Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income (loss)	$ 2,226	$ 894	$ (13,063)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	9,883	9,962	9,963
Stock-based compensation expense	3,092	2,493	2,968
Provision for excess and obsolete inventories	156	534	238
Deferred income taxes	378	(83)	6,090
Indemnification costs (paid) accrued	(3,225)	(2,672)	6,012
License agreement settlement	(3,000)	0	0
Asset impairment charge	0	0	939
Changes in operating assets and liabilities:
Trade accounts receivable, net	(1,791)	(2,552)	478
Inventories	(884)	(929)	229
Equipment held for rental or loan, net	(6,099)	(5,971)	(4,226)
Prepaid expenses and other current assets	(77)	(861)	607
Other assets	99	(276)	17
Accounts payable and accrued liabilities	4,399	6,305	(2,293)
Deferred revenue	4	(101)	(53)
Net cash provided by operating activities	5,161	6,743	7,906
Cash flows from investing activities:
Proceeds from sale, redemption or maturity of investment securities	0	4,360	6,222
Purchases of investment securities	0	0	(760)
Capital expenditures	(3,079)	(2,661)	(3,877)
Additional consideration—acquisition milestone payments	(7,727)	0	0
Decrease in restricted cash	0	0	817
Net cash (used in) provided by investing activities	(10,806)	1,699	2,402
Cash flows from financing activities:
Proceeds from the exercise of stock options and employee stock purchase plan	3,772	1,895	130
Net cash provided by financing activities	3,772	1,895	130
Effect of exchange rate changes on cash	10	(34)	(113)
Net (decrease) increase in cash and cash equivalents	(1,863)	10,303	10,325
Cash and cash equivalents at beginning of year	39,638	29,335	19,010
Cash and cash equivalents at end of year	37,775	39,638	29,335
Supplemental disclosures of cash flow information:
Cash paid during the year for interest	46	289	12
Cash paid during the year for income taxes	$ 135	$ 142	$ 187