Note 9 - Commitments and Contingencies (Details Textual)		9 Months Ended	12 Months Ended
	Sep. 04, 2022 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Number Of Purchase Commitments			2
Leksell Gamma Knife Icon Systems and Linear Accelerator System [Member]
Long-term Install Service and Purchase Commitment, Amount		$ 13,243,000
Long-term Commitment, Cash on Hand to Fund		11,664,000
Long-term Commitment, Line of Credit to Fund		7,000,000
LINAC System [Member]
Long-Term Service Commitment, Amount		$ 17,166,000
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