Rectal dose reduction using three-dimensional conformal radiotherapy for locally advanced prostate cancer: A combination of conformal dynamic-arc and five-static field technique.
OBJECTIVE
The aims of this study are to compare our three-dimensional conformal radiotherapy (3D-CRT) plan using a combination of conformal dynamic-arc and five-static field (DASF) technique with other 3D-CRT plans for prostate cancer, and to estimate whether dose escalation is possible with DASF radiotherapy (DASF-RT).


METHODS
Twenty patients with prostate cancer were included in this study. For each patient, five different treatment plans including DASF-RT were created to entire prostate and seminal vesicles. Dose distribution and rectal dose-volume histogram (DVH) for each planning technique were compared.


RESULTS
In DASF-RT treatment plan, rectum V40, V50, V60, and V70 were 61.6%, 39.6%, 21.4%, and 0.6%, respectively. Compared with four 3D-CRT techniques, DASF-RT technique significantly reduce rectum V50 to V70 without increasing irradiated bladder and femoral head volumes. In addition, in the simulation of dose escalation to 76Gy, the increase of each rectal dose-volume parameter (V40 to V75) was small enough. However, in dose escalation to 78Gy, rectum V75 exceeded 5%.


CONCLUSIONS
DASF-RT technique could significantly reduce rectal volumes receiving 50-70Gy compared with other 3D-CRT techniques. DASF-RT was safe and feasible for dose escalation to 76Gy in prostate radiotherapy.
Sasaoka
Masahiro
M
Department of Radiology, Ise Municipal Hospital, Ise-City, Japan. linac@hospital.ise.mie.jp
Nishikawa
Akimasa
A
Futami
Tomoyuki
T
Nishida
Kouichi
K
Miwa
Hiroki
H
Kadoya
Kyuuichi
K
D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011829:Radiation Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D012007:Rectum / Q000528:radiation effects*