Consolidated Statements of Cash Flows (Unaudited) - USD ($)	1 Months Ended	3 Months Ended				6 Months Ended		12 Months Ended
	Jul. 31, 2019	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss		$ (868,000)	$ (713,000)	$ (897,000)	$ (816,000)	$ (1,581,000)	$ (1,713,000)
Adjustments to reconcile net loss to net cash used by operating activities:
Depreciation expense						71,000	77,000
Loss on equipment disposals						7,000
Amortization of other assets						19,000	20,000
Accretion of asset retirement obligation						16,000	15,000
Gain on change in estimate of asset retirement obligation	$ (73,000)						(73,000)
Share-based compensation						166,000	185,000
Changes in operating assets and liabilities:
Accounts receivable, net						306,000	(255,000)
Inventory						(85,000)	13,000
Prepaid expenses and other current assets						125,000	(190,000)
Accounts payable and accrued expenses						(158,000)	(51,000)
Accrued protocol expense						31,000	(109,000)
Accrued radioactive waste disposal						7,000	15,000
Accrued payroll and related taxes						(36,000)	114,000
Accrued vacation						14,000	21,000
Net cash used by operating activities						(1,098,000)	(1,931,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property and equipment						(173,000)	(204,000)
Net cash used by investing activities						(173,000)	(204,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Preferred dividends paid						(9,000)	(11,000)
Proceeds from sales of common stock, pursuant to underwritten offering, net						8,471,000
Proceeds from sales of common stock, pursuant to exercise of options						3,000
Net cash provided (used) by financing activities						8,465,000	(11,000)
Net increase (decrease) in cash, cash equivalents, and restricted cash						7,194,000	(2,146,000)
Cash, cash equivalents, and restricted cash beginning of period	5,507,000		2,573,000		5,507,000	2,573,000	5,507,000	$ 5,507,000
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH END OF PERIOD		9,767,000		3,361,000		9,767,000	3,361,000	2,573,000
Reconciliation of cash, cash equivalents, and restricted cash to the consolidated balance sheets:
Cash and cash equivalents		9,585,000		3,180,000		9,585,000	3,180,000	2,392,000
Restricted cash		182,000		181,000		182,000	181,000	181,000
Total cash, cash equivalents, and restricted cash shown on the consolidated statements of cash flows	$ 5,507,000	$ 9,767,000	$ 2,573,000	$ 3,361,000	$ 5,507,000	9,767,000	3,361,000	$ 5,507,000
Non-cash investing and financing activities:
Recognition of operating lease liability and right of use asset						$ 8,000	$ 1,228,000