Balance Sheet Components - Additional Information (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) Customer	Jun. 30, 2021 USD ($) Customer	Dec. 31, 2021 USD ($) Customer
Schedule Of Balance Sheet Components [Line Items]
Accounts receivable, net	$ 31,146,000		$ 31,146,000		$ 24,452,000
Percentage of Non-US revenue invoiced in Euros	77.40%	67.40%	75.60%	72.40%
Transfer of inventory to rental equipment			$ 692,000	$ 706,000
Salvage value of expenditures for additions, improvements and replacements	$ 0		0
Repairs and maintenance expense			2,230,000	1,674,000
Depreciation and amortization	3,698,000	$ 3,038,000	7,311,000	5,872,000
Impairments of long-lived assets			0	0
Goodwill impairment loss			0
Impairment of finite lived intangible assets			0		0
Construction in Process and Computer Software or Development Cost
Schedule Of Balance Sheet Components [Line Items]
Depreciation and amortization			0	$ 0
Other Noncurrent Assets
Schedule Of Balance Sheet Components [Line Items]
Noncurrent inventories expected to be realized or consumed	734,000		734,000		1,943,000
Prepaid Expenses and Other Current Assets
Schedule Of Balance Sheet Components [Line Items]
Inventory raw materials	12,854,000		12,854,000		15,426,000
Customer Concentration Risk | Customer One
Schedule Of Balance Sheet Components [Line Items]
Accounts receivable, net	3,867,000		3,867,000		5,945,000
Customer Concentration Risk | Medicare's Service Reimbursement Programs
Schedule Of Balance Sheet Components [Line Items]
Accounts receivable, net	$ 2,461,000		$ 2,461,000		$ 2,685,000
Sales Revenue, Net | Customer Concentration Risk
Schedule Of Balance Sheet Components [Line Items]
Number of customers | Customer				1
Sales Revenue, Net | Customer Concentration Risk | Medicare's Service Reimbursement Programs
Schedule Of Balance Sheet Components [Line Items]
Concentration Risk, Percentage			11.60%	9.30%
Net Accounts Receivable | Customer Concentration Risk
Schedule Of Balance Sheet Components [Line Items]
Number of customers | Customer			1		1
Net Accounts Receivable | Customer Concentration Risk | Medicare's Service Reimbursement Programs
Schedule Of Balance Sheet Components [Line Items]
Concentration Risk, Percentage			7.90%		11.00%
Rental Revenue | Customer Concentration Risk | Medicare's Service Reimbursement Programs
Schedule Of Balance Sheet Components [Line Items]
Concentration Risk, Percentage			78.50%	83.10%
Raw materials | Supplier Concentration Risk | Vendor one
Schedule Of Balance Sheet Components [Line Items]
Concentration Risk, Percentage			24.40%	16.30%
Raw materials | Supplier Concentration Risk | Vendor two
Schedule Of Balance Sheet Components [Line Items]
Concentration Risk, Percentage			22.30%	14.10%
Raw materials | Supplier Concentration Risk | Vendor three
Schedule Of Balance Sheet Components [Line Items]
Concentration Risk, Percentage			8.80%	11.70%