compliance  With  Securities  Act. The holder of this Warrant,  by acceptance
hereof,  agrees that this  Warrant  and the shares of Common  Stock to be issued
upon exercise hereof (or shares of any security into which such Common Stock may
be converted)  are being  acquired for  investment  and that the holder will not
offer,  sell or otherwise dispose of this Warrant and any shares of Common Stock
to be issued upon  exercise  hereof (or shares of any  security  into which such
Common Stock may be converted) except under  circumstances which will not result
in a violation of the  Securities  Act of 1933,  as amended  (the  "Act").  Upon
exercise of this Warrant,  the holder hereof shall, if requested by the Company,
confirm in writing its investment  purpose and acceptance of the restrictions on
transfer of the shares of Common Stock.

10.  Registration  Rights.  The Company grants to the Holder those  registration
rights  contained  in that  certain  Warrant  Purchase  Agreement  of even  date
herewith between the Company and the Holder.

11.  Subdivision  of Warrant.  At the  request of the holder of this  Warrant in
connection  with a  transfer  or  exercise  of a portion  of the  Warrant,  upon
surrender of such  Warrant for such  purpose to the Company,  the Company at its
expense  (except for any transfer tax payable) will issue and exchange  therefor
warrants  of like  tenor and date  representing  in the  aggregate  the right to
purchase  such number of shares of such Common Stock as shall be  designated  by
such holder at the time of such surrender; provided, however, that the Company's
obligations to subdivide  securities  under this section shall be subject to and
conditioned  upon the compliance of any such  subdivision  with applicable state
securities laws and with the Act.

12. Loss,  Theft,  Destruction  or  Mutilation  of Warrant.  Upon receipt by the
Company  of  evidence  reasonably   satisfactory  to  it  of  the  loss,  theft,
destruction  or  mutilation  of this  Warrant,  and in case of  loss,  theft  or
destruction,  of indemnity or security  reasonably  satisfactory to it, and upon
reimbursement to the Company of all reasonable expenses incidental thereto,  and
upon surrender and cancellation of this Warrant, if mutilated,  the Company will
make and deliver a new Warrant of like tenor and dates as of such  cancellation,
in lieu of this Warrant.

13. No Impairment. The Company will not, by amendment of its Articles or through
any reclassification,  capital  reorganization,  consolidation,  merger, sale or
conveyance of assets, dissolution,  liquidation,  issue or sale of securities or
any other voluntary action, avoid or seek to avoid the observance or performance
of any of the terms of this Warrant,  but will at all times in good faith assist
in the  carrying  out of all such terms and in the taking of all such  action as
may be necessary or appropriate in order to protect the rights of the Holder.

14.  Successors  and Assigns.  This Warrant  shall be binding upon the Company's
successors  and  assigns  and  shall  inure  to  the  benefit  of  the  Holder's
successors, legal representatives and permitted assigns.

15.  Miscellaneous.  This Warrant  shall be governed by the laws of the State of
California.  The headings in this Warrant are for  purposes of  convenience  and
reference  only,  and shall not be deemed to  constitute a part hereof.  Neither
this  Warrant  nor  any  term  hereof  may be  changed,  waived,  discharged  or
terminated orally but only by an instrument in writing signed by the Company and
the registered  holder  hereof.  All notices and other  communications  from the
Company to the holder of this Warrant shall be by telecopy or expedited  courier
service to the address furnished to the Company in writing by the last holder of
this Warrant who shall have furnished an address to the Company in writing.

ISSUED this 21st day of October, 1997.

ATTEST:                                     IMATRON


__________________________________  By____________________________________
                                      S. Lewis Meyer, President