title: Preliminary analysis of the sequential simultaneous integrated boost technique for intensity-modulated radiotherapy for head and neck cancers.
abstract: The aim of this study was to compare three strategies for intensity-modulated radiotherapy (IMRT) for 20 head-and-neck cancer patients. For simultaneous integrated boost (SIB), doses were 66 and 54 Gy in 30 fractions for PTVboost and PTVelective, respectively. Two-phase IMRT delivered 50 Gy in 25 fractions to PTVelective in the First Plan, and 20 Gy in 10 fractions to PTVboost in the Second Plan. Sequential SIB (SEQ-SIB) delivered 55 Gy and 50 Gy in 25 fractions, respectively, to PTVboost and PTVelective using SIB in the First Plan and 11 Gy in 5 fractions to PTVboost in the Second Plan. Conformity indexes (CIs) (mean ± SD) for PTVboost and PTVelective were 1.09 ± 0.05 and 1.34 ± 0.12 for SIB, 1.39 ± 0.14 and 1.80 ± 0.28 for two-phase IMRT, and 1.14 ± 0.07 and 1.60 ± 0.18 for SEQ-SIB, respectively. CI was significantly highest for two-phase IMRT. Maximum doses (Dmax) to the spinal cord were 42.1 ± 1.5 Gy for SIB, 43.9 ± 1.0 Gy for two-phase IMRT and 40.3 ± 1.8 Gy for SEQ-SIB. Brainstem Dmax were 50.1 ± 2.2 Gy for SIB, 50.5 ± 4.6 Gy for two-phase IMRT and 47.4 ± 3.6 Gy for SEQ-SIB. Spinal cord Dmax for the three techniques was significantly different, and brainstem Dmax was significantly lower for SEQ-SIB. The compromised conformity of two-phase IMRT can result in higher doses to organs at risk (OARs). Lower OAR doses in SEQ-SIB made SEQ-SIB an alternative to SIB, which applies unconventional doses per fraction.
authors.affiliation: Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Miyazaki
authors.affiliation: Department of Radiation Oncology, Yao Municipal Hospital, Ryuge 1-3-1, Yao Osaka, 581-0069, Japan nisiyama2288@gmail.com.
authors.forename: Kinji
authors.initials: K
authors.lastname: Nishiyama
authors.affiliation: Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan Department of Radiation Oncology, Graduate School of Medicine, Osaka University, Suita, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ueda
authors.affiliation: Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Ohira
authors.affiliation: Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
authors.forename: Katsutomo
authors.initials: K
authors.lastname: Tsujii
authors.affiliation: Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Isono
authors.affiliation: Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Masaoka
authors.affiliation: Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
authors.forename: Teruki
authors.initials: T
authors.lastname: Teshima
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001933:Brain Stem / Q000473:pathology / Q000528:radiation effects; D019583:Dose Fractionation, Radiation; D004305:Dose-Response Relationship, Drug; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012307:Risk Factors; D013116:Spinal Cord / Q000473:pathology / Q000528:radiation effects
keywords: IMRT; SEQ-SIB; SIB; conformity index; head and neck cancer