Radiation therapy is a very common form of cancer treatment that is used in over 50% of all cancer patients. Which means you, as a rare cancer patient, may need to have this type of therapy at one time or another. It can be used for curative, and/or adjuvant, or palliative reasons. So, how does this type of therapy work? It breaks up the molecules within the cells and causes reactions that does irreparable damage to the cells. There are two main types of radiation in use. Here is a partial list of some of the various forms of radiotherapy:
External beam (EBRT, teletherapy) - delivered from a distant source outside of the body
» Carbon Ion Radiotherapy - A form of particle radiotherapy - fast carbon ion beams are used to treat 'deep seated' tumors - may also be used in conjunction with conformal and IMRT - recent developments allow for active beam shaping systems to be used.
» Conformal - utilizes computer mapping of the area to be radiated.
» Electron - stream of particles with limited depth of penetration that produces high-energy radiation.
» Hyperfractionated radiation - division of the total dose of radiation into smaller doses.
» Intensity modulated (IMRT) - breaks up the beam into thousands of tiny thin radiation beams, allowing entrance of the beam from many angles.
» Intraoperative (IORT) - delivers a high dose of radiation during surgery.
» Stereotactic radiosurgery (gamma knife) - delivers a high concentrated dose of radiation precisely at the tumor site.
» Thermoradiotherapy - utilizes the elevation of the tissue temperature prior to application of radiotherapy.
Internal (brachytherapy) - delivered by placing a radiation source (isotope) close to or inside the tumor.
» Interstitial - utilizes the surgical insertion of implants that are later filled with radioactive seeds.
» Intracavitary - containers filled with a radioactive source are implanted in existing body cavities.
» Intraluminal - used to radiate hollow organs by insertion of a tube.
» Radioactive (radiopharmaceutical) - radioactive material is taken orally or intravenously.
Collateral Damage: Many forms of radiation energy do not distinguish between cancer cells and healthy cells, which means that any cells, tissue, or organs within the field of radiation may also be affected. This is often referred to as collateral damage. The most common immediate side effects of radiation therapy are fatigue, nausea, and external tissue effects. I had, what I would consider, a relatively extensive sunburn and I was tired on many days. My radiation oncologist was able to give me additional skin medication that helped, and I learned to take naps if I needed one. Eventually, the skin healed and my energy level returned. I also had damage to my right lung tissue, because it was in the field of radiation.
Resolving Collateral Damage: There are new types of radiotherapy treatment, using software and imaging techniques, that help clinicians to pin point the actual tumor. Three Dimensional Conformal Radiotherapy (3DCRT), in which the profile of each radiation beam is shaped to fit the profile of the tumor. 3D-CRT utilizes a multi-leaf collimator (MLC) and a variable number of beams. This reduces collateral damage and allows delivery of a higher dose of radiation to the tumor.
An enhancement on 3DCRT is intensity-modulated radiotherapy (IMRT). It utilizes dynamic multi-leaf collimation to shape the profile of the beam and to vary the intensity of the beam. The goal is to achieve greater conformality than 3DCRT. IMRT also improves the ability to conform the treatment volume to concave shapes. This is important when the tumor is wrapped around a vulnerable structure such as the spinal cord, major organs, or blood vessels.
New techniques are being developed to improve this pin-pointing technology. Image-guided radiation therapy (IGRT). IGRT is radiotherapy that uses cross-sectional images of the patient's internal anatomy to better target the radiation dose to the tumor. This technology takes into consideration the movement of the body organs and changes in the tumor size and position during treatment.
Another new technology, on the horizon, is four-dimensional (time varying) computed tomography (4-CT). To learn more online about radiation therapy and it's effects, visit these websites:
ACS Treatment Decisions - good resource for information on radiation treatments.
International Radiosurgery Support Association - comprehensive website that explains gamma knife radiosurgery. and radiosurgery.
NCI Guide - a guide to radiation therapy with clickable links to answer your questions.