Modern 3D CT is an effective method for locating the prostatic apex for radiation therapy treatment planning in prostate cancer patients because it eliminates the need for an invasive procedure and the related side effects, according to a study in the May 1 issue of the International Journal of Radiation Oncology*Biology*Physics.
The researchers at the University of Texas Health Science Center at San Antonio departments of radiation oncology and urology conducted the study to determine if knowledge of the anatomic relationships of the prostatic base and the prostatic apex, along with modern 3D CT planning, could be used as a substitute for retrograde urethrography.
Retrograde urethrography is the standard method used to identify the area of the prostate to be treated with radiation, according to researchers. However, they noted that the method is invasive and uncomfortable to patients and comes with risks of side effects, such as urethral injury and infection, as well as additional costs.
According to the authors, 15 patients underwent a CT simulation both with and without bladder, urethral and rectal contrast.
The investigators “easily and consistently” identified the prostatic base and apex on both scans by taking a side view of the patient and drawing a line from the pubic bone straight down to the floor of the pelvis. The process was repeated and confirmed in another 57 patients, leading researchers to determine that it is not necessary to subject a patient to a urinary catheter for contrast delivery.
“By using CT scans to find the prostatic apex, patients are happier and we have the same results,” said study author Gregory Swanson, MD, associate professor of radiation oncology at the University of Texas Health Science Center at San Antonio. “I stopped doing contrast in 1995 or 1996 when I realized that I knew where the prostate was without using invasive methods. I have been successful in using CT since then.”