BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 31,637	$ 40,599
Accounts receivable, net of allowance of $47 and $19, respectively	4,638	2,012
Notes receivable, net of allowance of $61 and $9, respectively	350	444
Inventories	6,488	13,473
Prepaid and other current assets	1,700	1,857
Total current assets	44,813	58,385
Property and equipment, net	756	832
Equipment under lease, net	6,690	3,583
Notes and other receivables, long-term, net of allowance of $2 and $9, respectively	121	452
Intangible assets, net	10,870	12,110
Other assets	3,215	3,758
Total assets	66,465	79,120
Current liabilities:
Accounts payable	2,694	2,481
Accrued liabilities	4,604	4,570
Deferred revenue	904	923
Operating lease liabilities	512	493
Total current liabilities	8,714	8,467
Long-term operating lease liabilities	2,803	3,314
Other long-term liabilities	69	129
Total liabilities	11,586	11,910
Commitments and contingencies (Note 10)
Stockholders’ equity:
Preferred stock, par value $0.01 per share, 10,000 shares authorized at December 31, 2021 and 2020; no shares issued and outstanding at December 31, 2021 and 2020
Common stock, par value $0.01 per share, 150,000 shares authorized at December 31, 2021 and 2020; 10,990 and 10,933 shares issued and outstanding at December 31, 2021 and 2020, respectively	110	109
Additional paid-in capital	132,363	125,094
Accumulated deficit	(77,594)	(57,993)
Total stockholders’ equity	54,879	67,210
Total liabilities and stockholders’ equity	$ 66,465	$ 79,120