Varian news October 2019
Tracking Tumors with Calypso at The University Of Kansas Cancer Center: “Like Working In The Light”
When the University of Kansas Cancer Center (KUCC) acquired a linear accelerator in 2013, Habeeb Saleh, Ph.D., DABR, the center’s chief of medical physics, requested that the purchase include Calypso™ technology for soft tissue stereotactic body radiotherapy (SBRT). His colleague, Zachary Collins, M.D., also advocated for Calypso based on its growing word-of-mouth reputation and reported advantages for tumor tracking.
“Up to that point, we’d been using gold or braided wire, simple fiducial markers,” said Dr. Collins, KUCC’s director of interventional radiology. "We were looking to really push the envelope with a real-time system like Calypso. Broadly speaking, the huge benefit of Calypso is the ability to perform 3D tracking in the region of interest, thereby minimizing collateral damage, side effects, and symptoms. Our previous technology simply couldn’t do that. I think that long-term, this will be a game-changer for radiation oncology and interventional radiology in general.”
Previously, Dr. Saleh had often used a respiratory gating system with an infrared reflector block as a surrogate for tumor motion. Calypso tracks actual respiration in real time, an improvement Dr. Saleh likens to “working in the light versus working in the dark.”
“Now we can see the tumor motion in all three dimensions. You can say, ‘I need more tumor margin in the longitudinal direction than I need in the lateral direction.’ It’s absolutely intuitive,” says Dr. Saleh.
As an example, he offers prostate radiosurgery, where precise targeting is essential due to the prostate’s proximity to the rectum. “Calypso lets you minimize the potential for radiation to hit the rectum. So there’s less potential for rectal bleeding and discomfort for the patient.”
In the earliest days of using Calypso, Dr. Collins, as an interventional radiologist, was primarily concerned with the placement of the transponder: Could implantation be easy, accurate and atraumatic? “My first question was, are the needle cannulas stiff and steerable? The answer is yes. Getting the Calypso beacon to the right spot is actually quite straightforward.”
The use of Calypso has also helped deepen interdisciplinary relationships among clinicians at KUCC, in particular between the interventional radiology and the radiation oncology groups. “When we started doing prostate with Calypso, we had radiation oncologists placing the beacons,” said Dr. Saleh. “As a physicist, I was in the same room with them, giving feedback. Then, when we started doing liver and pancreas, I was reaching out to our interventional radiologists as well.”
Says Dr. Collins: “Radiation oncology has always been an independent entity, in some ways almost competitive with us. But Calypso has allowed us to collaborate more than ever before.”
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