title: RBE and OER within the spread-out Bragg peak for proton beam therapy: in vitro study at the Proton Medical Research Center at the University of Tsukuba.
abstract: There are few reports on the biological homogeneity within the spread-out Bragg peak (SOBP) of proton beams. Therefore, to evaluate the relative biological effectiveness (RBE) and the oxygen enhancement ratio (OER), human salivary gland tumor (HSG) cells were irradiated at the plateau position (position A) and three different positions within a 6-cm-wide SOBP (position B, 26 mm proximal to the middle; position C, middle; position D, 26 mm distal to the middle) using 155-MeV/n proton beams under both normoxic and hypoxic conditions at the Proton Medical Research Center, University of Tsukuba, Japan. The RBE to the plateau region (RBE(plateau)) and the OER value were calculated from the doses corresponding to 10% survival data. Under the normoxic condition, the RBE(plateau) was 1.00, 0.99 and 1.09 for positions B, C and D, respectively. Under the hypoxic condition, the RBE(plateau) was 1.10, 1.06 and 1.12 for positions B, C and D, respectively. The OER was 2.84, 2.60, 2.63 and 2.76 for positions A, B, C and D, respectively. There were no significant differences in either the RBE(plateau) or the OER between these three positions within the SOBP. In conclusion, biological homogeneity need not necessarily be taken into account for treatment planning for proton beam therapy at the University of Tsukuba.
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Ayae
authors.initials: A
authors.lastname: Kanemoto
authors.affiliation: Next Generation Medical Physics Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan.
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Hirayama
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan Department of Radiological Health Science, Institute of Industrial Ecological Sciences, University of Occupational and Environmental Health, Japan, Kitakyushu, Fukuoka, Japan moritake@pmrc.tsukuba.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Moritake
authors.affiliation: Next Generation Medical Physics Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan.
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Furusawa
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Lue
authors.initials: L
authors.lastname: Sun
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Takeji
authors.initials: T
authors.lastname: Sakae
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Kuno
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Terunuma
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yasuoka
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Mori
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Tsuboi
authors.affiliation: Proton Medical Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D065638:Absorption, Radiation; D002460:Cell Line; D006801:Humans; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000528:radiation effects*; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000379:methods*; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D012468:Salivary Gland Neoplasms / Q000473:pathology / Q000503:physiopathology* / Q000532:radiotherapy*; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen
keywords: oxygen enhancement ratio; proton; relative biological effectiveness; spread-out Bragg peak