A silicon photomultiplier includes a plurality of microcells providing a pulse output in response to an incident radiation, each microcell including circuitry configured to enable and disable the pulse output. Each microcell includes a cell disable switch. The control logic circuit controls the cell disable switch and a self-test circuit. A microcell's pulse output is disabled when the cell disable switch is in a first state. A method for self-test calibration of microcells includes providing a test enable signal to the microcells, integrating dark current for a predetermined time period, comparing the integrated dark current to a predetermined threshold level, and providing a signal if above the predetermined threshold level.