In medicine, these rays are mostly used to treat malignant tumours. The main principle is removing the two outermost electrons of the oxygen atoms that occur everywhere in the tissue. This requires high energy. Such oxygen atoms are referred to as "free radicals". These are extremely effective cytotoxins that can destroy the affected cell or surrounding area. Theoretically, any malignant tumour can be destroyed with radiotherapy. However, because the radiation source must be applied from the outside, healthy tissue is also affected. Therefore, when radiotherapy is applied, a certain degree of damage to healthy tissue must be accepted.
The future of radiotherapy will involve irradiating the tumour with the highest possible dose, while minimising the corresponding side effects to the greatest extent possible. Newer techniques will make this possible.