ABSTRACT
The use of ionizing radiation in therapy depends on the fact that tumour cells are more susceptible to radiation damage than normal cells. The radiation used is usually either x-rays or ϒ-rays from radioactive materials. The radiation dose which can be delivered to the tumour depends on the source-to-skin distance, how well the radiation penetrates the tissues, and how much radiation is scattered into the treatment area from the tissues outside this area. The collimator confines the radiation beam to the appropriate size and direction. The treatment set is always located in a treatment room which is designed to reduce the radiation dose to members of staff and general public to less than that permitted. The use of ionizing radiation in therapy depends on the fact that tumour cells are more susceptible to radiation damage than normal cells. The use of conformal techniques in radiotherapy is likely to increase with the use of volume imaging systems and powerful planning computers.
