Comparison of three radiotherapy treatment planning protocols of definitive external-beam radiation for localized prostate cancer.
BACKGROUND
Three radiotherapy treatment planning (RTTP) protocols for definitive external-beam radiation for localized prostate cancer, designed and clinically applied at Kyoto University, were compared.


METHODS
Treatment plans were created according to three different RTTP protocols (old three-dimensional conformal radiotherapy [3D-CRT], new 3D-CRT, and intensity-modulated radiotherapy [IMRT]) on computed tomography (CT) data sets of five patients with localized prostate cancer. The dynamic-arc conformal technique was used in the 3D-CRT protocols. Differences in dose distribution were evaluated and compared based on dose-volume histogram (DVH) analyses.


RESULTS
The coverage of the clinical target volume (= prostate alone) was comparable among the three RTTP protocols. However, the average values for the percent volume that received at least 95% of the prescription dose (V95), the percent of the prescription dose covering 95% of the volume (D95), and the conformity index of the planning target volume (PTV) were 99%, 97%, and 0.88 for the IMRT; 93.9%, 94.5%, and 0.76 for the new 3D-CRT; and 59.6%, 82.9%, and 0.6 for the old 3D-CRT protocol, respectively. Inhomogeneity of doses to the PTV was larger with the IMRT protocol than with the new 3D-CRT protocol. Doses to both the rectal wall and bladder wall were almost comparable with the new 3D-CRT and IMRT protocols, but were lower with the old 3D-CRT protocol, due to the lowest prescription dose and incomplete dose coverage of the PTV.


CONCLUSIONS
The old 3D-CRT protocol could not achieve the goals for the PTV set in the IMRT protocol. The new 3D-CRT and IMRT protocols were generally comparable in terms of both the PTV coverage and normal tissue-sparing, although the IMRT protocol achieved the most conformal dose distribution to the PTV, in return for a larger, but acceptable, dose inhomogeneity.
Zhu
SuYu
S
Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
Mizowaki
Takashi
T
Nagata
Yasushi
Y
Takayama
Kenji
K
Norihisa
Yoshiki
Y
Yano
Shinsuke
S
Hiraoka
Masahiro
M
D002985:Clinical Protocols; D006801:Humans; D008297:Male; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted