Influence of rectum delineation (rectal volume vs. rectal wall) on IMRT treatment planning of the prostate.
OBJECTIVE
To evaluate the delineation of either the rectal volume (RV) or the rectal wall (RW) in intensity-modulated radiotherapy (IMRT) for prostate cancer: influence on dose distribution to the targets and organs at risk (OARs) was investigated.


METHODS
For ten patients with localized prostate cancer IMRT treatment plans were generated with the RV, wall including the filling, and the RW without the lumen as OAR (plan-RV and plan-RW), respectively. Two different IMRT treatment- planning systems (TPS) were utilized. The influence on target coverage and sparing of OARs was investigated.


RESULTS
No influence was seen on target coverage and sparing of the bladder and femoral heads. Doses to the RV were significantly reduced in plan-RV for all evaluated dose levels: maximum 26% and 17%, respectively, in both TPS. The dose distribution to the RW was not significantly different between plan-RV and plan-RW.


CONCLUSIONS
The different delineation of the OAR rectum significantly affected the inverse IMRT treatment-planning process. The use of the RV as OAR resulted in improved dose distributions to the RV. Therefore, it is suggested using the RV as OAR in IMRT treatment planning of the prostate.
Guckenberger
Matthias
M
Department of Radiation Oncology, University of Wuerzburg, Wuerzburg, Germany. guckenberg_m@klinik.uni-wuerzberg.de
Pohl
Fabian
F
Baier
Kurt
K
Meyer
Juergen
J
Koelbl
Oliver
O
Flentje
Michael
M
Vordermark
Dirk
D
D005270:Femur Head / Q000000981:diagnostic imaging / Q000528:radiation effects; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012007:Rectum / Q000000981:diagnostic imaging / Q000528:radiation effects*; D012189:Retrospective Studies; D012669:Seminal Vesicles / Q000000981:diagnostic imaging / Q000528:radiation effects; D013223:Statistics as Topic; D036542:Tomography, Spiral Computed; D001743:Urinary Bladder / Q000000981:diagnostic imaging / Q000528:radiation effects