Search

A thermoluminescent dosimetry (TLD) postal dose inter-comparison was carried out amongst radiotherapy centres in Malaysia. The aim of this TLD inter-comparison was to compare the uniformity involved in the measurement of absorbed dose among the participating centres. A set of 5 TLD chips placed within acrylic trays were mailed to all participating centres for irradiation to an absorbed dose to water of 2 Gy. Measurements were made for 6 MV and 60Co photon beams. Results show an agreement of ±5% for all but three radiotherapy centres. The ratios of the TLD readings to that of the reference centre are comparable with other national/regional dose inter-comparisons. The importance of a proper ongoing quality assurance program is essential in maintaining the consistency and uniformity of doses delivered. [ABSTRACT FROM AUTHOR]

A method has been developed, based on thermoluminescent dosimeters and alanine, aimed at measuring the absorbed dose in tissue-equivalent phantoms exposed to an epithermal neutron beam suitable for neutron capture therapy (NCT), separating the contributions due to the various secondary radiations generated by neutrons. Exposures have been made at the TAPIRO nuclear reactor (ENEA, Italy), in the epithermal column properly designed and set up for experiments on boron NCT. [Copyright &y& Elsevier]

Electrons generated during a pinch implosion in a hollow anode Mather-like plasma focus device (PF) are considered as a possible X-ray source via the impinging of those particles on medium and high-Z targets. A usual PF device has been slightly modified to optimise the X-ray production and their measurements by means of a suitable and non-invasive spectrometer. This ensemble allows measurements of X-rays generated booth by electrons turning back to the anode and by target collision of the so-called relativistic electron beam. The spectrum of the emitted photons is evaluated by using a differential absorption based technique. The X-ray spectrometer consists of a stack of LiF dosimeters which act both as detectors and filters to give curves of attenuated intensities. Finally, the energy distribution is calculated from such attenuation curves using an iterative procedure based on spectral algebra formalism. [Copyright &y& Elsevier]

Radiation damage to undulator systems made of permanent magnet materials like NdFeB or SmCo is a critical issue in SASE projects. It is of even more interest in high-duty cycle machines using superconducting accelerators such as the TESLA Test Facility (TTF), which is a prototype for the future X-FEL at TESLA. This paper reports on experience on the undulator system of the VUV-FEL of TTF-1, which ended on May 6, 2002 after nearly 3 years of operation. The radiation exposure of the undulator system was recorded continuously and meticulously over the whole installation period in the TTF linac. Results of these dosage measurements as well as magnetic measurements after de-installation are reported. A comparison with magnetic field data taken prior to installation is given. [Copyright &y& Elsevier]

A dosimetric survey in paediatric radiology is currently being carried out at the paediatric units of two large hospitals in Rio de Janeiro city: IPPMG (Instituto de Pediatria e Puericultura Martaga˜o Gesteira, University Hospital of Federal University of Rio de Janeiro) and IFF (Instituto Fernandes Figueira, FIOCRUZ). Chest X-ray examination doses for AP, PA and LAT projections of paediatric patients have been obtained with thermoluminescent dosimeters (TLDs) and with use of a software package DoseCal. In IPPMG and IFF 100 patients have been evaluated with the use of the TLDs and another group of 100 patients with the DoseCal software. The aim of this work was to estimate the entrance skin dose (ESD) for frontal, back and lateral chest X-rays exposure of paediatric patients. For ESD evaluation, three different TL dosimeters have been used, namely LIF:Mg, Ti (TLD100), CaSO4:Dy and LiF:Mg, Cu, P (TLD100H). The age intervals considered were 0–1, 1–5, 5–10 and 10–15 years. The results obtained with all dosimeters are similar, and it is in good agreement with the DoseCal software, especially for AP and PA projections. However, some larger discrepancies are presented for the LAT projection. [Copyright &y& Elsevier]

Verification of tumor dose for patients undergoing external beam radiotherapy is an important part of quality assurance programs in radiation oncology. Among the various methods available, entrance dose in vivo is one reliable method used to verify the tumor dose delivered to a patient. In this work, entrance dose measurements using LiF:Mg;Ti and LiF:Mg;Cu;P thermoluminescent dosimeters (TLDs) without buildup cap was carried out. The TLDs were calibrated at the surface of a water equivalent phantom against the maximum dose, using 6- and 10-MV photon and 9-MeV electron beams. The calibration geometry was such that the TLDs were placed on the surface of the “solid-water” phantom and a calibrated ionization chamber was positioned inside the phantom at calibration depth. The calibrated TLDs were then utilized to measure the entrance dose during the treatment of actual patients. Measurements were also carried out in the same phantom simultaneously to check the stability of the system. The dose measured in the phantom using the TLDs calibrated for entrance dose to 6-and 10-MV photon beams was found to be close to the dose determined by the treatment planning system (TPS) with discrepancies of not more than 4.1% (mean 1.3%). Consequently, the measured entrance dose during dose delivery to the actual patients with a prescribed geometry was found to be compatible with a maximum discrepancy of 5.7% (mean 2.2%) when comparison was made with the dose determined by the TPS. Likewise, the measured entrance dose for electron beams in the phantom and in actual patients using the calibrated TLDs were also found to be close, with maximum discrepancies of 3.2% (mean 2.0%) and 4.8% (mean 2.3%), respectively. Careful implementation of this technique provides vital information with an ability to confidently accept treatment algorithms derived by the TPS or to re-evaluate the parameters when necessary. [Copyright &y& Elsevier]

The application of the generalised rank annihilation method (GRAM) and the trilinear decomposition (TLD) method to the resolution and quantitation of fluorescence excitation–emission matrices of a ternary mixture of pesticides, carbendazim, fuberidazole, and thiabendazole, with overlapped spectra is described. The results obtained with both methods are compared and evaluated using measures of similarity (correlation coefficients) between the real and estimated spectra. Both approaches have been tested using augmented data matrices containing only two samples, but none of these methods succeeded completely in resolution of the system. When TLD was applied to augmented data matrices containing more than two samples better performance was achieved. To illustrate the application of both algorithms to real samples, they were used in the analysis of water samples containing the target pesticides. Again, TLD had an advantage over GRAM because the ability to analyse data from multiple (more than two) samples simultaneously allowed the resolution of the mixtures. [ABSTRACT FROM AUTHOR]

Copyright of Strahlentherapie und Onkologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The TG-43 recommended dosimetric characteristics of a new 125I brachytherapy source have been experimentally and theoretically determined. The measurements were performed in Solid Water™ using LiF TLDs. The calculations were performed using Monte Carlo simulations in Solid Water™ and water. The measured data were compared with calculated values as well as the reported data in literature for other source designs. The dose rate constant this source in water was 1.01±3% cGy h−1 U−1 and the anisotropy constant was 0.956. [Copyright &y& Elsevier]

A procedure to evaluate the capability of detection of a second-order analytical technique to determine an analyte in presence of an interferent has been proposed taking into account α and β errors in a similar way as ISO norms indicate for the univariate analytical methods. The potentiality of spectroelectrochemistry as a quantitative three-way technique of analysis has been analysed. Trilinearity of spectroelectrochemical data has been studied since it is a necessary condition to apply the trilinear decomposition (TLD) method. As an example, the voltabsorptometric determination of o-tolidine in presence of high concentration of ferrocyanide was chosen to test the applicability of the proposed method. In the same way, the capability of discrimination has been determined. In addition, a second-order standard addition method (SOSAM) has been applied to calculate the concentration of the analyte of interest in the presence of this interferent, avoiding the need to previously identify and determine the quantity of the interferent. [Copyright &y& Elsevier]

Copyright of Strahlentherapie und Onkologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A rapidly changing landscape of antiretrovirals and their procurement at scale has permitted the evaluation of new optimised second-line antiretroviral therapy (ART) in low- and middle-income countries. D 2 EFT is an open-label randomised controlled non-inferiority phase IIIB/IV trial in people living with HIV-1 (PWH) whose first-line non-nucleoside reverse transcriptase inhibitor (NNRTI)-based ART is failing. At inception, it compared a standard of care of boosted darunavir with two nucleos(t)ide reverse transcriptase inhibitors (NRTIs) to the novel NRTI-sparing regimen of boosted darunavir with dolutegravir. Implemented in 2017, participating sites were across Africa, Asia and Latin America. Around the time of implementation, the World Health Organization updated its treatment guidelines and recommended scaling up tenofovir disoproxil fumarate-lamivudine-dolutegravir (TLD). This situation pushed D 2 EFT investigators to consider the impact of the roll-out of TLD on the D 2 EFT research question. The protocol team agreed it was important to study TLD in second-line when an NNRTI regimen was failing, and focused on options to expedite the work by studying the question within the existing trial and network. All key issues (statistical, programmatic and financial) were reviewed to assess the benefits and risks of adding a third arm to the ongoing study, as opposed to developing a new randomised clinical trial with the same control arm and within the same network. The development of a new trial was deemed to be longer than adding a third arm, and to create a challenging situation with two competing clinical trials at the same sites which would slow down recruitment and impair both trials. On the other hand, adding a third arm would be demanding in terms of operationalisation, increased sample size and statistical biases to control. The optimal strategy was deemed to be the addition of a third arm, arriving retrospectively at a simplified multi-arm multi-stage clinical trial design to achieve statistical validity. The D 2 EFT study maintains additional value in a quickly evolving second-line ART strategy allowed by the progress in global access to ART.

Background: The out-of-the-field absorbed dose affects the probability of primary second radiation-induced cancers. This is particularly relevant in the case of pediatric treatments. There are currently no methods employed in the clinical routine for the computation of dose distributions from stray radiation in radiotherapy. To overcome this limitation in the framework of conventional teletherapy with photon beams, two computational tools have been developed-one based on an analytical approach and another depending on a fast Monte Carlo algorithm. The purpose of this work is to evaluate the accuracy of these approaches by comparison with experimental data obtained from anthropomorphic phantom irradiations., Materials and Methods: An anthropomorphic phantom representing a 5-year-old child (ATOM, CIRS) was irradiated considering a brain tumor using a Varian TrueBeam linac. Two treatments for the same planned target volume (PTV) were considered, namely, intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). In all cases, the irradiation was conducted with a 6-MV energy beam using the flattening filter for a prescribed dose of 3.6 Gy to the PTV. The phantom had natLiF : Mg, Cu, P (MCP-N) thermoluminescent dosimeters (TLDs) in its 180 holes. The uncertainty of the experimental data was around 20%, which was mostly attributed to the MCP-N energy dependence. To calculate the out-of-field dose, an analytical algorithm was implemented to be run from a Varian Eclipse TPS. This algorithm considers that all anatomical structures are filled with water, with the exception of the lungs which are made of air. The fast Monte Carlo code dose planning method was also used for computing the out-of-field dose. It was executed from the dose verification system PRIMO using a phase-space file containing 3x10 9 histories, reaching an average standard statistical uncertainty of less than 0.2% (coverage factor k = 1 ) on all voxels scoring more than 50% of the maximum dose. The standard statistical uncertainty of out-of-field voxels in the Monte Carlo simulation did not exceed 5%. For the Monte Carlo simulation the actual chemical composition of the materials used in ATOM, as provided by the manufacturer, was employed., Results: In the out-of-the-field region, the absorbed dose was on average four orders of magnitude lower than the dose at the PTV. For the two modalities employed, the discrepancy between the central values of the TLDs located in the out-of-the-field region and the corresponding positions in the analytic model were in general less than 40%. The discrepancy in the lung doses was more pronounced for IMRT. The same comparison between the experimental and the Monte Carlo data yielded differences which are, in general, smaller than 20%. It was observed that the VMAT irradiation produces the smallest out-of-the-field dose when compared to IMRT., Conclusions: The proposed computational methods for the routine calculation of the out-of-the-field dose produce results that are similar, in most cases, with the experimental data. It has been experimentally found that the VMAT irradiation produces the smallest out-of-the-field dose when compared to IMRT for a given PTV., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 De Saint-Hubert, Suesselbeck, Vasi, Stuckmann, Rodriguez, Dabin, Timmermann, Thierry-Chef, Schneider and Brualla.)

Introduction: In 2019, the World Health Organization (WHO) recommended tenofovir disoproxil fumarate-lamivudine-dolutegravir (TLD) as the preferred first line regimen for adults and adolescents regardless of childbearing status. Nevertheless, final eligibility is determined by local policies which may vary from WHO recommendations. We examined TLD transition by gender across five PEPFAR-supported HIV care programs in sub-Saharan Africa., Methods: The African Cohort Study (AFRICOS) enrolls people living with HIV (PLWH) engaged in care in Uganda, Kenya (South Rift Valley and Kisumu West), Tanzania and Nigeria. PLWH with at least one study visit after the country introduced TLD were included. We generated Kaplan-Meier (KM) curves to compare TLD transition by gender from 1) time countries' introduction of TLD and 2) time of TLD eligibility according to local policies., Results: Among 2.476 participants enrolled through September 2021 at 4 sites in sub-Saharan Africa and eligible to transition to TLD, fewer women (68%) compared to men (80%, p < 0.001) were taking TLD. Kaplan-Meier analysis showed time to transition varied by site, with women in Tanzania transitioning at the same rate as men. In Nigeria, women initially had a slower transition but caught up to men. After adjusting for local policies, women[1] in Kisumu West transitioned at the same rate as men. In South Rift Valley and Uganda, women were less likely to be transitioned., Conclusions: Despite TLD being the WHO's preferred regimen since 2019, transition of women to potentially lifesaving TLD has been slower than men at certain clinical sites even after accounting for local eligibility criteria., (Published by Oxford University Press on behalf of Infectious Diseases Society of America 2022.)

Background  Personnel radiation monitoring equipment monitors the level of exposure to radiation and personnel will have to wear a personnel device for radiation detection while working. Personnel monitoring equipment is usually worn by a worker for 3 months. Aim  This study aims to evaluate the knowledge of radiology students about personnel radiation monitoring devices and their use. Materials and Methods  A questionnaire-based cross-sectional study was performed in the College of Paramedical Sciences, Teerthanker Mahaveer University, Delhi-Road Moradabad, Uttar Pradesh, India. This questionnaire-based study was performed for the period time of 1 year from June 2020 to May 2021. A validated questionnaire was circulated among undergraduate and postgraduate radiology students. Result  In this study the questionnaire was filled by a total of 140 students who were pursuing bachelor's and master's degree programs, including 61% (86) males and 39% (54) females from the radiology department. According to the data master's knowledge levels are greater than the bachelor's level. The level of knowledge of monitoring devices among MRIT (M.Sc. in Radiology and Imaging Technology) second year (81%) is more than those of MRIT first year (80%), BRIT (B.Sc. in Radiology and Imaging Technology) third year (65%), and BRIT second year (66%). Conclusion  It is concluded that there is a lack of awareness about personnel radiation monitoring systems. The level of knowledge of personnel radiation monitoring devices among students remains at a medium level from the results of our students as it has been concluded that master's knowledge level is greater than the bachelor's level. The level of knowledge of monitoring devices increases with the age of the students and the year completed., Competing Interests: Conflict of Interest None., (Indian Radiological Association. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. ( https://creativecommons.org/licenses/by-nc-nd/4.0/ ).)

Proton therapy enables to deliver highly conformed dose distributions owing to the characteristic Bragg peak and the finite range of protons. However, during proton therapy, secondary neutrons are created, which can travel long distances and deposit dose in out-of-field volumes. This out-of-field absorbed dose needs to be considered for radiation-induced secondary cancers, which are particularly relevant in the case of pediatric treatments. Unfortunately, no method exists in clinics for the computation of the out-of-field dose distributions in proton therapy. To help overcome this limitation, a computational tool has been developed based on the Monte Carlo code TOPAS. The purpose of this work is to evaluate the accuracy of this tool in comparison to experimental data obtained from an anthropomorphic phantom irradiation. An anthropomorphic phantom of a 5-year-old child (ATOM, CIRS) was irradiated for a brain tumor treatment in an IBA Proteus Plus facility using a pencil beam dedicated nozzle. The treatment consisted of three pencil beam scanning fields employing a lucite range shifter. Proton energies ranged from 100 to 165 MeV. A median dose of 50.4 Gy(RBE) with 1.8 Gy(RBE) per fraction was prescribed to the initial planning target volume (PTV), which was located in the cerebellum. Thermoluminescent detectors (TLDs), namely, Li-7-enriched LiF : Mg, Ti (MTS-7) type, were used to detect gamma radiation, which is produced by nuclear reactions, and secondary as well as recoil protons created out-of-field by secondary neutrons. Li-6-enriched LiF : Mg,Cu,P (MCP-6) was combined with Li-7-enriched MCP-7 to measure thermal neutrons. TLDs were calibrated in Co-60 and reported on absorbed dose in water per target dose (μGy/Gy) as well as thermal neutron dose equivalent per target dose (μSv/Gy). Additionally, bubble detectors for personal neutron dosimetry (BD-PND) were used for measuring neutrons (>50 keV), which were calibrated in a Cf-252 neutron beam to report on neutron dose equivalent dose data. The Monte Carlo code TOPAS (version 3.6) was run using a phase-space file containing 10 10 histories reaching an average standard statistical uncertainty of less than 0.2% (coverage factor k = 1) on all voxels scoring more than 50% of the maximum dose. The primary beam was modeled following a Fermi-Eyges description of the spot envelope fitted to measurements. For the Monte Carlo simulation, the chemical composition of the tissues represented in ATOM was employed. The dose was tallied as dose-to-water, and data were normalized to the target dose (physical dose) to report on absorbed doses per target dose (mSv/Gy) or neutron dose equivalent per target dose (μSv/Gy), while also an estimate of the total organ dose was provided for a target dose of 50.4 Gy(RBE). Out-of-field doses showed absorbed doses that were 5 to 6 orders of magnitude lower than the target dose. The discrepancy between TLD data and the corresponding scored values in the Monte Carlo calculations involving proton and gamma contributions was on average 18%. The comparison between the neutron equivalent doses between the Monte Carlo simulation and the measured neutron doses was on average 8%. Organ dose calculations revealed the highest dose for the thyroid, which was 120 mSv, while other organ doses ranged from 18 mSv in the lungs to 0.6 mSv in the testes. The proposed computational method for routine calculation of the out-of-the-field dose in proton therapy produces results that are compatible with the experimental data and allow to calculate out-of-field organ doses during proton therapy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 De Saint-Hubert, Verbeek, Bäumer, Esser, Wulff, Nabha, Van Hoey, Dabin, Stuckmann, Vasi, Radonic, Boissonnat, Schneider, Rodriguez, Timmermann, Thierry-Chef and Brualla.)

In 2020, the International Commission on Radiation Units and Measurements' Report Committee 26 (RC 26) proposed new operational quantities to be used in personal monitoring for external radiation. METROBRAS is a Brazilian laboratory that uses a TLD-based personal dosimeter calibrated in terms of the personal dose equivalent, H p (10, θ). In this paper, an evaluation of the METROBRAS personal dosimeter to the new operational quantity personal dose, H p (θ), was performed. This assessment was based on the determination of H p (10, θ) and H p (θ) using Monte Carlo simulation. The basic personal dosimeter design includes three CaSO 4 :Dy plus polytetrafluoroethylene (PTFE) detectors sandwiched between different filters inside of an acrylic badge. The determination of the relative response for six X-ray qualities and for gamma-rays from Cs-137 (662 keV) was carried out using the Monte Carlo transport code MCNPX. TLD detectors, filters and the plastic badge were simulated on the surface of a water ISO phantom with 30 cm × 30 cm x 15 cm with PMMA walls. The effect of the direction of radiation incidence has been determined for angles of 0° (anterior-posterior, AP), ±45° and ±60°. The new H p (θ) quantity affected the relative energy and angular response of the TLD badge mainly for the low photon energies with maximum factors of ∼1.94 and ∼2.91 for 33 keV and 24 keV, respectively. The TLD-badge exhibited not only photon energy but also angular dependence, that was larger for H p (θ). The major differences between the relative angular responses with respect to the response at 0° were found for the exposures at ± 60°. To comply with the requirements of the new quantity, an upgrade on the calculation algorithm and a new design of the filter set (that allows energy discrimination) should be made. The information provided by the Monte Carlo data helped to predict the METROBRAS badge response to the new operational quantity H p (θ). • The response of the TLD badge to the new operational quantity personal dose was investigated. • The angular response of the TLD badge was larger for the new quantity H p (θ). • Monte Carlo method helped to predict the METROBRAS badge response to the H p (θ). • A comparison between the relative response of H p (10, θ) and H p (θ) was performed. [ABSTRACT FROM AUTHOR]

In the present work, the thermal beam-tube of Isfahan Miniature Neutron Source Reactor (MNSR) with known neutron dose-equivalent rate and flux is investigated as a calibration source of thermal neutrons. It is shown that 90% of the neutrons emerging from this tube are thermal. Measuring the response of TLD-600 and TLD-700 dosimeters exposed to these neutrons reveals that the both dosimeters respond linearly to neutrons in the range of 0.1 to 38 mSv. Moreover, after subtracting the contribution of mixed gamma rays using the calibration curves obtained in a standard 60 Co gamma rays field, the response of TLD-600 dosimeter still behaves linearly with dose-equivalent. Finally, it is concluded that the dose-equivalent rate and flux of thermal neutrons in Isfahan MNSR are stable with time and this reactor can reliably be used as a calibration source for thermal neutrons. [ABSTRACT FROM AUTHOR]

A monitoring program in boundary areas of a country is an appropriate way to indicate the level of public exposure. In this research, gamma background radiation was measured using TL dosimeters at 12 boundary areas as well as in the capital city of Iran during the period 2010 to 2011. The measurements were carried out in semi-annual time intervals from January to June and July to December in each year. The maximum average dose equivalent value measured was approximately 70 μSv/month for Tehran city. Also, the average dose values obtained were less than 40 μSv/month for all the cities located at the sea level except that of high level natural radiation area of Ramsar, and more than 55 μSv/month for the higher elevation cities. The public exposure due to ambient gamma dose equivalent in Iran is within the levels reported by UNSCEAR. [ABSTRACT FROM AUTHOR]

Introduction: Radiography forms the cornerstone of the evaluation of shoulder disorders. While the benefits of radiography exceed the risks, there continues to be a compelling case for reduction of radiation exposure from diagnostic radiography. The aim of this project was to evaluate the radiation dose and risk for a variety of collimation settings used during anteroposterior (AP) shoulder radiography., Methods: This was a phantom based study where an ATOM adult dosimetry phantom was loaded with 272 thermoluminescent dosimeters (TLDs). Following loading, the phantom was setup for an AP shoulder X-ray projection with standard 25 × 30 cm rectangular collimation. The phantom was exposed three times and then the TLDs were removed and read. The experiment was repeated using a diamond shaped collimation and rectangular collimation with a minimum field of view to portray only relevant anatomy. Using the TLD dose measurements the effective doses and radiation risks were determined and compared., Results: As expected, organs neighbouring the shoulder experienced the highest absorbed doses (greater than 0.01 mGy); these organs included breast, lung and thyroid gland. The effective doses for standard rectangular, small rectangular and diamond collimation were 0.011, 0.008 and 0.016 mSv, respectively. When compared to standard collimation, a small field of view reduced effective dose by 27.3% and when moving to a diamond shape there was a 45.5% increase. The differences are likely driven by differences in the coverage of the radiosensitive lung and breast tissue., Conclusion: By utilising a variety of different collimation settings, effective dose can be reduced. Reducing the radiation dose is both financially beneficial and results in a lower stochastic risk for patients. Image quality must also be considered when choosing different collimation settings. It stands to reason that by reducing the field size, dose will be reduced, and our study has served to quantify the effects in a practical situation., Implications for Practice: The utilisation of smaller/tight collimation is recommended as it offers the lowest dose when compared with other types of collimations. Although well-known this study serves to remind practitioners of the practical importance of collimation and is associated effect on effective dose and risk., Competing Interests: Conflict of interest statement None., (Copyright © 2021 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.)

Copyright of Der Radiologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In radiotherapy but also as a part of quality assurance in diagnostic imaging, assessment of radiation dose to the skin of the patient is of particular importance. While skin dose is recommended to be measured at a reference depth of 70 μm, in practice in both diagnostic radiology as well as therapeutic applications, the dosimeter is placed on the skin surface, the measured dose depending in large part on dosimeter thickness. Thermoluminescent dosimeters (TLDs) are commonly applied as skin dosimeters, most of the commercial forms being thicker than 140 μm, also with a density greater than that of soft tissue, accordingly representing in effective point of measurement deeper than 70 μm. On the other hand, Monte Carlo (MC) simulations can be used to accurately calculate the dose at an intended depth. In this work we first validate our MC simulations, comparison being made with a previously published correction factor for LiF TLD of dimensions 3 × 3 × 0.1 mm3. Then correction factors to convert the dose measured by various commercial LiF-based TLDs (with thicknesses ranging from 0.15 to 1 mm) to skin dose at 70 μm depth are calculated for RQR reference diagnostic photon spectra and some common MV photon therapy spectra. These results are useful for correction of TLD responses in various clinical situations. • ICRP recommends the skin dose to be assessed at the depth of 70 μm in skin. • TLDs are common dosimeters for skin dose measurements. • Due to TLD thickness, its effective point of measurements is typically deeper than 70 μm. • In this work, various size commercial LiF TLDs are simulated using MCNPX code. • Correction factors to convert TLD dose to skin dose in various photon beams are calculated. [ABSTRACT FROM AUTHOR]

This study used thermoluminescent dosimeters (TLDs) to measure cumulative radiation doses in a PET/CT center. It covered 18 areas and four personnel groups. Because the isolated lead shielding separated the patients from the nurses, wearing protective clothing when injecting radiopharmaceuticals was unnecessary. Fingertip doses of the dispensing and nurse groups were below the occupational limit. Current radiopharmaceutical transportation and injection operations in this PET/CT center provide considerable radiation protection to medical personnel. • The center is a new design different from the layout of a traditional PET/CT. • To isolate patients and staff can minimize the exposure for medical personnel. • After isolating patients and staff, the use of protective clothing is superfluous. • Fingertip doses of the dispensing and nurse groups were below the occupational limit. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the dose characteristic for patient examinations at the first clinical X-ray dark-field chest radiography system and to determine whether the effective patient dose is within a clinically acceptable dose range., Methods: A clinical setup for grating-based dark-field chest radiography was constructed and commissioned, operating at a tube voltage of 70 kVp. Thermoluminescent dosimeter (TLD) measurements were conducted using an anthropomorphic phantom modeling the reference person to obtain a conversion coefficient relating dose area product (DAP) to effective patient dose at the dark-field system. For 92 patients, the DAP values for posterior-anterior measurements were collected at the dark-field system. Using the previously determined conversion coefficient, the effective dose was calculated., Results: A reference person, modeled by an anthropomorphic phantom, receives an effective dose of 35 µSv. For the examined patients, a mean effective dose of 39 µSv was found., Conclusions: The effective dose at the clinical dark-field radiography system, generating both attenuation and dark-field images, is within the range of reported standard dose values for chest radiography., (© 2021 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

This retrospective study provides an insight into the levels of radiation exposure of six nuclear medicine (NM) staff (four technologists and two nurses) performing routine diagnostic 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography-computed tomography (PET/CT) at the University Clinical Centre of the Republic of Srpska, Department of Nuclear Medicine and Thyroid Disorders, Banja Luka, Bosnia and Herzegovina. Data analysis included monthly staff exposure measured with personal thermoluminescent dosimeters (TLD) between June and December 2018, quantified in terms of normalised dose for the whole body [Hp(10)] and dominant hand [Hp(0.07)] and their comparison between each staff member and between the two groups (technologists and nurses). The study goal was to establish how our Department compared with reports from other PET/CT centres worldwide in terms of annual number of procedures and exposure limits and whether there could be room for further improvements in radiation protection. The number of procedures rose considerably from 208 in 2016 to 876 in 2019 and was 423 in the observed seven-month period. Mean individual whole-body exposure dose per GBq of injected 18 F-FDG activity, [Hp(10)/A] was 18.55 μSv/GBq for the four technologists and 15.61 μSv/GBq for the two nurses. Mean dominant-hand exposure dose per GBq of injected 18 F-FDG activity [Hp(0.07)/A] was 16.99 μSv/GBq and 25.44 μSv/GBq for the two groups, respectively. The average annual cumulative dose for all staff was (1.06±0.29) mSv for Hp(10) and (1.15±0.32) mSv for Hp(0.07). These results are comparable with those of similar studies. Staff doses were well below the annual limits. Nurses received slightly higher extremity doses than technologists. In view of the increasing trends in the number of PET/CT procedures, dose monitoring should be continued to identify exposure hotspots and maintain doses as low as possible., (© 2021 Bojan Pavičar, Jasna Davidović, Biljana Petrović, Goran Vuleta, Saša Trivić, Vlatko Šajinović, Nataša Egeljić-Mihailović, Nataša Todorović, and Branko Predojević, published by Sciendo.)

Objective: To assess the feasibility of performing dose measurements in the target (prostate) and an adjacent organ at risk (rectum) using polymer dosimetry gel and thermoluminescence detectors (TLDs) in an anthropomorphic, deformable, and multimodal pelvis phantom (ADAM PETer)., Methods: The 3D printed prostate organ surrogate of the ADAM PETer phantom was filled with polymer dosimetry gel. Nine TLD600 (LiF:Mg,Ti) were installed in 3 × 3 rows on a specifically designed 3D-printed TLD holder. The TLD holder was inserted into the rectum at the level of the prostate and fixed by a partially inflated endorectal balloon. Computed tomography (CT) images were taken and treatment planning was performed. A prescribed dose of 4.5 Gy was delivered to the planning target volume (PTV). The doses measured by the dosimetry gel in the prostate and the TLDs in the rectum ("measured dose") were compared to the doses calculated by the treatment planning system ("planned dose") on a voxel-by-voxel basis., Results: In the prostate organ surrogate, the 3D-γ-index was 97.7% for the 3% dose difference and 3 mm distance to agreement criterium. In the center of the prostate organ surrogate, measured and planned doses showed only minor deviations (<0.1 Gy, corresponding to a percentage error of 2.22%). On the edges of the prostate, slight differences between planned and measured doses were detected with a maximum deviation of 0.24 Gy, corresponding to 5.3% of the prescribed dose. The difference between planned and measured doses in the TLDs was on average 0.08 Gy (range: 0.02-0.21 Gy), corresponding to 1.78% of the prescribed dose (range: 0.44%-4.67%)., Conclusions: The present study demonstrates the feasibility of using polymer dosimetry gel and TLDs for 3D and 1D dose measurements in the prostate and the rectum organ surrogates in an anthropomorphic, deformable and multimodal phantom. The described methodology might offer new perspectives for end-to-end tests in image-guided adaptive radiotherapy workflows., (© 2021 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)