A combined format gamma-ray detector (D) for measuring impinging gamma-rays (10) includes an active upper level coded aperture detector plane member (12) that is suitable for detecting an impinging gamma-ray (10). An active lower level gamma ray detector plane member (14) that is spaced apart from the upper level coded aperture (12) detects an impinging gamma-ray (10). At low gamma-ray energies, the combined format gamma-ray detector device (D) operates as a conventional coded aperture system and at higher gamma-ray energies, the combined format gamma-ray detector device operates as a Compton scattering detector device.