Treatment of Cancer by Outside Radiation Technology
External beam therapy (also known as teletherapy) is a method of treatment in which a beam of high-energy X-ray is delivered to the patient’s tumor. This technique is frequently used under radiotherapy. The beam is generated outside and patient sits on a couch, so the radiation is pointed to a particular part of the body. The high energy X-rays can deposit their dose to a specific area of the tumor to destroy cancer cells. It needs a careful planning to spare the surrounding normal tissue. In contrast to the internal radiotherapy, in which radiation source is placed inside the body, external beam radiotherapy used the radiation from outside the body.
Kilovoltage X-rays are used for the treatment of skin cancer and superficial structure, while megavoltage X-rays are used to diagnose deep-seated tumors that can be in lung, brain, prostate, bladder and bowel. Medically useful beams can be derived from a radioactive source. Such photon beams are more or less monochromic gamma rays. Beam quality and hardness can be improved by special filters. In the medical field, X-rays are generated when electrons are accelerated or bombarding to a high energy. The electron beams usually have nominal energies in the range 4-20 MeV.
Usually, the external beam therapy is not used for cancers that take up iodine, but it is a useful method for the treatment of medullary thyroid cancer and anaplastic thyroid cancer. In the case when cancer does not respond to radioiodine therapy, external beam therapy can be used to diagnose local neck recurrence or distant metastases. This therapy usually takes 5 days a week for about 6 weeks. There are some side effects of this treatment such as the radiation may destroy nearby healthy tissue along with the infected cells, there may be the skin change, trouble swallowing, fatigue, hoarseness etc. Overall the careful use of this treatment is effective enough to treat dangerous cells of cancer.