UW Veterinary Care Cancer Patients To Benefit From New, More Precise Radiation Therapy Delivery System

Radixact radiation therapy treatment delivery system
The Radixact radiation therapy treatment delivery system. Photo: Ron Collins/Accuray

Beginning this week (Oct. 12), oncology patients undergoing radiation therapy at UW Veterinary Care will receive treatments through a cutting-edge system that provides several advantages for companion animals and their care providers.

“With this technology, we can now treat tumors and spare healthy tissue with more confidence and more accuracy, in addition to targeting tumors in areas of the body that we couldn’t previously,” says Professor Lisa Forrest, head of UW Veterinary Care’s Radiation Oncology Service.

Most significantly, the new Radixact system provides real-time motion tracking of tumors and treatment synchronization. For example, during treatment of a lung tumor, as the patient’s lungs expand and contract with each breath, the moving lung tumor will be tracked and the location of the treatment beam will be adjusted in real time. As the tumor moves, treatment moves with it – the delivery beam is continuously synchronized to the tumor’s position. This “adaptive radiotherapy” ensures accurate delivery of the treatment dose to the tumor and better sparing of the surrounding normal tissue.

“In real time the machine will track the tumor’s location, meaning we can now easily and accurately make changes to treatment plans during treatment as tumors or normal structures change size or shape,” Forrest explains.

“With this technology, we can now treat tumors and spare healthy tissue with more confidence and more accuracy, in addition to targeting tumors in areas of the body that we couldn’t previously.”

The live tracking and synchronization with tumors and surrounding normal tissue also opens up new treatment opportunities for cancers in the abdomen and thorax (for example lung, heart, liver and kidney tumors), where the close proximity of vital organs and other sensitive tissues made radiation therapy previously difficult or impossible.

In addition, the technology allows for improved speed and CT imaging detail during treatment planning for each patient, as well as better tumor dose accuracy and delivery. For example, the machine automatically monitors how tumors change in size during treatment or any time the radiation beam reaches surrounding normal tissue, then immediately alerts the clinical team that changes to the treatment plan may be necessary.

“The technology to measure and track these changes was not previously available and we did it ourselves. Now the machine tracks it for us with an even higher level of conformity. How we proceed with the treatment is still our decision, but it’s easier and more accurate,” notes Forrest.

UW Veterinary Care is currently the only veterinary medical hospital globally to offer this treatment. Gifts to the UW School of Veterinary Medicine’s Pets Make a Difference Fund – inspired by the late golden retriever Scout, whose cancer journey and care provided at the UW School of Veterinary Medicine were spotlighted in WeatherTech’s 2020 Super Bowl commercial – helped to make possible this important equipment upgrade.

Funds raised by the Super Bowl commercial are being used to support research at the school to better diagnose, treat and prevent cancer and for the purchase of specialized equipment that will aid clinicians and researchers in identifying new cancer-fighting drugs and treatments — discoveries that are shared with the world.

Successful clinical trials in dogs with nasal tumors at UW Veterinary Care, shepherded by Professor Lisa Forrest, led to widespread use of TomoTherapy in human medicine
Successful clinical trials at UW Veterinary Care, shepherded by Professor Lisa Forrest, pictured, led to widespread use of TomoTherapy in human medicine.

“We’re so thankful to WeatherTech, Scout and all of our Pets Make a Difference Fund donors who are having an immediate impact in the fight against cancer,” says UW Veterinary Care Director Ruthanne Chun. “This generous support will continue to benefit not only patients of our hospital but pets and people battling cancer all across the world as our clinical findings translate to innovations in treatments and technology.”

The Radixact machine builds on the TomoTherapy radiotherapy delivery system – a state-of-the-art radiation machine built into a CT scanner, developed at UW–Madison – that was previously utilized by UW Veterinary Care. Successful clinical trials in pet dogs with nasal tumors at UW Veterinary Care in the early 2000s, shepherded by Professor Forrest, led to the widespread use of TomoTherapy in human medicine. More than 500 TomoTherapy units are now installed in human hospitals worldwide.

Oncologists at the UW School of Veterinary Medicine are world-renowned for advancing clinical treatments for dogs and cats with cancer. The school is also a leader in comparative oncology research, where companion dogs and cats are included in clinical trials to investigate new cancer therapies with the goal of informing clinical treatments in both animal and human patients. Past clinical studies at the School of Veterinary Medicine have yielded new technologies and treatments with better effectiveness and less toxicity.

Dogs and people not only share similar cancer rates, but naturally occurring tumors in dogs often share almost identical characteristics to human cancers in terms of recurrence and spread, response to treatment, and more. The school is one of three institutions participating in a five-year clinical trial to test a vaccine for the prevention of many types of cancer in dogs — a potential paradigm shift in veterinary and human medicine.


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