Effects of pelvic rotation and needle angle on pubic arch interference during transperineal prostate implants.
OBJECTIVE
Pubic arch interference due to an enlarged prostate gland or a narrow pubic arch is often a limiting factor in adequate prostate coverage during transperineal brachytherapy. The purpose of this study was to evaluate the effects of both pelvic rotation and needle angles on pubic arch interference using CT-based 3-D information.


METHODS
Seven patients had CT imaging in both supine and lithotomy positions and 3-D treatment planning was performed with three needle angles (20 downward, 0, 20 upward). The pubic arch interference was then measured and comparisons were made for each needle trajectory and pelvic position.


RESULTS
Increasing pelvic rotation from supine to lithotomy position shows less pubic arch interference. Directing the needle tip upward shows less pubic arch interference in both supine and lithotomy positions when compared to needle tips directed downward.


CONCLUSIONS
Both pelvic position and needle angles are important factors influencing pubic arch interference. Preplanning CT-based 3-D information may assist for individualized treatment planning in patients with a significant bony interference, thus avoiding pubic arch interference during implantation.
Tincher
S A
SA
Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, AL 35233, USA.
Kim
R Y
RY
Ezekiel
M P
MP
Zinsli
T
T
Fiveash
J B
JB
Raben
D A
DA
Bueschen
A J
AJ
Urban
D A
DA
D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D008297:Male; D009339:Needles; D010388:Pelvis / Q000000981:diagnostic imaging; D011187:Posture; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011630:Pubic Bone / Q000000981:diagnostic imaging; D020266:Radiotherapy, Conformal; D012399:Rotation; D014057:Tomography, X-Ray Computed