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Abstract: Indoor gamma radiation measurement using TLD has been performed in the Coimbatore City. The indoor gamma radiation dose of Coimbatore City is in the range from 115 to 190.6 nGy/h with the geomentric mean value of 157.3 nGy/h. The gamma dose in Coimbatore City has been found to be lesser than that observed at beach side houses (276.25 nGy/h) and higher than that in inland houses (142.68 nGy/h) at Kalpakkam. The indoor gamma radiation in Coimbatore City is more or less equal to that observed along east coast of Tamil Nadu (153.31 nGy/h). The annual effective dose has been calculated as 772.3 μSv/year. [Copyright &y& Elsevier]

Abstract: Indoor gamma dose rate measurement using TLD has been performed in the East Coast of Tamilnadu. Totally, 56 places have been chosen for the study. Four TLD measurements have been performed throughout a year (July 1994–November 1995), covering four different seasons to find the annual effective dose. The average annual gamma dose has been found to be 1332.4 μGy·y−1. The annual effective dose to the public residing along the east coast region of Tamilnadu is 1.3 mSv·y−1. The calculated gamma dose from TLD and the observed gamma dose from the environmental survey meter have been compared. [Copyright &y& Elsevier]

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.

Purpose: To measure out-of-field doses in a phantom model to better quantify this radiation., Material and Methods: The individual contribution of photons and neutrons to the total out-of-field dose for 6 MV and 20 MV photons at open beam were measured in a purpose-designed water phantom. Radiation doses were measured at seven separate points (P1-P7) in the phantom with thermoluminescent detectors (TLD 100, 600, and 700) and GAFchromic™ EBT films., Results: At a prescribed dose of 75Gy to the isocentre, the photon dose level in the close-to-field area (P2) ranged from 2.0-2.5Gy for 6 MV and 1.5-2.0Gy for 20 MV; the total out-of-field doses at P2 and P7, respectively, were estimated to be as follows: for 6 MV: TLD 100 (<3.23% and<0.14%); radiochromic film (<2.52% and <0.03%); and for 20 MV: TLD 100 (<2.94% and <0.78%); TLD 700 (<2.02% and <0.14%); and radiochromic film (<1.73% and <0.01%). Although the dose decreased rapidly as the distance from the central beam axis increased, even distant doses could be as high as several centigrays. The neutron dose for 20 MV photons at a distance of 25cm from the isocentre was 4.0mSv/Gy., Conclusion: Our results show that in the close-to-field area, the dose level could be as high as 1.5Gy assuming a prescribed dose of 75Gy to the isocentre. By contrast, the doses delivered to more distant areas from the planning target volume were much lower (centigrays). These findings show that both 6 MV and 20 MV photons could produce dosimetrically important dose levels outside of the field. The data reported here may be of value to study the potential impact of even very low doses of radiation on human tissues., (Copyright © 2017 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Pre-irradiation background reading of thermoluminescent LiF dosimeters results in severe changes in the glow curve qualitatively and quantitatively. Current work focuses on the possible changes in the response of TLD-700 dosimeters after this effect. This work examines changes in the level of the glow curve as a whole and on the level of individual peaks as well. It was found that the response of TLD-700 dosimeters has increased by factors ranging from 20% to 44% in terms of area under the glow curve. Changes in individual peaks were examined by performing deconvolution for the glow curves. Results confirmed that the response due to such effect is not uniform over the studied temperature range and each individual peak has its own behavior either in terms of peak area or peak intensity. It was observed that the third peak (P 3 ) leads these changes as the change in its area after being exposed to this thermally enhanced thermoluminescence output (TETO) effect was in the range from 4.1 to 3.0 folds compared to the corresponding values obtained without reading the background prior to irradiation. Peak intensity possesses similar behavior where peaks P 2 and P 4 are following to P 3 in their response, the rest of peaks are either neutral or have negative response to TETO. Response curves of each deconvoluted peak in terms of peak area and maximum intensity are analyzed over the range (0.05-30) Gy and discussed in details., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The ionizing radiation received by patients and health workers due to radiological imaging may increase the risks of radiation effects, such as cancer and cataracts. We have investigated the dose received by specific areas around the head and related this to DNA damage in the blood lymphocytes of subjects exposed to interventional imaging. The entrance surface doses (ESD) to the forehead, neck, and shoulder were measured with a thermoluminescence dosimeter (CaSO 4 disc or polycrystalline powder of lithium tetraborate doped with Mn) and compared with that of dose area product (DAP). DNA damage was measured by γ-H2AX, p53 ser15 , chromosomal aberration (CA), and micronucleus (MN) assays in lymphocytes of patients (n=75), before and 2 and 24h after exposure. The measured ESD values were 230.5±4.9, 189.5±3.55 and 90.7±3.4mGy for the forehead, neck, and shoulder, respectively. The DAP varied from 1.8 to 2047 Gy*cm 2 , showing a correlation with fluoroscopy time (r=0.417). Received doses did not increase early markers of DNA damage (γ-H2AX and p53 ser15 assays), but residual damage (CA and MN frequencies) showed a significant (p<0.001) increase at 2 and 24h post-exposure compared to pre-imaging, despite poor correlation with DAP (r=0.1). Our results show that interventional imaging procedures deliver significant radiation doses and induce measurable DNA damage in lymphocytes of subjects, highlighting the need for rigorous patient safety protocols., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Purpose: To assess out-of-field dose using three different variants of LiF thermoluminescence dosimeters (TLD) for ten patients who underwent stereotactic ablative body radiotherapy (SABR) for primary renal cell carcinoma (RCC) and compare with treatment planning system (TPS) dose calculations., Methods and Materials: Thermoluminescent dosimeter (TLD) measurements were conducted at 20, 30, 40 and 50cm from isocentre on ten patients undergoing SABR for primary RCC. Three types of high-sensitivity LiF:Mg,Cu,P TLD material with different 6 Li/ 7 Li isotope ratios were used. Patient plans were calculated using Eclipse Anisotropic Analytical Algorithm (AAA) for clinical evaluation and recalculated using Pencil Beam Convolution (PBC) algorithm for comparison., Results: Both AAA and PBC showed diminished accuracy for photon doses at increasing distance out-of-field. At 50cm, measured photon dose was 0.3cGy normalised to a 10Gy prescription on average with only small variation across all patients. This is likely due to the leakage component of the out-of-field dose. The 6 Li-enriched TLD materials showed increased signal attributable to additional neutron contribution., Conclusion: LiF:Mg,Cu,P TLD containing 6 Li is sensitive enough to measure out-of-field dose 50cm from isocentre however will over-estimate the photon component of out-of-field dose in high energy treatments due to the presence of thermal neutrons. 7 Li enriched materials which are insensitive to neutrons are therefore required for accurate photon dosimetry. Neutron signal has been shown here to increase with MUs and is higher for patients treated using certain non coplanar beam arrangements. Further work is required to convert this additional neutron signal to dose., (Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Background: PET/CT imaging using [18F]-FDG is utilized in clinical oncology for tumor detecting, staging and responding to therapy procedures. Essential consideration must be taken for radiation staff due to high gamma radiation in PET/CT and cyclotron center. The aim of this study was to assess the staff exposure regarding whole body and organ dose and to evaluate environment dose in PET/CT and cyclotron center., Materials and Methods: 80 patients participated in this study. Thermoluminescence, electronic personal dosimeter and Geiger-Muller dosimeter were also utilized for measurement purpose., Results: The mean annual equivalent organ dose for scanning operator with regard to lens of eyes, thyroid, breast and finger according to mean±SD value, were 0.262±0.044, 0.256±0.046, 0.257±0.040 and 0.316±0.118, respectively. The maximum and minimum estimated annual whole body doses were observed for injector and the chemist group with values of (3.98±0.021) mSv/yr and (1.64±0.014) mSv/yr, respectively. The observed dose rates were 5.67 µSv/h in uptake room at the distance of 0.5 meter from the patient whereas the value 4.94 and 3.08 µSv/h were recorded close to patient's head in PET/CT room and 3.5 meter from the reception desk., Conclusion: In this study, the injector staff and scanning operator received the first high level and second high level of radiation. This study confirmed that low levels of radiation dose were received by all radiation staff during PET/CT procedure using 18F-FDG due to efficient shielding and using trained radiation staff in PET/CT and cyclotron center of Masih Daneshvari hospital.

The aim of this study has been the experimental determination of the energy dependent dose-to-water response of TLD600 and TLD700 thermoluminescent detectors (Harshaw) in X-ray beams with mean photon energies from about 20 to 200keV in comparison with 60 Co gamma rays and 6MV X-rays. Experiments were carried out in collaboration with the German secondary standard laboratory PTW Freiburg. The energy dependent relative responses of TLD600 and TLD700 thermoluminescence detectors were determined at radiation qualities between 30kV p and 280kV p . The overall uncertainty of the measured values was characterized by standard deviations varying from 1.2 to 3%. The present results agree with previous studies on the energy dependent dose-to-water response of TLD100. As an application example, the results were used to measure doses associated with X-ray imaging in image-guided radiotherapy., (Copyright © 2016. Published by Elsevier GmbH.)

Endoscopic retrograde cholangiopancreatography (ERCP) is an invasive technique that has been used for over 30 years in the diagnosis and management of pancreaticobiliary disorders. The objectives of this study were to evaluate the patient entrance surface air kerma doses (ESAK) and estimate the organ and effective doses during ERCP in three hospitals in Khartoum. A total of 55 patients were examined in three hospitals in Khartoum state, Sudan. Calibrated thermoluinescent dosimeters (TLD) were used to measure patients' ESAK. Organ and effective doses were estimated using National Radiological Protection Board (NRPB) software. The overall mean of ESAK for all ERCP procedures was 42.4mGy. The mean patient ESAK in Fedail (A), Soba (B) and Ibn sena (C) hospitals were 26.7mGy, 26.0mGy and 72.4mGy, respectively. The effective doses in three hospitals were 1.60, 1.56 and 2.67mSv in that order and the overall mean effective dose was 1.94mSv. Patient radiation doses vary widely among the hospitals. Patient ESAK is low compared to previous studies in the light of the current practice. Patient dose was decreased significantly in the last two decades., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Breast cancer is the most frequently diagnosed cancer and the leading global cause of cancer death among women worldwide. Radiotherapy plays a significant role in treatment of breast cancer and reduces locoregional recurrence and eventually improves survival. The treatment fields applied for breast cancer treatment include: tangential, axillary, supraclavicular and internal mammary fields., Objective: In the present study, due to the presence of sensitive organ such as thyroid inside the supraclavicular field, thyroid dose and its effective factors were investigated., Materials and Methods: Thyroid dose of 31 female patients of breast cancer with involved supraclavicular lymph nodes which had undergone radiotherapy were measured. For each patient, three TLD-100 chips were placed on their thyroid gland surface, and thyroid doses of patients were measured. The variables of the study include shield shape, the time of patient's setup, the technologists' experience and qualification. Finally, the results were analyzed by ANOVA test using SPSS 11.5 software., Results: The average age of the patients was 46±10 years. The average of thyroid dose of the patients was 140±45 mGy (ranged 288.2 and 80.8) in single fraction. There was a significant relationship between the thyroid dose and shield shape. There was also a significant relationship between the thyroid dose and the patient's setup time., Conclusion: Beside organ at risk such as thyroid which is in the supraclavicular field, thyroid dose possibility should be reduced. For solving this problem, an appropriate shield shape, the appropriate time of the patient's setup, etc. could be considered.

The aim of this research was to investigate the fetal doses of pregnant patients undergoing conformal radiotherapy or intensity-modulated radiation therapy (IMRT) for breast cancers. An Alderson Rando phantom was chosen to simulate a pregnant patient with breast cancer who is receiving radiation therapy. This phantom was irradiated using the Varian Clinac DBX 600 system (Varian Medical System, Palo Alto, CA) linear accelerator, according to the standard treatment plans of both three-dimensional conformal radiation therapy (3-D CRT) and IMRT techniques. Thermoluminescent dosimeters were used to measure the irradiated phantom׳s virtually designated uterus area. Thermoluminescent dosimeter measurements (in the phantom) revealed that the mean cumulative fetal dose for 3-D CRT is 1.39cGy and for IMRT it is 8.48cGy, for a pregnant breast cancer woman who received radiation treatment of 50Gy. The fetal dose was confirmed to increase by 70% for 3-D CRT and 40% for IMRT, if it is closer to the irradiated field by 5cm. The mean fetal dose from 3-D CRT is 1.39cGy and IMRT is 8.48cGy, consistent with theoretic calculations. The IMRT technique causes the fetal dose to be 5 times more than that of 3-D CRT. Theoretic knowledge concerning the increase in the peripheral doses as the measurements approached the beam was also practically proven., (Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.)

The reliability of Fricke gel dosimeters in form of layers for measurements aimed at the characterization of epithermal neutron beams has been studied. By means of dosimeters of different isotopic composition (standard, containing (10)B or prepared with heavy water) placed against the collimator exit, the spatial distribution of gamma and fast neutron doses and of thermal neutron fluence are attained. In order to investigate the accuracy of the results obtained with in-air measurements, suitable MC simulations have been developed and experimental measurements have been performed utilizing Fricke gel dosimeters, thermoluminescence detectors and activation foils. The studies were related to the epithermal beam designed for BNCT irradiations at the research reactor LVR-15 (Řež). The results of calculation and measurements have revealed good consistency of gamma dose and fast neutron 2D distributions obtained with gel dosimeters in form of layers. In contrast, noticeable modification of thermal neutron fluence is caused by the neutron moderation produced by the dosimeter material. Fricke gel dosimeters in thin cylinders, with diameter not greater than 3mm, have proved to give good results for thermal neutron profiling. For greater accuracy of all results, a better knowledge of the dependence of gel dosimeter sensitivity on radiation LET is needed., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Purpose: Point detectors are frequently used to measure patient's maximum skin dose (MSD) in fluoroscopically-guided interventional procedures (IP). However, their performance and ability to detect the actual MSD are rarely evaluated. The present study investigates the sampling uncertainty associated with the use of grids of point detectors to measure MSD in IP., Method: Chemoembolisation of the liver (CE), percutaneous coronary intervention (PCI) and neuroembolisation (NE) procedures were studied. Spatial dose distributions were measured with XR-RV3 Gafchromic(®) films for 176 procedures. These distributions were used to simulate measurements performed using grids of detectors such as thermoluminescence detectors, with detector spacing from 1.4 up to 10 cm., Results: The sampling uncertainty was the highest in PCI and NE procedures. With 40 detectors covering the film area (36 cm × 44 cm), the maximum dose would be on average 86% and 63% of the MSD measured with Gafchromic(®) films in CE and PCI procedures, respectively. In NE procedures, with 27 detectors covering the film area (14 cm × 35 cm), the maximum dose measured would be on average 82% of the MSD obtained with the Gafchromic(®) films., Conclusion: Thermoluminescence detectors show good energy and dose response in clinical beam qualities. However the poor spatial resolution of such point-like dosimeters may far outweigh their good dosimetric properties. The uncertainty from the sampling procedure should be estimated when point detectors are used in IP because it may lead to strong underestimation of the MSD., (Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Purpose: Computed tomography (CT) is a frequently used imaging modality that contributes to a tenfold increase in radiation exposure to the public when compared to other medical imaging modalities. The use of radiation for therapeutic need is always rationalized on the basis of risk versus benefit thereby increasing concerns on the dose received by patients undergoing CT imaging. Therefore, it was of interest to us to investigate the effects of low dose and low dose-rate X-irradiation in patients who underwent CT imaging by recording the doses received by the eye, forehead and thyroid, and to study the levels of damages in the lymphocytes in vivo., Materials and Methods: Lithium manganese borate doped with terbium (LMB:Tb) thermo luminescence dosimeters (TLD) were used to record the doses in the patient's (n = 27) eye, forehead, and thyroid and compared with the dose length product (DLP) values. The in vivo DNA damages measured were compared before and after CT imaging using chromosomal aberration (CA) and micronucleus (MN) assays., Results: The overall measured organ dose ranged between 2 ± 0.29 and 520 ± 41.63 mGy for the eye, 0.84 ± 0.29 and 210 ± 20.50 mGy for the forehead, and 1.79 ± 0.43 and 185 ± 0.70 mGy for the thyroid. The in vivo damages measured from the blood lymphocytes of the subjects showed an extremely significant (p < 0.0001) increase in CA frequency and significant (p < 0.001) increase in MN frequency after exposure, compared to before exposure., Conclusion: The results suggest that CT imaging delivers a considerable amount of radiation dose to the eye, forehead, and thyroid, and the observed increase in the CA and MN frequencies show low dose radiation effects calling for protective regulatory measures to increase patient's safety. This study is the first attempt to indicate the trend of doses received by the patient's eye, forehead and thyroid and measured directly in contrast to earlier values obtained by extrapolation from phantoms, and to assess the in vivo low dose effects in an Indian patient population undergoing CT procedures., (Copyright © 2015 Elsevier B.V. All rights reserved.)

This study derived a simple equation of effective dose (E) versus normal organ of patients with varying body weights undergoing lung cancer treatment of helical tomotherapy (TOMO). Five tissue-equivalent and Rando phantoms were used to simulate lung cancer patients. This study then measured E and equivalent dose of organ or tissues (DT) using thermoluminescent dosimetry (TLD-100H). The TLD-100H was calibrated using TOMO 6MV photons, then inserted into phantom positions that closely corresponded with the position of the represented organs and tissues. Both E and DT were evaluated by ICRP 103. Peripheral doses varied markedly at positions close to the tumor center. The maximum statistical and total errors were 16.7-22.3%. This analytical result indicates that E of Rando and tissue-equivalent phantoms was in the ranged of 9.44±1.70 (10kg) to 4.58±0.83 (90kg)mSv/Gy. Notably, E decreased exponentially as phantom weight increased. Peripheral doses were also evaluated by TLD as a function of distance from the tumor center. Finally, experimental results are compared with those in literature. These findings will prove useful to patients, physicians, radiologists, and the public., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Introduction: The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area., Objective: A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of measurement for environmental dosimetry., Method: Three personal TLD cards were rectangularly placed in a cylindrical holder, and calibrated using 1D and 3D calibration methods. Then, the dosimeter has been used simultaneously with a reference instrument in a real radiation field measuring the accumulated dose within a time interval., Result: The results show that the accuracy of measurement has been improved by 6.5% using 3D calibration factor in comparison with that of normal 1D calibration method., Conclusion: This system can be utilized in large scale environmental monitoring with a higher accuracy.

The aims of this study were to measure the patients' entrance surface air kerma doses (ESAK), effective doses and to compare practices between different hospitals in Sudan. ESAK were measured for patient using calibrated thermo luminance dosimeters (TLDs, GR200A). Effective doses were estimated using National radiological Protection Board (NRPB) software. This study was conducted in five radiological departments: Two Teaching Hospitals (A and D), two private hospitals (B and C) and one University Hospital (E). The mean ESAK was 20.1mGy, 28.9mGy, 13.6mGy, 17.5mGy, 35.7mGy for hospitals A, B, C, D, and E, respectively. The mean effective dose was 2.4mSv, 3.5mSv, 1.6mSv, 2.1mSv and 4.3mSv in the same order. The study showed wide variations in the ESDs with three of the hospitals having values above the internationally reported values., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This study intends to measure the radiation dose to patients and staff during (i) Dynamic Hip Screw (DHS) and (ii) Dynamic Cannula Screw (DCS) and to evaluate entrance surface Air kerma (ESAK) dose and organ doses and effective doses. Calibrated Thermoluminescence dosimeters (TLD-GR200A) were used. The mean patients' doses were 0.46mGy and 0.07mGy for DHS and DCS procedures, respectively. The mean staff doses at the thyroid and chest were 4.69mGy and 1.21mGy per procedure. The mean organ and effective dose for patients and staff were higher in DHS compared to DCS. Orthopedic surgeons were exposed to unnecessary radiation doses due to the lack of protection measures. The radiation dose per hip procedure is within the safety limit and less than the previous studies., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Determination of eye absorbed dose during head & neck radiotherapy is essential to estimate the risk of cataract. Dose measurements were made in 20 head & neck cancer patients undergoing 60Co radiotherapy using LiF(MCP) thermoluminescent dosimeters. Head & neck cancer radiotherapy was delivered by fields using SAD & SSD techniques. For each patient, 3 TLD chips were placed on each eye. Head & neck dose was about 700-6000 cGy in 8-28 equal fractions. The range of eye dose is estimated to be (3.49-639.1 mGy) with a mean of maximum dose (98.114 mGy), which is about 3 % of head & neck dose. Maximum eye dose was observed for distances of about 3 cm from edge of the field to eye. [ABSTRACT FROM AUTHOR]

Abstract: For the application of the BNCT for the excorporal treatment of organs at the TRIGA Mainz, the basic characteristics of the radiation field in the thermal column as beam geometry, neutron and gamma ray energies, angular distributions, neutron flux, as well as absorbed gamma and neutron doses must be determined in a reproducible way. To determine the mixed irradiation field thermoluminescence detectors (TLD) made of CaF2:Tm with a newly developed energy-compensation filter system and LiF:Mg,Ti materials with different 6Li concentrations and different thicknesses as well as thin gold foils were used. [Copyright &y& Elsevier]

The general purpose Monte Carlo N-Particle Radiation Transport Computer Code (MCNP4C) was used to calculate the equivalent dose to the person or people accompanying patients who have been exposed to radiation that was scattered from the patient. To do the calculations, two homogeneous water phantoms were used to simulate the patient and the accompanying person. Finally, in the case of source specification, only the focus of the X-ray tube was modelled, i.e., as a standard MCNP point source that emits a cone of photon. The X-ray spectra to be used in the MCNP simulations were generated with spectrum generating software. These calculations were done for different patient sizes and radiological operations. Dose measurements were made using standard methods that employ LiF TLD-100 dosimeters. A Thermoluminescent Dosimetry (TLD) card was placed on the main trunk of the body of the accompanying person(s), where the maximum dose was probable. In the case of TLD, for a group of 100 examinations, the dose equivalents ranged from 0.01 µSv to 0.13 mSv, with an average of 0.05 mSv. These results are seen to be in close agreement with Monte Carlo simulations. The results suggest that under the correct technical conditions, the radiation doses that are received by the accompanying person or people in radiodiagnostic examinations can be limited to acceptable values and can certainly be under the limits of a permissible dose to the public (1 mSv per year). However, if exposure is frequently repeated, it is probable that the limits that were mentioned above will be exceeded. [ABSTRACT FROM AUTHOR]

The scientific research and the application of the thermoluminescence phenomenon have been advancing for the last two decades. Thermoluminescent Detectors (TLDs) present advantages when used in dosimetry. These advantages include reduced size and the non-use of wires. As a disadvantage, we see the loss of all signals after the reading (information) of the detectors. In the present study, we used the TLD-100, TLD-600 and TLD-700 detectors, with the aim of evaluating them in mixed fields. The TLD-600 is a sensitive detector for thermal neutrons, as well as for gamma radiation, while the TLD-700 only responds to gamma radiation. [ABSTRACT FROM AUTHOR]

The primary mechanisms by which bacteria lose viability when deprived of thymine have been elusive for over half a century. Early research focused on stalled replication forks and the deleterious effects of uracil incorporation into DNA from thymidine-deficient nucleotide pools. The initiation of the replication cycle and origin-proximal DNA degradation during thymine starvation have now been quantified via whole-genome microarrays and other approaches. These advances have fostered innovative models and informative experiments in bacteria since this topic was last reviewed. Given that thymineless death is similar in mammalian cells and that certain antibacterial and chemotherapeutic drugs elicit thymine deficiency, a mechanistic understanding of this phenomenon might have valuable biomedical applications.

Ambient monitor and phantom studies were carried out in the international arrival hall of Taichung Airport, Taiwan. A total of 172 thermoluminescent dosimeters (TLDs) were used for ambient monitoring. The sites of the export conveyor, the outward face of the x-ray scanning chamber, and the x-ray image monitor were assessed as low-radiation areas because the possible annual effective doses were 0.12, 0.39, and 0.16 mSv, all less than 1 mSv per year. In addition, a phantom filled with 126 TLDs was used to simulate a 10-year-old child being exposed by the x-ray baggage scanner. The effective dose was evaluated as 3.39 ± 0.33 μSv/scan, using the tissue weighting factor of the International Commission on Radiological Protection (ICRP) 103 report. This figure is a useful reference should a person be accidentally scanned by the x-ray baggage scanner.

This study is the first to use 10- to 90-kg tissue-equivalent phantoms as patient surrogates to measure peripheral skin doses (Dskin) in lung cancer treatment through Volumetric Modulated Arc Therapy of the Axesse linac. Five tissue-equivalent and Rando phantoms were used to simulate lung cancer patients using the thermoluminescent dosimetry (TLD-100H) approach. TLD-100H was calibrated using 6 MV photons coming from the Axesse linac. Then it was inserted into phantom positions that closely corresponded with the position of the represented organs and tissues. TLDs were measured using the Harshaw 3500 TLD reader. The ICRP 60 evaluated the mean Dskin to the lung cancer for 1 fraction (7 Gy) undergoing VMAT. The Dskin of these phantoms ranged from 0.51±0.08 (10-kg) to 0.22±0.03 (90-kg) mSv/Gy. Each experiment examined the relationship between the Dskin and the distance from the treatment field. These revealed strong variations in positions close to the tumor center. The correlation between Dskin and body weight was Dskin (mSv) = -0.0034x + 0.5296, where x was phantom's weight in kg. R2 is equal to 0.9788. This equation can be used to derive an equation for lung cancer in males. Finally, the results are compared to other published research. These findings are pertinent to patients, physicians, radiologists, and the public.

Objectives: The portable dental radiographic systems are generally used in emergency situations (e.g. during natural disasters) for disabled/aged patients and in patient rooms. This study assesses the output exposure of a portable dental radiographic system measured using thermoluminescent dosemeters (TLDs)., Methods: Occupational exposure of the operator was determined when the portable dental unit was used for mandibular and maxillary teeth exposure., Results: The doses of some critical organs of an operator were measured using TLDs implanted within the Rando phantom., Conclusions: Considering the annual organ dose limits, the eye lens dose limit is the main factor determining the frequency of system application.

Purpose: To present experimental dosimetry results for the new IsoSeed I25.S17plus (125)I brachytherapy source, in fulfillment of the American Association of Physicists in Medicine recommendation for, at least one, experimental dosimetry characterization of new low-energy seeds before their clinical implementation., Methods and Materials: A batch of 100 LiF thermoluminescent dosimeter (TLD)-100 microcubes was used for the experimental determination of the dose-rate constant, radial dose, and anisotropy functions, in irradiations performed using two Solid Water phantoms. Monte Carlo (MC) simulations were used to determine appropriate correction factors that account for the use of Solid Water as a phantom material instead of liquid water and for the different energy response of the TLD dosimeters in the experimental (125)I photon energies relative to the 6 MV x-ray photon beam used for the TLD calibration. Measurements were performed for four I25.S17plus seeds; one with direct traceability of air-kerma strength calibration to National Institute of Standards and Technology and three with secondary National Institute of Standards and Technology traceability., Results: A mean dose-rate constant, Λ, of 0.956 ± 0.043 cGy h(-1) U(-1) was experimentally determined for the I25.S17plus source, which agrees within uncertainties with the MC result of 0.925 ± 0.013 cGy h(-1) U(-1) calculated independently for the same seed model in a previous study. Agreement was also observed between the measured and the MC-calculated radial dose and anisotropy function values., Conclusions: Experimental dosimetry results for the I25.S17plus (125)I source verify corresponding independent MC results in the form of Task Group-43 dosimetry parameters. The latter are found in agreement within uncertainties with sources of similar design incorporating a silver marker, such as the Oncura OncoSeed Model 6711., (Copyright © 2014 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Background: The accurate results of the individual doses in personal dosimety which are reported by the service providers in personal dosimetry are very important. There are national / international criteria for acceptable dosimetry system performance. Objective : In this research, the sources of uncertainties are identified, measured and calculated in a personal dosimetry system by TLD., Method: These sources are included; inhomogeneity of TLDs sensitivity, variability of TLD readings due to limited sensitivity and background, energy dependence, directional dependence, non-linearity of the response, fading, dependent on ambient temperature / humidity and calibration errors, which may affect on the dose responses. Some parameters which influence on the above sources of uncertainty are studied for Harshaw TLD-100 cards dosimeters as well as the hot gas Harshaw 6600 TLD reader system., Results: The individual uncertainties of each sources was measured less than 6.7% in 68% confidence level. The total uncertainty was calculated 17.5% with 95% confidence level., Conclusion: The TLD-100 personal dosimeters as well as the Harshaw TLD-100 reader 6600 system show the total uncertainty value which is less than that of admissible value of 42% for personal dosimetry services.

Suitable dosimeter methods have been proposed and tested, to measure the different dose contributions in small phantoms exposed to epithermal/thermal neutron beams designed for BNCT. One method is based on Fricke-gel dosimeter in small tubes of 2.8mm of external diameter, that allow determining profiles of gamma dose and of boron dose. The other method is based on the use of TLD-700 chips, from whose answer the contribution of thermal neutrons is subtracted by means of appropriate parameters of the glow curve., (© 2013 Published by Elsevier Ltd.)

Electron radiotherapy is applied to treat the chest wall close to the mediastinum. The performance of the GGPB and eMC algorithms implemented in the Varian Eclipse treatment planning system (TPS) was studied in this region for 9 and 16 MeV beams, against Monte Carlo (MC) simulations, point dosimetry in a water phantom and dose distributions calculated in virtual phantoms. For the 16 MeV beam, the accuracy of these algorithms was also compared over the lung-mediastinum interface region of an anthropomorphic phantom, against MC calculations and thermoluminescence dosimetry (TLD). In the phantom with a lung-equivalent slab the results were generally congruent, the eMC results for the 9 MeV beam slightly overestimating the lung dose, and the GGPB results for the 16 MeV beam underestimating the lung dose. Over the lung-mediastinum interface, for 9 and 16 MeV beams, the GGPB code underestimated the lung dose and overestimated the dose in water close to the lung, compared to the congruent eMC and MC results. In the anthropomorphic phantom, results of TLD measurements and MC and eMC calculations agreed, while the GGPB code underestimated the lung dose. Good agreement between TLD measurements and MC calculations attests to the accuracy of "full" MC simulations as a reference for benchmarking TPS codes. Application of the GGPB code in chest wall radiotherapy may result in significant underestimation of the lung dose and overestimation of dose to the mediastinum, affecting plan optimization over volumes close to the lung-mediastinum interface, such as the lung or heart., (Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Purpose: To develop an external quality control procedure for CyberKnife(®) beams. This work conducted in Nancy, has included a test protocol initially drawn by the medical physicist of Nancy and Lille in collaboration with Equal-Estro Laboratory., Materials and Methods: A head and neck anthropomorphic phantom and a water-equivalent homogeneous cubic plastic test-object, so-called "MiniCube", have been used. Powder and solid thermoluminescent dosimeters as well as radiochromic films have been used to perform absolute and relative dose studies, respectively. The comparison between doses calculated by Multiplan treatment planning system and measured doses have been studied in absolute dose. The dose distributions measured with films and treatment planning system calculations have been compared via the gamma function, configured with different tolerance criteria., Results: This work allowed, via solid thermoluminescent dosimeter measurements, verifying the beam reliability with a reproducibility of 1.7 %. The absolute dose measured in the phantom irradiated by the seven participating centres has shown an error inferior to the standard tolerance limits (± 5 %), for most of participating centres. The relative dose measurements performed at Nancy and by the Equal-Estro laboratory allowed defining the most adequate parameters for gamma index (5 %/2mm--with at least 95 % of pixels satisfying acceptability criteria: γ<1). These parameters should be independent of the film analysis software., Conclusion: This work allowed defining a dosimetric external quality control for CyberKnife(®) systems, based on a reproducible irradiation plan through measurements performed with thermoluminescent dosimeters and radiochromic films. This protocol should be validated by a new series of measurement and taking into account the lessons of this work., (Copyright © 2013 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Background: Total body irradiation is a protocol used to treat acute lymphoblastic leukemia in patients prior to their bone marrow transplant. It involves the treatment of the whole body using a large radiation field with extended source-skin distance. Therefore, it is important to measure and monitor the skin dose during the treatment. Thermoluminescent dosimeters (TLDs) and the OneDose(™) metal oxide semiconductor field effect transistor (MOSFET) detectors are used during treatment delivery to measure the radiation dose and compare it with the target prescribed dose., Aims: The primary goal of this study was to measure the variation of skin dose using OneDose MOSFET detectors and TLD detectors, and compare the results with the target prescribed dose. The secondary aim was to evaluate the simplicity of use and determine if one system was superior to the other in clinical use., Material and Methods: The measurements involved twelve adult patients diagnosed with acute lymphoblastic leukemia. TLD and OneDose MOSFET dosimetry were performed at ten different anatomical sites of each patient., Results: The results showed that there was a variation between skin dose measured with OneDose MOSFET detectors and TLD in all patients. However, the variation was not significant. Furthermore, the results showed for every anatomical site there was no significant different between the prescribed dose and the dose measured by either TLD or OneDose MOSFET detectors., Conclusion: There were no significant differences between the OneDose MOSFET and TLDs in comparison to the target prescribed dose. However, OneDose MOSFET detectors give a direct read-out immediately after the treatment, and their simplicity of use to compare with TLD detectors may make them preferred for clinical use.

Objective: To measure the radiation exposure to nuclear medicine personnel during synthesis and injection to the patients of Ga-68 1,4,7,10-tetraazacyclododecane-N,N',N″,N″'-tetraacetic acid (DOTA)-1-Nal(3)-octreotide (NOC)- (DOTA-NOC) using ring thermoluminescence dosimeters (TLDs)., Materials and Methods: Synthesis of Ga-68 DOTA-NOC was done on a semi-automated system. Finger doses were measured during synthesis and injection of Ga-68 DOTA-NOC. The occupational workers wore TLDs at the base of ring finger of both hands. The finger doses of two radio chemists were measured during synthesis of Ga-68 DOTA-NOC while that of a physician during its injection to the patients., Results: Duration of the study was eight months and a total of 20 samples were prepared. During synthesis, the mean dose to base of left ring finger was 3.02 ± 1.01 mSv and to base of right ring finger was 1.96 ± 0.86 mSv. Mean dose to base of left ring finger was 1.26 ± 0.35 mSv while that to base of right ring finger was 1.03 ± 0.13 mSv during injection. The mean dose was observed to be higher during synthesis than injection. However, the difference was not significant (P = 0.27 and P = 0.18, respectively). Overall mean finger dose of left hand was 2.43 ± 1.21 mSv, whereas for the right hand the same was 1.65± 0.82 mSv., Conclusion: Finger doses to radio chemists during semi-automated synthesis of Ga-68 DOTA-NOC and that to the physician involved in injection of Ga-68 DOTA-NOC were found to be within permissible limits. Ring dosimeters must be worn for the safety of the nuclear medicine personnel involved in synthesis and injection of Ga-68 DOTA-NOC.