CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $)	Jan. 31, 2013	Apr. 30, 2012
CURRENT ASSETS:
Cash and cash equivalents	$ 26,255,000	$ 18,033,000
Trade and other receivables, net	1,983,000	2,353,000
Inventories, net	4,635,000	3,611,000
Prepaid expenses and other current assets, net	878,000	795,000
Total current assets	33,751,000	24,792,000
Property, net	2,783,000	2,900,000
Other assets	623,000	570,000
TOTAL ASSETS	37,157,000	28,262,000
CURRENT LIABILITIES:
Accounts payable	1,620,000	3,492,000
Accrued clinical trial and related fees	1,478,000	2,111,000
Accrued payroll and related costs	2,949,000	2,468,000
Deferred revenue	5,061,000	3,651,000
Customer deposits	6,729,000	4,865,000
Other current liabilities	930,000	1,052,000
Total current liabilities	18,767,000	17,639,000
Deferred revenue	292,000	361,000
Other long-term liabilities	699,000	779,000
Commitments and contingencies
STOCKHOLDERS' EQUITY:
Preferred stock-$0.001 par value; authorized 5,000,000 shares; non-voting; nil shares outstanding	0	0
Common stock-$0.001 par value; authorized 325,000,000 shares; outstanding – 133,770,614 and 101,421,365, respectively	134,000	101,000
Additional paid-in-capital	376,720,000	347,506,000
Accumulated deficit	(359,455,000)	(338,124,000)
Total stockholders' equity	17,399,000	9,483,000
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 37,157,000	$ 28,262,000