State of The Art of Instrumentation in Experimental Nanodosimetry

Bantsar, A.; Colautti, P.; Conte, V.; Hilgers, G.; Pietrzak, Marcin; Pszona, S.; Rabus, Hans; Selva, A. Della

doi:10.1093/rpd/ncx263

Cited by 23 publications

(11 citation statements)

References 5 publications

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“…24 If probability distributions of ionizations are investigated instead of distributions of energy imparted, volumes down to single nm are reachable with measurements. 25,26 Interestingly, the ionization probability distribution in a propane-based tissue-equivalent gas has been shown to be close to the distribution in water following the traditional simulation principle but weighted with the ratio of the mean-free ionization path lengths of the particle in the two matters. 27,28 Relations between cell inactivation cross-sections derived from cell survival curves after proton irradiation and the first moment of the frequency of ionizations and different cumulative ionization functions have been published for cylindrical volumes of about 1 nm in diameter and height.…”

Section: Introductionmentioning

confidence: 91%

Dose‐mean lineal energy values for electrons by different Monte Carlo codes: Consequences for estimates of radiation quality in photon beams

et al. 2021

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Background:The microdosimetric quantity lineal energy and its mean values have proven useful for quantifying radiation quality in many situations. The ratio of dose-mean lineal energies is perhaps the simplest quantity for quantifying differences between two radiation qualities. However, published dose-mean lineal energy values from different codes may differ significantly with potential influence on radiation quality estimates. Purpose: The purpose was to compare dose-mean lineal energy values from different track-structure data sets for condensed water vapor and liquid water, and to evaluate the influence on radiation quality estimations for some photon sources. Methods: Published dose-mean lineal energy values for 0.1 keV to 1 MeV electrons in spheres with diameters 2 nm to 1 μm, calculated with water vapor and liquid water track structure codes and proximity functions, were collected, analyzed, and compared. Data for cylinders were converted to spheres using a theoretical transformation published by Kellerer. A new set of dose-mean lineal energy values was calculated to cover the whole range of volumes of interest here using the GEANT4-DNA code. The influence from the differences between codes on radiation quality calculations was estimated using dose-mean lineal energy ratios for the photon sources 125 I, 169 Yb, and 192 Ir relative to 60 Co. Results: The theoretical relation for converting the dose-mean lineal energy between different geometrical volumes, results in differences up to 10% between cylinders and spheres depending on electron energy and target size, in agreement with published simulated results. For spheres with diameter above 100 nm, dose-mean lineal energy values for condensed water vapor and liquid water are with few exceptions within ±10%. Below 100 nm, the difference increases with decreasing diameter reaching a factor of two at 2 nm. The values from water vapor codes are in general larger than from liquid water codes. If the dose-mean lineal energy ratio is based on condensed water vapor instead of liquid water, the ratio differs less than 9% for the nuclides 125 I, 169 Yb, and 192 Ir relative to 60 Co independent of the volume simulated. However, a specific value of the dose-mean lineal energy ratio, is found at a larger target diameter in liquid water than in condensed water vapor. Conclusions: When ratios of the dose-mean lineal energy are used as a measure of the radiation quality it is important to compare values for geometrically equal target shapes. A practical method of converting values for cylinders of equal diameter and height to spheres was demonstrated. Although dose-mean lineal energy values calculated with water vapor and liquid water codes may differ significantly, the radiation quality, in terms of ratios of dose-mean lineal 1286

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Section: Introductionmentioning

confidence: 91%

Dose‐mean lineal energy values for electrons by different Monte Carlo codes: Consequences for estimates of radiation quality in photon beams

et al. 2021

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“…Develop density scaling relationships for micro- and nano-dosimetry ( 19 , 20 ) using theoretical and simulation studies as well as the characterisation of existing ( 21 ) and emerging nanodosimetric detectors ( 22–24 ) .…”

Section: Vision 1: Towards Updated Fundamental Dose Concepts and Quantitiesmentioning

confidence: 99%

Eurados Strategic Research Agenda 2020: Vision for the Dosimetry of Ionising Radiation

Harrison

Ainsbury

Alves

et al. 2021

Radiation Protection Dosimetry

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Since 2012, the European Radiation Dosimetry Group (EURADOS) has developed its Strategic Research Agenda (SRA), which contributes to the identification of future research needs in radiation dosimetry in Europe. Continued scientific developments in this field necessitate regular updates and, consequently, this paper summarises the latest revision of the SRA, with input regarding the state of the art and vision for the future contributed by EURADOS Working Groups and through a stakeholder workshop. Five visions define key issues in dosimetry research that are considered important over at least the next decade. They include scientific objectives and developments in (i) updated fundamental dose concepts and quantities, (ii) improved radiation risk estimates deduced from epidemiological cohorts, (iii) efficient dose assessment for radiological emergencies, (iv) integrated personalised dosimetry in medical applications and (v) improved radiation protection of workers and the public. This SRA will be used as a guideline for future activities of EURADOS Working Groups but can also be used as guidance for research in radiation dosimetry by the wider community. It will also be used as input for a general European research roadmap for radiation protection, following similar previous contributions to the European Joint Programme for the Integration of Radiation Protection Research, under the Horizon 2020 programme (CONCERT). The full version of the SRA is available as a EURADOS report (www.eurados.org).

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“…For example, the equivalent mean path length in a TEPC can be selected by adjusting the operational pressure, but it is typically limited to a few micrometres, with a lower limit of operation of 0.3 µm in case of special design [53], which is not enough to obtain details on the particle track structure. Detectors with the best spatial resolutions tend to be complex and bulky [54]. Furthermore, conventional TEPCs feature only a single readout channel in a detection volume of fixed dimensions.…”

Section: Microdosimetrymentioning

confidence: 99%

Medical Applications of the GEMPix

2021

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The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 µm pixel pitch and a total of 262,144 pixels. A continuous flow of a gas mixture such as Ar:CO2:CF4, Ar:CO2 or propane-based tissue equivalent gas is supplied externally at a rate of 5 L/h. This article reviews the medical applications of the GEMPix. These include relative dose measurements in conventional photon radiation therapy and in carbon ion beams, by which on-line 2D dose images provided a similar or better performance compared to gafchromic films. Depth scans in a water phantom with 12C ions allowed measuring the 3D energy deposition and reconstructing the Bragg curve of a pencil beam. Microdosimetric measurements performed in neutron and photon fields allowed comparing dose spectra with those from Tissue Equivalent Proportional Counters and, additionally, to obtain particle track images. Some preliminary measurements performed to check the capabilities as the detector in proton tomography are also illustrated. The most important on-going developments are: (1) a new, larger area readout to cover the typical maximum field size in radiation therapy of 20 × 20 cm2; (2) a sealed and low-pressure version to facilitate measurements and to increase the equivalent spatial resolution for microdosimetry; (3) 3D particle track reconstruction when operating the GEMPix as a Time Projection Chamber.

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State of The Art of Instrumentation in Experimental Nanodosimetry

Cited by 23 publications

References 5 publications

Dose‐mean lineal energy values for electrons by different Monte Carlo codes: Consequences for estimates of radiation quality in photon beams

Dose‐mean lineal energy values for electrons by different Monte Carlo codes: Consequences for estimates of radiation quality in photon beams

Eurados Strategic Research Agenda 2020: Vision for the Dosimetry of Ionising Radiation

Medical Applications of the GEMPix

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