In 2006, PAMF's Department of Radiation Oncology completed an upgrade of its linear accelerator to include new technology that allows physicians to target tumors more accurately and adjust patients' positioning prior to treatment, thereby improving the precision and effectiveness of cancer treatments.

The department has implemented Varian Medical Systems' On-Board Imager, an automated system that uses high-resolution X-rays to produce contrasting images of cancerous tumors and surrounding soft tissue. Because it is natural for some movement of tumors due to a patient's normal breathing or other movement, it can be challenging to locate the tumor precisely during radiation therapy.

Before the On-Board Imager, which is also known as Image Guided Radiation Therapy (IGRT), physicians would have to treat a larger area of the body near the cancerous tumor to compensate for any tumor movement, as the radiation treatment would not be as effective if the entire tumor was not targeted. However, treating this larger area may have exposed healthy tissue to the radiation. Now, the On-Board Imager allows physicians to target the cancerous tumor more precisely during treatment, thereby ensuring healthy tissues are not exposed to radiation.

The On-Board Imager works with PAMF's existing Intensity-Modulated Radiation Therapy (IMRT) linear accelerator, which is also manufactured by Varian, to obtain the contrasting images. The Palo Alto Clinic's Department of Radiation Oncology serves as a demonstration and evaluation site for Varian's technology, ensuring patients have access to the latest and most sophisticated radiation treatment available.

"The On-Board Imager is a significant advancement in radiotherapy treatments that increases the accuracy of a patient's position during treatment," said Gordon Ray, M.D., head of the Department of Radiation Oncology, adding the technology will also further enhance the effectiveness of fiducial markers, or "gold seeds," during radiotherapy for prostate cancer. Gold seeds are non-radioactive markers that are placed in the prostate during radiation therapy to target the cancer more accurately and effectively while reducing side effects.

"The combination of the On-Board Imager with the gold seeds will allow us to know exactly where the prostate is at any given time and increase the success of treatment while minimizing exposure to nearby tissues," Dr. Ray said.

Beyond prostate cancer, the On-Board imaging system allows physicians to adjust the positioning of patients with central nervous system, head and neck cancers immediately prior to treatment. In the future, physicians will be able to track and adjust for tumor movement during individual treatment sessions rather than beforehand.