title: Dosimetric comparison of three different treatment modalities for total scalp irradiation: the conventional lateral photon-electron technique, helical tomotherapy, and volumetric-modulated arc therapy.
abstract: The aim of this study was to compare lateral photon-electron (LPE), helical tomotherapy (HT), and volumetric-modulated arc therapy (VMAT) plans for total scalp irradiation. We selected a single adult model case and compared the dosimetric results for the three plans. All plans mainly used 6-MV photon beams, and the prescription dose was 60 Gy in 30 fractions. First, we compared the LPE, HT and VMAT plans, with all plans including a 1-cm bolus. We also compared HT plans with and without the bolus. The conformity indices for LPE, HT and VMAT were 1.73, 1.35 and 1.49, respectively. The HT plan showed the best conformity and the LPE plan showed the worst. However, the plans had similar homogeneity indexes. The dose to the hippocampus was the highest in the VMAT plan, with a mean of 6.7 Gy, compared with 3.5 Gy in the LPE plan and 4.8 Gy in the HT plan. The doses to the optical structures were all within the clinically acceptable range. The beam-on time and monitor units were highest in the HT plan. The HT plans with and without a bolus showed similar target coverage and organ-at-risk (OAR) sparing. The HT plan showed the best target coverage and conformity, with low doses to the brain and hippocampus. This plan also had the advantage of not necessarily requiring a bolus. Although the VMAT plan showed better conformity than the LPE plan and acceptable OAR sparing, the dose to the hippocampus should be considered when high doses are prescribed.
authors.affiliation: Department of Radiation Oncology, Seoul St. Mary's hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Song
authors.affiliation: Department of Radiation Oncology, Incheon St. Mary's hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Jung
authors.affiliation: Department of Radiation Oncology, Yeouido St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Hyung-Wook
authors.initials: HW
authors.lastname: Park
authors.affiliation: Department of Radiation Oncology, Cheju Halla General Hospital, Jeju, Korea.
authors.forename: Gi Woong
authors.initials: GW
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Cheju Halla General Hospital, Jeju, Korea.
authors.forename: Soo-Min
authors.initials: SM
authors.lastname: Chae
authors.affiliation: Department of Radiation Oncology, Incheon St. Mary's hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Chul Seung
authors.initials: CS
authors.lastname: Kay
authors.affiliation: Department of Radiation Oncology, Incheon St. Mary's hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea sonshyun@catholic.ac.kr.
authors.forename: Seok Hyun
authors.initials: SH
authors.lastname: Son
mesh_terms: D065638:Absorption, Radiation; D000328:Adult; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D059351:Organ Sparing Treatments; D061766:Proton Therapy / Q000379:methods*; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D015203:Reproducibility of Results; D012535:Scalp / Q000528:radiation effects*; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000532:radiotherapy*; D016896:Treatment Outcome
keywords: hippocampus; total scalp irradiation; lateral photon–electron technique; helical tomotherapy; volumetric-modulated arc therapy