Intensity-modulated radiation therapy (IMRT)

Overview 

Intensity-modulated radiation therapy (IMRT) is a specialized form of external beam radiation therapy used to treat cancer and certain benign tumors. During treatment, a machine called a linear accelerator (LINAC) directs high-energy X-ray beams precisely at cancer cells. This non-invasive technique ensures that the machine never touches the body, and the radiation beams are carefully targeted to the area affected by cancer. 

IMRT uses advanced technology to adjust the intensity and shape of the radiation beams. This customization allows for the radiation to conform closely to the shape of the tumor, minimizing exposure to surrounding healthy tissues. By modulating the beam intensity and using dynamic angles, IMRT can deliver a tailored dose to the target while reducing the impact on nearby organs and structures.

This precision-focused approach makes IMRT an effective treatment for tumors throughout the body. By limiting radiation exposure outside the tumor area, IMRT not only enhances treatment effectiveness but also lowers the risk of adverse effects on healthy tissue, helping patients achieve better outcomes with fewer side effects. 

Reasons for undergoing the procedure 

Intensity-modulated radiation therapy (IMRT) is a type of external beam radiation that targets and destroys cancer cells, reducing tumors while minimizing harm to nearby healthy tissue. By directing high-energy beams with precision, IMRT is especially valuable for treating tumors located near sensitive structures like the spinal cord, brainstem, and optic nerves, where careful targeting helps protect these areas. This technique can be used for both cancerous and non-cancerous growths, focusing radiation precisely to limit exposure to surrounding tissues, making it an effective option for complex, sensitive cases.

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 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 computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (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.