Radiation oncologists use image guided radiation therapy, or IGRT, to help deliver radiation therapy to the cancer more accuratley each day since tumors can move between treatments due to differences in organ filling or movements while breathing.

IGRT involves conformal radiation treatment guided by imaging, such as CT, ultrasound or X-rays, taken on the treatment table just before the patient is given the radiation treatment. All patients first undergo a CT scan as part of the planning process. The imaging information from the CT scan is then transmitted to a computer in the treatment room to allow doctors to compare the earlier image with the images taken just before treatment. During IGRT, doctors compare these images to see if the treatment needs to be adjusted. This allows doctors to better target the cancer while avoiding nearby healthy tissue.

IGRT has an important role in the treatment of prosate cancer since the prostate can move on a daily basis depending on the shape of the bladder and rectum at the time of treatment. Three tiny metallic fiducial markers can be implanted into the prostate prior to radiation planning and treatment. These markers can then be imaged on a daily basis prior to treatment, and the patient's body position can be modified as needed. Alternatively, our linear accelerators are equipped with cone-beam CT technology that enables a CT scan to be taken to verify prostate positioning prior to radiation delivery.