title: Impact of multileaf collimator width on intraprostatic dose painting plans for dominant intraprostatic lesion of prostate cancer.
abstract: The aim of this study was to investigate the impact of multileaf collimator width (MLC-W) on intraprostatic dose painting plans for prostate cancer.Prostate cancer maps based on the histopathological findings were superimposed onto simulation CT images. Clinical target volume (CTV) 1 was defined as the prostate and the base of the seminal vesicles, and CTV2 was defined as the dominant intraprostatic lesions. Planning target volume (PTV) 1 and PTV2 were delineated by adding 5 mm margins to CTV1 and CTV2, respectively. For each case, two dose painting plans were created to deliver 74 Gy to PTV1 and 84 Gy to PTV2 with dynamic multileaf collimator technique using two different MLCs: m3 (MLC-W: 3mm) and Millennium (5 mm). Plans were evaluated by comparing the conformation number (CN), a quantity that defines the degree of conformality.The CNs for plans using the m3 and Millennium were 0.68 and 0.67 for PTV1 and 0.59 and 0.58 for PTV2, respectively. The CNs tended to be higher for a thinner leaf width (p < 0.05).Dosimetric advantages associated with smaller leaves were observed. However, differences between 3 mm and 5 mm leaf width were relatively small, which suggested that 5 mm leaf width would be acceptable in dose painting plans for prostate cancer.
authors.affiliation: Division of Radiation Oncology, Department of Molecular Genetics, Course for Molecular and Cellular Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan. eabe@med.niigata-u.ac.jp
authors.forename: Eisuke
authors.initials: E
authors.lastname: Abe
authors.forename: Takashi
authors.initials: T
authors.lastname: Mizowaki
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Norihisa
authors.forename: Yuuichirou
authors.initials: Y
authors.lastname: Narita
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Masaru
authors.initials: M
authors.lastname: Narabayashi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nagata
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hiraoka
mesh_terms: D006801:Humans; D008297:Male; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000532:radiotherapy*; D011859:Radiography; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation* / Q000379:methods; D012007:Rectum / Q000000981:diagnostic imaging* / Q000473:pathology; D001743:Urinary Bladder / Q000000981:diagnostic imaging* / Q000473:pathology