PROBLEM TO BE SOLVED: To provide a radiotherapy system and a radiotherapy program that can improve reproductivity of patients positioning and accuracy of radiotherapy by evaluating a respiratory phase directly from a three-dimensional movement of a marker in a patients body and can also automatically detect occurrence of baseline shift.SOLUTION: A radiotherapy system includes: a marker position calculation part 34 that calculates a three-dimensional marker position on the basis of a transparent image obtained by photographing the marker a respiratory phase evaluation part 35 that associates a three-dimensional marker position most distant from an average marker position in a patients respiratory cycle with an inspiratory phase, associates the three-dimensional marker position after moving from the previous inspiratory phase by a prescribed distance with a respiratory phase corresponding to a proportion of the prescribed distance to a moving distance when the marker moves from the previous inspiratory phase to the current inspiratory phase, and then evaluates the patients respiratory phase and a therapeutic irradiation determination part 38 that determines availability of therapeutic irradiation on the basis of the three-dimensional marker position and the patients respiratory phase.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2016,JPO&INPIT
