Radiation Oncology
Image Guided Radiation Therapy
What is Image Guided Radiation Therapy
Radiation oncologists at the Cancer Solutions use image guide radiation therapy or IGRT to better deliver the radiation to the cancerous cells, as tumors can move between treatments due to organ filling or movement differences while breathing. IGRT includes confirmed radiation treatment guided by imaging such as CT, ultrasound or X-ray taken in the treatment room before the patient is given radiation treatment on a daily basis.
How It is Done
All patients undergo a first CT scan as part of the planning process. The info obtained from the CT scan is then transmitted to a computer in the treatment room so that doctors can compare the previous image with the images taken before the treatment. During this process, doctors compare these images to see if treatment needs to be adjusted. This allows doctors to better target cancer while avoiding nearby healthy tissues. In some cases, doctors will implant a small marker near or near the tumor to point it to IGRT. This helps in calculating the motion of the limb / knot, even if the body is stationary through the casting device.
IGRT has been developed to enable the clinician to treat tumors advancing with internal motion. IGRT provides a very effective means of reducing the risk of tumor motion. Real-time image guidance and adaptive radiation therapy include continuous imaging of tumor motion during treatment delivery and replacement of beam delivery on the fly to compensate for unwanted motion. IGRT is best suited for prostate, urinary bladder, lung and gynecological cancer tumors.
How does IGRT Help You
The purpose of image guidance or IGRT is to achieve a very accurate target of the tumor. The use of kilovolt cone beam CT (KV CBCT) allows for 3D identification and matching the target (regularly) to achieve sub-millimeter accuracy. Such precision in delivery allows a reduction in normal tissue margins when planning treatment, resulting in a higher cure rate with lower radiation toxicity.
There are two types of tumor variations; Disruption and intrafraction. Disruption variation can be caused by many factors; Changes in the patient’s condition, deformity of body tissues, relative movement of organs e.g. Intestinal bladder, uterus, etc., changes in the patient’s weight due to nutritional factors, changes in tumor size due to reaction, etc. IGRT eliminates interstitial variability and can also help reduce intrafraction variation.