Radiobiological Effectiveness of Radiation Beams with Broad LET Spectra: Microdosimetric Analysis Using Biological Weighting Functions

Loncol, T.; Cosgrove, V.P.; Denis, Jm.; Gueulette, John; Mazal, A.; Menzel, H-G.; Pihet, P.; Sabattier, R.

doi:10.1093/oxfordjournals.rpd.a082212

Cited by 57 publications

(23 citation statements)

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“…The composition of the beam gets increasingly complex for a Spread-out Bragg Peak (SOBP) beam with multiple initial energies, and even more complex for treatments with many fields, often termed a "mixed treatment field" (Lam 1987, Inaniwa et al 2015. Alternative approaches to describe the radiation quality are the energy spectrum (Belli, Campa, and Ermolli 1997) or microdosimetric quantities such as lineal energy (l) or specific energy (z) (Loncol et al 1994, Inaniwa et al 2010 or the number of proton pencil beam track-end (Traneus and Ödén 2019).…”

Section: Linear Energy Transfer Spectrummentioning

confidence: 99%

Exploration and application of phenomenological RBE models for proton therapy

et al. 2018

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The relative biological effectiveness (RBE) of protons varies with multiple physical and biological factors. Phenomenological RBE models have been developed to include such factors in the estimation of a variable RBE, in contrast to the clinically applied constant RBE of 1.1. In this study, eleven published phenomenological RBE models and two plan-based models were explored and applied to simulated patient cases. All models were analysed with respect to the distribution and range of linear energy transfer (LET) and reference radiation fractionation sensitivity ((α/β) ) of their respective experimental databases. Proton therapy plans for a spread-out Bragg peak in water and three patient cases (prostate adenocarcinoma, pituitary adenoma and thoracic sarcoma) were optimised using an RBE of 1.1 in the Eclipse treatment planning system prior to recalculation and modelling in the FLUKA Monte Carlo code. Model estimated dose-volume parameters for the planning target volumes (PTVs) and organs at risk (OAR) were compared. The experimental in vitro databases for the various models differed greatly in the range of (α/β) values and dose-averaged LET (LET). There were significant variations between the model estimations, which arose from fundamental differences in the database definitions and model assumptions. The greatest variations appeared in organs with low (α/β) and high LET, e.g. biological doses given to late responding OARs located distal to the target in the treatment field. In general, the variation in maximum dose (D) was larger than the variation in mean dose and other dose metrics, with D of the left optic nerve ((α/β) = 2.1 Gy) in the pituitary adenoma case showing the greatest discrepancies between models: 28-52 Gy(RBE), while D for RBE was 30 Gy(RBE). For all patient cases, the estimated mean RBE to the PTV was in the range 1.09-1.29 ((α/β) = 1.5/3.1/10.6 Gy). There were considerable variations between the estimations of RBE and RBE-weighted doses from the different models. These variations were a consequence of fundamental differences in experimental databases, model assumptions and regression techniques. The results from the implementation of RBE models in dose planning studies should be evaluated in light of these deviations.

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Section: Linear Energy Transfer Spectrummentioning

confidence: 99%

Exploration and application of phenomenological RBE models for proton therapy

et al. 2018

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“…Its validity was discussed in the applications to photons, protons, and neutrons. [16] This equation was used to calculate the RBE for boron neutron capture therapy, [17] proton therapy, [18] and heavy-ion therapy. [19] Since lineal energy spectra are generally expressed in yd(y) versus log(y), Equation (4) can be rewritten as:…”

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confidence: 99%

Microdosimetric relative biological effectiveness of therapeutic proton beams

Tung

2015

Biomed J

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I n particle (proton or heavy-ion) therapy, the patient treatment planning includes assessments of radiation dose and radiation quality. Distributions of the absorbed dose and the relative biological effectiveness (RBE), a quality index, in the patient provide essential information in the treatment planning. To facilitate these assessments, the International Atomic Energy Agency and the International Commission on Radiation Units and Measurements (ICRU) have jointly recommended the reporting and recording of isoeffective doses in the treatment plan.[1] The isoeffective dose, that is, the product of absorbed dose and isoeffective weighting factor, of particle beam is defined as the equivalent dose of photon beam under the same irradiation conditions (e.g., 2 Gy per fraction, 5 daily fractions per week, etc.). The key factor determining the isoeffective weighting factor is the RBE. While absorbed dose relates to the total energy deposition in a macroscopic volume of the irradiated tissue, radiation quality regards the single-event energy deposition in a microscopic volume of the biologically sensitive target. [2] When compared to photon beams, particle beams have distinct spatial distributions on the energy depositions in both the macroscopic and microscopic volumes. [3] Such distributions are responsible for the different biological consequences in the tumor and healthy cells during radiotherapy. The macroscopic distribution, that When compared to photon beams, particle beams have distinct spatial distributions on the energy depositions in both the macroscopic and microscopic volumes. In a macroscopic volume, the absorbed dose distribution shows a rapid increase near the particle range, that is, Bragg peak, as particle penetrates deep inside the tissue. In a microscopic volume, individual particle deposits its energy along the particle track by producing localized ionizations through the formation of clusters. These highly localized clusters can induce complex types of deoxyribonucleic acid (DNA) damage which are more difficult to repair and lead to higher relative biological effectiveness (RBE) as compared to photons. To describe the biological actions, biophysical models on a microscopic level have been developed. In this review, microdosimetric approaches are discussed for the determination of RBE at different depths in a patient under particle therapy. These approaches apply the microdosimetric lineal energy spectra obtained from measurements or calculations. Methods to determine these spectra will be focused on the tissue equivalent proportional counter and the Monte Carlo program. Combining the lineal energy spectrum and the biological model, RBE can be determined. Three biological models are presented. A simplified model applies the dose-mean lineal energy and the measured RBE (linear energy transfer) data. A more detailed model makes use of the full lineal energy spectrum and the biological weighting function spectrum. A comprehensive model calculates the spectrum-averaged yields of DNA damages caused by ...

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“…The presented microdosimetric approach to determine a single parameter characterization of radiation quality is closely related to t h e clinical approach a n d appears to be promising in providing a tool with an accuracy commensurate with t h a t required in clinical dosimetry. Recent investigations b y Loncol et al (47) have shown t h a t this a p p r o a c h can be extended t o t h e use of protons in therapy.…”

Section: Discussionmentioning

confidence: 99%