Commitment and Contingencies (Details) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2022	Oct. 31, 2021	Oct. 31, 2022	Oct. 31, 2021
Commitments and Contingencies [Line Items]
Royalty expense	$ 32,000	$ 147,000	$ 108,000	$ 199,000
Minimum
Commitments and Contingencies [Line Items]
Royalty fee per tumor sample			$ 0
Royalty payment, as percent of contract price			2.00%
Maximum
Commitments and Contingencies [Line Items]
Royalty fee per tumor sample			$ 30,000
Royalty payment, as percent of contract price			20.00%