The Relative Biological Effectiveness of High-Energy Photons and Electrons

Radiology ◽  
1964 ◽  
Vol 82 (5) ◽  
pp. 800-815 ◽  
Author(s):  
Warren K. Sinclair ◽  
Henry I. Kohn
Keyword(s):  
Relative Biological Effectiveness ◽  
High Energy ◽  
Biological Effectiveness

Relative Biological Effectiveness of High-Energy Photons (up to 50 MV) and Electrons (50 MeV)

1991 ◽  
Vol 128 (2) ◽  
pp. 192 ◽  
Author(s):  
Björn Zackrisson ◽  
Bengt Johansson ◽  
Peter Östbergh ◽  
Bjorn Zackrisson ◽  
Peter Ostbergh
Keyword(s):  
Relative Biological Effectiveness ◽  
High Energy ◽  
Biological Effectiveness

scholarly journals High-Accuracy Relative Biological Effectiveness Values Following Low-Dose Thermal Neutron Exposures Support Bimodal Quality Factor Response with Neutron Energy

2022 ◽  
Vol 23 (2) ◽  
pp. 878
Author(s):  
Laura C. Paterson ◽  
Amy Festarini ◽  
Marilyne Stuart ◽  
Fawaz Ali ◽  
Christie Costello ◽  
...  
Keyword(s):  
Dna Damage ◽  
Thermal Neutron ◽  
Quality Factor ◽  
Neutron Energy ◽  
Relative Biological Effectiveness ◽  
High Energy ◽  
Weighting Factor ◽  
Radiological Protection ◽  
Thermal Neutrons ◽  
Biological Effectiveness

Theoretical evaluations indicate the radiation weighting factor for thermal neutrons differs from the current International Commission on Radiological Protection (ICRP) recommended value of 2.5, which has radiation protection implications for high-energy radiotherapy, inside spacecraft, on the lunar or Martian surface, and in nuclear reactor workplaces. We examined the relative biological effectiveness (RBE) of DNA damage generated by thermal neutrons compared to gamma radiation. Whole blood was irradiated by 64 meV thermal neutrons from the National Research Universal reactor. DNA damage and erroneous DNA double-strand break repair was evaluated by dicentric chromosome assay (DCA) and cytokinesis-block micronucleus (CBMN) assay with low doses ranging 6–85 mGy. Linear dose responses were observed. Significant DNA aberration clustering was found indicative of high ionizing density radiation. When the dose contribution of both the 14N(n,p)14C and 1H(n,γ)2H capture reactions were considered, the DCA and the CBMN assays generated similar maximum RBE values of 11.3 ± 1.6 and 9.0 ± 1.1, respectively. Consequently, thermal neutron RBE is approximately four times higher than the current ICRP radiation weighting factor value of 2.5. This lends support to bimodal peaks in the quality factor for RBE neutron energy response, underlining the importance of radiological protection against thermal neutron exposures.

Calculation of the Depth Dependence of Relative Biological Effectiveness For Clinical Proton Beams

2019 ◽  
pp. 5-10
Author(s):  
А. Белоусов ◽  
A. Belousov ◽  
Р. Бахтиозин ◽  
R. Bahtiosin ◽  
М. Колыва­нова ◽  
...  
Keyword(s):  
Bragg Peak ◽  
Relative Biological Effectiveness ◽  
Complex Function ◽  
Absorbed Dose ◽  
High Energy ◽  
Clinical Value ◽  
Proton Beams ◽  
Depth Dependence ◽  
Biological Effectiveness ◽  
The Impact

Purpose: Accurate establishing the value of relative biological effectiveness (RBE) for high energy protons is one of the main challenges of modern radiotherapy. The purpose of the study is to calculate the depth dependence of RBE for proton beams forming a spread-out Bragg peak. Material and methods: Spatial distributions of absorbed dose and dose-average linear energy transfer (LET) for 50-100 MeV (0.5 MeV energy step) monochromatic proton beams were obtained by Monte-Carlo computer simulation using Geant4 software. A linear dependence of RBE on the dose-average LET was used. Absorbed dose distributions were obtained in a water phantom for monochromatic pencil proton beams of 2.5 mm radius. The absorbed dose and the dose-average LET values were calculated in voxels with dimensions of 2×2×0.2 mm. Results: Calculations of depth dependencies of absorbed dose and dose-average LET for 50–100 MeV monochromatic proton beams were performed. Depth dependencies of RBE for these beams were established. The weighing coefficients values allowing to generate uniformspread-out Bragg peak (SOBP) were determined. Depth distribution of “RBE-weighted” dose and RBE values for SOBP were found. Conclusion: The impact of the initial beam energy step on the degree of homogeneity of the modified Bragg curve was investigated. It was shown that a step up to 1.5 MeV is acceptable for generate a smooth Bragg curve. The depth dependence of the average RBE value is a complex function, which rapidly changes especially at the far end of the SOBP. RBE may vary up to 10-30 % compared to current clinical value. The linear model of RBE-LET dependence shown in the study can be easily used in dosimetric planning systems, that may will significantly improve the quality of proton radiotherapy.

scholarly journals Multiparametric radiobiological assays show that variation of X-ray energy strongly impacts relative biological effectiveness: comparison between 220 kV and 4 MV

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vincent Paget ◽  
Mariam Ben Kacem ◽  
Morgane Dos Santos ◽  
Mohamed A. Benadjaoud ◽  
Frédéric Soysouvanh ◽  
...  
Keyword(s):  
Relative Biological Effectiveness ◽  
Clonogenic Assay ◽  
Umbilical Vein ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Biological Effectiveness ◽  
Umbilical Vein Endothelial Cells ◽  
Interventional Medicine

Abstract Based on classic clonogenic assay, it is accepted by the scientific community that, whatever the energy, the relative biological effectiveness of X-rays is equal to 1. However, although X-ray beams are widely used in diagnosis, interventional medicine and radiotherapy, comparisons of their energies are scarce. We therefore assessed in vitro the effects of low- and high-energy X-rays using Human umbilical vein endothelial cells (HUVECs) by performing clonogenic assay, measuring viability/mortality, counting γ-H2AX foci, studying cell proliferation and cellular senescence by flow cytometry and by performing gene analysis on custom arrays. Taken together, excepted for γ-H2AX foci counts, these experiments systematically show more adverse effects of high energy X-rays, while the relative biological effectiveness of photons is around 1, whatever the quality of the X-ray beam. These results strongly suggest that multiparametric analysis should be considered in support of clonogenic assay.

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