A radiation detector assembly (20) includes a detector array module (40) configured to convert radiation particles to electrical detection pulses, and an application specific integrated circuit (ASIC) (42) operatively connected with the detector array. The ASIC includes signal processing circuitry (60) configured to digitize an electrical detection pulse received from the detector array, and test circuitry (80) configured to inject a test electrical pulse into the signal processing circuitry. The test circuitry includes a current meter (84) configured to measure the test electrical pulse injected into the signal processing circuitry, and a charge pulse generator (82) configured to generate a test electrical pulse that is injected into the signal processing circuitry. The radiation detector assembly (20) is assembled by operatively connecting the ASIC (42) with the detector array module (40), and the signal processing circuitry (60) of the ASIC of the assembled radiation detector assembly is tested without the use of radiation.
