In order to provide a radiation detector having a structure for easily and precisely shielding X-rays directly incident on a photodiode element array and preventing vibrations due to high-speed rotation, it is necessary to provide a radiation detector on the radiation incidence surface of the scintillator element array 13 , And a shielding portion 17 for shielding the reflective material 12 between the adjacent scintillator elements 11. The width Ws of the shielding portion 17 is smaller than the width Wr of the reflecting material 12 and larger than the thickness Wc of the collimator plate 16. An adhesive layer 18 is disposed between the upper surface of the shielding portion 17 and the end surface of the collimator plate 16, and the upper surface of the shielding portion 17 and the end surface of the collimator plate 16 are adhered by an adhesive layer.フォトダイオード素子アレイに直接入射するX線を簡便に精度良く遮蔽し、かつ、高速回転による振動を防止する構造を備えた放射線検出器を提供するために、シンチレータ素子アレイ13の放射線の入射面の、隣り合うシンチレータ素子11の間の反射材12を遮蔽する遮蔽部17を備える。遮蔽部17の幅Wsは、反射材12の幅Wrより小さく、コリメータ板16の厚さWcより大きい。また、遮蔽部17の上面とコリメータ板16の端面との間には接着層18が配置され、遮蔽部17の上面とコリメータ板16の端面とが接着層により接着されている。
