Positional reproducibility and effects of a rectal balloon in prostate cancer radiotherapy.
Despite the increasing use of the rectal balloon in prostate cancer radiotherapy, many issues still remain to be verified objectively including its positional reproducibility and relevance to treatment morbidity. We have developed a custom rectal balloon that has a scale indicating the depth of insertion and dilates symmetrically ensuring positional reproducibility. Fifty patients with prostate cancer treated by definitive 3D-conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) with rectal balloon were analyzed. Each of first five patients undergone computed tomography (CT) three times with a rectal balloon. The positional reproducibility was tested by Intraclass Correlation Coefficient (ICC) from the CT-to-CT fusion images. Planning variables and clinical acute toxicities were compared between when or not applying balloon. An ICC of greater than 0.9 in all directions revealed an excellent reproducibility of the balloon. Rectal balloon improved considerably the mean dose and V(45Gy)-V(65Gy) in plan comparison, and especially in 3D-CRT the rectal volume exposed to more than 60 Gy dropped from 41.3% to 19.5%. Clinically, the balloon lowered acute toxicity, which was lowest when both the balloon and IMRT were applied simultaneously. The rectal balloon carries excellent reproducibility and reduces acute toxicity in 3D-CRT and IMRT for prostate cancer.
Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University Health System, Seoul, Korea.
Jae Ho
JH
Cho
Chang-Geol
CG
Lee
Dae Ryong
DR
Kang
Jooho
J
Kim
Sangkyu
S
Lee
Chang-Ok
CO
Suh
Jinsil
J
Seong
Yang Gun
YG
Suh
Ikjae
I
Lee
Gwi Eon
GE
Kim
D002404:Catheterization / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008297:Male; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated; D012007:Rectum; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome