Image-guided Radiation Therapy (IGRT) uses imaging of the body before and during the procedure to help guide the radiation with precision and accuracy to the exact area being treated. Radiation oncologists first perform a simulation to use as a baseline so that future images can be compared.
Using image guidance, fiducial markers can be placed in the body to pinpoint where treatment should be delivered. These can be small metal markers (about the size of a grain of rice) easily seen on imaging. Tattoos on the outside of the skin are also used in some cases. IGRT treats cancers in areas prone to movement, such as the lungs, liver, pancreas, and prostate gland.
It is also used when the cancer is located near critical organs and tissues. CT scans, MRIs, ultrasounds, and x-rays can be used in conjunction with IGRT to help visualize soft tissue or bony anatomy.