Data acquisition device, X-ray CT apparatus, and nuclear medicine diagnostic apparatus

A data acquisition device according to an embodiment includes processing circuitry. The processing circuitry is configured to compare the reference waveform of a signal, which is output from a detector that detects radiation, with the waveform of a detection signal based on the radiation, which enters the detector through the subject and which is detected by the detector. The processing circuitry is configured to estimate the information about the radiation, which enters the detector through the subject, in accordance with a comparison result.