title: Relative biological effectiveness in canine osteosarcoma cells irradiated with accelerated charged particles.
abstract: Heavy ions, characterized by high linear energy transfer (LET) radiation, have advantages compared with low LET protons and photons in their biological effects. The application of heavy ions within veterinary clinics requires additional background information to determine heavy ion efficacy. In the present study, comparison of the cell-killing effects of photons, protons and heavy ions was investigated in canine osteosarcoma (OSA) cellsin vitro. A total of four canine OSA cell lines with various radiosensitivities were irradiated with 137Cs gamma-rays, monoenergetic proton beams, 50 keV/µm carbon ion spread out Bragg peak beams and 200 keV/µm iron ion monoenergetic beams. Clonogenic survival was examined using colony-forming as says, and relative biological effectiveness (RBE) values were calculated relative to gamma-rays using the D10value, which is determined as the dose (Gy) resulting in 10% survival. For proton irradiation, the RBE values for all four cell lines were 1.0-1.1. For all four cell lines, exposure to carbon ions yielded a decreased cell survival compared with gamma-rays, with the RBE values ranging from 1.56-2.10. Iron ions yielded the lowest cell survival among tested radiation types, with RBE values ranging from 3.51-3.69 observed in the three radioresistant cell lines. The radiosensitive cell line investigated demonstrated similar cell survival for carbon and iron ion irradiation. The results of the present study suggest that heavy ions are more effective for killing radioresistant canine OSA cells when compared with gamma-rays and protons. This markedly increased efficiency of cell killing is an attractive reason for utilizing heavy ions for radioresistant canine OSA.
authors.affiliation: Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Junko
authors.initials: J
authors.lastname: Maeda
authors.affiliation: Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Cartwright
authors.affiliation: Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Haskins
authors.affiliation: Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Inashiki, Ibaraki 300-0394, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujii
authors.affiliation: School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fujisawa
authors.affiliation: Research Center for Charged Particle Therapy, International Open Laboratory, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Hirakawa
authors.affiliation: School of Engineering, The University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Uesaka
authors.affiliation: Research Development and Support Center, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kitamura
authors.affiliation: Research Center for Charged Particle Therapy, International Open Laboratory, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Fujimori
authors.affiliation: Department of Clinical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Douglas H
authors.initials: DH
authors.lastname: Thamm
authors.affiliation: Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors.forename: Takamitsu A
authors.initials: TA
authors.lastname: Kato
keywords: canine osteosarcoma; carbon-ion; photon; relative biological effectiveness