Radiation therapy, also known as radiotherapy and radiation oncology, is the treatment of cancer by the use of ionizing radiation to control malignant growth. Radiation Therapy is used to either cure the disease or to provide therapy and relief when a cure is not possible. Total body irradiation is used prior to a bone marrow transplant which is typically required in cases of leukemia.

In the treatment of malignant tumors, radiation therapy may be employed as the primary treatment, or combined with surgery, chemotherapy and hormone therapy. Most common forms of cancer respond positively to radiotherapy as at least part of the treatment. The actual intent of the treatment will depend on the type of tumor, its location, and stage – as well as the patient’s overall health.

Radiation oncology is also used for non-cancerous conditions like pterygium, a benign growth of the conjunctiva or on the eyelids, neck or joints, and for thyroid eye disease although other treatments are often chosen in such cases given the severity of radiation therapy.

Procedure information
Radiation therapy is typically applied directly to the tumor. Depending on the location of the tumor, the field of radiation may include the surrounding lymph nodes, if they are involved - or if there is a risk of malignant spread. In most radiotherapy treatments, a field of normal tissue surrounding the tumor is included. The reason for this is that the tumor’s position can be altered by internal and external factors, and it is important that the entire malignancy is treated.

To avoid damaging normal tissues, such as the skin or any organs that the radiation must pass through to reach the tumor, the beams are aimed at the tumor from several angles. This provides for a significantly larger dose to the tumor itself, rather than to the adjacent, healthy tissue.

The three main types of radiation oncology currently in use are external beam radiotherapy, sealed source radiotherapy and unsealed source radiotherapy. External beam radiotherapy is the most commonly used method where x-rays are used to bombard the treatment area such as the skin. Deep-lying tumors are treated with megavoltage x-rays such as those in the bowel or lung.

In sealed source radiotherapy, radioactive material is placed in or next to the cancer site and is especially useful in treating prostate cancer, whereas unsealed treatment involves the injection or ingestion of soluble radioactive material, a procedure often used to treat thyroid cancer.

Recovery time
Although often a substantial procedure, radiation oncology does not often entail as long a recovery period as chemotherapy. However, total body irradiation, as used ahead of a bone marrow transplant, is administered in doses that are lethal without the replacement of the infected cells, which begins a period of suppressed immune response that requires months of recovery.

With internal radiation therapy, treatment involves the hospitalization of the patient for a few days due to the high levels of radiation required. The levels are highest during the hospital stay and visitation may be restricted. Implants may be inserted either temporarily or permanently. The radiation from a permanent implant reaches a safe level before the patient is discharged. When an implant is removed, there is no further radioactivity in the patient’s body.

In the case of external beam radiotherapy, the recovery period is usually swift although high doses of radiation can often lead to side effects that take weeks or even months to overcome. Unsealed source radiotherapy means the patient is considered radioactive for a short period following treatment and must therefore avoid contact with other people until radioactive material has been passed and levels return to normal. External radiotherapy is typically done on an outpatient basis, in either a clinic or hospital setting, five days per week for a number of weeks.