UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Income Statement [Abstract]
Oncology services revenue	$ 10,812	$ 9,012	$ 30,476	$ 23,375
Costs and operating expenses:
Cost of oncology services	4,842	4,325	15,822	11,958
Research and development	1,879	1,391	5,125	4,035
Sales and marketing	1,492	1,307	4,048	3,155
General and administrative	1,836	1,556	4,686	4,118
Total costs and operating expenses	10,049	8,579	29,681	23,266
Income from operations	763	433	795	109
Other income (expense)	(8)	(14)	64	1
Income before provision for income taxes	755	419	859	110
Provision for income taxes	15	12	43	38
Net income	$ 740	$ 407	$ 816	$ 72
Net income per common share outstanding
Net income (loss) per common share outstanding, basic (in dollars per share)	$ 0.06	$ 0.03	$ 0.06	$ 0.01
Net income (loss) per common share outstanding, diluted (in dollars per share)	$ 0.05	$ 0.03	$ 0.06	$ 0.01
Weighted average common shares outstanding
Weighted average common shares outstanding, basic (in shares)	13,371,613	11,752,619	12,974,470	11,653,115
Weighted average common shares outstanding, diluted (in shares)	14,507,155	13,673,672	14,510,280	13,440,861
Revenue, Product and Service [Extensible List]	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember
Cost, Product and Service [Extensible List]	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember