CHRISTCHURCH, New Zealand, -- Cancer patients on New Zealand's South Island now have access to state-of-the-art radiation therapy treatment after the installation of a new linear accelerator from Varian Medical Systems. Christchurch Hospital has begun treating clinically using Varian's On-Board Imager^TM and is now able to offer image-guided radiation therapy (IGRT) that optimizes accuracy and enables clinicians to potentially improve outcomes for patients.

All patients treated on the clinic's new Varian Clinac© 2100iX medical linear accelerator are now imaged with the On-Board Imager device to check and adjust positioning prior to treatment delivery. The state-of-the-art imager enables clinicians to see and target tumors more precisely during treatment sessions.

"The images give us the confidence to increase doses, particularly for our prostate cancer patients, which has been shown through clinical trials to be beneficial for the patient," says Viv Ali, the hospital's radiation therapy clinical manager.

Christchurch Hospital, a public clinic in the Canterbury Health District, has one of only two radiotherapy departments on the South Island and one of only six such departments in New Zealand. The hospital services a population of about 500,000 people, covering approximately two-thirds of the South Island.

"We don't get many opportunities to replace equipment and we decided we wanted something that would make us stand out and was in the forefront of modern radiotherapy technology," says Viv Ali. "We felt that image-guided radiation therapy (IGRT) and respiratory gating were what we wanted to offer our patients." The hospital utilizes Varian's RPM Respiratory Gating system in conjunction with a GE CT Scanner to monitor and adjust for tumor motion caused by breathing.

Varian's On-Board Imager for IGRT makes it possible for clinicians to image and treat patients on a single machine that rotates around the patient to take X-ray images and deliver treatments from virtually any angle. Mounted on the linear accelerator, the On-Board Imager device produces high- resolution images of the tumor and tracks changes in tumor shape, size or position due to shrinkage or shifting over a multi-week course of treatment, and due to respiration.

IGRT can improve the quality of all forms of radiotherapy, including conventional, 3-D conformal, intensity-modulated, and stereotactic radiotherapies. "Techniques like intensity modulated radiation therapy (IMRT) have enabled clinicians to shape the radiation beam so it conforms to the tumor being treated. IGRT makes it easier to know exactly where to aim the beams," says Tim Guertin, president and chief operating officer at Varian Medical Systems.

Prior to the advent of IGRT, radiation oncologists had to contend with variations in patient positioning and with respiratory motion by treating a larger margin of healthy tissue around the tumor. IGRT enables doctors to further 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 tumor size and shape over a course of treatment, and make real-time adaptations to the treatment plan.

The clinic's new treatment machine is also equipped with a beam-shaping 120-leaf multileaf collimator for intensity modulated radiation therapy (IMRT) as well as a PortalVision^TM device for monitoring and verifying treatment accuracy.

According to Viv Ali, the new equipment has boosted staff morale within Christchurch Hospital's radiation oncology service. "The morale is great in the department right now," she says. "We're fully staffed with radiation therapists, physicists and oncologists and we're now in a position to develop more advanced treatments utilizing our new technology, such as intensity modulated radiation therapy and respiratory gated treatments."

She said she and her colleagues recently hosted a multidisciplinary workshop which allowed their fellow radiation therapists, radiation oncologists and physicists in New Zealand to see the On-Board Imager device in operation.