New technology allows faster delivery of radiation to the prostate
Posted Sep 28 2008 1:49pm
A new form of radiation delivery, known as RapidArc™ image-guided, intensity-modulated radiation therapy (IMRT), appears to be the “hot” new method for delivering radiation therapy to prostate cancer patients. The technology was introduced last year at the annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO) in Los Angeles. However, it only became commercially available in recent months.
The critical advantage of this technology is a major reduction in the time it takes to deliver radiation to the patient. According to Dow Wilson, president of Varian’s Oncology Systems business, “IMRT treatments that typically require at least 10 minutes can be completed in less than two. More importantly, our dose distribution studies show that RapidArc can enable more conformal delivery of the treatment beam, allowing more concentrated doses on tumors while protecting more of the surrounding healthy tissues. This is a tremendous benefit for patients and doctors alike.”
By reducing the time it takes to deliver IMRT and other highly-precise forms of radiation therapy, RapidArc may have the ability to improve quality of care and patient comfort, while making radiation oncology a more affordable treatment for prostate and other forms of cancer.
Two prostate cancer patients were the first people in New York state to receive radiotherapy using the RapidArc system. The two patients are a 65-year-old banker with early stage prostate cancer and a 77-year-old retired attorney with locally advanced prostate cancer.
“Our radiation treatment facilities are committed to being on the cutting edge of technology,” Shawn Zimberg, MD, the medical director for Radiation Oncology Associates of New York is quoted as saying. “RapidArc enables us to quickly deliver IMRT treatments that are designed to target tumors and malignancies very precisely while dramatically reducing the exposure of surrounding tissues.”
“The faster these sophisticated treatments are delivered, the more accuracy we can expect, because the patient is less likely to move during a shorter timeframe,” Zimberg explained. “Studies have shown that the prostate position can shift by up to several millimeters during a long treatment session as neighboring organs such as the bladder constantly change their volume. By completing each treatment more quickly, we make it less likely that tumor or organ motion will affect the accuracy of our treatments. I expect the speed and precision of RapidArc treatments will benefit a great many patients.”
Once the patient has been positioned properly, the RapidArc treatment delivers the prescribed dose in less than two minutes, with a single rotation of the treatment machine around the patient. Earlier forms of image-guided IMRT using fixed beams or helical tomotherapy typically require 10-15 minutes or more to complete. Most patients undergo a regimen of daily treatments Monday through Friday for 6-8 weeks, depending on the type of cancer.
John Keane, medical physicist at the Radiation Oncology Associates facility in Lake Success, said: “One of the reasons I find my work so compelling is that I have the opportunity to implement cutting edge technology to help people fight cancer. With RapidArc, I am witnessing a great advancement in medical technology that is further enhancing patient care in the practice.”
Allowing for the inevitable sense of excitment that comes with any major new piece of medical technology, it should be said that the ability to significantly reduce the time to deliver apporopriate doses of radiotherapy to the prostate certainly should impact risk for side effects of radiotherapy, as well as add to patient convenience. Whether such technology has any impact on effectiveness of radiotherapy as a treatment for localized or locally advanced prostate cancer is harder to determine.
According to Varian Oncology, “RapidArc technology utilizes a sophisticated algorithm that makes it possible to program a … linear accelerator to deliver a complete intensity-modulated radiation treatment in a single revolution. By varying three parameters simultaneously — the speed of rotation, the beam shaping aperture, and the dose delivery rate — doctors can create finely-shaped IMRT dose distributions that more closely match the size and shape of the tumor while sparing healthy tissues.”