title: Detailed dosimetric evaluation of intensity-modulated radiation therapy plans created for stage C prostate cancer based on a planning protocol.
abstract: BACKGROUND
  Intensity-modulated radiation therapy (IMRT) has been employed as a precision radiation therapy with higher conformity to the target. Although clinical outcomes have been reported for many investigations, detailed treatment planning results have not been mentioned to date. The aim of this study was to evaluate the dose specifications of our IMRT treatment plans for locally advanced prostate cancer.
  
  
  METHODS
  Seventy-seven clinically applied IMRT plans treated between September 2003 and December 2005, in which patients were irradiated with 78 Gy in the prone position, were retrospectively analyzed. Dosimetric data output from dose volume histograms were evaluated in detail.
  
  
  RESULTS
  The mean dose ± standard deviation, homogeneity index, and conformity index to the planning target volume (PTV) were 78.3 ± 0.7 Gy (100.4 ± 0.9%), 13.7 ± 3.0, and 0.83 ± 0.04, respectively. For the clinical target volume, the mean dose was 80.3 ± 0.7 Gy (102.9 ± 0.9%).The V40, V60, and V70 Gy of the rectal wall were 58.3 ± 2.8, 29.6 ± 2.7, and 15.2 ± 3.0%, respectively. Planning difficulties were encountered in patients whose bowels were displaced downward, as constraints imposed by the bowel position altered the dose index of the PTV. In many cases, additional bowel optimization parameters were required to satisfy constraints for organs at risk. However, major deviation could be avoided by inverse planning with computer optimization.
  
  
  CONCLUSIONS
  IMRT allowed the creation of acceptable and practical treatment plans for locally advanced prostate cancer. Reports regarding detailed dosimetric evaluations are mandatory for interpreting clinical outcomes in the future.
authors.affiliation: Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Norihisa
authors.forename: Takashi
authors.initials: T
authors.lastname: Mizowaki
authors.forename: Kenji
authors.initials: K
authors.lastname: Takayama
authors.forename: Yuki
authors.initials: Y
authors.lastname: Miyabe
authors.forename: Kiyotomo
authors.initials: K
authors.lastname: Matsugi
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Masaru
authors.initials: M
authors.lastname: Narabayashi
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Sakanaka
authors.forename: Akira
authors.initials: A
authors.lastname: Nakamura
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nagata
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hiraoka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies