In recent years, among radiation therapy systems for the purpose of cancer therapy, there have been advanced development and/or construction of a cancer therapy system that utilizes a particle beam of proton, heavy ion, etc. (called, in particular, as a particle beam therapy system) As is well known, according to a particle beam therapy utilizing the particle beam, a cancer diseased site can be irradiated in a concentrated manner as compared to the conventional radiation therapy using an X-ray, a γ-ray, etc., that is, the particle beam can be radiated in a pinpoint manner to be matched to a shape of the diseased site, and thus it is possible to perform the therapy without affecting normal tissues.
In the particle beam therapy, it is important to highly accurately radiate the particle beam to the diseased site such as a cancer. For that purpose, during the particle beam therapy, the patient is fastened using a fastener, etc. in order not to shift his/her position relative to a patient support table in a treatment room (irradiation room). In order to accurately position the diseased site such as a cancer within a radiation exposure region, there is made a setting including roughly emplacing the patient with the aid of a laser pointer, etc., and then, an accurate positioning of the diseased site of the patient is performed using an X-ray image, a CT (Computed Tomography) image or the like.
In Patent Document 1, there is described a treatment table system in which, after being precisely positioned using a three-dimensional diagnosis apparatus (CT apparatus) and while keeping this positioned state, the diseased site is highly accurately positioned at an isocenter of a particle beam therapy system by moving a placing board (top board). Using an isocenter of the three-dimensional diagnosis apparatus (CT apparatus) as a virtual isocenter of the particle beam therapy system, the treatment table system of Patent Document 1 makes positioning so that an image by the three-dimensional diagnosis apparatus is matched to a reference image for positioning. Such a positioning using images, is referred to as an image-matching positioning. After completion of the image-matching positioning at the virtual isocenter, the treatment table system moves the placing board (top board) on which the patient is laid by a movement mechanism of the patient support table, to thereby position the diseased site at the isocenter of the particle beam therapy system.