Introduction to Radiation Therapy
X-rays, a form of invisible, high-energy radiation, was discovered by German physicist Wilhelm Roentgen. X-rays have been used to both diagnose and treat diseases. X-rays can penetrate through many objects, forming images covered by other objects. This is the principle on which x-ray imaging of the body for medical diagnostic purpose is based. It was later discovered that x-rays can kill cancerous cells and shrink tumors because of the high energy emission. This method of treatment is called radiation therapy.
Radiation therapy uses x-rays, gamma rays and other sources of radiation to destroy cancer cells. Radiation kills cells by breaking up molecules and causing reactions that damage living cells. Sometimes the cells are destroyed immediately; sometimes certain components of cells, such as their deoxyribonucleic acid (DNA), are damaged, thereby affecting the ability of the cell to divide.
The radiation treatment is usually given using sophisticated equipment which produces a beam of high energy x-rays. The patient lies on a bed under the machine and the beam is directed at the site of the cancer. Due to the advancement of technologies, newly developed machines are able to produce radiation beams of much greater energy while maintaining pinpoint accuracy. Therefore, severe skin damage during treatment, which was common in the early days of radiation therapy treatment, is very rare with modern techniques.
Since emitted radiation energy does not distinguish between cancer cells and normal tissue, radiation fields are very carefully planned, during the process of radiation treatment, to protect uninvolved tissue and vital organs of the patient. Certain predictable side effects may occur after radiation treatment, with fatigue being the most common one. However, most side effects are temporary and easily treated.
Two main types of radiation treatment exist: external beam radiation, known as teletherapy, and internal therapy, or brachytheraphy. External beam radiation directs radiation from a remote source aimed at the body while with internal therapy a radioactive source is placed inside the body close to cancer cells or the tumor mass.
The goal of radiation therapy can be curative or palliative. Radiation therapy is frequently used as adjuvant therapy to other treatments, most often with surgery and chemotherapy.