Revenue from Contracts with Customers (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2023	Jan. 31, 2022	Jan. 31, 2023	Jan. 31, 2022
Disaggregation of Revenue [Line Items]
Oncology services revenue	$ 12,773	$ 13,193	$ 40,799	$ 36,232
Pharmacology services
Disaggregation of Revenue [Line Items]
Oncology services revenue	12,119	12,622	38,355	34,468
Other TOS revenue
Disaggregation of Revenue [Line Items]
Oncology services revenue	648	546	2,328	1,715
Personalized oncology services
Disaggregation of Revenue [Line Items]
Oncology services revenue	$ 6	$ 25	$ 116	$ 49