PORTLAND, Ore. Oregon Health & Science University researchers have determined exactly how much breathing affects prostate movement during radiation treatment.
The results of this research are being presented from 5 p.m. to 6:30 p.m. today at the 50th annual American Society for Therapeutic Radiology and Oncology in Boston.
"Many people think that the prostate is a static organ, meaning that it doesn't move in relation to the bony pelvis, but that is not the case. The prostate is a moving organ, and we know it moves because of many factors including how full other organs are, such as the bladder," said Tasha McDonald, M.D., Radiological Society of North America research resident grant recipient, OHSU Department of Radiation Medicine.
Although previous studies have demonstrated that the prostate moves during the breathing cycle, McDonald used the new image-guided Calypso Medical System because it offers "real time" tracking. It works by using tiny beacons, inserted into the prostate, that report the exact location and the motion patterns inside the body over time.
"Our research demonstrates that the prostate moves during the breathing cycle, mostly up and down, as much as 2 millimeters. We were able to determine this motion by evaluating the Calypso tracings of patients," McDonald said. The Calypso results were also verified by other radiation technology.
"This is important information because in low-risk prostate patients, we treat the prostate (and seminal vesicles) with a small margin, 5 to 7 millimeters to account for prostate motion and set-up error. By knowing all the factors that contribute to prostate motion, we will be able to determine appropriate margins. If the margins are too large, there can be more normal tissue toxicity and if too small we could miss the prostate," McDonald said.
Greater accuracy allows the delivery of higher-dose radiation, leaving healthy cells alone. This process sim
|Contact: Christine Decker|
Oregon Health & Science University