IMRT or intensity modulated radiation therapy involves varying (or modulating) the intensity of the radiation (in this case, X-rays), being used as therapy for cancer. It is a new form of radiation therapy that uses computer-generated images to plan and then deliver more tightly focused radiation beams to cancerous tumors than is possible with conventional radiotherapy. With this capability, clinicians can deliver a precise radiation dose that conforms to the shape of the tumor, while significantly reducing the amount of radiation to surrounding healthy tissues. Consequently, the technique can increase the rate of tumor control while significantly reducing adverse side effects.
Currently, photons (X-rays) are used to deliver IMRT. The radiation is generated by a machine called a medical linear accelerator. This machine stands approximately nine feet tall, is nearly 15 feet long and can be rotated around the patient with great precision. Operationally, microwave energy, similar to that used in satellite television transmission, is used to accelerate electrons to nearly the speed of light. As they reach maximum speed they collide with a tungsten target, which in turn releases photons, or X-rays. Very small beams with varying intensities can be aimed at a tumor from various angles to attack the target in a complete three-dimensional manner. The idea is to deliver the lowest dose possible to the surrounding tissue, reducing the chance of causing a radiation side effect, while still delivering the maximum dose to the tumor.
Dynamic Targeting IGRT (image-guided radiotherapy) involves using a variety of digital imaging techniques to pinpoint the exact location of a targeted tumor while the patient is in the treatment position, just prior to each daily treatment. It is the most advanced—and most precise—form of radiation therapy currently available. This precision is very important because tumors are not stationary. They can shift and move slightly between treatments, and even during treatments due to normal physiological processes, such as breathing. IGRT uses advanced imaging techniques to verify the patient’s exact position and the tumor’s precise location at the moment of treatment. Dynamic Targeting IGRT is a radiotherapy treatment approach that utilizes multiple imaging and motion management techniques for ultra-accurate tumor targeting.
Because it enhances radiotherapy treatment precision, IGRT allows physicians to escalate the radiation dose to cancer cells while keeping the dose to surrounding tissues as low as possible. This increases the chances of eradicating the tumor and minimizing treatment side effects.