Thermoluminescent detectors applied in individual monitoring of radiation workers in Europe—a review based on the EURADOS questionnaire

Among the activities of EURADOS Working Group 2 formed by experts from several European countries is the harmonisation of individual monitoring as part of radiation protection of occupationally exposed persons. Here, we provide information about thermoluminescent detectors (TLDs) applied by the European dosimetric services and the dosimetric characteristics of dosemeters in which these detectors are applied. Among 91 services from 29 countries which responded to the EURADOS questionnaire, 61 apply dosemeters with TLDs for the determination of personal dose equivalent Hp(10) for photons and beta radiation, and 16 services use TLDs for neutron albedo dosemeters. Those most frequently used are standard lithium fluoride TLDs (mainly TLD-100, TLD-700, Polish MTS-N and MTS-7, Russian DTG-4), high-sensitive lithium fluoride (GR-200, MCP-N) and lithium borate TLDs. Some services use calcium sulphate and calcium fluoride detectors. For neutron dosimetry, most services apply pairs of LiF:Mg,Ti TLDs with 6Li and 7Li. The characteristics (energy response) of individual dosemeters are mainly related to the energy response of the detectors and filters applied. The construction of filters in dosemeters applied for measurements of Hp(10) and their energy response are also reviewe

Individual monitoring for internal exposures in Europe: Conclusions of an EURADOS action

Once the EC Directive 96/29 has been implemented into national regulation across Europe, the coordination of dosimetry laboratories for the monitoring of occupational exposures becomes the principal aim to achieve. Within this framework the European Radiation Dosimetry Group, EURADOS, carried out an Action on ‘Harmonisation of Individual Monitoring' (2000-2004) to promote coordination in the field of individual monitoring of occupational exposures throughout Europe. With reference to internal exposures, the main aims were the completion of a catalogue of internal dosimetry services and an inventory of methods and techniques used for individual monitoring at European internal dosimetry facilities. At the end of this EURADOS Action, a report was published in Radiation Protection Dosimetry in 2004. The information collected related to various topics: the equipments used for the measurement of internal exposures, calibration and sensitivity data, the methods applied for the assessment of internal doses, Quality Control procedures, Quality Assurance Programmes in the facilities and legal requirements. The information to be presented here will give a general overview of the actual status of individual monitoring for internal exposures in Europ

Some clinical applications of MTS-type TLD detectors

An important part of any QA programme for radiotherapy is verification, in vitro or in vivo, of calculated doses and dose distributions. We studied the clinical applicability of LiF:MG, Ti sintered TL detectors produced, as type MTS-N, by the Institute of Nuclear Physics in Kraków (INP). These are solid pellets of diam 4.5mm and 0.8mm thickness. The TL reader was a modified planchet-type 770A, also produced at the INP, with linear heating and computerised glow curve recording.For analysis of in vivo applications, we measured, in a water phantom, the dose at 14 points aroud the Standard gynaecological applicator of our SELECTRON LDR/MDR afterloading unit with Cs-137 pellets and compared the measured values with doses calculated at these points by the in-house developed SELKOM computer code used for planning gynaecological brachytherapy at the Centre of Oncology in Kraków (COK). Agreement to within 5% was stated.To demonstrate the applicability of MTS dosemeters in calibration dosimetry, we studied the accuracy, stability and reproducibility of a batch of 100 detectors over several readout cycles at doses ranging from 0.5 to 2.5 Gy. At 1 Gy, the relative standard deviation of Individual Calibration Factors (ICF) over six readout cycles did not exceed 2.5% indicating that the error of dose estimation using individual MTS detectors should not exceed 2%.In an intercomparison of Co-60 beams at the COK and at Louvain performed with MTS detectors agreement to within less than 0.5% was found with an accuracy better than 1%.This work is partly supported by KBN Polish State Committee for Scientific Research, Research Project No. 8T11E02908

A catalogue of dosemeters and dosimetric services within Europe—an update

The catalogue of dosemeters and dosimetric services within the European Union (EU) Member States and Switzerland that was issued by EURADOS in the year 2000 has been updated and extended with information on dosimetric services in the new EU Member States and Bulgaria, Croatia, Romania, Serbia and Montenegro, and Ukraine. The total number of dosimetric services in these European countries is now estimated to be about 200. The present catalogue is based on information collected from 90 European dosimetric services, among which 34 questionnaires from 32 services were obtained over the years 2001-2004 for the first time. This article assesses and updates the present use of personal dosemeters and the extent to which occupationally exposed persons in Europe are monitored with dosemeters able to measure the operational quantity—personal dose equivalent, HP(d). The perspective of joining EU by the new countries accelerated the implementation of the EU Basic Safety Standard Directive to their national regulations. As a result, all newly investigated services reported their ability to measure HP(d). The catalogue provides information on the dosemeters, dose calculation and background subtraction algorithms, calibration methods, energy and angular response, and performanc

Preliminary studies of sediments from the Dobczyce drinking water reservoir

The analysis of river and lake sediments indicates that the physical, chemical, biochemical and geochemical processes that influence the fate of toxic compounds and elements in sediments are numerous and complex (for example: sorption - desorption, oxidation - reduction, ion-exchange, biological activity). Due to the above-mentioned general statement, only a long term and complex research programme can lead to satisfactory answers to the questions relating to possible changes of water and environmental quality in the future. The aim of our study consisted in physical and chemical characterisation of sediments in in-depth profiles taken from the Dobczyce reservoir in southern Poland that is a main source of drinking water for the city of Kraków. Due to morphological reasons, 7 layers of sediment samples were distinguished from the ground level to about 90 cm below (total thickness of the sediments in the sampling site). Analysis of grain size distribution and application of x-ray diffraction method, enabled mineralogical description of sediments. The use of proton-induced x-ray emission (PIXE) and atomic absorption spectrometry (AAS) revealed elemental composition of the samples (Al, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn). Concentrations of natural 40K and artificial 137Cs radionuclides were determined by the use of gamma spectrometry. The following facts were established: 1) the oldest (deepest) and newest, recently deposited layers of sediments are similar in their physical and chemical properties. It means that the inflow of contaminants and biogenic compounds to the reservoir has changed little since it was constructed and filled with water; 2) the severe flood in 1997 changed significantly sediment composition and, in fact, led to purification of sediments in the Dobczyce reservoir

Characterization of a novel proton-CT scanner based on Silicon and LaBr3_3(Ce) detectors

Treatment planning systems at proton-therapy centres generally use X-ray computed tomography (CT) as primary imaging technique to infer the proton treatment doses to tumour and healthy tissues. However, proton stopping powers in the body, as derived from X-ray images, suffer from important proton-range uncertainties. In order to reduce this uncertainty in range, one could use proton-CT images instead. The main goal of this work is to test the capabilities of a newly-developed proton-CT scanner, based on the use of a set of tracking detectors and a high energy resolution scintillator for the residual energy of the protons. Different custom-made phantoms were positioned at the field of view of the scanner and were irradiated with protons at the CCB proton-therapy center in Krakow. We measured with the phantoms at different angles and produced sinograms that were used to obtain reconstructed images by Filtered Back-Projection (FBP). The obtained images were used to determine the capabilities of our scanner in terms of spatial resolution and proton Relative Stopping Power mapping and validate its use as proton-CT scanner. The results show that the scanner can produce medium-high quality images, with spatial resolution better than 2 mm in radiography, below 3 mm in tomography and resolving power in the RSP comparable to other state of the art pCT cameras

Proton radiographs using position-sensitive silicon detectors and high-resolution scintillators

Proton therapy is a cancer treatment technique currently in growth worldwide. It offers advantages with respect to conventional X-ray and $\gamma$-ray radiotherapy, in particular, a better control of the dose deposition allowing to reach a higher conformity in the treatments. Therefore, it causes less damage to the surrounding healthy tissue and less secondary effects. However, in order to take full advantage of its potential, improvements in treatment planning and dose verification are required. A new prototype of proton Computed Tomography scanner is proposed to design more accurate and precise treatment plans for proton therapy. Here, results obtained from an experiment performed using a 100-MeV proton beam at the CCB facility in Krakow (Poland) are presented. Proton radiographs of PMMA samples of 50-mm thickness with spatial patterns in aluminum were taken. Their properties were studied, including reproduction of the dimensions, spatial resolution and sensitivity to different materials. They demonstrate the capabilities of the system to produce images with protons. Structures of up to 2 mm are nicely resolved and the sensitivity of the system was enough to distinguish thicknesses of 10 mm of aluminum or PMMA. This constitutes a first step to validate the device as a proton radiography scanner previous to the future tests as a proton CT scanner.Comment: 7 pages, 11 figures, submitted to IEEE TNS ANIMMA 2021 Conference Proceeding

24. Validation of conformal radiotherapy treatment planning systems using an antro-pomorphic phantom and thermoluminescence dosimetry

Within the requirements of a Quality Assurance programme in a radiotherapy department, the ability of a treatment planning system (TPS) to accurately calculate dose distributions under realistic conditions encountered in radiotherapy (RT) should be validated. This may be accomplished by thermoluminescence (TL) dosimetry in simulated treatment of antropomorphic phantoms. In our radiotherapy department, several planning systems are used concurrently in 3D conformal treatment of larger volumes (with irregular fields obtained via individual shielding or multileaf collimation) and of very small volumes (stereotactic technique), by external megavoltage photon beams. Realistic 3D treatment plans were prepared using CadPlan, Theraplan and BrainLab TPS for treating volumes in an Alderson phantom, which was prepared for topometry (CT-scanned) and irradiated in fully simulated conditions of patient RT. Suitably selected TL detectors (some custom-produced for these measurements), were placed inside and around the treated volumes in the phantom. For every photon beam applied (Co-60, 6 MV or 9 MV) the TL detectors, individually corrected, were calibrated in a standard solid phantom against ionisation chamber dosimetry. For irradiation of larger volumes, standard MTS-N (LiF:Mg,Ti) detectors were used. For stereotactic irradiation of small volumes in the head (6 MV) special miniature thermoluminescent LiF:Mg,Ti and LiF:Mg,Cu,P were developed. The technique of detector calibration, preparation of Alderson phantom for simulated RT, detector readout and interpretation of the measured versus calculated values of dose at measurement points inside the phantom, will be described