A radiotherapy system comprising at least one pulsed radiation source, at least one imaging system, a control system, and a synchronization system is disclosed. The pulsed radiation source deposits high dose radiation pulses to a target region inside the patient; simultaneously the imaging system is used to monitor the target region, synchronized by the synchronization system. The dose per radiation pulse is high enough to deposit, within few pulses, 1 Gy at a depth of at least 1 cm in water. At each irradiation time step, the pulsed radiation source delivers short pulses of radiation (