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Background: Proton beam therapy, when integrated with MRI guidance, presents complex dosimetric challenges due to interactions with magnetic fields. Prior research has emphasized the nuanced impact of magnetic fields on dosimetry. For thermoluminescent dosimeters (TLDs) the electron-return effect, alongside small air cavities surrounding the pellets, can lead to nonuniform dose distributions. Future MR-guided proton therapy will require reliable methods for end-to-end tests and dosimetric audits, which so far are often performed using TLDs equipped with phantoms. This implicates the necessity of accounting for these interactions., Purpose: This study investigates the influence of magnetic fields on TLDs at two proton energies, using magnetic field strengths of 0, 0.25, and 1 T $1 \,\mathrm{T}$ , aiming to clarify their impact on dose measurement accuracy., Methods: The study was conducted at a synchrotron-based ion beam therapy beam line, enhanced by a resistive dipole magnet for creating magnetic fields up to 1 T $1 \,\mathrm{T}$ to simulate MR-guided proton therapy. Individual correction factors were applied for TLD measurements. The impact of air gaps on the TLD signal was evaluated using three dedicated TLD holders with air gaps of 0.1, 0.25, and 0.5 mm surrounding the TLD pellets using the highest available proton energy of 252.7 M e V $252.7 \,\mathrm{M}\mathrm{e\mathrm{V}}$ . Additionally, the influence of the magnetic field strength on the TLD response was evaluated for two proton energies of 97.4 M e V $97.4 \,\mathrm{M}\mathrm{e\mathrm{V}}$ and 252.7 M e V $252.7 \,\mathrm{M}\mathrm{e\mathrm{V}}$ ., Results: The study found no statistically significant variation in TLD dose response attributable to changes in the air gap or the presence of magnetic fields. A power analysis indicated an upper limit on a potential change in dose-response as small as 1.5%., Conclusions: The findings suggested that the impact of air gap variations and magnetic field strengths on the TLD response was below the detection threshold of TLD sensitivity. This emphasizes the suitability of TLDs for dose measurement in MR-guided proton therapy, indicating that additional correction factors may not be necessary despite the influence of magnetic fields., (© 2024 The Author(s). Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Background: A passive dosimeter framework for the measurement of dose in carbon ion beams has yet to be characterized or implemented for regular use., Purpose: This work determined the dose calculation correction factors for absorbed dose in thermoluminescent dosimeters (TLDs) in a therapeutic carbon ion beam. TLD could be a useful tool for remote audits, particularly in the context of clinical trials as new protocols are developed for carbon ion radiotherapy., Methods: TLD-100 were irradiated in a carbon ion beam at the Centro Nazionale di Adroterapia Oncologica (CNAO) in Pavia, Italy. The dose correction factors for linearity, fading, and beam quality were characterized. Fading was characterized from 5 to 100 days post-irradiation. For linearity, the TLDs were irradiated to absorbed doses ranging from 1 to 15 Gy in both the entrance of a high-energy pristine carbon ion peak and the center of a 2 cm spread-out Bragg peak. For beam quality, the TLD was irradiated to the same absorbed dose (3 Gy) in several pristine carbon ion Bragg peaks, as well as in several spread-out Bragg peaks. Each correction factor was calculated and compared to photon correction factors. The correction factors were also compared between high and low dose-averaged linear energy transfer (LET D ) in the carbon ion beams. The absorbed dose was compared between ion chamber and TLD-100 in the several tissue substitute phantom materials, applying the carbon ion TLD correction factors., Results: There was no statistically significant difference in the TLD fading correction factor between photons, low LET D carbon ion beams, or high LET D carbon ion beams. The TLD linearity correction factor did differ between photons, low LET D carbon ions, and high LET D carbon ions. The beam quality correction factor was large and changed linearly with LET D . The overall uncertainty of the carbon ion absorbed dose calculation was 3.9% at the one-sigma level, driven largely by a 3.5% uncertainty in the beam quality correction. TLD measurements were within 1.2% of ion chamber measurements in the phantom material for polyethylene, solid water (Gammex and Sun Nuclear), acrylic, blue water, and techtron HPV. TLD measurements in balsa wood were within 3.0% and cork was 6.6% low compared to ion chamber., Conclusion: TLD-100 can be used for passive dosimetry in a therapeutic carbon ion beam. Importantly, the linearity and beam quality correction factors are both different from photon therapy, and dependent on LET D of the carbon ion beam. This opens the possibility of TLD use for carbon ion output audits, phantom audits, and in vivo dose measurements, but may be subject to more complicated management and slightly larger uncertainties than are achieved in photon beams., (© 2024 American Association of Physicists in Medicine.)

Introduction: Human immunodeficiency virus HIV causes a well-known global disease, acquired immunodeficiency syndrome (AIDS), which has a high disease burden in Africa. HIV infection is known to be associated with oxidative stress, which may contribute to disease severity. However, the effect of HAART is equivocal, and requires more studies. 8-hydroxy-2-deoxyguanosine (8-OHdG), a useful biomarker to assess oxidative DNA damage in biological fluids, was therefore measured in this study., Objectives: The study measured 8-OHdG in HIV seronegative and seropositive participants and correlated it with the duration of HAART., Research Question: Does HIV infection have an effect on oxidative DNA damage? Does HAART have an effect on oxidative DNA damage? Does HAART duration have an effect on oxidative DNA damage?, Methods: This was a cross-sectional study consisting of 99 participants in 4 strata: 20 HIV seronegative, 25 HAART naïve, 26 on HAART <5 years, and 28 on HAART >5 years. Those on HAART were all on Tenofovir, Lamivudine, and Dolutegravir (TLD) combination. The questionnaires were administered, and blood samples were collected from all the participants. The serum 8-OHdG was measured with enzyme-linked immunosorbent assay in all the participants. The universal biosafety standards were strictly adhered to. The data were collected and analyzed with SPSS 2016 version., Results/discussion: The serum levels of 8-OHdG of the participants were shown below. Our findings showed higher 8-OHdG in HIV patients than the Controls and is much higher in HAART naïve when compared with those on HAART (p = 0.005). The serum 8-OHdG and HAART duration were compared and showed a statistically significant negative correlation (r = - 0.331, p= 0.014)., Conclusion: This study found that HIV infection causes oxidative DNA damage which is more in patients who have not started HAART than those on HAART. This showed that the TLD-HAART regimen reduces HIV-associated oxidative stress over time, though not completely. This finding further supports a critical role of oxidative stress in HIV infection, a protective effect of HAART, and a potential role of antioxidants that requires further research., Competing Interests: The Authors declare that no competing interest exists, (Copyright © 2024 by West African Journal of Medicine.)

Background  Despite the presence of safety protocols, the manual manipulation of radiopharmaceuticals continues to pose a significant occupational radiation risk. Health care professionals in nuclear medicine are at risk of radiation exposure, particularly to their hands and eyes. Despite existing protective measures, manual handling of radiopharmaceuticals remains a significant source of occupational radiation. Objective  This study evaluates the effectiveness of automated injectors in reducing radiation exposure among health care workers during fluorine-18 fluorodeoxyglucose ( 18 F-FDG) administrations, compared with traditional manual injection methods. Methods  We assessed radiation exposure levels associated with manual versus automated 18 F-FDG injection techniques using specialized dosimeters. Measurements focused on whole-body, extremity, and eye-lens radiation doses to evaluate the potential benefits of automation in minimizing exposure. Results  Findings reveal that automated injectors significantly reduce radiation exposure, with decreases of 97.97 and 98.96% in left- and right-hand extremity doses, respectively, 43.24% in eye-lens dose, and 91.66% in whole-body dose compared with manual methods. Conclusion  Automated injection systems offer considerable advantages in reducing health care worker radiation exposure in nuclear medicine. The substantial reduction in staff doses underscores the necessity of transitioning to such technology to promote safer clinical environments. This study highlights the critical role of automation in enhancing occupational safety standards within diagnostic radiology settings., Competing Interests: Conflict of Interest None declared., (The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. ( https://creativecommons.org/licenses/by/4.0/ ).)

Background: Tenofovir/lamivudine/dolutegravir (TLD) is the preferred first-line antiretroviral therapy (ART) regimen for people with HIV (PWH), including those who were previously virologically suppressed on nonnucleoside reverse transcriptase inhibitors (NNRTIs). We sought to estimate the real-world effectiveness of the TLD transition in Ugandan public-sector clinics., Methods: We conducted a prospective cohort study of PWH aged ≥18 years who were transitioned from NNRTI-based ART to TLD. Study visits were conducted on the day of TLD transition and 24 and 48 weeks later. The primary end point was viral suppression (<200 copies/mL) at 48 weeks. We collected blood for retrospective viral load (VL) assessment and conducted genotypic resistance tests for specimens with VL >500 copies/mL., Results: We enrolled 500 participants (median age 47 years; 41% women). At 48 weeks after TLD transition, 94% of participants were in care with a VL <200 copies/mL (n = 469/500); 2% (n = 11/500) were lost from care or died; and only 2% (n = 9/500) had a VL >500 copies/mL. No incident resistance to DTG was identified. Few participants (2%, n = 9/500) discontinued TLD due to adverse events., Conclusions: High rates of viral suppression, high tolerability, and lack of emergent drug resistance support use of TLD as the preferred first-line regimen in the region., Clinical Trials Registration: NCT04066036., Competing Interests: Potential conflicts of interest. V. C. M. received investigator-initiated research grants and consultation fees from Eli Lilly, Bayer, Gilead Sciences, Merck, and ViiV Healthcare. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Objective. This work investigates the use of passive luminescence detectors to determine different types of averaged linear energy transfer (LET-) for the energies relevant to proton therapy. The experimental results are compared to reference values obtained from Monte Carlo simulations. Approach. Optically stimulated luminescence detectors (OSLDs), fluorescent nuclear track detectors (FNTDs), and two different groups of thermoluminescence detectors (TLDs) were irradiated at four different radiation qualities. For each irradiation, the fluence- (LET-f) and dose-averaged LET (LET-d) were determined. For both quantities, two sub-types of averages were calculated, either considering the contributions from primary and secondary protons or from all protons and heavier, charged particles. Both simulated and experimental data were used in combination with a phenomenological model to estimate the relative biological effectiveness (RBE). Main results. All types ofLET-could be assessed with the luminescence detectors. The experimental determination ofLET-fis in agreement with reference data obtained from simulations across all measurement techniques and types of averaging. On the other hand,LET-dcan present challenges as a radiation quality metric to describe the detector response in mixed particle fields. However, excluding secondaries heavier than protons from theLET-dcalculation, as their contribution to the luminescence is suppressed by ionization quenching, leads to equal accuracy betweenLET-fandLET-d. Assessment of RBE through the experimentally determinedLET-dvalues agrees with independently acquired reference values, indicating that the investigated detectors can determineLET-with sufficient accuracy for proton therapy. Significance. OSLDs, TLDs, and FNTDs can be used to determineLET-and RBE in proton therapy. With the capability to determine dose through ionization quenching corrections derived fromLET-, OSLDs and TLDs can simultaneously ascertain dose,LET-, and RBE. This makes passive detectors appealing for measurements in phantoms to facilitate validation of clinical treatment plans or experiments related to proton therapy., (Creative Commons Attribution license.)

Radiotherapy (RT) is one of the major treatment modalities among surgery and chemotherapy for carcinoma breast. The surface dose study of modified reconstructive constructive Mastectomy (MRM) breast is important due to the heterogeneity in the body contour and the conventional treatment angle to save the lungs and heart from the radiation. These angular entries of radiation beam cause an unpredictable dose deposition on the body surface, which has to be monitored. Thermoluminescent dosimeter (TLD) or optically stimulated luminescent dosimeter (nano OSLD) are commonly preferable dosimeters for this purpose. The surface dose response of TLD and nano OSLD during MRM irradiation has been compared with the predicted dose from the treatment planning system (TPS). The study monitored 100 MRM patients by employing a total 500 dosimeters consisting of TLD (n = 250) and nano OSLD (n = 250), during irradiation from an Elekta Versa HD 6 MV Linear accelerator. The study observed a variance of 3.9% in the dose measurements for TLD and 3.2% for nano OSLD from the planned surface dose, with a median percentage dose of 44.02 for nano OSLD and 40.30 for TLD (p value 0.01). There was no discernible evidence of variation in dose measurements attributable to differences in field size or from patient to patient. Additionally, no variation was observed in dose measurements when comparing the placement of the dosimeter from central to off-centre positions. In comparison, a minor difference in dose measurements were noted between TLD and nano OSLD, The study's outcomes support the applicability of both TLD and nano OSLD as effective dosimeters during MRM breast irradiation for surface dose evaluation., (© 2024 IOP Publishing Ltd.)

Thermoluminescent dosimeters (TLDs) serve as compact and user-friendly tools for various applications, including personal radiation dosimetry and radiation therapy. This study explores the potential of utilizing TLD-100 personal dosimetry, conventionally applied in PET/CT (positron emission tomography/computed tomography) settings, in the PET/MRI (magnetic resonance imaging) environment. The integration of MRI into conventional radiotherapy and PET systems necessitates ionizing radiation dosimetry in the presence of static magnetic fields. In this study, TLD-100 dosimeters were exposed on the surface of a water-filled cylindrical phantom containing PET-radioisotope and positioned on the patient table of a 3 T PET/MRI, where the magnetic field strength is around 0.2 T, aiming to replicate real-world scenarios experienced by personnel in PET/MRI environments. Results indicate that the modified MR-safe TLD-100 personal dosimeters exhibit no significant impact from the static magnetic field of the 3 T PET/MRI, supporting their suitability for personal dosimetry in PET/MRI settings. This study addresses a notable gap in existing literature on the effect of MRI static magnetic field on TLDs., (Creative Commons Attribution license.)

A TLD is a passive damping device that works by dissipating energy through the sloshing of the liquid and the effect of wave breaking, thereby controlling the vibrations of the structure. One of the applications where TLDs are of great interest is in the case of industrial chimneys since these structures often have a very low natural frequency, which can be easily achieved in a control device of this type. The main objective of this study is to evaluate the behaviour of an annular TLD composed of multiple cells through laboratory tests and investigate if it is adequate to design it as an agglomeration of smaller rectangular TLDs. The influence of the amplitude of displacement on the behaviour of the annular TLD will also be analysed. The tests were performed on a shaking table and recurring with pendulums of the same length but of different masses. Three reservoirs were studied as TLDs: a rectangular one, a cell of an annular TLD and a quarter-ring of an annular TLD. This study concluded that the analytical methods developed in previous studies were, in general, adequate for the design of a rectangular TLD and that it was reasonable to design the annular TLD studied as a combination of rectangular ones, as its cells were a close match to a rectangle of similar dimensions. It was also concluded that a compartmentalised annular TLD is an adequate solution for the vibration control of structures with high displacements.

Background: Dosimetry in ultra-high dose rate (UHDR) electron beamlines poses a significant challenge owing to the limited usability of standard dosimeters in high dose and high dose-per-pulse (DPP) applications., Purpose: In this study, Al 2 O 3 :C nanoDot optically stimulated luminescent dosimeters (OSLDs), single-use powder-based LiF:Mg,Ti thermoluminescent dosimeters (TLDs), and Gafchromic EBT3 film were evaluated at extended dose ranges (up to 40 Gy) in conventional dose rate (CONV) and UHDR beamlines to determine their usability for calibration and dose verification in the setting of FLASH radiation therapy., Methods: OSLDs and TLDs were evaluated against established dose-rate-independent Gafchromic EBT3 film with regard to the potential influence of mean dose rate, instantaneous dose rate, and DPP on signal response. The dosimeters were irradiated at CONV or UHDR conditions on a 9-MeV electron beam. Under UHDR conditions, different settings of pulse repetition frequency (PRF), pulse width (PW), and pulse amplitude were used to characterize the individual dosimeters' response in order to isolate their potential dependencies on dose, dose rate, and DPP., Results: The OSLDs, TLDs, and Gafchromic EBT3 film were found to be suitable at a dose range of up to 40 Gy without any indication of saturation in signal. The response of OSLDs and TLDs in UHDR conditions were found to be independent of mean dose rate (up to 1440 Gy/s), instantaneous dose rate (up to 2 MGy/s), and DPP (up to 7 Gy), with uncertainties on par with nominal values established in CONV beamlines (± 4%). In cross-comparing the response of OSLDs, TLDs and Gafchromic film at dose rates of 0.18-245 Gy/s, the coefficient of variation or relative standard deviation in the measured dose between the three dosimeters (inter-dosimeter comparison) was found to be within 2%., Conclusions: We demonstrated the dynamic range of OSLDs, TLDs, and Gafchromic film to be suitable up to 40 Gy, and we developed a protocol that can be used to accurately translate the measured signal in each respective dosimeter to dose. OSLDs and powdered TLDs were shown to be viable for dosimetric measurement in UHDR beamlines, providing dose measurements with accuracies on par with Gafchromic EBT3 film and their concurrent use demonstrating a means for redundant dosimetry in UHDR conditions., (© 2023 American Association of Physicists in Medicine.)

We report a case of a 54-year-old female diagnosed with HIV and antiretroviral therapy (ART) for the same. Seven years ago, she suffered from fever, cough and weight loss, was diagnosed with pulmonary tuberculosis and also seropositive for HIV. She suffered from Herpes Zoster infection, after which her ART regimen was changed to TLD (tenofovir, lamivudine and dolutegravir). The patient presented with two episodes of pyoderma gangrenosum (PG), which were biopsy-proven, corresponding to a rise in CD4 counts above 500. She responded to glucocorticoids, both systemic and topical., Competing Interests: There are no conflicts of interest., (Copyright: © 2024 Indian Journal of Dermatology.)

Introduction: The aim of this study was to experimentally measure organ doses for computed tomography (CT) procedures using thermoluminescence dosimeters (TLDs) on a RANDO anthropomorphic phantom and verify the measured doses using CT-Expo software., Methods: The phantom was irradiated using clinical CT scan protocols routinely used for specific procedures in the radiology department. Fifty TLD chips were used in this study. The scanning parameters (kVp, mA, s) used to scan the phantom were used as input parameters for CT-Expo dose estimations., Results: The TLD measured organ doses varied between 3.97 mGy for the esophagus and 56.22 mGy for the brain. High doses were recorded in the brain (37.80-56.22 mGy) and the eye lens (29.94-36.16 mGy). Comparing the organ dose measurements between TLD and CT-Expo, the maximum organ dose difference was obtained for the eye lens. A comparison between the two methods for the other organs were all less than 32 %. The effective doses from the TLD measurements for the head, chest, and abdominopelvic CT examinations were 2.78, 6.67, and 17 mSv, respectively and CT-Expo were 2.20, 10.30, and 16.70 mSv, respectively., Conclusion: The experimental and computational results are comparable, and the reliability of the TLD measurements and CT-Expo dose calculator has been proven., Implications for Study: A reason for the difference in dose measurements between the two methods has been attributed to the dissimilarity in the organ position in the Rando anthropomorphic phantom and the standard mathematical phantom used by CT-Expo. The experimental and computational results have been found to be comparable., Competing Interests: Conflict of interest statement None., (Copyright © 2023 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.)

The Thermoluminescent dosimeter is a solid material used as instrumentation for environmental monitoring through determining environmental equivalent dose H∗(10). This work presents the calibration methodology for TLDs LiF:Mg, Cu, P dosimeters and their application to measure H∗(10) in internal buildings occupied by inhabitants of an urban area. The calibration factor and type tests were made according to ISO 4037-3 and IEC 62387, and the uncertainty was determined. The values found are under the reference values. Therefore, the dosimeters can be applied., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In chest computed tomography (CT), the breasts located within the scan range receive a substantial radiation dose. Due to the risk of breast-related carcinogenesis, analyzing the breast dose for justification of CT examinations seems necessary. The main goal of this study is to overcome the limitations of conventional dosimetry methods, such as thermoluminescent dosimeters (TLDs) by introducing the adaptive neuro-fuzzy inference system (ANFIS) approach. In this study, the breast dose of 50 adult female patients who underwent chest CT examinations was measured directly by TLDs. Then, the ANFIS model was developed with four inputs including dose length product (DLP), volumetric CT dose index (CTDI vol ), total mAs, and size-specific dose estimate (SSDE), and one output (TLD dose). Additionally, multiple linear regression (MLR) as a traditional prediction model was used for linear modeling and its results were compared with the ANFIS. The TLD reader results showed that the breast dose value was 12.37 ± 2.46 mGy. Performance indices of the ANFIS model, including root mean square error (RMSE) and correlation coefficient (R), were calculated at 0.172 and 0.93 for the testing dataset, respectively. Also, the ANFIS model had superior performance in predicting the breast dose than the MLR model (R = 0.805). This study demonstrates that the proposed ANFIS model is efficient for patient dose prediction in CT scans. Therefore, intelligence models such as ANFIS are suggested to estimate and optimize patient dose in CT examinations., (© 2023. Australasian College of Physical Scientists and Engineers in Medicine.)

Increased HIV drug resistance (HIVDR) with antiretroviral therapy (ART) rollout may jeopardize therapeutic options, especially in this era of transition to fixed-dose tenofovir-lamivudine-dolutegravir (TLD). We studied acquired HIVDR (ADR) patterns and describe potentially active drugs after first- and second-line failure in resource-limited settings (RLS) like Cameroon. A laboratory-based study with 759 patients (≥15 years) experiencing virological failure was carried out at the Chantal Biya International Reference Centre (CIRCB), Yaoundé, Cameroon. Socio-demographic, therapeutic and immunovirological data from patient records were analysed according to HIV-1 genotypic profiles. Median (IQR) ART-duration was 63 (50-308) months. Median CD4 and viremia were 153 (IQR:50-308) cells/mm 3 and 138,666 (IQR:28,979-533,066) copies/mL, respectively. Overall ADR was high (93.4% first-line; 92.9%-second-line). TDF, potentially active in 35.7% of participants after first-line and 45.1% after second-line, suggested sub-optimal TLD-efficacy in second-line (64.3%) and third-line (54.9%). All PI/r preserved high efficacy after first-line failure while only DRV/r preserved high-level efficacy (87.9%) after second-line failure. In this resource-limited setting (RLS), ADR is high in ART-failing patients. PI/r strategies remain potent backbones for second-line ART, while only DRV/r remains very potent despite second-line failure. Though TLD use would be preferable, blind use for second- and third-line regimens may be sub-optimal (functional monotherapy with dolutegravir) with high risk of further failure, thus suggesting strategies for selective ART switch to TLD in failing patients in RLS.

Nuclear medicine procedures play an important role in medical diagnostics and therapy. They are related to the use of ionizing radiation, which affects the radiological exposure of all of the persons involved in their performance. The goal of the study was to estimate the doses associated with the performance of various nuclear medicine procedures in order to optimize workload management. The analysis was performed for 158 myocardial perfusion scintigraphy procedures, 24 bone scintigraphies, 9 thyroid scintigraphies (6 with use of 131 I and 3 with 99m Tc), 5 parathyroid glands and 5 renal scintigraphies. In this evaluation, two possible locations of thermoluminescent detectors, used for measurements, were taken into consideration: in the control room and directly next to the patient. It was shown how the radiological exposure varies depending on the performed procedure. For high activity procedures, ambient dose equivalent registered in the control room reached the level over 50% of allowed dose limit. For example, ambient dose equivalent obtained in control room when performing bone scintigraphy only was 1.13 ± 0.3 mSv. It is 68% of calculated dose limit in the examined time span. It has been shown that risk associated with nuclear medicine procedures is influenced not only by the type of procedure, but also by the frequency of their performance and compliance with the ALARA principle. Myocardial perfusion scintigraphy accounted for 79% of all evaluated procedures. The use of radiation shielding reduced the obtained doses from 14.7 ± 2.1 mSv in patient's vicinity to 1.47 ± 0.6 mSv behind the shielding. By comparing the results obtained for procedures and dose limits established by Polish Ministry of Health, it is possible to estimate what should be the optimal division of duties between staff, so that everyone receives similar doses.

Occupational radiation exposure can occur due to various human activities, including the use of radiation in medicine. Occupationally exposed personnel surpassing 7.4 millions, and respresent the biggest single group of employees who are exposed to artificial radiation sources at work. This study compares the occupational radiation dose levels for 145 workers in four different hospitals located in the Aseer region in Saudi Arabia. The occupational exposure was quantified using thermoluminescence dosimeters (TLD-100). The levels of annual occupational exposures in targeted hospitals were calculated and compared with the levels of the international atomic energy agency (IAEA) Safety Standards. An average yearly cumulative dose for the two consecutive years. The average, highest and lowest resulted occupational doses under examination in this work is 1.42, 3.9 mSv and 0.72 for workers in various diagnostic radiology procedures. The resulted annual effective dose were within the IAEA approved yearly dose limit for occupational exposure of workers over 18, which is 20 mSv. Staff should be monitored on a regular basis, according to current practice, because their annual exposure may surpass 15% of the annual effective doses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

To ensure optimal prescribing practices in the dolutegravir-era in Cameroon, we compared first-line virological response (VR) under tenofovir + lamivudine + dolutegravir (TLD) according to prior exposure to tenofovir + lamivudine + efavirenz (TLE). A facility-based survey was conducted among patients initiating antiretroviral therapy (ART) with TLD (I-TLD) versus those transitioning from TLE to TLD (T-TLD). HIV viral load was performed and unsuppressed participants (VL > 1000 copies/mL) had genotyping performed by Sanger sequencing. Of the 12,093 patients followed, 310 (mean-age: 41 ± 11 years; 52.26% female) complied with study criteria (171 I-TLD vs. 139 T-TLD). The median ART-duration was 14 (12−17) months among I-TLDs versus 28 (24.5−31) months among T-TLDs (15 (11−19) on TLE and 14 (9−15) on TLD), and 83.15% (148/178) were at WHO clinical stages I/II. The viral suppression rate (<1000 copies/mL) was 96.45%, with 97.08% among I-TLDs versus 95.68% among T-TLDs (p = 0.55). VR was similar in I-TLD versus T-TLD at <400 copies/mL (94.15% versus 94.42%) and age, gender, residence, ART-duration, and WHO stages were not associated with VR (p > 0.05). Genotyping was successful for 72.7% (8/11), with no major mutations to integrase inhibitors found. VR is optimal under first-line TLD after 14 months, even among TLE-exposed, thus confirming the effectiveness of transitioning from TLE to TLD in similar settings, supported by strong pharmacological potency and genetic barrier of dolutegravir.

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.)

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.)

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.)

In this study, thermoluminescence detectors (TLD)-600 and TLD-700 were used under different conditions to study neutron dosimetry for its application in medical dosimetry as albedo dosimeters. 6 LiF has a high cross-section for neutrons and is more sensitive to neutrons than to gamma radiation. Conversely, TLD-700 showed a better response to gamma radiation. Therefore, to obtain the response for neutrons, the responses for TLD-600 and TLD-700 were subtracted. A cadmium sheet was used to absorb incident thermal neutrons so that detector measured only backscattered neutrons from the albedo dosimeter. A Perspex sheet was used as a moderator to thermalize the fast neutron source Am-Be used in the experiment. CR-39 was used to detect fast neutrons and act as an albedo dosimeter when covered with a 10 B disc. Both TLD and CR-39 dosimeters were successful in detecting scattered neutrons in radiotherapy rooms., (© 2021 John Wiley & Sons, Ltd.)

Proton radiotherapy has been shown to offer a significant dosimetric advantage in cancer patients, in comparison to conventional radiotherapy, with a decrease in dose to healthy tissue and organs at risk, because the bulk of the beam energy is deposited in the Bragg peak to be located within a tumour. However, it should be kept in mind that radiotherapy of cancer is still accompanied by adverse side effects, and a better understanding and improvement of radiotherapy can extend the life expectancy of patients following the treatment of malignant tumours. In this study, the dose distributions measured with thermoluminescent detectors (TLDs) inside a tissue-equivalent adult human phantom exposed for lung and prostate cancer using the modern proton beam scanning radiotherapy technique were compared. Since the TLD detection efficiency depends on the ionization density of the radiation to be detected, and since this efficiency is detector specific, four different types of TLDs were used to compare their response in the mixed radiation fields. Additionally, the dose distributions from two different cancer treatment modalities were compared using the selected detectors. The measured dose values were benchmarked against Monte Carlo simulations and available literature data. The results indicate an increase in the lateral dose with an increase of the primary proton energy. However, the radiation quality factor of the mixed radiation increases by 20% in the vicinity to the target for the lower initial proton energy, due to the production of secondary charged particles of low-energy and short range. For the cases presented here the MTS-N TLD detector seems to be the most optimal tool for dose measurements within the target volume, while the MCP-N TLD detector, due to an interplay of its enhanced thermal neutron response and decreased detection efficiency to highly ionising radiation, is a better choice for the out-of-field measurements. The pairs of MTS-6 and MTS-7 TLDs used also in this study allowed for a direct measurement of the neutron dose equivalent. Before it can be concluded that they offer an alternative to the time-consuming nuclear track detectors, however, more research is needed to unambiguously confirm whether this observation was just accidental or whether it only applies to certain cases. Since there is no universal detector, which would allow the determination of the dosimetric quantities relevant for risk estimation, this work expands the knowledge necessary to improve the quality of dosimetry data and might help scientists and clinicians in choosing the right tools to measure radiation doses in mixed radiation fields.

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., (Copyright © 2020. Published by Elsevier Ltd.)

Purpose: A dosimetric audit of Ir-192 high dose rate (HDR) brachytherapy remote after-loading units was carried out in 2019. All six brachytherapy departments on the island of Ireland participated in an end-to-end test and in a review of local HDR dosimetry procedures., Materials and Methods: A 3D-printed customised phantom was created to position the following detectors at known distances from the HDR source: a Farmer ionization chamber, GafChromic film and thermoluminescent dosimeters (TLDs). Dedicated HDR applicator needles were used to position an Ir-192 source at 2 cm distance from these detectors. The end-to-end dosimetry audit pathway was performed at each host site and included the stages of imaging, applicator reconstruction, treatment planning and delivery. Deviations between planned and measured dose distributions were quantified using gamma analysis methods. Local procedures were also discussed between auditors and hosts., Results: The mean difference between Reference Air Kerma Rate (RAKR) measured during the audit and RAKR specified by the vendor source certificate was 1.3%. The results of end-to-end tests showed a mean difference between calculated and measured dose of 2.5% with TLDs and less than 0.5% with Farmer chamber measurements. GafChromic films showed a mean gamma passing rates of >95% for plastic and metal applicators with 2%/1 mm global tolerance criteria., Conclusions: The results of this audit indicate dosimetric consistency between centres. The 'end to end' dosimetry audit methodology for HDR brachytherapy has been successfully implemented in a multicentre environment, which included different models of Ir-192 sources and different treatment planning systems. The ability to create a 3D-printed water-equivalent phantom customised to accurately position all three detector types simultaneously at controlled distances from the Ir-192 source under evaluation gives good reproducibility for end-to-end methodology., (Copyright © 2020 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

This paper describes the role of the Polish Secondary Standard Dosimetry Laboratory (SSDL) in quality assurance in radiotherapy by means of providing calibration of ionisation chambers, TLD postal dosimetry audits and end-to-end audits for radiation therapy. A historical review of the methods and results are presented. The influence of the SSDL in Warsaw on radiation protection of patients in Poland is discussed. The International Atomic Energy Agency together with World Health Organisation (IAEA/WHO), through its network of SSDLs around the world, propagates newly developed methods for calibration and auditing. Suitable high quality equipment was provided by the IAEA, as well as special materials and technical support to the SSDL in Warsaw. The activity of the SSDL and the services provided for Polish radiotherapy centres have resulted in a reduction of discrepancies between planned doses and doses delivered to patients. The newly tested IAEA methods of end-to-end on-site dosimetry audits allow for monitoring and improving the quality of IMRT in Poland. The traceability of standards used for the calibration of therapy level dosimeters from Polish radiotherapy centres is assured by the IAEA dosimetry laboratory. The consistency of methods performed in the Polish SSDL with the ISO:17025 norm is supervised by the Polish Centre for Accreditation - a member of International Laboratory Accreditation Cooperation (ILAC), for calibration and testing. Due to the rapid technological development of radiotherapy, special attention has to be paid to newly developed methods for dosimetry auditing and institutions which provide services for assuring radiation safety of patients., (© 2020 Greater Poland Cancer Centre. Published by Elsevier B.V. All rights reserved.)

The idea of using a device with thermo-luminescent detectors (TLD) for the simultaneous measurement of radon (Rn-222) and thoron (Rn-220) decay products' concentrations was invented and developed in the Silesian Centre for Environmental Radioactivity at the Central Mining Institute, Katowice, Poland. The results of a preliminary analysis of the technical applicability, the required minimum period of air sampling and the optimised time schedule proved that such measurements can provide information about the potential alpha energy concentrations (PAECs) of radon and thoron decay products (TnDP).Following the analysis, preliminary measurements were performed at several locations-in a thoron chamber, in dwellings and even outdoors. Surprisingly, the maximum PAEC of the TnDP in the basement of a twin house in the Upper Silesia region was as high as 0.68 ± 0.15 µ J m -3 . This paper presents the results of those measurements., (© 2020 Society for Radiological Protection. Published on behalf of SRP by IOP Publishing Limited. All rights reserved.)

Purpose: The aim of the study was to exploit the feasibility of thermoluminescent dosimeters (TLDs) in radiation therapy techniques in which high dose per fraction is involved., Methods: Dose-response of TLD-100 (LiF: Mg, Ti) was investigated in both 6-MV photon and 6-MeV electron beams. The element correction factor (ECF) generation method was applied to check the variability of the TLDs response. Two batches of 50 TLDs were divided into groups and exposed in the dose range 0 to 30 Gy. Regression analysis was performed with both linear and quadratic models. For each irradiation beam, the calibration curves were obtained in 3 dose range 0 to 8 Gy, 0 to 10 Gy, and 0 to 30 Gy. The best-fitting model was assessed by the Akaike Information Criterion test., Results: The ECF process resulted a useful tool to reduce the coefficients of variation from original values higher than 5% to about 3.5%, for all the batches exposed. The results confirm the linearity of dose-response curve below the dose level of 10 Gy for photon and electron beam and the supralinear trend above., Conclusion: The TLDs are suitable dosimeters for dose monitoring and verification in radiation treatment involving dose up to 30 Gy in a single fraction., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2020.)

Thermoluminescent dosimeters (TLD) and optically stimulated luminescent dosimeters (OSLD) are practical, accurate, and precise tools for point dosimetry in medical physics applications. The charges of Task Group 191 were to detail the methodologies for practical and optimal luminescence dosimetry in a clinical setting. This includes: (a) to review the variety of TLD/OSLD materials available, including features and limitations of each; (b) to outline the optimal steps to achieve accurate and precise dosimetry with luminescent detectors and to evaluate the uncertainty induced when less rigorous procedures are used; (c) to develop consensus guidelines on the optimal use of luminescent dosimeters for clinical practice; and (d) to develop guidelines for special medically relevant uses of TLDs/OSLDs such as mixed photon/neutron field dosimetry, particle beam dosimetry, and skin dosimetry. While this report provides general guidelines for TLD and OSLD processes, the report provides specific details for TLD-100 and nanoDot TM dosimeters because of their prevalence in clinical practice., (© 2019 American Association of Physicists in Medicine.)

Purpose: The thermoluminescence dosimeter (TLD) has desirable features including low cost, reusability, small size, and relatively low energy dependence. However, the commonly available poly-crystal TLDs (e.g., TLD-100) exhibit high interdetector variability that requires individual calibration for high detection accuracy. To improve individual TLD tracking robustness, we developed an optical fingerprinting method to identify the TLD-100 chips., Methods: Seven hundred and fifty-two images were initially captured using a digital microscope camera to build a feature library for both facets of 376 TLD-100 chips. A median intensity thresholding method was used to segment images into foreground and background. The affine transformation was used to register the segmented images to the same position. The fingerprint of each image was calculated from its registered image. All fingerprints were then recorded in an Elasticsearch® search database. The TLD fingerprint match was tested three times when the library was established and repeated once 20 months later. All chips were irradiated at 0, 1, 4, and 8 Gy on a calibrated clinical MV linac to establish the individual calibration curve., Results: The true positive rate of identifying TLDs based on their optical fingerprints was 100% at initialization of the inventory. After 20 months and multiple deployments for characterization, calibration, and dose measurement, the true positive match rate dropped to 99% with zero false-positive matches. The TLDs exhibited high self-consistency in the dose-response test with R 2 between 0.988 and 1 with linear regression., Conclusions: The TLD-100 chips surface textures are unique and sufficient to support accurate identification based on the optical fingerprinting. This method provides inexpensive and robust management of the TLDs for individual calibration and dosimetry., (© 2019 American Association of Physicists in Medicine.)

Introduction: Scoliosis is defined as a deformity of the spine with lateral curvature in the coronal plane. It requires regular X-ray imaging to monitor the progress of the disorder, therefore scoliotic patients are frequently exposed to radiation. It is important to lower the risk from these exposures for young patients. The aim of this work is to compare organ dose (OD) values resulting from Scan Projection Radiograph (SPR) mode in CT against projection radiography and EOS ® imaging system when assessing scoliosis., Methods: A dosimetry phantom was used to represent a 10-year old child. Thermoluminescent dosimetry detectors were used for measuring OD. The phantom was imaged with CT in SPR mode using 27 imaging parameters; projection radiography and EOS machines using local scoliosis imaging procedures. Imaging was performed in anteroposterior, posteroanterior and lateral positions., Results: 17 protocols delivered significantly lower radiation dose than projection radiography (p < 0.05). OD values from the CT SPR imaging protocols and projection radiography were statistically significant higher than the results from EOS. No statistically significant differences in OD were observed between 10 imaging protocols and those from projection radiography and EOS imaging protocols (p > 0.05)., Conclusion: EOS has the lowest dose. Where this technology is not available we suggest there is a potential for OD reduction in scoliosis imaging using CT SPR compared to projection radiography. Further work is required to investigate image quality in relation to the measurement of Cobb angle with CT SPR., (Copyright © 2019 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.)

Background: Effective and skin doses gain much attention since the cardiac catheterization laboratory (CCL) is a place where both patients and medical staff are exposed to X-ray or fluoroscopy environment and gain a cumulative dose during the cardiac interventional procedure., Objective: These doses for pediatric and adult patients undergone cardiac interventional examination using five PMMA phantoms and thermoluminescence dosimeter (TLD)/ionization chamber technique were estimated in this work with the further clinical verification., Methods: Five PMMA phantoms (10, 30, 50, 70, and 90 kg) were customized to represent baby, child, adult female, adult male, and overweight adult (by Asian complexion standards), respectively, in accordance with the ICRU-48 report. Each phantom could be disassembled into 31 plates to insert TLD chips for measuring X-ray exposed dose or assisted with an auxiliary plate to insert high-sensitivity ionization chamber for surveying low-energy fluoroscopy dose., Results: The data acquired from five phantoms were integrated into four semi-empirical formulas, in order to fit the binary quadratic form "Dose = A⋅BMI2+B⋅DAP2+C⋅BMI+ D⋅DAP+E". The latter linked the X-ray and fluoroscopy effective/skin doses, respectively, with a high coefficient of determination R2(from 0.888 to 0.986)., Conclusions: The model refinement with DAP share adjustment is envisaged.

Soil is inhabited by a range of microbes, invertebrates and vertebrates that disintegrate and decompose dead wood and leaf litter. These communities can be perturbed by ionizing radiation from natural radiation sources or from radiation originating from nuclear accidents such as those at Chernobyl, Fukushima and Three Mile Island. We used experimental manipulations of wood quality due to differences in exposure to ionizing radiation among tree trunks and ambient radiation levels of the soil to test the hypothesis that radioactively contaminated wood would result in a negative correlation between the abundance of soil invertebrates colonizing slices of wood and level of radioactive contamination. We extracted soil invertebrates underneath decomposing wood using mustard powder diluted in water. The abundance of soil invertebrates extracted was highly repeatable at study sites and decreased with increasing ambient radiation and total dose measured with thermoluminescent dosimeters (TLDs). Four 10 cm thick slices of ca. 70-year old Scots pines (Pinus sylvestris) were deposited at 20 sites and the invertebrate taxa and their colonization and their abundance was assessed annually during 2014-2017. There were more soil invertebrates under uncontaminated than contaminated slices of wood. In addition, there were more soil invertebrates in areas with less ambient radioactivity, and there was an interaction effect between contamination of wood and ambient radiation implying that the role of contamination differed among slices. Finally, there was an increase in the abundance of soil invertebrates under wood slices during 2013-2017 implying that the abundance of soil invertebrates increased over time. These findings imply that the abundance of soil animals colonizing wood slices was dependent on background radiation, radioactive contamination of wood and the interaction between contamination of wood and ambient radiation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The increasing use of daily CBCT in radiotherapy has raised concerns about the additional dose delivered to the patient, and it can also become a concern issue for those patients with cardiovascular implantable electronic devices (CIEDs) (Pacemaker [PM] and Implantable Cardioverter Defibrillator [ICD]). Although guidelines highly recommend that the cumulative dose received by CIEDs should be kept as low as possible, and a safe threshold based on patient risk classification needs to be respected, this additional imaging dose is not usually considered. Four centers with different dosimetry systems and different CBCT imaging protocols participated in this multicenter study to investigate the imaging dose to the CIEDs from Elekta XVI and Varian OBI kV-CBCT systems. It was found that although imaging doses received by CIEDs outside the CBCT field are negligible, special attention should be paid to this value when CIEDs are inside the field because the daily use of CBCT can sometimes contribute considerably to the total dose received by a CIED., (Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Background: The purpose of this study was to estimate the secondary cancer risk of thyroid in standard radiotherapy methods which are commonly used for breast cancer patients., Methods: A total of 64 breast cancer patients (their age range was around 50 years old) who referred to Seyed-Al-Shohada hospital (Isfahan, Iran) were included in this study. The radiotherapy of the mentioned patients was performed using 6-MV photon beams. Dose measurements were also done using thermoluminescent dosimeters. Calculation of the risk of developing secondary cancer in thyroid was done using the Biological Effects of Ionizing Radiation Committee VII and recommended quantity of the International Radiation Protection Commission, excess relative risk., Results: The mean radiation dose to thyroid for the tangential beams, tangential field with supraclavicular (SC) field, and also a tangential field with SC field in modified radical mastectomy (MRM) were 0.883 ± 0.472, 1.512 ± 0.365, and 1.587 ± 0.37, respectively. The risk of developing secondary thyroid cancer over a period of 5 years after breast cancer therapy in the tangential, tangential with a SC field, and also tangential beam with SC field in MRM were 9.974 ± 4.318, 17.891 ± 0.365, and 18.783 ± 4.384, respectively. The mean of the measured thyroid doses in patients treated with tangent fields was significantly lower than the patients under the irradiation of the tangent fields with SC field ( P < 0.001)., Conclusions: Using radiation protection equipment is suggested for breast cancer patients who treated with the studied radiotherapy methods., Competing Interests: There are no conflicts of interest.

Aim: This study aims at examining absolute dose verification of step-and-shoot intensity modulated radiation treatment (IMRT) of prostate and brain patients by use of ion chambers of two different volumes and thermoluminescent detectors (TLD)., Background: The volume of the ion chamber (IC) is very important for absolute dose verification of IMRT plans since the IC has a volume average effect. With TLD detectors absolute dose verification can be done measuring the dose of multiple points simultaneously., Materials and Methods: Ion chambers FC65-P of volume 0.65 cc and semiflex of volume 0.125 cc as well as TLDs were used to measure the central axis absolute dose of IMRT quality assurance (QA) plans. The results were compared with doses calculated by a treatment planning system (TPS). The absolute doses of off axis points located 2 cm and 4 cm away from the isocenter were measured with TLDs., Results: The measurements of the 0.125 cc ion chamber were found to be closer to TPS calculations compared to the 0.65 cc ion chamber, for both patient groups. For both groups the root mean square (RMS) differences between doses of the TPS and the TLD detectors are within 3.0% for the central axis and points 2 cm away from the isocenter of each axis. Larger deviations were found at the field edges, which have steep dose gradient., Conclusions: The 0.125 cc ion chamber measures the absolute dose of the isocenter more accurately compared to the 0.65 cc chamber. TLDs have good accuracy (within 3.0%) for absolute dose measurements of in-field points.

Purpose: To investigate the performance, such as energy dependence and sensitivity, of thermoluminescent dosimeters (TLD), metal oxide semiconductor field-effect transistor dosimeters (MOSFET), and GafChromic™ films, and to validate the estimates of local dose deposition of a Monte Carlo (MC) simulation for breast dosimetry applications., Methods: Experimental measurements were performed using a monoenergetic beam at the ELETTRA synchrotron radiation light source (Trieste, Italy). The three types of dosimeters were irradiated in a plane transversal to the beam axis and calibrated in terms of air kerma. The sensitivity of MOSFET dosimeters and GafChromic™ films was evaluated in the range of 18-28 keV. Three different calibration curves for the GafChromic™ films were tested (logarithmic, rational, and exponential functions) to evaluate the best-fit curve in the dose range of 1-20 mGy. Internal phantom dose measurements were performed at 20 keV for four different depths (range 0-3 cm, with 1 cm steps) using a homogeneous 50% glandular breast phantom. A GEANT4 MC simulation was modified to match the experimental setup. Thirty sensitive volumes, on the axial-phantom plane were included at each depth in the simulation to characterize the internal dose variation and compare it to the experimental TLD and MOSFET measurements. Experimental 2D dose maps were obtained with the GafChromic™ films and compared to the simulated 2D dose distributions estimated with the MC simulations., Results: The sensitivity of the MOSFET dosimeters and GafChromic™ films increased with x-ray energy, by up to 37% and 48%, respectively. Dose-response curves for the GafChromic™ film result in an uncertainty lower than 5% above 6 mGy, when a logarithmic relationship is used in the dose range of 1-10 mGy. All experimental values fall within the experimental uncertainty and a good agreement (within 5%) is found against the MC simulation. The dose decreased with increasing phantom depth, with the reduction being ~80% after 3 cm. The uncertainty of the empirical measurements makes the experimental values compatible with a flat behavior across the phantom slab for all the investigated depths, while the MC points to a dose profile with a maximum toward the center of the phantom., Conclusions: The calibration procedures and the experimental methodologies proposed lead to good accuracy for internal breast dose estimation. In addition, these procedures can be successfully applied to validate MC codes for breast dosimetry at the local dose level. The agreement among the experimental and MC results not only shows the correctness of the empirical procedures used but also of the simulation parameters., (© 2018 The Authors Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Purpose: Long-term survivors of cancer who were treated with radiotherapy are at risk of a radiation-induced tumor. Hence, it is important to model the out-of-field dose resulting from a cancer treatment. These models have to be verified with measurements, due to the small size, the high sensitivity to ionizing radiation and the tissue-equivalent composition, LiF thermoluminescence dosimeters (TLD) are well-suited for out-of-field dose measurements. However, the photon energy variation of the stray dose leads to systematic dose errors caused by the variation in response with radiation energy of the TLDs. We present a dosimeter which automatically corrects for the energy variation of the measured photons by combining LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P (TLD100H) chips., Methods: The response with radiation energy of TLD100 and TLD100H compared to 60 Co was taken from the literature. For the measurement, a TLD100H was placed on top of a TLD100 chip. The dose ratio between the TLD100 and TLD100H, combined with the ratio of the response curves was used to determine the mean energy. With the energy, the individual correction factors for TLD100 and TLD100H could be found. The accuracy in determining the in- and out-of-field dose for a nominal beam energy of 6MV using the double-TLD unit was evaluated by an end-to-end measurement. Furthermore, published Monte Carlo (M.C.) simulations of the mean photon energy for brachytherapy sources, stray radiation of a treatment machine and cone beam CT (CBCT) were compared to the measured mean energies. Finally, the photon energy distribution in an Alderson phantom was measured for different treatment techniques applied with a linear accelerator. Additionally, a treatment plan was measured with a cobalt machine combined with an MRI., Results: For external radiotherapy, the presented double-TLD unit showed a relative type A uncertainty in doses of -1%±2% at the two standard deviation level compared to an ionization chamber. The type A uncertainty in dose was in agreement with the theoretically calculated type B uncertainty. The measured energies for brachytherapy sources, stray radiation of a treatment machine and CBCT imaging were in agreement with M.C. simulations. A shift in energy with increasing distance to the isocenter was noticed for the various treatment plans measured with the Alderson phantom. The calculated type B uncertainties in energy were in line with the experimentally evaluated type A uncertainties., Conclusion: The double-TLD unit is able to predict the photon energy of scatter radiation in external radiotherapy, X-ray imagine and brachytherapy sources. For external radiotherapy, the individual energy correction factors enabled a more accurate dose determination compared to conventional TLD measurements., (Copyright © 2017. Published by Elsevier GmbH.)

Background and Purpose: Accurate quantification of the relatively small radiation doses delivered to untargeted regions during breast irradiation in patients with breast cancer is of increasing clinical interest for the purpose of estimating long-term radiation-related risks. Out-of-field dose calculations from commercial planning systems however may be inaccurate which can impact estimates for long-term risks associated with treatment. This work compares calculated and measured dose out-of-field and explores the application of a correction for leakage radiation., Materials and Methods: Dose calculations of a Boltzmann transport equation solver, pencil beam-type, and superposition-type algorithms from a commercial treatment planning system (TPS) were compared with in vivo thermoluminescent dosimetry (TLD) measurements conducted out-of-field on the contralateral chest at points corresponding to the thyroid, axilla and contralateral breast of eleven patients undergoing tangential beam radiotherapy for breast cancer., Results: Overall, the TPS was found to under-estimate doses at points distal to the radiation field edge with a modern linear Boltzmann transport equation solver providing the best estimates. Application of an additive correction for leakage (0.04% of central axis dose) improved correlation between the measured and calculated doses at points greater than 15 cm from the field edge., Conclusions: Application of a correction for leakage doses within peripheral regions is feasible and could improve accuracy of TPS in estimating out-of-field doses in breast radiotherapy., (© 2018 The Authors.)

Background: Timely identification of patients in need of palliative care is especially challenging in a geriatric population because of prognostic uncertainty. The Supportive and Palliative Care Indicators Tool (SPICT™) aims at facilitating this identification, yet has not been validated in a geriatric population., Objective: This study validates the SPICT in a geriatric patient population admitted to the hospital., Design: This is a retrospective cohort study., Setting: Subject were patients admitted to the acute geriatric ward of a Belgian university hospital between January 1 and June 30, 2014., Measurements: Data including demographics, functional status, comorbidities, treatment limitation decision (TLD), and one-year mortality were collected. SPICT was measured retrospectively by an independent assessor., Results: Out of 435 included patients, 54.7% had a positive SPICT, using a cut-off value of 2 for the general indicators and a cut-off value of 1 for the clinical questions. SPICT-positive patients were older (p = 0.033), more frequently male (p = 0.028), and had more comorbidities (p = 0.015) than SPICT-negative patients. The overall one-year mortality was 32.2%, 48.7% in SPICT-positive patients, and 11.5% in SPICT-negative patients (p < 0.001). SPICT predicted one-year mortality with a sensitivity of 0.841 and a specificity of 0.579. The area under the curve of the general indicators (0.758) and the clinical indicators of SPICT (0.748) did not differ (p = 0.638). In 71.4% of SPICT-positive cases, a TLD was present versus 26.9% in SPICT-negative cases (p < 0.001)., Conclusion: SPICT seems to be valuable for identifying geriatric patients in need of palliative care as it demonstrates significant association with one-year mortality and with clinical survival predictions of experienced geriatricians, as reflected by TLDs given.

Dosimeters attached to wild animals can be used to validate regulatory assessment approaches and models for estimating radiation exposure of wild animals. Such measurements are also necessary to ensure that robust dose-effect relationships can be developed from the results of field research programmes. This paper presents the first comprehensive evaluation of the different dosimetry technologies available for specifically measuring the external exposure of wildlife. Guidance is provided on the selection of appropriate passive dosimetry approaches for directly measuring external exposure of terrestrial wildlife under field conditions. The characteristics and performance of four available dosimetry technologies (thermoluminescent dosimeter (TLD), optically stimulated luminescent dosimeter (OSLD), radiophotoluminescent dosimeter (RPLD) and direct ion storage, (DIS)) are reviewed. Dosimeter properties, detection limit and dose range, study organisms and the intended application are variables that need to be considered when selecting a suitable dosimetry technology. Evaluated against these criteria, it is suggested that LiF based and Al 2 O 3 :C TLDs, OSLD and RPLD could all be used to estimate doses to wildlife. However, only LiF based TLDs have been used to directly measure wildlife doses in field studies to date. DIS is only suitable for comparatively large species (e.g. medium to large mammals), but has the advantage that temporal variation in dose can be recorded. In all cases, dosimeter calibration is required to ensure that the dose measurements reported can be interpreted appropriately for the organisms of interest., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In vivo dosimetry is a powerful tool for dose verification in radiotherapy. Its application in high dose rate (HDR) brachytherapy is usually limited to the estimation of gross errors, due to inability of the dosimetry system/ method to record non-uniform dose distribution in steep dose gradient fields close to the radioactive source. In vivo dose verification in interstitial catheter based HDR brachytherapy is crucial since the treatment is performed inserting radioactive source at the certain positions within the catheters that are pre-implanted into the tumour. We propose in vivo dose verification method for this type of brachytherapy treatment which is based on the comparison between experimentally measured and theoretical dose values calculated at well-defined locations corresponding dosemeter positions in the catheter. Dose measurements were performed using TLD 100-H rods (6 mm long, 1 mm diameter) inserted in a certain sequences into additionally pre-implanted dosimetry catheter. The adjustment of dosemeter positioning in the catheter was performed using reconstructed CT scans of patient with pre-implanted catheters. Doses to three Head&Neck and one Breast cancer patient have been measured during several randomly selected treatment fractions. It was found that the average experimental dose error varied from 4.02% to 12.93% during independent in vivo dosimetry control measurements for selected Head&Neck cancer patients and from 7.17% to 8.63% - for Breast cancer patient. Average experimental dose error was below the AAPM recommended margin of 20% and did not exceed the measurement uncertainty of 17.87% estimated for this type of dosemeters. Tendency of slightly increasing average dose error was observed in every following treatment fraction of the same patient. It was linked to the changes of theoretically estimated dosemeter positions due to the possible patient's organ movement between different treatment fractions, since catheter reconstruction was performed for the first treatment fraction only. These findings indicate potential for further average dose error reduction in catheter based brachytherapy by at least 2-3% in the case that catheter locations will be adjusted before each following treatment fraction, however it requires more detailed investigation., (Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

The Imaging and Radiation Oncology Core QA Center in Houston (IROC-H) performs remote dosimetry audits of more than 20,000 megavoltage photon and electron beams each year. Both a thermoluminescent dosimeter (TLD-100) and optically stimulated luminescent dosimeter (OSLD; nanoDot) system are commissioned for this task, with the OSLD system being predominant due to the more time-efficient read-out process. The measurement apparatus includes 3 TLD or 2 OSLD in an acrylic mini-phantom, which are irradiated by the institution under reference geometry. Dosimetry systems are calibrated based on the signal-to-dose conversion established with reference dosimeters irradiated in a Co-60 beam, using a reference dose of 300 cGy for TLD and 100 cGy for OSLD. The uncertainty in the dose determination is 1.3% for TLD and 1.6% for OSLD at the one sigma level. This accuracy allows for a tolerance of ±5% to be used.

Among the various incidents in industrial radiography, inadvertent handling of sources by hands is one of the most frequent incidents in which some parts of the hands may be locally exposed to high doses. An accurate assessment of extremity dose assists medical doctors in selecting appropriate treatments, preventing the injury expansion in the region. In this study, a phantom was designed to simulate a fisted hand of a radiographer when the worker holds a radioactive source in their hands. The local doses were measured using implanted TLDs in the phantom at different distances from a source. Furthermore, skin dose distribution was measured by Gaf-chromic films in the palm region of the phantom. The reliability of the measurements has been studied via analytical as well as Monte-Carlo simulation methods. The results showed that the new phantom design can be used reliably in extremity dose assessments, particularly at the points next to the source.