Radiotherapy is one method doctors can use to treat cancer. Radiotherapy can be performed without surgery and avoids the side effects that a patient may experience during chemotherapy.
In the most common form of radiotherapy, high energy x-rays are used to kill the cells in the tumour. The treatment must be planned carefully to make sure that healthy cells are not damaged by the x-rays. The dose required to kill the cancerous cells is normally delivered in smaller doses and at different angles (as shown in the diagram) to make sure that only the cells in the tumour are destroyed.
- Each beam delivers one third of the dose required.
- The beams overlap at the tumour, which receives the full dose.
Here are some slides about radiotheraphy. I have attached a copy of them (as a pdf file) to the bottom of this post.