Note 10 - Related Party Transactions - Schedule of Related Party Transactions (Details) - US Subsidiary Of Elekta Member - USD ($)	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Equipment purchases and de-install costs	$ 201,000	$ 1,232,000
Costs incurred to maintain equipment	295,000	269,000
Total related party transactions	496,000	$ 1,501,000
Related Party [Member]
Accounts payable, asset retirement obligation and other accrued liabilities	$ 791,000		$ 857,000

Amount of accounts payable, asset retirement obligations and other accrued liabilities as of balance sheet date.

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-3

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

Amount of operating expense for routine plant maintenance and repairs of regulated operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

+ Details

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Period Type:	duration

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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