Radiotherapy
Radiotherapy or radiation is a treatment for cancer using high energy radiation. It is used to destroy cancer cells. Radiation acts on the DNA of the cancer cells and acts by not allowing the cancer cells to divide properly. The dose of radiation delivered is calculated and determined to be such as to destroy the cancer cells as much as possible and to protect the surrounding healthy tissues at the same time. Some normal tissues may be damaged during the course of radiotherapy but the side effects are generally temporary. The normal tissues start dividing after the conclusion of radiotherapy.
Radiotherapy may be given as the sole treatment in certain cancers. It may be given along with chemotherapy in other types of cancers or following surgery in certain other tumours. Palliative radiotherapy is given in situations when it helps to alleviate pain and or other symptoms in patients with incurable disease.
Radiation is given in fractions or small dose per fraction. The modern technological advancement coupled with software integration permits one to deliver high tech radiation these days. Radiation may be external or internal.
Following are the various types of external radiation:-
- Three Dimensional Conformal Technique (3DCRT) allows one to conform the dose distribution according to the shape of the tumor.
- Intensity Modulated Radiotherapy (IMRT) permits changing the intensity of the radiation dose as well in addition to conforming to the tumor shape.
- By Image Guided Radiotherapy (IGRT) frequent matching of the tumor shape can be performed before radiation.
- By Stereotactic Radiotherapy (SRT) one can deliver a higher dose of radiation to a small, irregularly shaped tumor within the brain and spare the surrounding critical organs as well. The same may be done in other parts of the body with the help of Stereotactic Body Radiotherapy.
- Brachytherapy /Internal Radiation: When radiation is delivered by placing the source of radiation within and/or close to the tumor/tumor cavity it is called brachytherapy.