Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2022	Apr. 30, 2021
Disaggregation of Revenue [Line Items]
Total oncology services revenue	$ 49,109	$ 41,040
Pharmacology services
Disaggregation of Revenue [Line Items]
Total oncology services revenue	46,833	39,473
Other TOS revenue
Disaggregation of Revenue [Line Items]
Total oncology services revenue	2,227	1,401
Personalized oncology services
Disaggregation of Revenue [Line Items]
Total oncology services revenue	$ 49	$ 166