Relative biological effectiveness study of Lipiodol based on microdosimetric-kinetic model

Daisuke Kawahara; Hisashi Nakano; Shuichi Ozawa; Akito Saito; Tomoki Kimura; Tatsuhiko Suzuki; Masato Tsuneda; Sodai Tanaka; Yoshimi Ohno; Yuji Murakami; Yasushi Nagata

doi:10.1016/j.ejmp.2018.01.018

Relative biological effectiveness study of Lipiodol based on microdosimetric-kinetic model

Phys Med. 2018 Feb:46:89-95. doi: 10.1016/j.ejmp.2018.01.018.

Authors

Affiliations

¹ Radiation Therapy Section, Department of Clinical Support, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima 734-8551, Japan; Medical and Dental Sciences Course, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima 734-8551, Japan. Electronic address: daika99@hiroshima-u.ac.jp.
² Hiroshima Heiwa Clinic, State of the Art Treatment Center, 1-31 Kawara-machi, Naka-ku, Hiroshima City, Hiroshima 730-0856, Japan.
³ Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima 734-8551, Japan; Hiroshima High-Precision Radiotherapy Cancer Center, 10-52 Motomachi, Naka-ku, Hiroshima City, Hiroshima 730-8511, Japan.
⁴ Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima 734-8551, Japan.
⁵ Medical and Dental Sciences Course, Graduate School of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima 734-8551, Japan.
⁶ Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
⁷ Radiation Therapy Section, Department of Clinical Support, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima City, Hiroshima 734-8551, Japan.

PMID: 29519415
DOI: 10.1016/j.ejmp.2018.01.018

Abstract

Objectives: We examine the contrast agent Lipiodol effect on the relative biological effectiveness (RBE) values for flattening filter free (FFF) and flattening filter (FF) beams of 6 MV-Xray (6 MVX) and 10 MVX.

Methods: Lipiodol was placed at 5 cm depth in water. According to the microdosimetric kinetic model, the RBE values for killing the human liver hepatocellular cells were calculated from dose and lineal energy (yd(y)) from Monte Carlo simulations. RBE_200kVX and RBE_Co were defined as the ratios of dose using reference radiation (200 kVX, Co-ɤ) to the dose of test radiation (FFF and FF beams for 6 MV and 10 MV) to produce the same biological effects. The dose enhancement RBE (RBE_DE) was defined as the ratios of a dose without Lipiodol to with Lipiodol using to produce the same biological effects. The dose needed to achieve 10% (D_10%) and 1% cell survival (D_1%) was evaluated by cell surviving fraction (SF) formula.

Results: The deviation of mean y‾_D values with and without Lipiodol were 3.9-4.8% for 6 MVX and 3.5-3.6% for 10 MVX. The RBE_200kVX and RBE_Co with Lipiodol were larger than that without Lipiodol. The RBE_DE was larger for FFF beam than for FF beam. The deviation of RBE_DE for FFF and FF beams of 6 MVX was larger than that of 10 MVX.

Conclusion: The presence of Lipiodol seemed to locally increase the absorbed dose and to also cause an enhancement of the relative biological effectiveness.

Keywords: Lipiodol; MK model; Monte Carlo calculation; RBE enhancement.

MeSH terms

Ethiodized Oil*
Kinetics
Models, Biological*
Radiometry
Relative Biological Effectiveness*

Substances

Ethiodized Oil