PROBLEM TO BE SOLVED: To suppress leakage of a radiation to a subject P due to expansion of half shadow of the radiation and positional deviation of a radiation irradiation region 13 on a radiation detector 11 due to positional deviation of a radiation generation tube 8 in a mammographic tomography apparatus comprising a gantry 2 having a front plate 7 on which a breast inlet/outlet 17 for putting a breast 15 into/out from a breast storage part 3 is opened, the radiation generation tube 8 and the radiation detector 11 oppositely provided with the breast storage part 3 held therebetween in the gantry 2, and a rotation drive part for rotating the radiation generation tube 8 and the radiation detector 11 at the same angular velocity around a rotation shaft D passing inside the breast storage part 3.SOLUTION: A collimator 12 rotating in synchronization with the radiation generation tube 8 and the radiation detector 11 around the rotation shaft D is provided in a space closer to the breast storage part 3 between the breast storage part 3 and a radiation emission part 10.COPYRIGHT: (C)2015,JPO&INPIT【課題】乳房収納部3へ乳房15を入出するための乳房入出口17が開口した前面板7を有するガントリ2と、ガントリ2内に乳房収納部3を挟んで対向して設けられた放射線発生管8及び放射線検出器11と、乳房収納部3の内側を通る回転軸Dの周りに放射線発生管8及び放射線検出器11を同一角速度で回転させる回転駆動部とを有するマンモ断層撮影装置において、放射線の半陰影が広がることによる被検者Pへの放射線の漏洩と、放射線発生管8の位置ずれに伴う放射線検出器11上での放射線照射領域13の位置ずれを抑制する。【解決手段】乳房収納部3と放射線放出部10との間の乳房収納部3寄りに、回転軸Dの周りを放射線発生管8及び放射線検出器11と同期して回転するコリメータ12を設ける。【選択図】図2
