Biophysical Studies with High-Energy Argon Ions 2. Determinations of the Relative Biological Effectiveness, the Oxygen Enhancement Ratio, and the Cell Cycle Response

1977 ◽  
Vol 70 (3) ◽  
pp. 469 ◽  
Author(s):  
Eric J. Hall ◽  
Richard P. Bird ◽  
Harald H. Rossi ◽  
Robert Coffey ◽  
John Varga ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Relative Biological Effectiveness ◽  
High Energy ◽  
Enhancement Ratio ◽  
Biophysical Studies ◽  
Oxygen Enhancement Ratio ◽  
Biological Effectiveness ◽  
Argon Ions ◽  
Oxygen Enhancement

scholarly journals Impact of Hypoxia on Relative Biological Effectiveness and Oxygen Enhancement Ratio for a 62-MeV Therapeutic Proton Beam

Cancers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2997
Author(s):  
Chun-Chieh Chan ◽  
Fang-Hsin Chen ◽  
Ya-Yun Hsiao
Keyword(s):  
Monte Carlo ◽  
Cell Survival ◽  
Relative Biological Effectiveness ◽  
Excision Repair ◽  
Enhancement Ratio ◽  
Proton Beams ◽  
Oxygen Enhancement Ratio ◽  
Biological Effectiveness ◽  
Rmf Model ◽  
Oxygen Enhancement

This study uses the yields of double-strand breaks (DSBs) to determine the relative biological effectiveness (RBE) of proton beams, using cell survival as a biological endpoint. DSB induction is determined when cells locate at different depths (6 positions) along the track of 62 MeV proton beams. The DNA damage yields are estimated using Monte Carlo Damage Simulation (MCDS) software. The repair outcomes are estimated using Monte Carlo excision repair (MCER) simulations. The RBE for cell survival at different oxygen concentrations is calculated using the repair-misrepair-fixation (RMF) model. Using 60Co γ-rays (linear energy transfer (LET) = 2.4 keV/μm) as the reference radiation, the RBE for DSB induction and enzymatic DSB under aerobic condition (21% O2) are in the range 1.0–1.5 and 1.0–1.6 along the track depth, respectively. In accord with RBE obtained from experimental data, RMF model-derived RBE values for cell survival are in the range of 1.0–3.0. The oxygen enhancement ratio (OER) for cell survival (10%) decreases from 3.0 to 2.5 as LET increases from 1.1 to 22.6 keV/μm. The RBE values for severe hypoxia (0.1% O2) are in the range of 1.1–4.4 as LET increases, indicating greater contributions of direct effects for protons. Compared with photon therapy, the overall effect of 62 MeV proton beams results in greater cell death and is further intensified under hypoxic conditions.

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