Radiotherapeutic apparatus

摘要

A radiotherapeutic apparatus employs a collimator (52) set below a radiation source (50) and is adapted to move along an arc (54) substantially centred on the radiation source (50). As it sweeps the arc, the collimator (52) is adjusted so as to define the appropriate shape of radiation beam. A continuous sweep over the patient avoids edge artefacts and localised accumulation of leakage.