A radiation imaging cassette. The cassette includes a housing, a latch member, and guide edges. The housing is adapted to house a stimulable phosphor sheet. The housing includes a light-protected region and an opening for extraction and/or insertion of the stimulable phosphor sheet. The latch member releasably engages the stimulable phosphor sheet to secure at least a portion of the stimulable phosphor sheet within the light-protected region. The edge guides are disposed within the housing and operate to guide movement of the stimulable phosphor sheet through the opening.