Inactivation of V79 cells by low-energy protons, deuterons and helium-3 ions

Folkard, M.; Prise, Kevin M.; Vojnovic, B.; Newman, H.C.; Roper, M.J.; Michael, B.D.

doi:10.1080/095530096145472

Cited by 147 publications

(110 citation statements)

References 8 publications

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“…In general, experimental data on proton RBE versus LET d (Folkard et al 1996, Belli et al 1989, 1993, Perris et al 1986, Coutrakon et al 1997, Wouters et al 1996, Schettino et al 2001 and proton RBE versus (α/β) x (Gerweck andKozin 1999, Paganetti et al 2000) indicate that RBE increases with increasing LET d (note that for protons the eventual decrease with LET d happens at LET d values irrelevant for clinical considerations) but decreases with increasing (α/β) x . The current data sets used to relate RBE with LET d and (α/β) x are subject to uncertainties (Carabe et al 2012, Carabe 2013).…”

Section: Methodsmentioning

confidence: 99%

Clinical consequences of relative biological effectiveness variations in proton radiotherapy of the prostate, brain and liver

et al. 2013

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Proton relative biological effectiveness (RBE) is known to depend on the (α/β) x of irradiated tissues, with evidence of ∼60% variation over (α/β) x values from 1-10 Gy. The range of (α/β) x values reported for prostate tumors (1.2-5.0 Gy), brain tumors (10-15 Gy) and liver tumors (13-17 Gy) imply that the proton RBE for these tissues could vary significantly compared to the commonly used generic value of 1.1. Our aim is to evaluate the impact of this uncertainty on the proton dose in Gy(RBE) absorbed in normal and tumor tissues. This evaluation was performed for standard and hypofractionated regimens. RBE-weighted total dose (RWTD) distributions for 15 patients (five prostate tumors, five brain tumors and five liver tumors) were calculated using an in-house developed RBE model as a function of dose, dose-averaged linear energy transfer (LET d ) and (α/β) x . Variations of the dose-volume histograms (DVHs) for the gross tumor volume (GTV) and the organs at risk due to changes of (α/β) x and fractionation regimen were calculated and the RWTD received by 10% and 90% of the organ volume reported. The goodness of the plan, bearing the uncertainties, was then evaluated compared to the delivered plan, which considers a constant RBE of 1.1. For standard fractionated regimens, the prostate tumors, liver tumors and all critical structures in the brain showed typically larger RBE values than 1.1. However, in hypofractionated regimens lower values of RBE than 1.1 were observed in most cases. Based on DVH analysis we found that the RBE variations were clinically significant in particular for the prostate GTV and the critical structures in the brain. Despite the uncertainties in the biological input parameters when estimating RBE values, the results show that the use of a variable RBE with dose, LET d and (α/β) x could help to further optimize the target dose in proton treatment

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Section: Methodsmentioning

confidence: 99%

Clinical consequences of relative biological effectiveness variations in proton radiotherapy of the prostate, brain and liver

et al. 2013

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“…The present model offers an efficient method to model such effects. Differences in biological response have been seen between hydrogen and helium ions at the same LET [27,28] and with low-energy heavy ions [29,30], but useful comparisons of fast and slow ions have not been made. For estimating the risk to astronauts from space radiation, differences in radiation quality for ions with the same LET may have important implications.…”

Section: Model For Radial Electron Spectrummentioning

confidence: 99%

Radial distribution of electron spectra from high-energy ions

Cucinotta

Katz

Wilson

1998

Radiation and Environmental Biophysics

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The average track model describes the response of physical and biological systems using radial dose distribution as the key physical descriptor. We report on an extension of this model to describe the average distribution of electron spectra as a function of radial distance from an ion. We present calculations of these spectra for ions of identical linear energy transfer (LET), but dissimilar charge and velocity to evaluate the differences in electron spectra from these ions. To illustrate the usefulness of the radial electron spectra for describing effects that are not described by electron dose, we consider the evaluation of the indirect events in microdosimetric distributions for ions. We show that folding our average electron spectra model with experimentally determined frequency distributions for photons or electrons provides a good representation of radial event spectra from high-energy ions in 0.5-2 µm sites.

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“…At 32 keV µm -1 , Folkard measured an RBE of about 3.3, while for Belli it was about 2. Folkard et al (1996) later revised the RBE to about 2 in accordance with Belli's data, proposing that a better experimental set-up excluded very low energy protons which were probably present in the original measurements.…”

Section: Discussionmentioning

confidence: 77%