Note 9 - Commitments (Details Textual) - USD ($)		3 Months Ended
	Sep. 04, 2022	Mar. 31, 2023
Leksell Gamma Knife Icon Systems and Linear Accelerator System [Member]
Long-term Install Service and Purchase Commitment, Amount		$ 16,228,000
Long-term Commitment, Cash on Hand to Fund		13,201,000
Long-term Commitment, Line of Credit to Fund		7,000,000
LINAC System [Member]
Long-Term Service Commitment, Amount		$ 15,168,000
LINAC System [Member] | Maximum [Member]
Long-Term Service Commitment, Period (Year)		9 years
LINAC System [Member] | Minimum [Member]
Long-Term Service Commitment, Period (Year)		5 years
Mevion PBRT Units [Member] | Upgrade and Purchase MEVION Systems [Member]
Long-term Purchase Commitment, Amount		$ 34,000,000
Mevion Medical Systems Inc [Member] | Maintenance And Support Agreement, Mevion Service Agreement [Member]
Purchase Agreement Annual Prepayment	$ 1,800,000
Long-term Purchase Commitment, Period (Year)	1 year