Experimental microdosimetry is concerned with the determination of radiation quality and how this can be specified in terms of the distribution of energy deposition arising from the interaction of a radiation field with a particular target site. This paper discusses various techniques that have been developed to measure radiation energy deposition over the three orders of magnitude of site-size; nanometer, micrometer and millimetre, which radiation biology suggests is required to fully account for radiation quality. Inevitably, much of the discussion will concern the use of tissue-equivalent proportional counters and variants of this device, but other technologies that have been studied, or are under development, for their potential in experimental microdosimetry are also covered. Through an examination of some of the quantities used in radiation metrology and dosimetry the natural link with microdosimetric techniques will be shown and the particular benefits of using microdosimetric methods for dosimetry illustrated.
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http://dx.doi.org/10.1093/rpd/ncl497 | DOI Listing |
Med Phys
January 2025
Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, USA.
Purpose: In locations where the proton energy spectrum is broad, lineal energy spectrum-based proton biological effects models may be more accurate than dose-averaged linear energy transfer (LET) based models. However, the development of microdosimetric spectrum-based biological effects models is hampered by the extreme computational difficulty of calculating microdosimetric spectra. Given a precomputed library of lineal energy spectra for monoenergetic protons, a weighted summation can be performed which yields the lineal energy spectrum of an arbitrary polyenergetic beam.
View Article and Find Full Text PDFJ Radiat Res
December 2024
The Center for Peace, Hiroshima University, Higashisenda-machi 1-1-89, Naka-ku, Hiroshima 730-0053, Japan.
Radiobiological studies are ongoing to understand the consequences of internal exposure to neutron-activated radioactive microparticles, which were sprayed over experimental rats and mice. Special attention in these experiments is given to internal irradiation with radioactive microparticles with short-lived neutron-activated radionuclides 31Si (T1/2 = 2.62 h) and 56Mn (T1/2 = 2.
View Article and Find Full Text PDFPhys Med Biol
January 2025
Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia.
the recently developed V79-RBEbiological weighting function (BWF) model is a simple and robust tool for a fast relative biological effectiveness (RBE) assessment for comparing different exposure conditions in particle therapy. In this study, the RBEderived by this model (through the particle and heavy ion transport code system (PHITS) simulatedspectra) is compared with values of RBEusing experimentally derivedspectra from a silicon-on-insulator (SOI) microdosimeter.experimentally measuredspectra are used to calculate an RBEvalue utilizing the V79-RBEBWF model as well as the modified microdosimetric kinetic model (MKM) to produce an RBE-vs-trend for a wide range of ions.
View Article and Find Full Text PDFPhys Med Biol
December 2024
Trento Institute for Fundamental Physics and Application (TIFPA), via Sommarive 15, 38123 Trento, Italy.
. The present work shows the first extensive validation of the(GSM). This mechanistic and probabilistic model is trained and tested over cell survival experiments conducted with two cell lines (H460 and H1437), three different types of radiation (protons, helium, and carbon ions), spanning a very broad LET range from1 keVμm-1up to more than300 keVμm-1.
View Article and Find Full Text PDFPhys Med Biol
December 2024
NPL-National Physical Laboratories, Teddington, United Kingdom.
Microdosimetry is gaining increasing interest in particle therapy. Thanks to the advancements in microdosimeter technologies and the increasing number of experimental studies carried out in hadron therapy frameworks, it is proving to be a reliable experimental technique for radiation quality characterisation, quality assurance, and radiobiology studies. However, considering the variety of detectors used for microdosimetry, it is important to ensure the consistency of microdosimetric results measured with different types of microdosimeters.
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