CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
	Jul. 31, 2011	Jul. 31, 2010
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (8,092,000)	$ (7,695,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	884,000	643,000
Depreciation and amortization	203,000	138,000
Amortization of discount on notes payable and debt issuance costs	21,000	108,000
Amortization of expenses paid in shares of common stock	0	239,000
Changes in operating assets and liabilities:
Trade and other receivables, net	302,000	189,000
Government contract receivables	93,000	(223,000)
Inventories, net	803,000	(1,569,000)
Prepaid expenses and other current assets, net	108,000	62,000
Other non-current assets	98,000	129,000
Accounts payable	(1,159,000)	(534,000)
Accrued clinical trial and related fees	494,000	(49,000)
Accrued payroll and related expenses	77,000	150,000
Deferred revenue	(1,550,000)	1,438,000
Deferred government contract revenue	0	(31,000)
Customer deposits	(1,470,000)	(427,000)
Other current liabilities	83,000	106,000
Other long-term liabilities	(166,000)	255,000
Net cash used in operating activities	(9,271,000)	(7,071,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property acquisitions	(363,000)	(514,000)
Decrease in other assets	31,000	30,000
Net cash used in investing activities	(332,000)	(484,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock, net of issuance costs of $126,000 and $162,000, respectively	3,587,000	6,482,000
Principal payments on notes payable and capital leases	(519,000)	(625,000)
Net cash provided by financing activities	3,068,000	5,857,000
NET DECREASE IN CASH AND CASH EQUIVALENTS	(6,535,000)	(1,698,000)
CASH AND CASH EQUIVALENTS, beginning of period	23,075,000	19,681,000
CASH AND CASH EQUIVALENTS, end of period	16,540,000	17,983,000
SCHEDULE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Property acquired under capital lease	0	180,000
Accounts payable for purchase of property	$ 72,000	$ 6,000