Offer of the method of being possible 2 dimensional distribution measurement of the radiation absorbed dose which uses 3D phantom, efficiently and precision to be good, furthermore reproducibility high to do. Between the 3D phantom which consists of the top and bottom 2 divided body which possesses 90 symmetry of rotation cross section, the radiation dosimetry body in horizontal state keep the step which closes The particular radiation dosimetry body at the gantry of the radiotherapy device irradiating radiation to the 3D phantom which keeps, in horizontal state, the step which measures the dose distribution of the roller null aspect 2 dimensional distribution measuring method of the radiation absorbed dose which uses the 3D phantom which features that it possesses the step where the 90 it turns the gantry without changing the position of particular 3D phantom, irradiates radiation to particular 3D phantom in the state and measures the dose distribution of the sagittal aspect.3Dファントムを用いた放射線吸収線量の2次元分布測定を、効率的にかつ精度良く、しかも再現性高く行なうことができる方法の提供。90°回転対称の断面形状を有する上下2分割体から成る3Dファントムの間に、放射線量測定体を水平状態に挾持せしめるステップと;当該放射線量測定体を水平状態に挾持した3Dファントムに、放射線治療装置のガントリにて放射線を照射してコロナル面の線量分布を測定するステップと;当該3Dファントムの位置を変えることなく、ガントリを90°回転させ、その状態で当該3Dファントムに放射線を照射してサジタル面の線量分布を測定するステップとを有することを特徴とする3Dファントムを用いた放射線吸収線量の2次元分布測定方法。
