Note 2 - Accounting Policies (Details Textual)		12 Months Ended
	Jun. 12, 2020 USD ($)	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares
Advertising Expense		$ 233,000	$ 211,000
Net Income (Loss) Attributable to Parent, Total		$ 1,328,000	$ 194,000
Earnings Per Share, Diluted, Total (in dollars per share) | $ / shares		$ 0.21	$ 0.03
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total		$ 74,237,000
Gain (Loss) on Sale of Assets and Asset Impairment Charges		$ (0)	$ (105,000)
Lessee, Operating Lease, Term of Contract (Year)		10 years
Weighted Average Number of Shares Outstanding, Basic, Total (in shares) | shares		6,297,000	6,044,000
Number of Reportable Segments		2	2
Goodwill and Intangible Asset Impairment, Total		$ 0	$ 0
Gamma Knife Center Ecuador S.A. (GKCE) [Member]
Goodwill, Acquired During Period	$ 1,265,000
Gamma Knife Center Ecuador S.A. (GKCE) [Member] | Trade Names [Member]
Indefinite-lived Intangible Assets Acquired	$ 78,000
Restricted Stock Units (RSUs) [Member]
Weighted Average Number of Shares Outstanding, Basic, Total (in shares) | shares		123,000	123,000
Share-Based Payment Arrangement, Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares		20,000	31,000
GK Peru [Member]
Accounts Receivable, Related Parties		$ 0	$ 0
GKCE [Member]
Accounts Receivable, Related Parties		862,000	$ 435,000
Gamma Knife Units [Member]
Number of Customer with Intent to Terminate Contract			4
Gamma Knife Units One [Member]
Asset Retirement Obligation, Ending Balance			$ 105,000
Gamma Knife Unit Removed [Member]
Asset Retirement Obligation, Cash Paid to Settle		457,000
Other Gamma Knife Units [Member]
Asset Retirement Obligation, Ending Balance		0
Rental Income from Medical Services [Member]
Revenue from Contract with Customer, Including Assessed Tax		16,655,000	14,719,000
PBRT Services [Member]
Revenue from Contract with Customer, Including Assessed Tax		8,952,000	6,058,000
Patient Income [Member]
Revenue from Contract with Customer, Including Assessed Tax		3,091,000	2,909,000
Salvage Value [Member]
Net Income (Loss) Attributable to Parent, Total		$ 17,000
Earnings Per Share, Diluted, Total (in dollars per share) | $ / shares		$ 0.00
Minimum [Member]
Property, Plant, and Equipment, Salvage Value		$ 140,000	175,000
Maximum [Member]
Property, Plant, and Equipment, Salvage Value		$ 300,000	400,000
Office Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)		3 years
Office Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)		10 years
Building [Member]
Property, Plant and Equipment, Useful Life (Year)		20 years
Proton Beam Radiation Therapy PBRT [Member]
Property, Plant and Equipment, Useful Life (Year)		20 years
Gamma Knife And Radiation Therapy Equipment [Member]
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total		$ 69,306,000	68,994,000
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization		$ 47,992,000	$ 43,400,000
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Number of Major Customers		15	17
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | One Customer [Member]
Concentration Risk, Percentage		45.00%	34.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Number of Major Customers		4	2
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer One [Member]
Concentration Risk, Percentage		12.00%	31.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer Two [Member]
Concentration Risk, Percentage		14.00%	10.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer Three [Member]
Concentration Risk, Percentage		16.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Customer Four [Member]
Concentration Risk, Percentage		22.00%