Note 9 - Commitments and Contingencies (Details Textual) - USD ($)		3 Months Ended
Sep. 04, 2022	Mar. 31, 2024
Leksell Gamma Knife Icon Systems and Linear Accelerator System [Member]
Long-term Install Service and Purchase Commitment, Amount		$ 13,752,000
Long-term Commitment, Cash on Hand to Fund		13,042,000
Long-term Commitment, Line of Credit to Fund		7,000,000
Long-Term Line of Credit		2,400,000
Maintenance And Support Agreement, Mevion Service Agreement [Member] \| Mevion Medical Systems Inc [Member]
Purchase Agreement Annual Prepayment	$ 1,865,000
Long-term Purchase Commitment, Period (Year)	1 year
LINAC System [Member]
Long-Term Service Commitment, Amount		$ 14,120,000
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

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-SubTopic 10
-Topic 210
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16)(a)(2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant