Image Guided Radiation
technology has been used to produce three-dimensional scans of the patient's
anatomy to identify the exact location of the cancer tumor prior to treatment.
However, difficulty arises when trying to administer the radiation, since
cancer tumors are constantly moving within the body (for example, from movement
caused by breathing). Hence, the exact location of the tumor may have changed
between the time of scan and actual treatment.
IGRT combines a new form of scanning technology, which allows planar or X-ray
Volume Imaging (XVI), with IMRT. This enables physicians to adjust the
radiation beam based on the position of the target tumor and critical organs,
while the patient is in the treatment position.
Image-guided radiation therapy is conformal radiation treatment guided by
imaging equipment, such as CT, ultrasound or stereoscopic X-rays, taken in the
treatment room just before the patient is given the radiation treatment. IGRT
allows radiation to be delivered to tumors with more precision than was
traditionally possible. One of the challenges encountered when radiation is
delivered to a tumor is that the tumor can move based on the patient's
day-to-day position on the treatment table (as well as from breathing). IGRT
allows the physician to better deliver the radiation dose directly to the
cancer by using a variety of automated and tracking systems. Clinicians obtain
daily high-resolution imagery to pinpoint tumor sites, adjust patient positioning
when necessary, and complete a treatment, all within the standard treatment
time period. By Imaging the tumor daily, we can detect movement in normal
structures or changes in tumor location or size which permits the physician to
precisely locate the tumor while the patient is in the treatment position. This
minimizes the volume of healthy tissue exposed to radiation during treatment,
yet allows the delivery of higher doses of radiation to the tumor volume.