Cadmium manganese telluride (CMT) has high potential as a material for room-temperature nuclear-radiation detectors. We investigated indium-doped CMT crystals taken from the stable growth region of the ingot and compared its characteristics with that from the last-to-freeze region. We employed different techniques, including synchrotron white-beam x-ray topography (SWBXT), current–voltage (I–V) measurement, and low-temperature photoluminescence spectra, and we also assessed their responses as detectors of radiation exposure. The crystal from the stable growth region proved to be superior to that from the last-to-freeze region; it is a single-grain crystal, free of twins, and displayed a resistivity higher by one order of magnitude. The segregation of indium dopant in the ingot might be responsible for its better resistivity. Furthermore, we recorded a good response in the detector fabricated from the crystal taken from the stable growth region; its (μτ)e value was 2.6 × 10−3 cm2/V, which is acceptable for thin detectors, including their application in medicine.