scholarly journals The relative biological effectiveness of carbon ion irradiations of the rat spinal cord increases linearly with LET up to 99 keV/μm

2016 ◽  
Vol 55 (12) ◽  
pp. 1512-1515 ◽  
Author(s):  
Maria Saager ◽  
Christin Glowa ◽  
Peter Peschke ◽  
Stephan Brons ◽  
Rebecca Grün ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Relative Biological Effectiveness ◽  
Rat Spinal Cord ◽  
Carbon Ion ◽  
Biological Effectiveness

scholarly journals Fractionated carbon ion irradiations of the rat spinal cord: comparison of the relative biological effectiveness with predictions of the local effect model

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Maria Saager ◽  
Christin Glowa ◽  
Peter Peschke ◽  
Stephan Brons ◽  
Rebecca Grün ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Relative Biological Effectiveness ◽  
Local Effect ◽  
Published Data ◽  
Carbon Ions ◽  
Rat Spinal Cord ◽  
Model Calculations ◽  
Carbon Ion ◽  
Effect Model ◽  
Biological Effectiveness

Abstract Background To determine the relative biological effectiveness (RBE) and α/β-values after fractionated carbon ion irradiations of the rat spinal cord with varying linear energy transfer (LET) to benchmark RBE-model calculations. Material and methods The rat spinal cord was irradiated with 6 fractions of carbon ions at 6 positions within a 6 cm spread-out Bragg-peak (SOBP, LET: 16–99 keV/μm). TD50-values (dose at 50% complication probability) were determined from dose-response curves for the endpoint radiation induced myelopathy (paresis grade II) within 300 days after irradiation. Based on TD50-values of 15 MV photons, RBE-values were calculated and adding previously published data, the LET and fractional dose-dependence of the RBE was used to benchmark the local effect model (LEM I and IV). Results At six fractions, TD50-values decreased from 39.1 ± 0.4 Gy at 16 keV/μm to 17.5 ± 0.3 Gy at 99 keV/μm and the RBE increased accordingly from 1.46 ± 0.05 to 3.26 ± 0.13. Experimental α/β-ratios ranged from 6.9 ± 1.1 Gy to 44.3 ± 7.2 Gy and increased strongly with LET. Including all available data, comparison with model-predictions revealed that (i) LEM IV agrees better in the SOBP, while LEM I fits better in the entrance region, (ii) LEM IV describes the slope of the RBE within the SOBP better than LEM I, and (iii) in contrast to the strong LET-dependence, the RBE-deviations depend only weakly on fractionation within the measured range. Conclusions This study extends the available RBE data base to significantly lower fractional doses and performes detailed tests of the RBE-models LEM I and IV. In this comparison, LEM IV agrees better with the experimental data in the SOBP than LEM I. While this could support a model replacement in treatment planning, careful dosimetric analysis is required for the individual patient to evaluate potential clinical consequences.

scholarly journals OC-0264: Determination of RBE in the rat spinal cord after carbon ion irradiations with different LET and fractional doses

2015 ◽  
Vol 115 ◽  
pp. S135
Author(s):  
M. Saager ◽  
C. Glowa ◽  
P. Peschke ◽  
S. Brons ◽  
M. Scholz ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Rat Spinal Cord ◽  
Carbon Ion

scholarly journals An empirical model to predict survival curve and relative biological effectiveness after helium and carbon ion irradiation based solely on the cell survival after photon irradiation

2020 ◽  
Author(s):  
David B. Flint ◽  
Scott J. Bright ◽  
Conor H. McFadden ◽  
Teruaki Konishi ◽  
Daisuke Ohsawa ◽  
...  
Keyword(s):  
Cell Survival ◽  
Cell Lines ◽  
Empirical Model ◽  
Linear Correlation ◽  
Relative Biological Effectiveness ◽  
Ion Irradiation ◽  
Survival Curve ◽  
Carbon Ion ◽  
Wide Range ◽  
Biological Effectiveness

ABSTRACTPurposeTo develop an empirical model to predict radiosensitivity and relative biological effectiveness (RBE) after helium (He) and carbon (C) ion irradiation with or without DNA repair inhibitors.MethodsWe characterized survival in eight human cancer cell lines exposed to 6 MV photons and to He- and C-ions with linear energy transfer (LET) values of 2.2-60.5 keV/μm to verify that the radiosensitivity parameters (D5%, D10%, D20%, D37%, D50% and SF2Gy) correlate linearly between photon and ion radiation with or without DNA-PKcs or ATR inhibitors. Then, we parameterized the LET response of the parameters governing these linear correlations up to LET values of 225 keV/μm using the data in the Particle Irradiation Data Ensemble (PIDE) v3.2 database, creating a model that predicts a cell’s ion radiosensitivity, RBE and ion survival curve for a given LET on the basis of the cell’s photon radiosensitivity. We then trained this model using the PIDE database as a training dataset, and validated it by predicting the radiosensitivity of the cell lines we exposed to He- and C- ions with LET ranging from 2.2-60.5 keV/μm.ResultsRadiosensitivity to ions depended linearly with radiosensitivity of photons in the range of investigated LET values and the slopes and intercepts of these linear relationships within the PIDE database vary exponentially and linearly, respectively. Our model predicted ion radiosensitivity (e.g., D10%) within 5.1–21.3%, RBED10% within 5.0-17.1%, and ion mean inactivation dose within 6.7-25.1% for He- and C-ion LET ranging from 2.2-60.5 keV/μm.ConclusionsRadiosensitivity to He- and C-ions depend linearly with radiosensitivity to photons and can be used to predict ion radiosensitivity, RBE and cell survival curves for clinically relevant LET values from 2.2–60.5 keV/μm, with or without drug treatment.SUMMARYWe present a new empirical model capable of predicting clonogenic cell survival of cell lines exposed to helium and carbon ion beams. Our model is based on an observed linear correlation between radiosensitivity to ions and photons across a wide range of LET values. This linear correlation can be used to predict ion RBE, radiosensitivity, and the cell survival curve for a given LET all based on a cell’s photon survival curve.

scholarly journals Proton RBE dependence on dose in the setting of hypofractionation

2020 ◽  
Vol 93 (1107) ◽  
pp. 20190291 ◽  
Author(s):  
Thomas Friedrich
Keyword(s):  
Relative Biological Effectiveness ◽  
Review Article ◽  
Carbon Ion Therapy ◽  
Carbon Ion ◽  
Ion Therapy ◽  
Therapy Costs ◽  
Biological Effectiveness ◽  
Dose Dependent ◽  
Higher Doses ◽  
Patient Burden

Hypofractionated radiotherapy is attractive concerning patient burden and therapy costs, but many aspects play a role when it comes to assess its safety. While exploited for conventional photon therapy and carbon ion therapy, hypofractionation with protons is only rarely applied. One reason for this is uncertainty in the described dose, mainly due to the relative biological effectiveness (RBE), which is small for protons, but not negligible. RBE is generally dose-dependent, and for higher doses as used in hypofractionation, a thorough RBE evaluation is needed. This review article focuses on the RBE variability in protons and associated issues or implications for hypofractionation.

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