A radiation treatment system, comprising:a) a computer (12, 13) for controlling a process of monitoring the position of at least a part of a patients body (1) during a radiation treatment configured to execute the following steps:i) providing an energy data which describe an energy value which is dependent on the radiation energy applied to the patients body (1) andii) determining control data in accordance with the energy data, wherein the control data are designed to control the time at which monitoring is performed in accordance with the energy valuewherein the computer is designed to determine the control data on the basis of the energy data provided and to issue the control data in order to control a monitoring device (19)b) a monitoring device (19), which is designed to monitor the position of at least a part of a patients body (1) which is to be treated using treatment radiation (6) and designed to be controlled in accordance with the control data andc) a treatment device (5) which is designed to emit the treatment radiation (6) used for the radiation treatment.
