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The Total Skin Electron Beam (TSEB) irradiation is a radiotherapeutic technique that aims to provide the patient's skin surface with a more homogeneous dose, in order to treat cutaneous T-cell lymphomas, both for curative and palliative purposes. Electron irradiation penetrates a few millimeters into the skin, reaching the affected parts completely, without penetrating the internal organs. In vivo dosimetry has become an important role for the treatment of total skin irradiation within a rigorous quality assurance program that should be an integral part of the radiotherapy departments. The use of TLDs in vivo can identify variations in the prescribed dose because its measurement accuracy and great precision. The LiF:Mg,Ti is the most used TL material and widely studied in radiotherapy dosimetry due to near tissue-equivalence of the material, along with its overall reliability. The dosimeters of μLiF:Mg,Ti have been gaining considerable importance in the radiotherapy departments. These detectors allow measurements in vivo with great advantages due to their minimum dimensions of 1 × 1 × 1 mm 3 . This paper reports a comparative study of the TL responses of both materials to dose evaluation in TSEB treatments. The TL response of both materials in several TSEB parameter tests and in clinical application were evaluated, analyzing the dose distribution in a treatment simulation using AldersonRando anthropomorphic phantom. The results showed that the μLiF:Mg,Ti presented greater variation of the response in relation to LiF dosemeters in some parameters analyzed, due to the small dimensions and to evaluate doses absorbed in the surface over a large area in the treatment plan. • LiF:Mg,Ti TLdosimeters applied to TSEB six-dual-field parameter's evaluation. • μLiF:Mg,Ti TL dosimeters applied to TSEB compared with LiF:Mg,Ti. • LiF:Mg,Ti and μLiF:Mg,Ti TL results comparison. [ABSTRACT FROM AUTHOR]

Abstract A TEPC capable of simulating site sizes down to 25 nm was designed and constructed in order to fill the gap between nanodosimetry and experimental microdosimetry. In this paper, this device was proposed for assessing the quality of the therapeutic CATANA (INFN-LNS) proton beam. The detector was irradiated with a modulated 62 MeV proton beam and was placed at different depths across the spread-out of Bragg peak. For each position, several microdosimetric distributions for different simulated site size from 0.5 μm to 35 nm were acquired. The 0.5 μm spectra are in good agreement with spectra measured employing a reference TEPC in the same experimental conditions. The results show that, for bigger sites, microdosimetric distributions follow the slowing down of the primary particles, while, for smaller sites, they exhibit a bimodal shape, in particular at smaller depths in PMMA. The comparison between different simulated volumes shows an increment of the dose-averaged lineal energy with the reduction of the site. Moreover, a comparison between a ratio of the dose-averaged lineal energy for different simulates site sizes and the microdosimetric R B E shows that the smaller is the simulated volume, the better is the resembling of the microdosimetric R B E even if, the agreement is not yet fully reached for any site size. Finally, Monte Carlo simulations show that the electron energy threshold in FLUKA is too high for reproducing microdosimetric distributions for nanometric sites for proton beams. Highlights • Avalanche-confinement TEPC able to simulate site sizes down to nanometric region. • Nano-microdosimetric characterization of the CATANA proton beam line. • New methods for assessing the relative biological effectiveness of a proton beam. [ABSTRACT FROM AUTHOR]

Abstract This paper presents experimental and theoretical determination of CR-39 and Makrofol calibration coefficients in diffusion chambers for radon measurements. Experimental calibration was performed by irradiation of detectors in a calibration chamber; radon concentration in the chamber was continuosly measured by RAD7 device. Calculations were performed by the previously developed software for CR-39 detector. In addition the software was modified to enable calculation for Makrofol by implementing V function and other relevant data for this kind of detector. A good agreement was found between experimental and theoretical approaches. The comparison enabled selecting V function for CR-39 that gave the best agreement with the experimental results. Optimisation of chamber and detector dimensions was theoretically performed for different etching times. The dependence of calibration coefficient on 218Po deposition fraction was also analysed. Highlights • Experimental and theoretical calibration of CR-39 and Makrofol detectors were done. • V function for Makrofol was presented. • Previously developed software was modified to enable Makrofol calibration. • Optimisation of chamber and detector dimensions was theoretically performed. [ABSTRACT FROM AUTHOR]

The paper presents the dosimetric characterization of lithium calcium aluminum fluoride doped with europium and yttrium (LiCaAlF 6 :Eu,Y), synthesized by simple melt process. The characterization involved thermoluminescence (TL), optically stimulated luminescence (OSL), photoluminescence (PL) spectra, OSL emission spectra, minimum measurable dose, fading, dose response and photon energy dependence measurements. The OSL sensitivity of this phosphor to ionizing radiation was found to be ∼20 times to that of commercially available Al 2 O 3 :C, whereas, the TL sensitivity was ∼2.5 times to that of CaSO 4 :Dy (0.05 mol%). Photoluminescence (PL) and OSL emission spectra suggest that the Eu 2+ ions are responsible for OSL emission. The reusability of OSL discs for 50 cycles for a test dose of 20 mGy has been established. Minimum detectable dose for the phosphor in continuous wave OSL (CW-OSL) mode was found to be 0.5 μGy with negligible fading post 9 days of irradiation. Owing to its excellent dosimetric characteristics the phosphor is a highly sensitive dosimetric grade phosphor and is a serious contender for various radiological applications. [ABSTRACT FROM AUTHOR]

The tissue equivalent proportional counter (TEPC) is the most accurate device for measuring the microdosimetric properties of a particle beam, showing to assess the relative biological effectiveness by linking the physical parameters of the radiation field with the corresponding biological response. Nevertheless, no detailed information on the track structure of the impinging particles can be obtained, since the lower operation limit of the common TEPCs is about 0.3 μm. On the other hand, the pattern of particle interactions at the nanometer level, which demonstrated to have a strong correlation with radiation-induced damages to the DNA, is measured directly by only three different nanodosimeters worldwide: practical instruments are not yet available. The gap between microdosimetry and track-nanodosimetry can be filled partially by extending the TEPC response down to the nanometric region. A feasibility study of a novel TEPC designed to simulate tissue-equivalent sites in the nanometric domain was performed. The present paper aims at describing the design, the development and the characterization of this avalanche-confinement TEPC. Irradiations with photons, fast neutrons and low-energy carbon ions demonstrated the capability of this TEPC of measuring in the range 0.3 μm–25 nm. [ABSTRACT FROM AUTHOR]

Thermoluminescence (TL) glow curves from feldspar samples have been studied extensively in luminescence dating and dosimetry applications. However, the mechanism responsible for their unusual shape and behavior in preheated samples is not well understood. This paper presents new experimental TL glow curves for four types of preheated feldspar samples; an orthoclase, a sanidine and two microclines. Both the preheat temperature and the duration of the preheat are varied, before measurement of the remnant TL glow curve. Kinetic analysis of the experimental results is carried out using a recently proposed physical kinetic model which describes localized electronic recombination in a random distribution of donor-acceptor pairs, with nearest-neighbor interaction. The experimental data are analyzed using two different methods within the model. In the first method one follows the development of the distribution of nearest neighbor distances for each of the four stages of the experiment, namely irradiation followed by heating to a temperature and holding the sample at this temperature for certain time, and finally measurement of the TL glow curve. In the second method the TL glow curves are analyzed by using a single adjustable parameter in the model, which characterizes the thermal history of the sample. Good agreement is found between the two methods. However, the second method is much simpler to use in practical situations, and in principle it can be applied for any thermally or optically pretreated feldspar sample. [ABSTRACT FROM AUTHOR]

Extended Bonner Spheres spectrometer was used to measure the angular distribution of neutron spectral fluence around NYLON6 phantom irradiated with pencil beam of 100, 150 and 200 MeV protons at the Proton Therapy Center Praha. Measurements were supplemented by a calculation of neutron spectral fluences at different depths of the phantom. The calculation of neutron spectral fluence at different depth of the phantom demonstrated that the majority of high energy neutrons was generated at the beginning of the proton trajectory in the phantom and the neutron yield decreased with increasing depth, with a minimum at the depth corresponding to the Bragg peak. Therefore, attention should be paid not only to the tissue behind the irradiated volume, but also to the preceding tissue. However, the neutron spectral fluence in the vicinity of the treated tissue can only be determined by calculation, mainly due to the dimensions of the neutron spectroscopic instrumentation. This paper presents a suitable technique and experimental conditions to acquire reliable data necessary for the proper determination of neutron spectral fluence. From the measured spectral fluences, the neutron fluence in whole-range and partial energy intervals were determined together with the corresponding ambient dose equivalents at measurement positions. The obtained results indicate that high energy neutrons predominate at the direction of the proton beam and more neutrons are generated by higher energy protons. [ABSTRACT FROM AUTHOR]

In the present paper the formation of defects in LiKSO 4 andK 2 SO 4 crystals after excitation by 4–11 eV photons at the temperature of liquid nitrogen was studied by the methods of thermal activation and vacuum-ultraviolet spectroscopy. It is shown experimentally that electron-hole trapping centers are formed as a result of capture of electrons and holes by anion complexes S O 4 2 − created by the transition of electrons from 1t 1 ; 3t 2 ; e; 2t 2 orbitals in the valence band to the s-state of the cation in the conduction band. It is supposed that the formation of defects in LiKSO 4 and K 2 SO 4 crystals is caused by the dissociation of excited anion complexes, created by the transition of electrons from 1t 1 ; 3t 2 ; e; 2t 2 orbitals in the valence band to free, antibinding orbitals 4 t 2 ∗ and 3 a 1 ∗ in the conduction band. In this case, stable electron S O 3 − v a + e − and hole O 3 − trapping centers are formed. [ABSTRACT FROM AUTHOR]

This work aims at assessing the performance of a235U enriched fission chamber in order to localize fuel debris, prior to dismantling operations, in a flooded primary containment vessel of a damaged nuclear reactor such as Fukushima Daiichi. Based on both a comprehensive scan of the environment and the detection of neutrons emitted by the melted core, fuel debris can be localized. In this paper, we carry out a simulation study using the MCNP6 code to investigate fission chamber response in the frame of fuel debris localization measurements in a damaged nuclear reactor. The CFUF34 fission chamber (manufactured by PHOTONIS) and the primary containment vessel of Fukushima Daiichi Unit 1 were chosen to conduct this work. Impact of different parameters were investigated with MCNP6, such as: neutron energy, water temperature, fission chamber position (altitude, lateral shift, and rotation), and sensitivity loss due to sediments potentially covering fuel debris. In summary, we show that fuel debris should be sought by their thermal neutron signature at a distance of a few centimeters and that potential rotational movements of the fission chamber up to 60° have a limited impact on signals measured. We also show that sensitivity loss due to sediments potentially covering fuel debris has been evaluated on the order of a factor 10 considering a 30 cm-thick sediment layer. On the other hand, experiments were performed to assess the impact of a strong gamma dose rate on fission chamber measurements. These irradiation trials involved a CFUE32 fission chamber (also manufactured by PHOTONIS) available in our laboratory and three different irradiation means: an X-ray tube, an 192Ir source, and a linear electron accelerator. These experiments enable to draw the conclusion that the fission chamber is not impacted by the gamma dose rate up to 104 Gy h−1, which is in good agreement with specifications provided by the manufacturer (PHOTONIS). In addition, no performance degradation was observed after an integrated gamma dose of 2200 Gy on the fission chamber in a 10 min irradiation. However, when the fission chamber is irradiated by gamma dose rates above 104 Gy h−1 (upper limit of the operating domain specified by PHOTONIS), a significant gamma background is observed. Nevertheless, as the gamma dose rates at Fukushima Daiichi should not exceed 103 Gy h−1, fission chamber measurements performed towards fuel debris localization in the primary containment vessels of the units would not be affected by the severe gamma-ray irradiation. • Investigation of fission chamber response in the frame of fuel debris localization measurements by MCNP6 simulation study. • Fuel debris sought underwater by their thermal neutron signature at a distance of a few centimeters. • Sensitivity loss on the order of a factor 10 considering a 30 cm-thick sediment layer on the top of fuel debris. • Experiments to assess the impact of strong gamma dose rates on fission chamber measurements. • No impact of gamma dose rates up to 104 Gy h−1. Beyond, the fission chamber registers a significant gamma background. [ABSTRACT FROM AUTHOR]

The response of the photochromic compound 2,3-dihydro-2-spiro-4'-[8′-aminonaphtalen-1′(4′H)-on]perimidine (PNO-p) dispersed in a polystyrene (PS) and a polymethyl methacrylate (PMMA) film to X-ray irradiation was evaluated with the aim to develop an organic dosimeter. The effect of co-doping with the organic phosphor 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (b-PBD) on the sensitivity to X-ray irradiation was also determined. The photochromic reaction of PNO-p was induced by X-ray irradiation. The sensitivity of PNO-p in the PMMA films to X-ray irradiation was enhanced by co-doping with b-PBD. The stability of the isomer of PNO-p generated by photochromic reaction (open form of PNO-p) at room temperature under 575 nm irradiation was also investigated. Only 0.4% of the open form of PNO-p in the PS film was changed to the closed form at room temperature for 1 h. In addition, the open form of PNO-p was more stable against 575 nm irradiation in the PS films than in the PMMA film. • Isomerization reaction of PNO-p was induced by X-ray irradiation. • The sensitivity of PNO-p in the PMMA films to X-ray irradiation was enhanced by co-doping of b-PBD. • The absorbance of PS film containing 1.0 mol% of PNO-p was related to the X-ray dose in the range of 0–30 kGy. • Only 0.4% of the open form of PNO-p in the PS film was changed to the closed form at room temperature for 1 h. [ABSTRACT FROM AUTHOR]