Note 10 - Related Party Transactions - Schedule of Related Party Transactions (Details) - US Subsidiary Of Elekta Member - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Equipment purchases and de-install costs	$ 1,217,000	$ 131,000	$ 1,418,000	$ 1,363,000
Costs incurred to maintain equipment	295,000	279,000	590,000	548,000
Total related party transactions	1,512,000	$ 410,000	2,008,000	$ 1,911,000
Accounts payable, asset retirement obligation and other accrued liabilities	$ 2,091,000		$ 2,091,000		$ 857,000