The Southern California Regional Gamma Knife Center (Details)		3 Months Ended		12 Months Ended
	Apr. 01, 2016 USD ($)	Mar. 31, 2021 USD ($) Payment	Mar. 31, 2020 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		$ 89,000	$ 370,000
Condensed Income Statement Information [Abstract]
Patient revenue		1,061,000	747,000
USNC's equity in (loss) earnings		(139,000)	(146,000)
Condensed Balance Sheet Information [Abstract]
Current assets		3,451,000		$ 3,007,000
TOTAL ASSETS		4,614,000		4,173,000
Current liabilities		322,000		410,000
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY		4,614,000		4,173,000
Neuro Partners LLC and CGK [Member]
The Southern California Regional Gamma Knife Center [Abstract]
Recorded amount of equity method income		24,000		26,000
Neuro Partners LLC and CGK [Member] | Investment in Unconsolidated Entity [Member]
Condensed Income Statement Information [Abstract]
Patient revenue		166,000	316,000
Net income		19,000	156,000
USNC's equity in (loss) earnings		(2,000)	$ 53,000
Condensed Balance Sheet Information [Abstract]
Current assets		140,000		121,000
Noncurrent assets		487,000		551,000
TOTAL ASSETS		627,000		672,000
Current liabilities		570,000		634,000
Equity		57,000		38,000
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY		$ 627,000		672,000
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 obligations		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		$ 11,000		$ 9,000