UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	3 Months Ended		9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Income Statement [Abstract]
Oncology services revenue	$ 6,430,000	$ 5,082,000	$ 19,348,000	$ 15,319,000
Costs and operating expenses:
Cost of oncology services	3,429,000	2,473,000	9,963,000	7,737,000
Research and development	1,269,000	1,045,000	3,550,000	3,308,000
Sales and marketing	879,000	627,000	2,138,000	1,862,000
General and administrative	1,223,000	1,004,000	3,311,000	3,167,000
Total costs and operating expenses	6,800,000	5,149,000	18,962,000	16,074,000
Income (loss) from operations	(370,000)	(67,000)	386,000	(755,000)
Other expense:
Other (income) expense	(1,000)	7,000	5,000	71,000
Total other (income) expense	(1,000)	7,000	5,000	71,000
Income (loss) before provision for income taxes	(369,000)	(74,000)	381,000	(826,000)
Provision for income taxes	0	2,000	0	18,000
Net income (loss)	$ (369,000)	$ (76,000)	$ 381,000	$ (844,000)
Net income (loss) per common share outstanding
Net income (loss) per common share outstanding, basic (in dollars per share)	$ (0.03)	$ (0.01)	$ 0.03	$ (0.08)
Net income (loss) per common share outstanding, diluted (in dollars per share)	$ (0.03)	$ (0.01)	$ 0.03	$ (0.08)
Weighted average common shares outstanding
Weighted average common shares outstanding, basic (in shares)	11,508,180	10,994,434	11,257,314	10,987,797
Weighted average common shares outstanding, diluted (in shares)	11,508,180	10,994,434	13,909,063	10,987,797