The prostate is located between the bladder and the rectum and depending on whether the bladder or rectum is full, the prostate can move not only from day to day but also during traditional radiation treatment.
“It can be quite substantial and could account for missing the prostate target and not delivering the prescribed dose of radiation which could result in a failure of the treatment,” says Hiram Gay, MD, radiation oncologist at Siteman Cancer Center.
Using a new technology that gives what some refer to as a “GPS” of the prostate, Dr. Gay and his colleagues can monitor position of the prostate in real time throughout the treatment.
The prostate is practically invisible to the x-rays that we take on a daily basis so we have a surrogate way of finding out where the prostate is by implanting what are called beacons,” says Dr. Gay. “These three transponders serve as a GPS to triangulate where the prostate is located.”
Recently added is a technology called “gating” that allows for the ability to not only monitor the position of the prostate during treatment, but turn on or off the machine if the target moves outside of the safety zone of treating the target.
“Let’s say the patient takes a deep breath, the machine will actually turn off if the prostate moves if it moves outside the radiation zone,” says Dr. Gay. “It’s been shown in multiple studies that even though we think we’re hitting the prostate 100 percent of the time, without these types of technologies we risk underdosing the prostate and in some patients that may make the difference between curing the cancer or not curing the cancer.”
Siteman Cancer Center is the first facility to use the “Calypso System” in combination with “Dynamic Edge Gating” technology.
For more information about prostate cancer, call 800-600-3606 or visit www.siteman.wustl.edu.