A Radiobiological Model for the Relative Biological Effectiveness of High-Dose-Rate252Cf Brachytherapy

2005 ◽  
Vol 164 (3) ◽  
pp. 319-323 ◽  
Author(s):  
Mark J. Rivard ◽  
Christopher S. Melhus ◽  
Heather D. Zinkin ◽  
Liza J. Stapleford ◽  
Krista E. Evans ◽  
...  
Keyword(s):  
Relative Biological Effectiveness ◽  
High Dose ◽  
Radiobiological Model ◽  
Biological Effectiveness

scholarly journals A simple model for calculating relative biological effectiveness of X-rays and gamma radiation in cell survival

2020 ◽  
Vol 93 (1112) ◽  
pp. 20190949 ◽  
Author(s):  
Oleg N. Vassiliev ◽  
Christine B. Peterson ◽  
David R. Grosshans ◽  
Radhe Mohan
Keyword(s):  
Experimental Data ◽  
Cell Survival ◽  
Relative Biological Effectiveness ◽  
Survival Curve ◽  
Linear Functions ◽  
Model Parameters ◽  
High Dose ◽  
X Rays ◽  
Γ Radiation ◽  
Biological Effectiveness

Objectives: The relative biological effectiveness (RBE) of X-rays and γ radiation increases substantially with decreasing beam energy. This trend affects the efficacy of medical applications of this type of radiation. This study was designed to develop a model based on a survey of experimental data that can reliably predict this trend. Methods: In our model, parameters α and β of a cell survival curve are simple functions of the frequency-average linear energy transfer (LF) of delta electrons. The choice of these functions was guided by a microdosimetry-based model. We calculated LF by using an innovative algorithm in which LF is associated with only those electrons that reach a sensitive-to-radiation volume (SV) within the cell. We determined model parameters by fitting the model to 139 measured (α,β) pairs. Results: We tested nine versions of the model. The best agreement was achieved with [Formula: see text] and β being linear functions of [Formula: see text] .The estimated SV diameter was 0.1–1 µm. We also found that α, β, and the α/β ratio increased with increasing [Formula: see text] . Conclusions: By combining an innovative method for calculating [Formula: see text] with a microdosimetric model, we developed a model that is consistent with extensive experimental data involving photon energies from 0.27 keV to 1.25 MeV. Advances in knowledge: We have developed a photon RBE model applicable to an energy range from ultra-soft X-rays to megaelectron volt γ radiation, including high-dose levels where the RBE cannot be calculated as the ratio of α values. In this model, the ionization density represented by [Formula: see text] determines the RBE for a given photon spectrum.

scholarly journals Mechanistic Modeling of the Relative Biological Effectiveness of Boron Neutron Capture Therapy

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2302
Author(s):  
Seth W. Streitmatter ◽  
Robert D. Stewart ◽  
Gregory Moffitt ◽  
Tatjana Jevremovic
Keyword(s):  
Cell Survival ◽  
Boron Neutron Capture Therapy ◽  
Neutron Capture ◽  
Relative Biological Effectiveness ◽  
Mechanistic Modeling ◽  
Neutron Capture Therapy ◽  
Boron Neutron Capture ◽  
Radiobiological Model ◽  
Biological Effectiveness ◽  
Her 2

Accurate dosimetry and determination of the biological effectiveness of boron neutron capture therapy (BNCT) is challenging because of the mix of different types and energies of radiation at the cellular and subcellular levels. In this paper, we present a computational, multiscale system of models to better assess the relative biological effectiveness (RBE) and compound biological effectiveness (CBE) of several neutron sources as applied to BNCT using boronophenylalanine (BPA) and a potential monoclonal antibody (mAb) that targets HER-2-positive cells with Trastuzumab. The multiscale model is tested against published in vitro and in vivo measurements of cell survival with and without boron. The combined dosimetric and radiobiological model includes an analytical formulation that accounts for the type of neutron source, the tissue- or cancer-specific dose–response characteristics, and the microdistribution of boron. Tests of the model against results from published experiments with and without boron show good agreement between modeled and experimentally determined cell survival for neutrons alone and in combination with boron. The system of models developed in this work is potentially useful as an aid for the optimization and individualization of BNCT for HER-2-positive cancers, as well as other cancers, that can be targeted with mAb or a conventional BPA compound.

scholarly journals NIMG-64. DISTINCT IMAGING PATTERNS OF PSEUDOPROGRESSION IN GLIOMA PATIENTS FOLLOWING PROTON VERSUS PHOTON RADIATION THERAPY

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii162-ii162
Author(s):  
Jerome Graber ◽  
Reed Ritterbusch ◽  
Lia Halasz
Keyword(s):  
Tumor Progression ◽  
Relative Biological Effectiveness ◽  
Clinical Symptoms ◽  
Photon Radiation ◽  
High Dose ◽  
Tumor Type ◽  
Beam Angle ◽  
Biological Effectiveness ◽  
Mri Changes ◽  
Dose Radiation

Abstract PURPOSE Radiologic Assessment in Neuro-Oncology (RANO) criteria define pseudoprogression (Ps) after photon radiation for gliomas, as occurring less than twelve weeks from radiation, within the high dose radiation field. However, some patients receiving proton manifest lesions that appear subjectively different from photon Ps based on timing and location (more than six months from radiation and deeper to the prior tumor), which would be called tumor progression by RANO. We retrospectively reviewed MRI changes after proton or photon radiation for gliomas. We propose criteria to characterize proton pseudoprogression (ProPs) distinct from photon pseudoprogression or tumor progression. METHODS Post-treatment MRIs of patients with gliomas were reviewed, along with clinical and pathological data. 77 proton patients were reviewed for the presence of ProPs, and 64 photon patients were reviewed for imaging changes. Data collected included the location, timing, and morphology of the lesions, tumor type, chemotherapy, and clinical symptoms. RESULTS 16 (21%) of the patients who received protons had imaging changes unique to protons, at a mean of 14.6 months after radiation. We established the following criteria to characterize ProPs: not immediately in or adjacent to the resection cavity; ~ 2cm opposite from target beam entry; can resolve without treatment; subjectively multifocal, patchy, small (< 1cm). None of the photon patients had lesions that met our criteria for ProPs (p< 0.001). CONCLUSION Patients who receive protons can have a unique subtype of pseudoprogression (Ps), which we refer to as proton pseudoprogression (or ProPs). These lesions could be mistaken for tumor progression, but typically resolve spontaneously. ProPs can possibly be explained by the increased relative biological effectiveness of protons and beam angle selection which may deposit at ~2cm deep to the target. Recognizing these lesions can prevent unnecessary treatment for mistaken tumor progression, especially in the context of clinical trials that include proton.

Sign in / Sign up

Export Citation Format

Share Document