**Exhibit
        10.45**
  **LOAN
        AGREEMENT**
  This
        Loan
        Agreement (this “Agreement”) is entered into as of October 30, 2007 by and
        between North American Scientific, Inc., a Delaware corporation (the “Company”),
        and John A. Friede, a resident of the State of New York (the
“Lender”).
  **RECITAL**
  The
        Company and the Lender are entering into this Agreement to evidence the
        agreement of the Lender to loan $500,000 to the Company (the “Loan”), in two
        installments of $250,000 each, and the Company’s agreement to issue promissory
        notes (the “Notes”) to the Lender in the form attached hereto as Exhibit
        A to
        evidence the Loan.
  **WHEREFORE** ,
        the
        parties hereto mutually agree as follows:
  1.  Recital .
        The
        parties hereby agree to the matters set forth in the above-stated
        Recital.
  2.  Loan
        and Note Issuance .
        Subject
        to the terms of this Agreement, the Lender hereby agrees to advance to the
        Company installments of the Loan in the principal amount of (a) $250,000
        on or
        before October 31, 2007 and (b) $250,000 on or before November 14, 2007.
        Such amounts shall be paid by the Lender by wire transfer of immediately
        available funds to such account or accounts as may be designated by the Company.
        At the time of each such advance, the Company will issue to the Lender a
        Note in
        a principal amount equal to the amount of such advance.
  3.  Loan
        Fee .
        At the
        time of each advance pursuant to Section 2 above, the Company shall pay $10,000
        to the Lender as a loan fee, which payment shall be made by reducing the
        amount
        of funds then being advanced by the Lender by the amount of such
        fee.
  4.  Warrants .
        At the
        time of the first advance by the Lender to the Company pursuant to Section
        2
        above, the Company shall issue to the Lender a warrant (the “Warrant”) to
        purchase shares of Common Stock of the Company (the “Warrant Shares”) in the
        form set forth as Exhibit
        B hereto.
        The purchase price per share for the Warrant Shares (the “Exercise Price”) shall
        be equal to the per share closing price of the Common Stock on the trading
        day
        before the issuance of the Warrant as reported in the *Wall
        Street Journal* .
        The
        number of Warrant Shares which may be purchased upon exercise of the Warrant
        shall be equal to $200,000, divided by the per share Exercise Price, provided
        that the Exercise Price and the number of Warrant Shares shall be subject
        to
        subsequent adjustment in accordance with the terms of the Warrant.
  5.  The
        Lender’s Representations and Covenants .
        The
        Lender represents and warrants to the Company as follows:
  
  (a)  The
        Lender is acquiring the Notes, the Warrant and the Warrant Shares for investment
        for the Lender’s own account, not with a view to the public resale or
        distribution thereof within the meaning of the Securities Act of 1933, as
        amended (the “Securities Act”). The Lender has no present intention of selling,
        granting any participation in, or otherwise distributing the Notes, the Warrant
        or the Warrant Shares. No other person has a direct or indirect beneficial
        interest in the Notes, the Warrant or the Warrant Shares, in whole or in
        part.
        The Lender understands that the Notes, the Warrant and the Warrant Shares
        have
        not been registered under the Securities Act with the Securities and Exchange
        Commission.
  (b)  The
        Lender is an “accredited investor” as defined in Rule 501(a) of Regulation
        D promulgated under the Securities Act.
  (c)  By
        reason
        of the Lender’s business or financial experience, the Lender has the ability to
        evaluate the merits and risks of the Loan and to make an informed investment
        decision with respect to the Loan. The Lender is aware that the Loan is a
        high
        risk and speculative investment, and that there can be no assurance as to
        the
        ultimate success of the Company. The Lender acknowledges and represents that
        he
        is able to bear the risks of investing in the Company.
  (d)  The
        Lender acknowledges and agrees that the Lender has had an opportunity to
        discuss
        with the Company’s executives the business and financial affairs of the Company,
        and the Lender has had an opportunity to inspect and review the Company’s
        facilities, financial statements, business plan and related materials. The
        Lender acknowledges that the Lender has reviewed such information concerning
        the
        Company as the Lender deems necessary in order for the Lender to make the
        investment decision to acquire the Notes, the Warrant and the Warrant
        Shares.
  (e)  The
        Lender acknowledges that there is no public market for the resale of the
        Notes
        or the Warrant. The Lender acknowledges and agrees that any resales of the
        Notes, the Warrant and the Warrant Shares are subject to restrictions under
        applicable securities laws, and the Lender agrees to comply with said
        restrictions; and the Lender understands that a legend referencing said
        restrictions will be placed on the Notes, the Warrant, and certificates relating
        to the Warrant Shares.
  6.  General
        Provisions .
  6.1  Governing
        Law .
        This
        Agreement (irrespective of where it is executed, delivered and/or performed)
        shall be governed by and construed in accordance with the laws of the state
        of
        California, without giving effect to principles of conflicts of
        law.
  6.2  Waiver
        of Jury Trial .
        The
        parties hereby knowingly, voluntarily and intentionally waive the right any
        of
        them may have to a trial by jury in respect to any litigation based hereon,
        arising out of, or under or in connection with this Agreement or any course
        of
        conduct or course of dealing, statements (whether verbal or written), or
        actions
        of the parties. This provision is a material inducement for the parties to
        enter
        into this Agreement.
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  6.3  Survival .
        All of
        the representations, warranties, covenants and agreements of the parties
        contained in this Agreement shall survive the closing and shall survive until
        they have been performed in full or until the applicable statute of limitation
        has expired.
  6.4  Severability .
        Any
        provision of this Agreement which is prohibited or unenforceable in any
        jurisdiction shall, as to such jurisdiction only, be ineffective only to
        the
        extent of such prohibition or unenforceability, without invalidating the
        remaining provisions hereof or affecting the validity or enforceability of
        all
        other provisions in such jurisdiction, and without affecting the validity
        or
        enforceability of this Agreement and all other jurisdictions.
  6.5  Entirety .
        This
        Agreement constitutes the full and entire understanding and agreement between
        the parties with respect to the subject matters hereof.
  6.6  Amendment
        and Waiver .
        The
        terms of this Agreement may be amended and the performance or observance
        of any
        term of this Agreement may be waived (either generally or in a particular
        instance, and either retroactively or prospectively) only with a written
        consent
        of both parties.
  6.7  Successors
        and Assigns .
        Except
        as otherwise provided herein, the provisions hereof shall inure to the benefit
        of, and be binding upon, the successors, assigns, heirs, executors and
        administrators of the parties. A party shall not be entitled to assign any
        of
        its rights or obligations under this Agreement without the other party’s prior
        written consent. Notwithstanding the foregoing, in the event that a party
        is
        acquired by another entity (by merger, purchase of assets, or other change
        of
        control), then this Agreement may be assigned to the acquiring entity, so
        long
        as the acquiring entity agrees in writing to be bound by the terms of this
        Agreement.
  6.8  Notices .
        All
        notices or communications required or permitted in this Agreement shall be
        in
        writing and may be given by any means (e.g. mail, telecopier, electronic
        mail,
        hand delivery, messenger, overnight courier service, etc.) addressed as set
        forth on the signature page of this Agreement, or at such other address a
        party
        may designate in the future. All such notices and other communications will
        be
        deemed given upon delivery at the party’s proper address.
  6.9  Counterparts .
        This
        Agreement may be executed in counterparts, each of which shall be enforceable
        against the signing party, all of which together shall constitute one instrument
        and agreement. A party may evidence its execution and delivery of this Agreement
        by signing this Agreement and sending it to the other party by
        telecopier/facsimile.
  6.10  Attorneys’
        Fees .
        In the
        event a party breaches its or his obligations under this Agreement, and the
        other party incurs attorneys’ fees to enforce the terms of this Agreement
        through legal proceedings (litigation, arbitration, mediation), the party
        which
        is determined in such legal proceedings to be the most prevailing party shall
        be
        entitled to recover from the other party the prevailing party’s reasonable
        attorneys’ fees and costs incurred in said legal proceedings.
  *     
        *      *     
*      *
  3
  IN
        WITNESS WHEREOF, the parties have executed and delivered this Loan Agreement
        as
        of the date first set forth above.
  COMPANY:NORTH
                  AMERICAN SCIENTIFIC, INC.By:
              /s/James W. KlinglerJames W. KlinglerSr. Vice President and CFO
 
 Address:
              20200
                  Sunburst StreetChatsworth,
                  CA 91311Fax:
              (818)
                  734-5223
 
 LENDER:/s/John
                  A. FriedeName:
              John
                  A. Friede
 
 Address:
              One Shore RoadRye, NY 10580Fax:
              (914) 698-1034
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  **Exhibit
        A**
  **THIS
        PROMISSORY NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
        AS
        AMENDED (THE “** **ACT** **”),
        OR UNDER THE SECURITIES OR BLUE SKY LAWS OF ANY STATE. THIS NOTE MAY NOT
        BE SOLD
        OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM
        UNDER SAID ACT AND ANY APPLICABLE STATE SECURITIES OR BLUE SKY LAWS.**
  **THIS
        NOTE AND THE INDEBTEDNESS EVIDENCED HEREBY IS SUBORDINATED TO THE
“** **SENIOR
        INDEBTEDNESS** **”
        AS DEFINED IN AND PURSUANT TO SUBORDINATION PROVISIONS CONTAINED HEREIN.**
  **SUBORDINATED
        PROMISSORY NOTE**
 $250,000
                October
                    30, 2007
  FOR
        VALUE
        RECEIVED, NORTH AMERICAN SCIENTIFIC, INC., a Delaware corporation (“ Maker ”),
        hereby promises to pay to John A. Friede, an individual resident of New York,
        New York (the “ Holder ”),
        in
        lawful money of the United States of America, the principal sum of Two Hundred
        Fifty Thousand and No/100 Dollars ($250,000) together with interest in arrears
        on the unpaid principal balance at an annual rate equal to the prime rate
        in
        effect from time to time (as set forth in the *Wall
        Street Journal* ),
        plus
        six percent (6%), in the manner provided below. Interest shall be calculated
        on
        the basis of a year of 365 or 366 days, as applicable, and charged for the
        actual number of days elapsed.
  1.  Payments .
  (a)  Principal
        and Interest .
        The
        principal amount of this Note shall be due and payable on November 20, 2007
        (the
“ Payment
        Date ”).
        Interest on the unpaid principal balance of this Note shall be due and payable
        on the Payment Date.
  (b)  Usurious
        Interest .
        Notwithstanding any other provision of this Note, the Holder does not intend
        to
        charge, and the Maker shall not be required to pay, any interest or other
        fees
        or charges in excess of the maximum permitted by applicable law; any payments
        in
        excess of such maximum shall be refunded to the Maker or credited to reduce
        the
        principal hereunder. All payments received by the Holder will be applied
        first
        to costs of collection, if any, then to interest and the balance to
        principal.
  2.  Manner
        of Payment .
        All
        payments of principal and interest on this Note shall be made by Maker’s check
        to Holder at Holder’s residential address at One Shore Road, Rye, NY 10580 or at
        such other place in the United States of America as Holder shall designate
        to
        Maker in writing or by wire transfer of immediately available funds to an
        account designated by Holder in writing. If any payment of principal or interest
        on this Note is due on a day which is not a business day, such payment shall
        be
        due on the next succeeding business day, and such extension of time shall
        be
        taken into account in calculating the amount of interest payable under this
        Note.
  
  3.  Prepayment .
        Maker
        may, without premium or penalty, at any time and from time to time, prepay
        all
        or any portion of the outstanding principal balance due under this Note,
        provided that each such prepayment is accompanied by accrued interest on
        the
        amount of principal prepaid calculated to the date of such prepayment. Any
        partial prepayments shall be applied to installments of principal in inverse
        order of their maturity.
  4.  Subordination .
        By
        acceptance hereof, the Holder agrees that the payment of the principal of
        and
        interest on this Note shall be subordinated to the prior payment of the
        principal of and interest on all obligations of Maker for money borrowed
        from
        any bank, trust company, venture capital entity, insurance company, or other
        financial institution engaged in the business of lending money (hereinafter
        called “ Senior
        Indebtedness ”).
        Upon
        any default or event of default under any Senior Indebtedness, (a) no amount
        shall be paid by the Maker in respect of the principal of or interest on
        this
        Note at the time outstanding, unless and until such default or event of default
        under such Senior Indebtedness shall have been cured (i) by payment in full
        of
        the then outstanding principal thereof and interest accrued thereon; or (ii)
        otherwise, and (b) no claim or proof of claim shall be filed by or on behalf
        of
        the Holder of this Note which shall assert any right to receive any payment
        in
        respect of the principal of and interest on this Note except subject to payment
        in full of the principal of and interest on all Senior Indebtedness then
        outstanding. Without limitation of the foregoing, the payment of the principal
        of and interest on this Note is subordinated to the obligations of the Maker
        to
        Silicon Valley Bank and Agility Capital LLC in accordance with subordination
        agreements between each of such entities and the Holder.
  5.  Events
        of Default .
  (a)  The
        following shall constitute “ Events
        of Default ”
under
        this Note:
  (i)  failure
        to pay any principal or any interest within five (5) business days following
        its
        due date hereunder;
  (ii)  default
        in the performance by the Maker of any material obligation to the Holder
        under
        this Note, which default is not cured within thirty (30) days after written
        notice of such default from the Holder;
  (iii)  the
        filing of any petition or the commencement of any proceeding against the
        Maker
        or any endorser or guarantor of this Note for any relief under any bankruptcy
        or
        insolvency laws, or any laws relating to the relief of debtors, readjustment
        of
        indebtedness, reorganizations, compositions, or extensions, which proceeding
        is
        not dismissed within one hundred twenty (120) days.
  (b)  Acceleration
        Upon Default; Default Rate *.* Subject
        to the subordination of this Note in accordance with Paragraph 4 above, if
        an
        Event of Default has occurred and is continuing under this Note, the entire
        principal balance, interest then accrued, and all other sums due hereunder,
        whether or not otherwise then due, shall, at the at option of the Holder,
        become
        immediately due and payable without demand or notice. Upon any Event of Default
        hereunder, and during the continuation thereof, the interest rate on this
        Note
        will increase to one percent (1%) per annum above the interest rate otherwise
        being charged hereunder.
  2
  6.  Expenses
        of Collection .
        The
        Maker agrees to pay the Holder’s reasonable costs in collecting and enforcing
        this Note, including reasonable attorney’s fees.
  7.  Waiver
        by Holder .
        No
        waiver of any obligation of the Maker under this Note shall be effective
        unless
        it is in a writing signed by the Holder. A waiver by the Holder of any right
        or
        remedy under this Note on any occasion shall not be a bar to exercise of
        the
        same right or remedy on any subsequent occasion or of any other right or
        remedy
        at any time.
  8.  Notice .
        Any
        notice required or permitted under this Note shall be in writing and shall
        be
        deemed to have been given on the date of delivery, if personally delivered
        to
        the party to whom notice is to be given, or on the fifth business day after
        mailing, if mailed to the party to whom notice is to be given, by certified
        mail, return receipt requested, postage prepaid, or overnight courier service
        with proof of receipt, and addressed as follows:
 (a)
                If
                    to the Maker:
                North
                    American Scientific, Inc.Attn:
                    Mr. James W. Klingler20200
                    Sunburst StreetChatsworth,
                    CA 91311Phone:
                    (818) 734-8600with
                    a copy to:
                Seyfarth
                    Shaw LLPAttn:
                    Alan J. Reich131
                    S. Dearborn StreetSuite
                    2400Chicago,
                    IL 60603Phone:
                    (312) 460-5650(b)
                If
                    to the Holder:
                Mr.
                    John A. FriedeOne
                    Shore RoadRye,
                    NY 10580Phone:
                    (914) 698-2015
  9.  Waiver
        by Maker .
        The
        Maker hereby expressly waives presentment, demand and protest, notice of
        demand,
        dishonor and nonpayment of this Note, and all other notices or demands of
        any
        kind in connection with the delivery, acceptance, performance, default or
        enforcement hereof, and hereby consents to any delays, extensions of time,
        renewals, waivers or modifications that may be granted or consented to by
        the
        Holder hereof with respect to the time of payment or any other provision
        hereof.
  10.  Severability .
        In the
        event any one or more of the provisions of this Note shall for any reason
        be
        held to be invalid, illegal or unenforceable, in whole or in part or in any
        respect, or in the event that any one or more of the provisions of this Note
        operate or would prospectively operate to invalidate this Note, then and
        in any
        such event, such provision(s) only shall be deemed null and void and shall
        not
        affect any other provision of this Note and the remaining provisions of this
        Note shall remain operative and in full force and effect and in no way shall
        be
        affected, prejudiced, or disturbed thereby.
  3
  11.  Governing
        Law .
        This
        Note shall be governed by and construed and enforced in accordance with the
        laws
        of the State of California without giving effect to the conflict of laws
        principles thereof.
  12.  Parties
        in Interest .
        This
        Note shall bind Maker and its successors and assigns. This Note shall not
        be
        assigned or transferred by Holder without the express prior written consent
        of
        Maker, except by will or, in default thereof, by operation of law.
  IN
        WITNESS WHEREOF, the undersigned has executed this Note as of the date first
        written above.
  NORTH
                  AMERICAN SCIENTIFIC, INC.a
                  Delaware corporationBy:
              /s/James
                  W. KlinglerName:
                  James W. KlinglerTitle:
                  Sr. VP & CFO
  4