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Radiat Prot Dosimetry. 2019 May 1;183(1-2):93-97. doi: 10.1093/rpd/ncy270.

DIFFERENCE IN DEGREE OF SUB-LETHAL DAMAGE RECOVERY BETWEEN CLINICAL PROTON BEAMS AND X-RAYS.

Author information

1
Radiation Oncology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, Japan.
2
Radiation Biology, Proton Medical Research Center, University of Tsukuba Hospital, 2-1-1 Amakubo, Tsukuba, Ibaraki, Japan.
3
Medicine & Biology Division, Heavy Ion Medical Center, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma, Japan.
4
Radiation Cancer Biology and Oncology, Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA.

Abstract

Fractionated proton beam radiotherapy is spreading worldwide these days. However, biological data of sub-lethal damage recovery (SLDR) after proton irradiation is not known yet. We here conducted split-dose experiments (20-360 min intervals) to clarify SLDR kinetics, and also compared the kinetics between cells with different repairability of DNA double-strand breaks. CHO and 51D1 cell lines but not V3 cell line showed significant SLDR, which reached plateau in 4-6 h. The recovery rates and recovery halftime of SLDR after X-rays were significantly higher and shorter than proton beams for CHO and 51D1 cells, respectively. Additionally, the frequency of remaining gamma-H2AX foci after two fractions was remarkably higher for X-rays than proton beams. These data suggest that there is a difference between proton beam and X-rays in SLDR and the retained DNA double-strand breaks after split-dose irradiation.

PMID:
30576477
DOI:
10.1093/rpd/ncy270
[Indexed for MEDLINE]

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