A simple technique for determining accurate urethral dosimetry after seed brachytherapy for prostate cancer.
OBJECTIVE
To describe a simple technique to define the anatomically accurate urethral location in the postimplant CT scans, after permanent prostate seed implants, without the discomfort associated with use of a catheter.


METHODS
We perform preplanned, preloaded transperineal transrectal ultrasound-guided permanent seed implants for men with low-risk prostate cancer. In postimplant CT scans performed 4 weeks after the procedure we previously used a catheter to identify the urethra. We now use retrograde injection of contrast, followed by the retrograde injection of a mixture of contrast and aerated sterile lubricant jelly to opacify the urethra on our CT scans.


RESULTS
This technique is economical, simple, and more comfortable than the use of a catheter. It reliably allows identification of the urethra for the purposes of deriving dose-volume histogram statistics, for quality control. It provides a reference for more accurate determination of the prostate apex.


CONCLUSIONS
We recommend this technique to those performing prostate seed implants wishing to most accurately determine the precise urethral dose parameters in delayed postimplant CT scans, without the need for the discomfort associated with a urethral catheter.
Melbourne Prostate Institute, William Buckland Radiotherapy Centre, The Alfred Hospital, Melbourne, Victoria, Australia. jeremy.millar@med.monash.edu.au
Jeremy L
JL
Millar
Angelene Z
AZ
Longano
Samantha J
SJ
Imbert
Deborah
D
Stokes
D001918:Brachytherapy / Q000379:methods*; D019160:Endosonography; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014521:Urethra / Q000000981:diagnostic imaging