CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	3 Months Ended
	Jul. 31, 2015	Jul. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (13,723,000)	$ (13,129,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	1,183,000	1,776,000
Depreciation and amortization	234,000	277,000
Changes in operating assets and liabilities:
Trade and other receivables, net	2,008,000	(59,000)
Inventories	(3,103,000)	(468,000)
Prepaid expenses and other current assets, net	303,000	536,000
Other non-current assets	15,000	(29,000)
Accounts payable	(2,851,000)	2,518,000
Accrued clinical trial and related fees	196,000	(2,546,000)
Accrued payroll and related expenses	(1,512,000)	(1,183,000)
Deferred revenue	1,661,000	(863,000)
Customer deposits	(1,764,000)	466,000
Other accrued expenses and current liabilities	183,000	108,000
Deferred rent	(62,000)	(47,000)
Net cash used in operating activities	(17,232,000)	(12,643,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Property and equipment acquisitions	(1,099,000)	(1,349,000)
Decrease in other assets	395,000	516,000
Net cash used in investing activities	(704,000)	(833,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock, net of issuance costs of $275,000 and $14,000, respectively	9,891,000	421,000
Proceeds from issuance of Series E preferred stock, net of issuance costs of $516,000	0	9,484,000
Proceeds from exercise of stock options, net of issuance costs of nil and $3,000, respectively	93,000	112,000
Dividends paid on preferred stock	(1,033,000)	(771,000)
Principal payments on capital leases	0	(4,000)
Net cash provided by financing activities	8,951,000	9,242,000
NET DECREASE IN CASH AND CASH EQUIVALENTS	(8,985,000)	(4,234,000)
CASH AND CASH EQUIVALENTS, beginning of period	68,001,000	77,490,000
CASH AND CASH EQUIVALENTS, end of period	59,016,000	73,256,000
SCHEDULE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Accounts payable for purchase of property and equipment	2,306,000	128,000
Lease incentives	$ 0	$ 592,000