Image-guided radiotherapy (IGRT) represents a significant advancement in cancer treatment, leveraging medical imaging to deliver radiation therapy with exceptional precision and accuracy. This technique is particularly beneficial for treating tumors located in areas of the body prone to movement, such as the lungs. Before each radiation delivery session, IGRT employs imaging tools to meticulously scan the treatment area. These real-time images empower your doctor to precisely adjust your position and target radiation directly at the tumor, minimizing exposure to surrounding healthy tissues.
Certain IGRT procedures incorporate specialized methods to further enhance treatment accuracy. These may include the use of fiducial markers, tiny objects implanted near the tumor, or advanced techniques like 4D gating, which synchronizes radiation delivery with tumor motion during breathing. Furthermore, specialized devices might be used to ensure you maintain the exact same position throughout each treatment session, contributing to consistent and effective therapy.
Prior to commencing IGRT treatment, you will undergo a simulation session. This crucial step involves CT scanning to generate reference images that serve as a baseline for subsequent treatments. MRI or PET scans might also be utilized to precisely define the tumor’s shape and location. Your healthcare provider will provide detailed instructions on how to prepare for these initial procedures.
Delving Deeper into Image-Guided Radiation Therapy
Image-Guided Radiation Therapy (IGRT) is a sophisticated method of cancer treatment that utilizes medical imaging to enhance the precision and accuracy of radiation delivery.
IGRT systems are typically integrated with a linear accelerator or cyclotron/synchrotron, machines that generate and deliver radiation therapy. These advanced machines are often equipped with imaging technology capable of scanning the tumor immediately before or even during treatment administration. Your radiation oncologist and radiation therapists will meticulously compare these real-time scans with the reference images obtained during the initial simulation. This comparative analysis allows for precise adjustments to your body position and the radiation beams themselves. By making these subtle but crucial corrections, the treatment team can ensure that radiation is delivered directly to the tumor target, while significantly minimizing exposure and potential damage to adjacent healthy tissues.
IGRT systems can employ a range of imaging modalities to visualize the tumor, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), or X-ray imaging. In some cases, fiducial markers, or electromagnetic transponders, may be placed in or near the tumor. These markers act as reference points, enabling the treatment team to accurately pinpoint the target area and precisely position the radiation equipment for optimal treatment delivery. For more in-depth information, please refer to resources on Fiducial Marker Placement.
IGRT is particularly advantageous for treating tumors in locations susceptible to movement, such as those found in the lungs, liver, pancreas, and prostate gland. Techniques like fiducial markers, 4D gating, or adaptive strategies utilizing high soft tissue resolution imaging are employed to account for this motion. IGRT is also highly valuable for treating tumors situated close to critical organs and tissues, where minimizing radiation exposure to healthy structures is paramount. Doctors frequently combine IGRT with other advanced radiation therapy techniques, such as intensity-modulated radiation therapy (IMRT), proton beam therapy, and stereotactic radiosurgery or stereotactic body radiotherapy (SBRT). These cutting-edge radiotherapy modalities utilize computer control of X-ray accelerators to deliver highly focused and precisely dosed radiation to the tumor or specific sub-regions within it.
The Multidisciplinary Team Behind Your IGRT Procedure
Radiation therapy is a complex treatment that necessitates a dedicated and specialized treatment team. This team typically comprises a radiation oncologist, a therapeutic medical physicist, a dosimetrist, and radiation therapists. The radiation oncologist holds the responsibility for determining the most appropriate radiation therapies, specifying the treatment area(s), and calculating the optimal therapeutic radiation dose. Radiation therapists play a vital role in obtaining images before and during treatment and administering the daily radiation sessions. A radiation oncology nurse is an integral part of the team, providing patients with comprehensive information about the treatment process and potential side effects. The nurse also plays a crucial role in managing any treatment-related reactions or side effects, working under the supervision and guidance of the radiation oncologists.
Equipment Utilized in IGRT
IGRT procedures rely on radiation delivery machines that are integrated with sophisticated imaging equipment. In some systems, the imaging equipment is built directly into the radiation delivery machine, while in others, it is mounted on the machine or positioned within the treatment room. IGRT systems may also incorporate detectors designed to track movement by identifying external markers placed on your body or internal electromagnetic transponders.
Roles and Responsibilities in Operating IGRT Equipment
The radiation oncologist is responsible for creating and meticulously overseeing your individualized treatment plan. The actual operation of the IGRT equipment during treatment sessions is performed by trained radiation therapists.
Special Preparation for IGRT
It is crucial for women to inform their doctor and technologist if they are pregnant or breastfeeding prior to undergoing radiation treatment. For further information on radiation safety during pregnancy and breastfeeding, please consult resources on Radiation Safety. Patients who have loose metal within their bodies should notify the treatment team, particularly if MRI is part of the IGRT plan. Similarly, patients with pacemakers need to inform the treatment team if MRI or radiation treatment is planned.
If fiducial markers are required for your treatment, your doctor will implant them at least one to two weeks before your CT simulation session. Your doctor or a radiation therapist may also use colored ink to mark or tattoo your skin. These markings serve as visual guides to ensure accurate alignment and targeting of the radiation equipment during each treatment session. Your doctor will provide specific instructions regarding fasting or bladder fullness prior to treatment, if necessary.
Generally, there is no specific preparation solely for IGRT itself, beyond the preparation required for the particular type of radiation therapy you will be receiving. Please refer to specific resources for detailed preparation instructions related to IMRT, Proton Beam Therapy, or SBRT.
The IGRT Procedure: What to Expect
At the commencement of each treatment session, radiation therapists will carefully position you on the treatment couch. They may utilize specialized devices to help you maintain the necessary, consistent position throughout the session. In some instances, you may be asked to hold your breath for brief periods, typically 30 to 60 seconds, while the technologist acquires a series of images.
On each treatment day, the first step is imaging. The treatment team then meticulously reviews and compares these newly acquired images with the reference images from your initial simulation. Based on this comparison, the therapists may make fine adjustments to your position and acquire additional images to ensure optimal alignment. Once the therapists have finalized all necessary adjustments, the radiation treatment is delivered.
It is important to note that the image-guidance process inherent to IGRT will add some additional time to each treatment session compared to traditional radiation therapy.
What to Anticipate During and After IGRT Treatment
The medical imaging component of IGRT, whether performed before or during treatment, is a painless procedure.
During the radiation delivery itself, you might observe or hear the movement of the equipment. You may also detect a distinctive odor, as the linear accelerator can produce ozone. Some patients, particularly those undergoing treatment for brain cancer, may even perceive colored lights during treatment. These are all normal occurrences associated with the operation of the radiation equipment.
Radiation treatment can induce side effects, which can arise either directly from the treatment itself or as a consequence of radiation damage to healthy cells within the treatment area.
The specific side effects experienced, as well as their severity, will vary depending on factors such as the type of radiation used, the total radiation dose, and the specific body part being treated. It is crucial to have open communication with your doctor and/or nurse, who can provide guidance and support in managing any side effects that may arise.
Radiation side effects are broadly categorized as early and late side effects. Early side effects typically manifest during or shortly after treatment and generally resolve within a few weeks. Common early side effects include fatigue and skin reactions. The skin in the treated area may become more sensitive, red, irritated, or swollen, and you might experience dryness, itching, peeling, or blistering.
Depending on the specific area undergoing treatment, other early side effects can include:
- Hair loss in the treatment area
- Mouth problems and difficulty swallowing
- Eating and digestive issues
- Diarrhea
- Nausea and vomiting
- Headaches
- Soreness and swelling in the treatment area
- Urinary and bladder changes
Late side effects, while less common, can emerge months or even years after treatment completion. Although often permanent, they are relatively rare. Potential late side effects include:
- Brain changes
- Spinal cord changes
- Lung changes
- Kidney changes
- Colon and rectal changes
- Infertility
- Joint changes
- Lymphedema
- Mouth changes
- Secondary cancer
There is a slightly elevated risk of developing cancer as a late effect of radiation therapy. Following treatment, your radiation oncologist will schedule regular follow-up appointments to monitor for any complications, recurrence of the original cancer, or the development of new cancers.
IGRT represents a significant advancement in radiation therapy, empowering doctors to maximize the cancer-destroying potential of radiation while simultaneously minimizing its impact on healthy tissues and reducing the incidence and severity of treatment-related side effects.
This page was last reviewed on October 14, 2024.
