Note 3 - Inventory - Noncurrent Inventory (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Jun. 30, 2020
Total inventory, non-current	$ 76	$ 137
Enriched Barium Inventory [Member]
Total inventory, non-current		117
Raw Materials [Member]
Total inventory, non-current	$ 76	$ 20

Inventories not expected to be converted to cash, sold or exchanged within the normal operating cycle.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(d))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_InventoryNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant