SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Three Arch Management IV, L.L.C. (Last) (First) (Middle) 3200 ALPINE ROAD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol NORTH AMERICAN SCIENTIFIC INC [ NASI ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 01/18/2008
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	01/18/2008		A		15,908,898	A	$0.246	17,913,296	I	See Footnote(1)
Common Stock	01/18/2008		A		351,270	A	$0.246	395,528	I	See Footnote(2)
Common Stock	01/18/2008		A		23,289,233	A	$0.246	26,223,495	I	See Footnote(3)
Common Stock	01/18/2008		A		1,101,019	A	$0.246	1,239,739	I	See Footnote(4)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Common Stock Warrant (Right to Buy)	$0.246	01/18/2008		A		795,445		07/16/2008	01/17/2015	Common Stock	795,445	$0	795,445	I	See Footnote(1)
Common Stock Warrant (Right to Buy)	$0.246	01/18/2008		A		17,564		07/16/2008	01/17/2015	Common Stock	17,564	$0	17,564	I	See Footnote(2)
Common Stock Warrant (Right to Buy)	$0.246	01/18/2008		A		1,164,462		07/16/2008	01/17/2015	Common Stock	1,164,462	$0	1,164,462	I	See Footnote(3)
Common Stock Warrant (Right to Buy)	$0.246	01/18/2008		A		55,051		07/16/2008	01/17/2015	Common Stock	55,051	$0	55,051	I	See Footnote(4)

1. Name and Address of Reporting Person* Three Arch Management IV, L.L.C. (Last) (First) (Middle) 3200 ALPINE ROAD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* THREE ARCH PARTNERS IV LP (Last) (First) (Middle) (Street) (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* THREE ARCH ASSOCIATES IV LP (Last) (First) (Middle) 3200 ALPINE ROAD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* TAC MANAGEMENT LLC (Last) (First) (Middle) C/O THREE ARCH PARTNERS 3200 ALPINE RD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* THREE ARCH CAPITAL LP (Last) (First) (Middle) 3200 ALPINE RD C/O THREE ARCH PARTNERS (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* TAC ASSOCIATES LP (Last) (First) (Middle) 3200 ALPINE RD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* WAN MARK A (Last) (First) (Middle) C/O THREE ARCH PARTNERS 3200 ALPINE RD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* JAEGER WILFRED E (Last) (First) (Middle) C/O THREE ARCH PARTNERS 3200 ALPINE RD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* NICHOLSON BARCLAY (Last) (First) (Middle) C/O THREE ARCH PARTNERS 3200 ALPINE RD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Young Roderick A (Last) (First) (Middle) 3200 ALPINE ROAD (Street) PORTOLA VALLEY CA 94028 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. The reportable securities are owned directly by Three Arch Partners IV, L.P. Three Arch Management IV, L.L.C. is the general partner of Three Arch Partners IV, L.P. Three Arch Management IV, L.L.C. disclaims beneficial ownership of these securities and this report shall not be deemed an admission that Three Arch Management IV, L.L.C. is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Mark A. Wan ("Wan"), Wilfred E. Jaeger ("Jaeger"), and Barclay Nicholson ("Nicholson"), are managing members of Three Arch Management IV, L.L.C. Each of Wan, Jaeger, and Nicholson disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 except to the extent of his or her pecuniary interest therein.

2. The reportable securities are owned directly by Three Arch Associates IV, L.P. Three Arch Management IV, L.L.C. is the general partner of Three Arch Associates IV, L.P. Three Arch Management IV, L.L.C. disclaims beneficial ownership of these securities and this report shall not be deemed an admission that Three Arch Management IV, L.L.C. is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Wan, Jaeger, and Nicholson are managing members of Three Arch Management IV, L.L.C. Each of Wan, Jaeger, and Nicholson disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 except to the extent of his or her pecuniary interest therein.

3. The reportable securities are owned directly by Three Arch Capital, L.P. TAC Management, L.L.C. is the general partner of Three Arch Capital, L.P. TAC Management, L.L.C. disclaims beneficial ownership of these securities and this report shall not be deemed an admission that TAC Management, L.L.C. is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Wan, Jaeger, and Nicholson are managing members of TAC Management, L.L.C. Each of Wan, Jaeger, and Nicholson disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 except to the extent of his or her pecuniary interest therein.

4. The reportable securities are owned directly by TAC Associates, L.P. TAC Management, L.L.C. is the general partner of TAC Associates, L.P. TAC Management, L.L.C. disclaims beneficial ownership of these securities and this report shall not be deemed an admission that TAC Management, L.L.C. is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Wan, Jaeger, and Nicholson are managing members of TAC Management, L.L.C. Each of Wan, Jaeger, and Nicholson disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 except to the extent of his or her pecuniary interest therein.

	Barclay Nicholson, Authorized Signatory	01/28/2008
	** Signature of Reporting Person	Date
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* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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