Image Guided Radiation Therapy (IGRT)
The Department of Radiation at St. Joseph Hospital uses kilovoltage (KV)
radiographs, megavoltage (MV) radiographs and cone beam computed tomography
(CBCT) for our image guided radiation therapy procedures. IGRT corrects
for variability in daily patient position as well as tumor motion/location
by using daily imaging to localize the treatment area. All three of our
linear accelerators are equipped with special imaging technology that
allow for precise tumor localization. These IGRT images are taken prior
to each daily treatment to localize the treatment volume. The images are
then compared to references images taken during the CT simulation procedure.
With these images the patient’s position and treatment volume are
localized and verified to ensure the proper position has been achieved
before the daily treatment is delivered. The technical capabilities provided
by IGRT enable our clinical expects to dose escalate the treatment volume
while sparing local normal tissues and organs. Dose escalating contributes
to superior clinical outcomes for our patients and sparing the local normal
tissues and organs provides improved quality of life to patients during
treatment and after.
An example on an IGRT prostate treatment is shown below. This patient had
gold markers inserted into the prostate before CT simulation. The image
on the left is from the patient’s CT simulation. Notice the “X”
on the gold markers. The image on the right was taken prior to his daily
treatment to localize the markers and confirm the location of the treatment
volume relative to the planning CT simulation image.
Metal markers are inserted into the prostate and are visible on a CT scan.
This is the planning image used to record the location of markers to ensure
proper location of treatment.
Additional X-rays are taken prior to treatment to verify the position of
the markers relative to the planning image. Verification images ensure
pinpoint treatment accuracy.
These detailed images allow the radiation oncology team to see the exact
location and shape of the tumor once the patient is on the treatment table.
This means that the patient (and, most importantly, the tumor) is in the
exact position necessary and remains in the same position throughout the
The sophisticated technical capabilities provided by IGRT and cone beam
CT enable our clinical experts to deliver high-quality radiation, contributing
to superior clinical outcomes and improved quality of life for patients.