Patent ID: 7459688

Claim:
An apparatus for radiographic examination, comprising: a detection unit which comprises a detector configured to detect a gamma ray emitted from a radioactive isotope in an object and to output a detected signal, a first measurement unit configured to determine a first crossing time at which a pulse height of the detected signal becomes substantially equal to a first threshold value, a second measurement unit configured to determine a second crossing time at which the pulse height of the detected signal becomes substantially equal to a second threshold value that is greater than the first threshold value, and an incidence time calculation unit configured to calculate a starting time of the detected signal based on the first crossing time and the second crossing time, which the starting time indicates when a waveform of the detected signal has started to rise and is used as an incidence time indicating when the gamma ray has entered the detector, and to output detection data including the incidence time; and an information processing unit configured to determine distribution of radioactive isotopes in the object based on multiple sets of said detection data that are valid according to the incidence time.