Image-Guided Radiation Therapy (IGRT)

Image-Guided Radiation Therapy (IGRT) is an advanced radiation treatment that combines imaging and treatment capabilities on a single machine. Tumors can move, so IGRT allows a radiation oncologist and the radiation therapists to see and track the tumor at the time of treatment. This enables very fine adjustments to the patient’s position, greatly increasing the precision and accuracy of radiation therapy. Knowing exactly where the tumor is allows clinicians to target only the tumor, sparing the surrounding normal tissue. This accuracy results in higher radiation doses to the tumor, increasing the likelihood of controlling or eliminating the cancer.

Intensity Modulated Radiation Therapy (IMRT)

Intensity Modulated Radiation Therapy (IMRT) is an advanced form of radiation treatment that allows radiation oncologists and the radiation cancer care team to precisely target tumor cells. This noninvasive therapy uses Computed Tomography (CT) or other imaging modalities to create three-dimensional diagnostic images and map treatment plans. IMRT delivers tightly focused radiation beams of varying intensity to cancerous tumors without the use of needles, tubes, or catheters. Varying the intensity of these beams enhances IMRTs ability to maximize the dosage to the tumor while minimizing the amount of radiation affecting surrounding healthy tissue.

What is IMRT (Intensity Modulated Radiation Therapy)?

Intensity Modulated Radiation Therapy (IMRT) is an advanced form of 3D conformal radiation treatment that involves varying (modulating) the intensity of the radiation beams used to treat cancer. This technology enables the oncologists, dosimetrists, and physicists to shape the radiation beams precisely to the tumor and control their intensity throughout the treatment area. This means the radiation dose can be higher in the most aggressive parts of the tumor and lower in areas near healthy tissues and structures.

Conventional Radiation Therapy targets a uniform shape over the entire area to cover the tumor, often irradiating some healthy tissue and providing an even dose across the entire target area

Why is IMRT Used?

• Better Tumor Control: IMRT delivers higher doses directly to the tumor while sparing surrounding healthy tissue.
• Less Damage to Healthy Tissues: By minimizing exposure to healthy tissues and structures, IMRT results in fewer side effects.
• Improved Quality of Life: Patients experience more manageable side effects and better overall outcomes.
• Expanded Treatment Options: IMRT allows for the treatment of tumors located near vital organs and structures that were previously considered untreatable.

IMRT is commonly used to treat tumors in areas such as the prostate, spine, lung, breast, kidney, pancreas, liver, larynx, sinus, head and neck, and brain.

How is IMRT Planned and Delivered?

IMRT begins with an intensive, computerized treatment planning process coordinated by a team of radiation oncology experts, radiation oncologist, dosimetrists, and physics. The process includes:

• Tumor Mapping: A radiation oncologist uses 3D scanning images to outline the tumor’s shape, size, and location.
• Treatment Planning: A dosimetrist creates a personalized treatment plan using specialized software, optimizing it based on the physician’s dose instructions and diagnostic images and is checked and monitored during treatment by a physicist.
• Patient Immobilization: Customized devices ensure consistent patient positioning during each treatment session.
• Beam Shaping: A linear accelerator generates high-energy radiation, and a multi-leaf collimator shapes and modulates the radiation beams according to the treatment plan.
• CT Simulation: The initial step involves a consultation, a CT scan while positioned for treatment, and skin markings for precise targeting. Verification imaging is done prior to the first treatment to ensure accuracy.