UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Income Statement [Abstract]
Oncology services revenue	$ 13,193	$ 10,812	$ 36,232	$ 30,476
Costs and operating expenses:
Cost of oncology services	6,406	4,623	17,411	15,603
Research and development	2,181	1,879	6,783	5,125
Sales and marketing	1,549	1,492	4,764	4,048
General and administrative	2,227	1,836	6,356	4,686
Total costs and operating expenses	12,363	9,830	35,314	29,462
Income from operations	830	982	918	1,014
Other income (expense), net	(32)	(8)	11	64
Income before provision for income taxes	798	974	929	1,078
Provision for income taxes	11	15	37	43
Net income	$ 787	$ 959	$ 892	$ 1,035
Net income per common share outstanding
Net income (loss) per common share outstanding, basic (in dollars per share)	$ 0.06	$ 0.07	$ 0.07	$ 0.08
Net income (loss) per common share outstanding, diluted (in dollars per share)	$ 0.05	$ 0.07	$ 0.06	$ 0.07
Weighted average common shares outstanding
Weighted average common shares outstanding, basic (in shares)	13,500,444	13,371,613	13,170,880	12,974,470
Weighted average common shares outstanding, diluted (in shares)	14,387,009	14,507,155	14,178,082	14,510,280
Revenue, Product and Service [Extensible List]	Service [Member]	Service [Member]	Service [Member]	Service [Member]
Cost, Product and Service [Extensible List]	Service [Member]	Service [Member]	Service [Member]	Service [Member]