Updated: July 21, 2018
Radiation therapy is a treatment mostly used for cancer and tumors, as well as other conditions. It can have a targeted, powerful effect on tumors that are confined to a specific area.
It is also used for the treatment of thyroid disease, blood disorders, and noncancerous growths in some cases. Powerful waves of energy are delivered in this therapy to disrupt the ability of cancer cells to grow and divide. These are also helpful in killing cancer cells, slowing their growth, and shrinking tumors before a surgery to make it easy. Because healthy tissue near the tumor is affected along with the cancerous tissue, there will be some side effects which are localized to the area treated, but are usually short term. However, some effects, such as fatigue, can occur body wide.
The treatment is often simulated during planning before the real treatment is administered to ensure accurate placement of radiation therapy. Radiation means waves of energy, such as light or heat. Ionizing radiation is the form of radiation used in cancer therapy which is a high energy. Radiation works by breaking up the DNA of cancer cells in a way that disrupts their growth and division and can even kill them. Radiation therapy will sometimes be used as standalone, and in some cases will be used in combination with other cancer treatments, such as chemotherapy in order to enhance the effect of the treatment.
There are two forms of radiation therapy:
External beam radiation therapy is the more commonly used form of radiation therapy. There are different forms of external beam radiation therapy which have specific effects on the particular tumor. Depending on the type that best suit you will be decided by your doctor. For example, a high-energy X-rays can reach deeper cancers. Some form of external beams narrow in, on their target for best effect and the lowest level of risk.
Internal radiation therapy may be used when trying to limit radiation exposure to undamaged tissue around the cancer.
Doses are measured in terms of the amount of energy absorbed per kilogram of body mass exposed to radiation. For example, 1 joule of energy deposited in 1 kilogram of mass amounts to 1 international unit of energy absorbed, or 1 gray (Gy).
Doctors will keep a record of the amount of radiation being administered. There is a risk of long term side effects in both individual and cumulative doses. Different cancers and areas of the body respond in different ways to the therapy. Protective steps should be taken by professionals delivering radiation or working in the vicinity of treatment to keep their own exposure to a minimum. They should also measure how much they receive.
If the potential benefits outweigh the potential risks, then only the treatment is recommended for an individual. Radiation treatment planning is designed to maximize benefits and keep potential risks to a minimum which involves working out an exact site, an angle of radiation, and an optimal dose.
A number of healthcare workers, including oncologists and specialist radiologists, nurses, radiographers, and other technicians are involved in radiation planning.
As the side effects depend on the individual's circumstances, the type of radiation therapy and proper planning is required based on certain criteria.
The planning involves:
Modern radiation planning is usually computer assisted and sophisticated enough to produce 3D images of tumors.
An oncologist will decide on the dose and type of radiation before the treatment begin. Normally it takes several sessions over the course of treatment that are spread over a few weeks. Mostly people have five treatments per week. However, this can change depending on the stage and type of cancer.
CT scan might be done before treatment to pinpoint the exact location and size of the tumor. A permanent but small ink mark will be made on the skin following the scan to ensure that the radiation is targeted accurately.
The different types of radiation therapy are administered in different ways.
In external radiation therapy, a linear accelerator is used to emit X-rays within a specific energy range. Other machines are also available that use other forms of energy, including electrons, protons, gamma rays, or a combination of these.
During the procedure, the person receiving radiation lies on a table, and the machine will be operated remotely by a technician from a near by room. The patient and technician can communicate through an intercom. The technician will monitor the individual receiving radiation therapy through a camera. The duration of the procedure is usually very short and painless, and a person can return home shortly after the end of the session.
There are variations on the procedure. For example, in image guided radiation therapy (IGRT), scans are performed between sessions to maintain accuracy in the treatment, where as in stereotactic surgery (SRS), several tiny beams are used to enhance the strength of the dose.
Internal radiation therapy involves an implant of metal tubes, wires, or seeds that can be placed inside the body without surgery. Surgery may be needed in some cases to locate the implant nearer to the tumor. The implant will remain in the body for any duration of time, ranging from a few minutes to the rest of the life of a person. As the implants pose a radiation risk to other people, probably the person with implants will need to remain in hospital. However, permanent implants release far smaller doses of radiation and are considered safe for people around the individual receiving treatment.
Radiation therapy will be recommended by a doctor to target well-defined and contained cancers. Cancers that are confined to a specific area can be suitable for radiation therapy. This allows the radiation to target the whole area of cancerous tissue.
Some forms of cancer, such as leukemia or lymphoma, can be treated with total body radiation. radiation therapy may be deployed in the following ways:
Sarcomas or tumors of the breast, esophagus, lung, or rectum may be treated with all three types of treatment.
The side effects of radiation therapy occur when non-cancerous, healthy cells are also affected by the treatment. Radiation therapy reacts in the same way with cancer cells and non-cancerous cells.
However, as cancer cells tend to copy themselves at a faster rate and repair more slowly, these are more vulnerable to the effects of treatment. Some non-cancerous cells are also affected by radiation therapy leading to potential severe side effects.
Depending on which part of the body being treated, the overall health of the person receiving radiation therapy, and the type and dose of radiation used, side effects vary.
Short-term effects of radiation treatment can include:
Long-term effects also depend on the location of treatment and can include:
Not necessarily all these side effects are likely or even possible with all types of radiation therapy. The likelihood of getting any one of the longer-term side effects depends largely on the individual. People opting for radiation therapy should, therefore, receive guidance from their healthcare team about the balance of risks and benefits.
In addition to help stopping or cure a cancer, it can also be used to treat symptoms in cancers that have spread too widely or advanced so far that they cannot be fully cured. This is known as palliative radiation therapy, which can help to reduce tumor size and the pain caused by tumors. Quality of life may also be improved by radiation therapy for someone who is in advance stage of cancer. For example, cancer that has spread from its original site, such as bowel, breast, or prostate cancer and has developed to a bone cancer. In this case, the cancer will not be cured by the radiation treatment, but it can help to stop the formation of further painful bone cancers and reduce pain by strengthening weakened bone.
Radiation therapy is not always suitable for palliative use. When it is considered to be used, it is often accompanied by other forms of cancer treatment and palliative care.
Other examples of palliative radiation therapy include:
Radiation therapy and chemotherapy are different cancer treatments. However, they might be used together depending on the requirement of treatment.
Chemotherapy involves the infusion of cancer-killing substances into the blood using a drip or prescribed medications, where as Radiation therapy targets a specific area or tumor.
Chemotherapy can be given before a radiation therapy to help reduce the size of a tumor, making the targeted radiation therapy treatment more effective.
It can also be applied after radiation therapy to help prevent the return of tumors that have been removed. Chemotherapy achieves this by killing cancer cells that have split from the original tumor.
When both radiation therapy and chemotherapy are prescribed at the same time by an oncologist, it is known as chemoradiation. This can increase the impact of radiation therapy on cancer. However, the side effects can be severe when receiving chemoradiation.
Radiation is not effective against cancers that have spread to other parts of the body. However, it is more powerful and can have a greater effect when shrinking tumors.