UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Income Statement [Abstract]
Oncology services revenue	$ 7,625	$ 6,693	$ 14,362	$ 12,919
Costs and operating expenses:
Cost of oncology services	3,881	3,451	7,633	6,533
Research and development	1,341	1,193	2,644	2,282
Sales and marketing	977	740	1,847	1,259
General and administrative	1,135	1,034	2,561	2,088
Total costs and operating expenses	7,334	6,418	14,685	12,162
Income (loss) from operations	291	275	(323)	757
Other income (expense):
Other income (expense)	27	(7)	15	(6)
Income (loss) before provision for income taxes	318	268	(308)	751
Provision for income taxes	11	1	26	1
Net income (loss)	$ 307	$ 267	$ (334)	$ 750
Net income (loss) per common share outstanding
Net income (loss) per common share outstanding, basic (in dollars per share)	$ 0.03	$ 0.02	$ (0.03)	$ 0.07
Net income (loss) per common share outstanding, diluted (in dollars per share)	$ 0.02	$ 0.02	$ (0.03)	$ 0.06
Weighted average common shares outstanding
Weighted average common shares outstanding, basic (in shares)	11,619,686	11,278,312	11,619,569	11,135,358
Weighted average common shares outstanding, diluted (in shares)	12,964,792	14,037,090	11,619,569	13,491,502