A type of cancer treatment in which beams of intense energy are used to kill cancer cells is known as radiation therapy or radiotherapy. Radiation therapy usually uses x-rays or protons to kill the cancer cells. However, other types of energies may also be used.
Purpose:
Radiation therapy can be used for treating cancer and some types of non-cancerous or benign tumors. The different reasons for which radiation therapy can be used include:
Types:
The different types of radiation therapies are:
1. External beam radiation therapy: This is the most common type of radiation therapy in which high-energy beams of radiation are directed at the tumor.
The machine’s position can be changed so that it can aim at the beams at different angles. It is usually given five days a week for approximately one to eight weeks, depending on the type of cancer. Occasionally, a single treatment could be recommended.
The different types of external beam radiation therapies include:
a) 3D conformal radiation therapy: Computed tomography (CT) scans and special computer software help in creating a three-dimensional computer model of the treatment area. Treatment is precisely targeted to the tumor, not affecting the surrounding normal tissue.
Intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT): IMRT provides precise radiation therapy. The multi-beam system varies in dose intensity and narrows in on the diseased cells. VMAT performs this procedure over an arc, which is quicker.
b) Image guided radiotherapy (IGRT): Three-dimensional imaging may be done before treatment to help in the better precision of the target. This can be done by using imaging tests like CT scans, x-rays, and ultrasounds.
c) Stereotactic radiosurgery or gamma knife radiosurgery: This type of treatment involves focuses on providing high doses of intense radiation to the targets outside the head region.
Intraoperative radiation therapy (IORT): It helps radiation delivery at the time of the surgery, avoiding the need for external radiation later on. The radiation is more focused on areas having some tumors left behind.
2) Internal radiation therapy or brachytherapy: It involves the implantation of a radioactive source or seed in or around the tumor. This source emits a high radiation dose to a small area to kill cancer cells.
The different types of internal radiation therapies are:
Permanent implants: They are small steel seeds containing radioactive material. Most of the radiation therapy is provided around the area of the implant. Although, some radiation may exit the body of the patient. The implants lose their radioactivity over time and the inactive seeds stay in the body.
Temporary internal radiation therapy: It can be given by a needle, through a tube known as a catheter, using special applicators.
Radiopharmaceuticals: Radioisotope is bound to a carrier in this type of radiation therapy.
The type of radiation therapy performed for a particular patient depends on several factors, like:
Types of cancers treated
External beam radiation therapy may be used to treat the following types of cancer:
Lung cancer
Breast cancer
Colon cancer
Prostate cancer
Cancers of the neck or head
Brachytherapy may be recommended as a treatment option for cancers that occur in the following body parts:
Vagina
Cervix
Uterus
Rectum
Eye
Head and neck
Brachytherapy may also be recommended for cancers of the following body parts:
Brain
Lung
Skin
Breast
Prostate
Anus
Bladder
Esophagus
The following diagnostic tests may be performed before radiation therapy:
The radiation therapist takes an x-ray, known as a port film, on the first day of treatment.
The port films are normally taken every week to verify that you have been positioned accurately during each treatment.
CT scans are taken throughout the procedure. Sometimes, ultrasounds or x-rays may be used instead of CT scans.
The procedure can be carried out in the following ways:
1. External beam radiation therapy:
A machine known as a linear accelerator directs the high-energy beams of radiation into the body.
The linear accelerator moves around you to provide radiation from several angles as you lie on the table.
This linear accelerator makes a buzzing sound and can be adjusted to deliver the precise dose of radiation that the doctor recommends.
This procedure is usually performed on an outpatient basis (the patient goes home on the same day after treatment), five times a week.
Each treatment session lasts for about ten to thirty minutes.
Sometimes, a single treatment may be performed to relieve the symptoms associated with advanced types of cancers.
The session is usually not painful and the doctors are usually in an adjacent room monitoring the session.
2. Internal radiation therapy:
This procedure is performed when the radiation source is placed inside the body.
This source is taken in the form of seeds, capsules, or through an intravenous (injected into the vein) line in case of a liquid which helps in the detection of the cancer cells and killing them.
The side effects of radiation therapy depend on which part of the body is getting exposed to radiation and how much radiation is being used. The common side effects of radiation therapy include:
The common side effects of radiation therapy depending on the part of the body being treated include:
Head and neck:
Chest:
Pelvis:
MBBS, M.D. (Radiotherapy) - Radiation Oncologist