Pioneering image-guided radiotherapy at university hospital of Leuven,
7 October 2006
Leuven, Belgium. The university hospital of Leuven in Belgium has
installed a new type of cancer treatment called image-guided radiotherapy
(IGRT) from Varian Medical Systems. The new equipment enables cancer
patients to receive more precise radiotherapy using X-ray imaging during
treatment to locate and focus beams more closely on tumours.
Clinicians at the hospital, UZ Gasthuisberg, are using a new Clinac
medical linear accelerator equipped with an On-Board Imager device to
capture high-quality images of tumours at the time of treatment. The fully
automated device enables medical staff to sharpen their aim on the tumor by
quickly repositioning patients on the treatment couch immediately prior to
The system takes radiographic, fluoroscopic and 3D conebeam CT images to
give clinicians an optimum view of the tumour site and surrounding bones,
organs and soft tissue. Using this information, they can adjust the position
of the patient automatically without having to re-enter the treatment room,
avoiding the need for time-consuming manual adjustments and ensuring the
busy centre can avoid longer treatment times and growing waiting lists for
Dr. Karin Haustermans, professor in radiation oncology, said, "This is a
major benefit because it means these improved imaging techniques can be
introduced without putting too much pressure on the system."
Prior to the advent of IGRT, radiation oncologists had to contend with
variations in patient positioning and with respiratory motion by treating a
relatively large margin of healthy tissue around the tumour. IGRT enables
doctors to minimize the volume of healthy tissue exposed to the treatment
beam. Potentially, image data from IGRT tools like the On-Board Imager
device will be used to note changes in tumour size and shape over a course
of treatment, and make real-time adaptations to the treatment plan.
All prostate cancer patients at the hospital are imaged using the
On-Board Imager device's radiographic mode immediately prior to treatment.
In August, the hospital used the imager for the first time to capture a 3D
conebeam CT image of a 62-year-old rectal cancer patient.
"We were very impressed with the conebeam CT image and online matching
with the original CT image worked perfectly," adds Dr. Haustermans. "As the
patient is male we were also able to check the prostate, which was very
visible despite the lack of markers." Images from the new device are also
incorporated into the hospital's ongoing research programs, including major
studies on image guided radiotherapy and PET imaging for rectal cancer.
Varian's Acuity imager for treatment planning and verification is also
used at the hospital for patient set-up, especially for rectal cancer
patients who lie on a "belly-board" and cannot therefore have conventional
UZ Gasthuisberg treats up to 200 patients per day on four Varian Clinac
linear accelerators, with a fifth machine due to be installed in the near
future. The hospital was one of the earliest in Europe to introduce
intensity modulated radiotherapy (IMRT), a more accurate treatment process
that limits side effects while enabling doses to be increased by
automatically shaping beams to match the shape of the tumor. The hospital is
now using IMRT for prostate, head & neck, oesophagus and rectal cancer
Walter Frei, head of Varian's oncology systems business in Europe, says,
"This leading scientific center is a great example of how these advanced
radiotherapy techniques are being put into practice in a routine clinical
fashion. In addition to improving precision, our systems focus on automation
and fast, comfortable treatment processes, which makes them particularly
suitable for busy centers such as this one."