The current state-of-the-art in the solid state dosimetry are briefly reviewed and some vision on future trends of advancements in solid state dosimetry technology and their various applications are presented.
There is well established evidence that radiation therapy is making a crucial contribution to long-term survival of childhood cancers, but it is also causing a high evidence of secondary cancers among survivors of childhood cancer. The measurement of out-of-field doses (including concomitant imaging doses) for paediatric population is important for input to epidemiological studies and risk estimations.
Positron emission tomography and other radiation imaging techniques provide biological functions and molecular information. We are developing new sensor technologies and studying new imaging methods, which can be used for new cancer diagnostics and high-resolution tracer imaging, as well as new dosimetry applications.
Main goal of this scientific investigation is the characterization of two applications (“RadioactivityCounter and “GammaPix”) that enable dose-rate measurements with an ordinary smartphone, using the CMOS sensor of the built-in camera as a radiation detector.
Thin polymer films loaded with luminescent materials have been developed for entrance surface dosimetry in radiation protection and clinical applications. Most notably, the films can be shaped as gloves and measure extremity doses without interfering with the tactile sense. Their photon energy dependence improves when worn under shielding gloves.
A series of tests have been performed on active personal dosemeters (APD), with the emphasis on their use in interventional radiology/cardiology radiation fields. The results lead to some recommendations and attention points, mainly focused on the influence of pulsed fields and the lead apron backscatter.
The international intercomparisons for calibration methods of passive dosemeters IC2017calm and IC2018calm were organized by EURADOS to study the precision of calibrations of participating dosimetry services and institutes.
Under optimized conditions, CO2 and UV treatments combined in an original two-phase etching technique increase the total number of tracks by more than 230 % in nuclear track detectors, and the maximum diameter of the tracks by more than 60 %, compared to the standard routine processing.
We present studies using artificial neural networks to investigate the time- and temperature-resolved photon counts from thermoluminescence dosemeters that can yield accurate information not only about the irradiation dose, but also about the time of the irradiation, the number of irradiation fractions and the radiation type. Applied to personal dose monitoring, this introduces additional value to the use of passive dosemeters.
This paper presents the organization details and the analysis of results of the EURADOS intercomparisons 2016 and 2018 for whole body dosemeters in photon and beta fields.
IC2017n was the second EURADOS intercomparison exercise for neutron dosemeters after IC2012n. Previous proficiency tests for neutron personal dosimetry at an international level have been performed irregularly every 8 to 10 years only.
Preliminary measurements indicate that passive detectors show a significant increase in their response when exposed at high current and high voltage generators simulating lightning discharge in laboratory conditions.
(a) Interaction of high-energy protons from galactic origin with the air molecules in the Earth’s atmosphere generates Cosmic Ray Shower (CRS). (b) The CRS is composed of neutrons, electrons, protons, photons, muons and pions of diverse energy and intensity distributions. (c) A TLD-microdosimeter (LiBe-14) based on LiF and BeO TLD chip was developed. (d) LiBe-14 microdosimeter was used to assess the ambient dose equivalent of the CRS at “Kugel Alm” Laboratory located atop mount Zugspitze at the Environmental Research Station (UFS Schneefernerhaus; 2650 m above sea level).
The glass dosimeter (GD) which utilizes the phenomenon of radio- photoluminescence (RPL) is applied to various fields in addition to the individual monitoring. Especially, in order to contribute to restoration of the contaminated area in Fukushima the bead-type and sheet-type glass dosimeters have been developed and utilized to observe the distribution of radioactive contaminants. The new glass material that is resistant to severe environment of high temperature has been developed.
New OSL technique is presented – the harmonically modulated optically stimulated luminescence (HM-OSL). During HM-OSL the stimulating light changes sinusoidally. The OSL response is also sinusoidal. The phase shift between stimulation and OSL is related to several trap parameters. The HM-OSL method was implemented in the Helios OSL reader.
A new sensor based on Al2O3:C has been designed based on the Bragg-Gray cavity theory to improve its energy response. An optimization of the physical parameters using Monte Carlo modeling is presented along with a comparison with experimental results. The metrological performance versus IEC 62387 requirements is also discussed.
To improve angular dependence of a passive-type OSL dosimeter, we fabricated a novel disk-shaped dosimeter which consists of two sensitive regions. The angular dependence of our dosimeters improved without significant loss of the detection efficiency from the results of simulation and experiment
A new approach to the spatial radiation dosimetry based on optically-stimulated luminescence (OSL) is presented. By embedding OSL-active particles into a transparent silicone elastomer matrix, the favorable dosimetric properties of an OSL material are exploited towards spatial OSL dosimeter. The new dosimeter formula, carry the advantages known from personal dosimetry: which is its reusability as they can be reset e.g. by an intense light field (bleaching) as well as storage ability as the dose following irradiation can be stored with extended periods of time.
The next technological breakthrough in tools for radiation protection, medical dosimetry and radiobiology research was achieved with Fluorescent Nuclear Track detectors (FNTD) that have some important advantages in measuring neutrons, high energy heavy charge particles (HCP) and even electrons and photons. Second generation of FNTD reader with improved image quality and 30 times faster scanning was developed.
The MBD-2 Personal Dosimeter is a device which incorporates the benefits of passive radiation detection with active, self-reading and recording functionality but without alarm indication capability. It is a wrist worn watch-type of dosimeter suitable for photon and neutron dose measurements. Data transfer is achieved via Near Field Communication (NFC) or Bluetooth Low Energy (BLE) communication to a smart device (phone, tablet, laptop).
In this study, we propose an original approach for particle discrimination in a mixed radiation field using scintillators. The method relies on the possibility to identify the point of interaction in a phoswich detector from the emission spectra of the produced scintillation light, using optical filters as passive selectors. As a proof of concept, we developed a compact prototype thermal neutron active dosimeter for mixed neutron/γ fields.
Radiation doses received by astronauts outside the geomagnetic field are a main risk factor for human space exploration. Determination of LET spectra is necessary in the standard paradigm of risk assessment for mixed radiation fields1), because it allows calculation of dose equivalent, while identification of ions by species (or at least by group) is required, if the risk assessment tools developed by NASA are used. The MIDAS device is developed with purpose to achieve mass <50 g, volume < 5 x 5 x 1 cm3 and power consumption <10 mW for an instrument capable to determine the fluence spectrum as a function of charge and energy of the impinging particles, at least for those species with the most significant contribution to dose in space. In addition it is capable to measure fast neutron spectra for use either in the ISS environment or as radiation monitor.
Characterization of a pixelated silicon telescope using a microbeam. The low energy tail of the spectrum is due to partial collection of the charge. This solid state telescope is a suitable device for measuring the microdosimetric quantities of light-ion beams.
We succeed in fabricating tailor-made 3D dosimeter with radiochromic material and 3D printer. We propose the novel method to precisely copy the shape of personal internal organs with our 3D printed dosimeter, and use for the more accurate and safe radiotherapy.
This talk presents the recently developed Microdosimetric d(z) Model able to describe and predict the relative efficiency of luminescent detectors for measuring different radiation qualities by studying the changes in the microscopic pattern of energy deposition through an analysis of the simulated microdosimetric specific energy probability distributions in nanometric targets. The model was tested for different types of luminescent detectors, showing a very good agreement with experimentally determined efficiency data.
New experimental data are presented for both natural and laboratory made dosimetric materials, and they are fitted using a quantum tunneling model for luminescence processes. New analytical equations are derived, which are useful metrics in the research areas of retrospective dosimetry, temperature sensing and thermochronometry.
Infrared photoluminescence (IRPL), a new method of trapped charge dating based on non-destructive probe of trapped electrons.
For more than 70 years, defects responsible for the thermoluminescent (TL) glow-curve have been studied experimental and theoretically without a complete understanding. For the first time, a quantum approach based on first principle is used to investigate the role of ionizing radiation on the formation of defects induced by Mg and Ti interstitials in LiF. The results indicated that most of the defects that might be responsible for the complex TL glow curve are created by ionizing radiation.
The real-time response of radiophotoluminescence (RPL) from Ag-doped alkali-phosphate glass during irradiation with high-energy pulsed X-rays from a LINAC is reported. The non-linear growth of RPL versus irradiation time is correlated with the build-up effect for RPL in this material.
Residual dose correction mandatory in ESR dating using Al-hole signals-ESR residuals of Al-hole signals yield hundreds of Gys.
Al-hole residuals increase exponentially with preceding given dose. Mechanism of Al-hole bleaching by electron-hole recombination is supported.
Al-hole signals measured at 90 K are heavily interfered by signals form intrinsic defects (peroxy radicals)
A sum of a single saturating exponential function and a term proportional to the square-root of the accumulated dose describes well the dose response curve of Al-hole signals
A new method of determining equivalent dose (De) for luminescence dating of sediments is presented. This method overcomes the De underestimation problem associated with conventional methods when dating old samples.
Timepix analysis allows spatially-resolved beta dose rates to be estimated for intact sediment samples; Beta dose rates of archaeological and geological samples were studied using this technique and compared with single-grain De values; Beta dose rate heterogeneity contributes about 10–20% to the observed spread in De values for the samples studied.
The positive Electron Paramagnetic Resonance (EPR) signals possibly due to radiation exposure were nondestructively detectable among affected Cattle in Namie town, Fukushima even by using L Band Electron Paramagnetic Resonance Tooth Dosimetry.
Fabrics were used to reconstruct dose following a blind gamma irradiation using luminescence techniques; An indicative accuracy sufficient for medical triage in a radiological emergency was obtained; The use of fabrics potentially provide spatial mapping of dose; Advantages of this approach are the wide availability of fabrics and prompt processing of samples.
Individual variability in the dose-response curves in re-irradiated fingernails was observed. Increasing drying temperature and time generates strong ESR signals.
Particle and Heavy Ion Transport code System, PHITS, is a general purpose Monte Carlo code that can simulate the motion of various particles over wide energy ranges, using several nuclear reaction models and data libraries. This paper summarizes the features of specific functions useful for detector response simulations implemented in PHITS
The intent of this research is to modify the TL dose response of composite peak 5 via excitation following irradiation at appropriate photon excitation energies and to obtain a linear dose response up to at least 30 Gy.
Recombination mechanism in LiF:Mg,Ti detectors (MTS-N) was studied based on spectrally resolved thermoluminescence (SR-TL) measurements. It was found that in the vicinity of the peak 5 of MTS-N detectors the recombination does not obey the pure localized nor pure delocalized mechanism.
The fading of thermoluminescence (TL) and optically stimulated luminescence (OSL) has been studied within the framework of a model with deep-level competing traps, using Monte-Carlo simulations.
Progress is presented on the studies of Radial Electron Fluence around Ion Tracks, REFIT, which has been proposed to describe the detection thresholds of etched track detectors, including the relationship with former experimental results.
High dose irradiation of quartz with 100/200 keV electrons shows a cumulative effect on the luminescence sensitivity, irreversible unless heated to high temperatures (500-700oC). We attribute at least part of these observations to the accumulation of negative charge in the phosphor grains.
BNCT neutron beams can be measured in real time, directly, and easily using the neutron detector (DAD-BNCT) based on combination of thin silicon sensor and thin LiF radiator. The DAD-BNCT can measure thermal neutrons produced at KURRI and NCC BNCT neutron beams, up to 1×109 (n/cm2/s), separately from gamma rays with high dose rates around 500 mGy/h. The DAD-BNCT presents good linear response to neutron flux, and also, could be used to monitor BNCT beams.
The neutron personal dose equivalent, Hp(10), was measured with an electronic neutron dosimeter (ELDO) at different positions around a PMMA phantom at the Heidelberg Ion-Beam Therapy Center (HIT), Germany. The PMMA phantom was irradiated with a mono-energetic beam of protons, helium ions, carbon ions and oxygen ions delivered to the fixed horizontal quality assurance (QA) beam line. Pencil beam scanning (PBS) dose delivery technique was used.
Silicon diode array detectors implemented in various modalities for fast and high resolution beam profiling and range determination for clinical proton therapy beams.
Plastic scintillator fibre-optic dosimeters have been tested for their applicability in synchrotron radiation therapy. Microbeams have been resolved with a 10 μm resolution probe. Sensitivity remains a challenge for this method of dosimetry.
Leksell Gamma Knife dose profiles measured with the small volume point detectors show excellent agreement with the profiles measured in the standard reference geometry with the radiochromic dosimetry film
The response of plastic scintillators and ionization chambers, unlike calorimeters, depend on the linear energy transfer (LET). We propose a graphite calorimeter to investigate the quenching in scintillators and the effect of the LET from all particles.
The issues of safety and security involving nuclear and other radioactive materials in Africa are to be discussed.
The unmanned airborne monitoring system on the basis of a CeBr3 spectrometer is being developed to meet the need for a fast acquisition of metrologically sound data on a large-scale ground contamination following a radiological emergency.
The complexity and machine settings of neurovascular interventional radiology (NIR) procedures result in significantly high occupational exposure to physicians. However, there is a lack of actual measurement and assessment of eye lens dose in recent studies in NIR procedures. In this research, clinical measurements of Hp(3) and Hp(0.07) provide not only the direct dosimetry to the eye lens but also the correlation between eye lens dosimeters and additional over-apron neck personal dosimeters for the estimation of eye lens dose when only Hp(0.07) is available in clinical practices.
The responses of the Glass Badge (GB) system for mixed irradiations were assessed. The responses for 14 877 mixed irradiation combinations with two different radiation qualities were evaluated. It was confirmed that the calculated dose with the GB system was sufficient for practical use. The GB system was met the requirement of IEC 62387 standard.
Asian Radiation Dosimetry Group (ARADOS) was established in 2015 with a main purpose to promote collaborations on the relevant activities among Asian countries. Members of ARADOS discussed its missions and structure in past annual meetings and several collaborative study projects have been launched in the last years. Strategies to further activate ARADOS are now being considered for the next step.
The prompt measurement of dose to individual members of the public exposed during a radiological emergency is critical to medical triage. An assessment is made of the luminescent properties of polymer-based fabrics used in the manufacture of clothing and accessories and their potential to be deployed as dosemeters.
The dosimetric properties of glasses extracted from screen protectors for mobile phones are investigated using thermoluminescence. Their potential use as fortuitous retrospective dosimeters in the event of a radiological accident is discussed.
Uncertainty for OSL on resistors around 25 % (1 sigma); TL method on display glass validated for arbitrary phone sample; ISO 13528 useful for statistical analysis
Protective glasses of modern smartphones were tested with an optically stimulated luminescence (OSL) technique. An optical fiber was used to deliver the stimulation light to the glass and collect the emission back. This enables the potential for the prompt dose evaluation without disassembly of the phone. The current sensitivity of this technique is several Gy depending on the phone manufacturer and model.
Dosimetry of a gamma-irradiated phantom exposed in different geometries. Dose estimation using MC simulations and comparison with experimental measurements using external smartphones and internals TLDs. Calculations of conversion factor for dose from smartphones to dose to internal organs.
Solid-state detectors have favorable features with potential to develop the next generation of detectors for applications in complex radiation fields generated by new radiotherapy technologies.
A proton pencil-beam scanning (PBS) and passive double scattering (DS) systems at the proton therapy centres at Massachusetts General Hospital (MGH), USA and University Medical Center Groningen (UMCG), Netherlands have been characterised using 3D silicon microdosimeter. Recently measured dose mean lineal energy values (y–D) ̅at UMCG were compared to LETd values calculated for delivered plan by Raystation (v5.99) treatment planning system (TPS) in a head and neck anthropomorphic phantom and the relative biological effectiveness (RBE) of the beam are presented.
There has been a rapid increase in the use of small fields in modern radiotherapy techniques such as stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SBRT). The dosimetry of megavoltage small fields can be challenging due to lateral charged particle disequilibrium, detector volume averaging effect, and high dose gradients. 3-D radiochromic plastic dosimeter, PRESAGE, can be used to acquire small-field beam data as well as patient-specific IMRT/VMAT QA precisely and accurately.
We developed an integral condenser dosimeter with a surface-mounted silicon X-ray diode, Patient-skin doses using 4 MV radiotherapy can be measured, Integral doses measured corresponded well to those of ionization chamber with small SDs.
A mini-TEPC without gas flow measures y–D and µRBE of a therapeutic proton beam. The y–D values are equal to (LET)–D calculated values. The µRBE values are almost the same as the RBE values. The detector response does not change over time.
This presentation reviews the data on the optically stimulated luminescence (OSL) of BeO in light of the recent discovery of strong thermally transferred OSL (TT-OSL) in this material. We discuss how the existing contradictions may be solved by the new information available and present a model for BeO that takes into account these findings.
TL and OSL signals of MgO doped with various lanthanides were investigated. A recombination mechanism for the TL and OSL signal in MgO was proposed.
The paper discusses dosimetric characterization of various phosphors developed at Bhabha Atomic Research centre (BARC)
New approach to obtain optical trap depth and excited states of the principal trap in feldspar. UV resonance in the excitation spectra indicates the existence of a deep electron trap.
TL, PL and optical absorption of calcium silicate produced in our Laboratory was studied. The results indicate that calcium silicate undoped or doped with silver could be suitable for use as TL, OSL or RPL dosimeters.
The radiation response of rare earth doped silica glasses fabricated using powder sintering (REPUSIL) and melt quenching (termed SAL) were investigated. Extreme sensitivity was observed and rare earth doped glasses were identified for a range of radiation detection applications.
Absorbed doses from 64Cu are evaluated using Fluorescence Nuclear Track Detector (FNTD).
RPL dosimeters were applied to measurements of mammograph diagnostic doses for the improvement of radiation protection of patients. Two-dimensional dose distribution graphs were plotted, using RPL dosimeters, to observe the uniformity of the field emitted by conventional and microdose mammography equipments.
Out of field doses of scattered radiation in proton radiotherapy are lower in comparison to different photon radiotherapy techniques for the same delivered tumour dose