The present invention relates to a radiation therapy machine. The radiation therapy machine includes a number of lightings, a detecting structure, a determine module, and a control module. The detecting structure is configured for detecting a parameter of a human being. The determine module is configured for receiving the parameter of the human being and determining a tiredness level of the human being, according to the parameter. The control module stores a chart of the tiredness level corresponding to a radiation degree and a radiation time. The control module is configured for controlling the lightings to emit radiation to the human being according to the corresponding tiredness level, the radiation degree, and the radiation time in the chart.
