Radiation Therapy involves the use of ionizing radiation (commonly X rays) for the treatment of malignant and some benign tumors. Since the discovery of X rays in late 19th century, the technology of radiation delivery, understanding of tumor biology and radiobiology has grown by leaps and bounds.
Radiation Therapy uses carefully targeted and regulated doses of high-energy radiation to kill cancer cells. Radiation causes some cancer cells to die immediately after treatment, but most die or become incapacitated as a result of the radiation-induced damage to the cancer cell’s chromosomes and DNA. There are two modes of radiation delivery – External Beam Radiation and Brachytherapy. Now-a-days, a variety of novel external beam radiation planning and delivery techniques are available, which gives the best opportunity for positive outcomes with the least side-effects. It’s important to discuss with the treating oncologist which technique is better in a patient for the given clinical scenario. These cutting edge technologies are:
- Intensity Modulated Radiation Therapy (IMRT): It is an advanced type of high precision radiotherapy technique used to treat cancers and non cancerous tumors. It uses an advanced technology to manipulate beams of radiation to conform to the shape of tumor and to reduce the incident dose to normal tissues, to limit the side effects of treatment. Each radiation beam is divided into several small beamlets that can vary their intensity. This allows different doses of radiation to be given across the tumor.
- Image Guided Radiation Therapy (IGRT): This technique uses frequent imaging during a course of radiation therapy to improve the precision and accuracy of radiation delivery. IGRT is especially useful in tumors which may move during treatment or between treatments like lung, prostate tumors. The advantage is that a Radiation Oncologist can target the radiation delivery accurately, hence improving the chances of tumor control and reducing the side effects.
- Volumetric Modulated Arc Therapy (VMAT): This is an advanced high precision radiotherapy where a linac delivers radiation in a single or multi arc treatment by rotation of the gantry. It allows the treatment to be delivered faster with greater accuracy and patient comfort.
It is a form of radiation delivery where the radioactive source is placed in a close contact with the tumor or target tissue. Brachytherapy delivers very high doses to the target and low doses to the adjacent normal tissue. Thus, it forms an integral part in management of several malignancies – cervical, uterine. The High Dose Rate (HDR) brachytherapy delivers the entire treatment in 15-30 minutes.