Note 10 - Related Party Transactions - Schedule of Related Party Transactions (Details) - US Subsidiary Of Elekta Member - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Equipment purchases and de-install costs	$ 2,147,000	$ 231,000	$ 3,565,000	$ 1,594,000
Costs incurred to maintain equipment	191,000	272,000	781,000	820,000
Total related party transactions	2,338,000	$ 503,000	4,346,000	$ 2,414,000
Accounts payable, asset retirement obligation and other accrued liabilities	$ 3,726,000		$ 3,726,000		$ 857,000