PURPOSE: To improve the quality of an image by lessening events caused by isotope elements having a plurality of photo-peaks or undesirable photons such as Compton scattered photons.
CONSTITUTION: Photons are detected as a number of events by a γ-ray detector 7, the photons are grouped 32 based on the measured energy 23 and the X, Y positions, the number of photons at respective X, Y positions is counted for every energy level to calculate a measured energy spectrum 33, the energy distribution of undesirable photons is computed, and then the energy dispersion function of a γ-ray apparatus to be used is determined. Using the energy dispersion of undesirable photons and the energy dispersion function of the apparatus, energy dispersion of undesirable photons for every position depending on the apparatus is computed and the energy dispersion function depending on the apparatus is multiplied by unknown coefficients of respective desirable and undesirable photons to produce 14 a trial function. The unknown coefficient of desirable photons is solved by partially applying the measured energy distribution and an image 16 only of desirable photons is produced.
DOBU MAORU
IGARU SHIYUREMU
ADORIAN SOIRU
