Abstract: A sensor is inserted into a closed water tank filled with water to the brim and the closed water tank is fixed directly to a radiation beam irradiating section, and the sensor is moved freely with respect to a mounted frame used for fixation. Therefore, a rapid and accurate prediction of the actual dose distribution of radiation beam prior to radiation therapy can be conducted, even when the irradiating section is attached to a rotation gantry.

Abstract: In a treatment bed system for radiation therapy a rotation drive mechanism (relative isocentric rotation drive mechanism, rolling rotation drive mechanism, and pitching rotation drive mechanism) for rotating the bed independently around three axes (i, r, and p) perpendicular with respect to a patient each other and a parallel transfer mechanism (X-axis direction transfer mechanism, Z-axis direction transfer mechanism, and Y-axis direction transfer mechanism) for transferring the bed independently in parallel in the directions of three axes (X, Z, and Y) perpendicular with respect to a floor surface each other are provided. Thereby, the irradiation from arbitrary directions and distances to a patient held stationary on the bed can be performed.

Abstract: A fixed ring rail and a moving ring rail sandwiching a moving route of a radiation beam irradiating section therebetween, forms a cylindrical passage with a semicircular cross-section having a horizontal floor. Upon that passage is placed a moving floor composed of a continuous series of multiple plates which are connected freely flexible with each other. The moving floor is moved in synchrony with the rotation of radiation beam irradiation section, and, at the same time, the moving ring rail is allowed to rotate in the reverse direction by the same distance. A horizontal floor necessary as an access floor to the treatment bed and to the radiation beam irradiating section is formed regardless of the rotating position of the radiation beam irradiation section, and the patient is surrounded completely to remove him/her of fear.