Intensity-modulated radiation therapy (IMRT)

Overview

Intensity-modulated radiation therapy (IMRT) is an advanced radiation treatment option for cancer that belongs to the external beam radiation therapy category. Using a linear accelerator (LINAC) machine, high-energy X-ray beams are precisely directed at cancer cells. This targeted approach not only aids in destroying cancer cells and reducing tumor size but also minimizes radiation exposure to the surrounding healthy tissues. Notably, the machine never makes direct contact with your body during the treatment.

IMRT utilizes advanced technologies to customize radiation beams with varying intensity. This level of precision allows your healthcare provider, usually a radiation oncologist, to accurately target cancer cells while minimizing radiation to adjacent healthy tissue. IMRT is effective in treating both cancerous tumors and non-cancerous growths, known as benign tumors, in various locations throughout the body.

The primary goal of IMRT is to reduce radiation exposure to nearby healthy tissues while delivering the appropriate dose to the targeted area. This technique significantly lowers the risk of damaging surrounding healthy tissue. (1,2)

Reasons for undergoing the procedure

Intensity-modulated radiation treatment (IMRT) minimizes damage to surrounding healthy tissue by focusing high-energy beams on tumors, successfully eliminating cancer cells and shrinking tumor size. The fact that tumors are often located in close proximity to healthy cells makes this accuracy important.

Compared to certain other radiation treatments, IMRT may allow for a more targeted killing of cells inside a treatment area. IMRT is very useful for treating cancers in delicate areas where radiation exposure may affect delicate organs because of its accuracy. For instance, IMRT can effectively treat tumors while safeguarding surrounding tissues such as the spinal cord, brainstem, and optic nerves.

IMRT are utilized to treat the following:

• Breast cancer.
• Cervical cancer.
• Colon cancer.
• Lung cancer.
• Prostate cancer.
• Stomach cancer.
• Uterine cancer.
• Other cancer types.

Risk

Although IMRT poses a lower risk of harming healthy cells compared to other treatment options, it can still result in side effects. Furthermore, due to its complexity, IMRT may necessitate a longer planning period than other forms of external beam radiation therapy, even though the actual administration of the treatment is relatively quick.

Procedure

Intensity-modulated radiation therapy (IMRT) utilizes personalized energy beams that are specifically directed at the tumor, guided by imaging studies. Prior to treatment, you will undergo imaging tests such as CT, MRI, or PET scans to obtain detailed images of the tumor, revealing its exact location, size, and shape. Your radiation oncologist will use these measurements to design a rotating arc beam that can cover a full 360 degrees, or they may input the images into a specialized computer program for further planning.

By individually adjusting the intensity of each beam, higher radiation doses can be precisely calibrated to target areas of the tumor with a higher concentration of cancer cells. Meanwhile, portions of the tumor that are closer to healthy tissues can receive lower radiation doses to minimize damage to surrounding healthy cells.

Before the procedure

Prior to starting treatment, you will attend a planning session referred to as simulation, or “sim.” This session aims to collect essential data for your radiation oncology team to develop your treatment plan. During the simulation you will:

• Undergo a CT scan to capture detailed images of the tumor. An MRI or PET scan may also be performed.
• Small tattoo dots will be placed on your body to ensure proper alignment with the LINAC machine. These markings are about the size of a freckle and must remain throughout the treatment. In some cases, they may be drawn on instead of tattooed.
• Your radiation oncology team will determine your optimal position during simulation, ensuring the machine can deliver energy beams at the precise angles needed to target the tumor. You may be fitted with special accessories to help maintain this position during treatment, such as a custom mold to keep your body stable.

During the procedure

The IMRT dosing schedule varies based on the type of cancer. Typically, you will undergo treatment in short sessions lasting about 30 minutes, spread out over several days to weeks. Most patients receive IMRT daily, from Monday through Friday, with the entire course of treatment potentially lasting several weeks, depending on the specific cancer being treated.

During the treatment, the patient will:

• Be positioned exactly as they were during the simulation session. The radiation therapist will assist with any molds or devices used to keep the treatment area stable.
• The radiation therapist will then move to a separate room to operate the LINAC machine. They will monitor the patient through a video feed to ensure everything proceeds smoothly. Communication is maintained via a two-way intercom.
• The LINAC machine will adjust its position to deliver multiple energy beams to the targeted areas. It may produce clicking and whirring sounds as it moves, which is normal.

After the procedure

Intensity-modulated radiation therapy (IMRT) is a painless procedure, and patients do not feel any discomfort during the treatment. Once your IMRT session is complete, you are free to leave the facility. Typically administered on an outpatient basis, IMRT allows you to return home on the same day as your treatment.

Outcome

Intensity-modulated radiation therapy (IMRT) employs advanced technology to accurately target and destroy cancer cells while minimizing radiation exposure to surrounding healthy tissue. This protection of healthy tissues helps reduce potential damage, resulting in fewer side effects for patients undergoing treatment.

IMRT is often used for tumors located near vital organs, such as the brain or spinal cord, making it a safer option. Recovery time can vary based on several factors, including the radiation dose, the frequency of treatments, and the specific area of the body receiving radiation. Many individuals who experience side effects typically begin to feel better within a few weeks, while others may take a month or two to recover. Your radiation oncologist will discuss potential side effects and what to expect during your recovery based on your unique situation.

During treatment and recovery, your body may need ample rest. Staying hydrated and consuming a balanced diet can support your recovery process. Depending on the area being treated, your skin may become more sensitive to sunlight. Here are some tips for caring for sensitive skin:

• Wear loose-fitting, comfortable clothing.
• Use personal hygiene products that are free of fragrances and harsh chemicals.
• Avoid applying cold packs or heating pads to areas that have been exposed to radiation.
• To prevent sunburn, dress in lightweight, loose clothing when outdoors, and apply sunscreen to exposed skin.

It’s essential to follow the guidance provided by your radiation oncologist regarding self-care during and after treatment.