Investments in Unconsolidated Entities, The Southern California Regional Gamma Knife Center (Details)		12 Months Ended
	Apr. 01, 2016 USD ($)	Dec. 31, 2022 USD ($) Payment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Feb. 29, 2016 USD ($)
The Southern California Regional Gamma Knife Center [Abstract]
Renovation installation and operation agreement period		14 years
Lease payment		$ 0	$ 89,000
Condensed Income Statement Information [Abstract]
Patient revenue		0	1,061,000
Net (loss) income		(1,572,000)	(973,000)
USNC's equity in (loss) income		16,000	(19,000)
Condensed Balance Sheet Information [Abstract]
Current assets		1,555,000	2,243,000
Total assets		1,747,000	3,688,000
Current liabilities		280,000	626,000
Equity		1,456,000	3,028,000	$ 3,686,000
Total liabilities and equity		1,747,000	3,688,000
Neuro Partners LLC and CGK [Member]
Condensed Income Statement Information [Abstract]
Patient revenue		356,000	606,000
Net (loss) income		(252,000)	(9,000)
Condensed Balance Sheet Information [Abstract]
Current assets		375,000	299,000
Noncurrent assets		42,000	294,000
Total assets		417,000	593,000
Current liabilities		632,000	564,000
Noncurrent liabilities		0	0
Equity		(215,000)	29,000
Total liabilities and equity		$ 417,000	593,000
Neuro Partners LLC [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage		20.00%
Neuro Partners LLC [Member] | Lease One [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Share of guarantee in lease obligation		20.00%
Lease term		7 years
Lease obligation					$ 668,000
Neuro Partners LLC [Member] | Lease Two [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Lease term		5 years
Lease obligation					$ 1,663,000
Number of lease payments | Payment		60
Lease payment	$ 31,000
CGK [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Ownership percentage		39.00%
Due from related parties		$ 7,000	6,000
Neuro Partners LLC and CGK [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Recorded amount of equity method income (loss)		0	(10,000)
Condensed Income Statement Information [Abstract]
USNC's equity in (loss) income		$ (133,000)	$ (36,000)