Intensity-modulated radiation therapy, known as IMRT, is an advanced type of radiation therapy, which is used for treating cancer as well as noncancerous tumors. This procedure uses advanced technology in order to manipulate photon and proton beams of radiation to conform to the shape of a tumor. The goal of the procedure is to conform the radiation dose to the target while avoiding or reducing exposure of healthy tissue to limit the side effects of treatment.
The procedure is used mostly to treat prostate cancer, head and neck cancers, gastrointestinal and gynecologic cancers, brain tumors and lung cancers, among others.
Doctors generally consider this procedure when a tumor partially surrounds or is close to a healthy part of your body that cannot tolerate the full dose of radiation being given to the tumor. When the tumor is not near any sensitive area, IMRT might not be required. You can talk in detail with the radiation team regarding which type of treatment is best for you.
Before the treatment, doctors need to conduct a physical examination and medical history. After this is done, there is a treatment simulation session, which might include a CT scan. A small mark or a tattoo might be placed on the skin of the patient, as this can help to align and target the equipment. This radiation oncologist can use this scan to make an individual plan for the patient.
Sometimes it might be important to follow a certain bowel and bladder preparation regimen, or too fast, before the simulation and treatment. The patient might be injected with intravenous contrast material, during the CT scan, as it can help to define the tumor better.
Sometimes additional scanning procedures, which include magnetic resonance imaging (MRI), or positron emission tomography (PET) might also be required for IMRT planning. These diagnostic images can be merged with the planning CT, to help the radiation oncologist determine the exact location of the tumor target.
Sometimes it is also necessary to insert radiodense markers into the target for more accurate positioning. In general, IMRT sessions usually begin around a week or two after the simulation.
The team involved in this procedure generally includes the medical oncologist, medical physicist, radiation therapist, dosimetrist, and radiation therapy nurse.
Generally, IMRT often requires multiple treatment sessions on different days. The radiation oncologist will consider the type, location and size of the tumor, doses to normal structures, as well as the health of the patient, to decide the number of treatment. Generally, patients are scheduled for IMRT sessions five days a week for about a month or two.
At the beginning of each session, first, the radiation therapist will position the patient on the treatment table, guided by the marks on the skin, i.e. tattoos that help identify the treatment area. If there were molding devices made, then they will be used to help the patient maintain a proper position. The patient might be repositioned during the procedure as well. Imaging systems on the treatment machine such as X-ray or CT might be used for checking positioning and marker location.
After the patient is positioned, the radiation will be turned on for a brief time. For each position of the machine, the radiation is on for only a minute or two. During the entire procedure, the machine rotates over you, while you lie as still as you can, breathe normally and relax.
The treatment generally should not take more than 30 minutes.
After the procedure
Risks and complications
Though IMRT has many advantages, it might not always be the best option for patients. Sometimes there are side effects of radiation treatment which may include problems that might occur as a result of the treatment itself as well as from radiation damage to any healthy cells in the treatment area.
The severity of the side effects that you experience can generally depend on the type of radiation and dosage that was prescribed and the part of the body which was being treated. Let your doctor and healthcare team know if you experience any side effects so that they can help you to manage them.
Side effects might be early or in some cases, late. Early side effects generally occur during or immediately after the treatment and should typically go in just a few weeks.
Some of the early side effects of radiation therapy can include tiredness or fatigue as well as skin problems. Skin in the treatment area can sometimes become more sensitive, red, irritated, or even swollen. Other skin changes generally include itching, dryness, peeling, and blistering.
Some of the early side effects may include the following:
- Mouth problems and difficulty swallowing
- Hair loss in the treatment area
- Soreness and swelling in the treatment area
- Eating and digestion problems
- Nausea and vomiting
- Urinary and bladder changes
Rarely, late side effects generally occur months or years after the treatment and are generally permanent. They may include:
- brain changes
- spinal cord changes
- colon and rectal changes
- joint changes
- lung changes
- kidney changes
- secondary cancer
- mouth changes
There is also a slight risk of cancer from radiation therapy. Therefore it is important that you are assessed regularly by the radiation oncologist for complications.