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In this research, thermoluminescent pellets were prepared by adding Mg, Cu, Na and Si impurities to lithium fluoride (LiF) crystal powder via melting and quenching methods to study dosimetric characteristics. Here, its reproducibility, dose response, dosimeter sensitivity, thermal and optical fading were investigated and the obtained results were compared with the properties of LiF: Cu, Mg, P crystal nominated as GR-200.

Measurement of background gamma radiation was carried out in two active municipal dumpsites (Olusosun and Soluos III) in Lagos metropolis, Nigeria. This study aimed to measure absorbed dose rates (ADRs) in the air in relation to distances from the dumpsites and to evaluate the annual effective dose (AED). The measurements of background gamma radiation were carried out at two active municipal dumpsites (Olusosun and Soluos III) for 3 months during the dry season in Lagos, Nigeria, with lithium fluoride thermoluminescent dosimeters (TLDs) which were arranged in a three-dimensional setup to eliminate the angular dependency of TLD dosimeter chips for environmental measurement. The dosimeters were retrieved, analyzed, and replaced at each location every month for the mentioned period. The mean ADR at Olusosun and Soluos III was 24.53-71.88 nGyh-1 with an average value of 52.91 ± 14.41 nGyh-1 and 53.67-100.67 nGyh-1 with an average value of 74.67 ± 11.28 nGyh-1, respectively. The computed mean AED was 0.065 ± 0.018 mSv/year at Soluos III, whereas at Olusosun, it was 0.092 ± 0.014 mSv/year. It was found that the mean values of ADR and AED values at Olusosun were slightly higher than the world's average values but decreased with varying distances away from the respective dumpsites. The people living close to these dumpsites are exposed daily to low-dose gamma radiation emanating from the dumpsites and lie within global background variations. [ABSTRACT FROM AUTHOR]

Background: Radiation protection plays a key role in medicine, due to the considerable usage of radiation in diagnosis and treatment. The protection against radiation exposure with inappropriate equipment is concerning. Objective: The current study aimed to investigate the efficiency and quality of the radiation protection gowns with multi-layered nanoparticles compositions of Bismuth, Tungsten, Barium, and Copper, and light non-lead commercial gowns in angiography departments for approval of the manufacturers’ declarations and improve the quality of gowns.Material and Methods: In this case study, physicians, physician assistants, radiology technologists, and nurses were asked to wear two commercial and proposed gowns in the angiography departments. Dosimetry of personnel was conducted using a Thermoluminescent Dosimeter (TLD) (GR-200), and the radiation dose received by personnel was compared in both cases. The participants were asked to fill out a questionnaire about the quality and comfort of two radiation protection gowns. Results: However, both gowns provide the necessary radiation protection; the multi-layer proposed gown has better radiation protection than the commercial sample (2 to 14 percent reduction in effective dose). The proposed gown has higher flexibility and efficiency than the commercial sample due to the use of nanoparticles and multi-layers (2.3 percent increase in personnel satisfaction according to the questionnaires). Conclusion: However, the multi-layer gown containing nanoparticles of Bismuth, Tungsten, Barium, and Copper has no significant difference from the non-lead commercial sample in terms of radiation protection, it has higher flexibility and comfort with more satisfaction for the personnel.

Surface brachytherapy (BT) lacks standard quality assurance (QA) protocols. Commercially available treatment planning systems (TPSs) are based on a dose calculation formalism that assumes the patient is made of water, resulting in potential deviations between planned and delivered doses. Here, a method for treatment plan verification for skin surface BT is reported. Chips of thermoluminescent dosimeters (TLDs) were used for dose point measurements. High-dose-rate treatments were simulated and delivered through a custom-flap applicator provided with four fixed catheters to guide the Iridium-192 (Ir-192) source by way of a remote afterloading system. A flat water-equivalent phantom was used to simulate patient skin. Elekta TPS Oncentra Brachy was used for planning. TLDs were calibrated to Ir-192 through an indirect method of linear interpolation between calibration factors (CFs) measured for 250 kV X-rays, Cesium-137, and Cobalt-60. Subsequently, plans were designed and delivered to test the reproducibility of the irradiation set-up and to make comparisons between planned and delivered dose. The obtained CF for Ir-192 was (4.96 ± 0.25) μC/Gy. Deviations between measured and TPS calculated doses for multi-catheter treatment configuration ranged from −8.4% to 13.3% with an average of 0.6%. TLDs could be included in clinical practice for QA in skin BT with a customized flap applicator. [ABSTRACT FROM AUTHOR]

Background: Positron emission tomography/computed tomography (PET/CT) is an imaging modality that combines images from high-energy gamma rays emitted by a positron emitting radiopharmaceutical and those from the CT component. The images are then used in the diagnosis of severe diseases. Procedures with PET radiopharmaceuticals introduce a risk of high occupational radiation exposure to staff handling them. 18Fluorine-Fluorodeoxyglucose ([18F]FDG) is the most commonly used PET radiopharmaceutical. Aim: To determine the radiation exposure of staff working at the PET/CT facility. Setting: Academic hospital in Gauteng. Methods: The study was quantitative and descriptive. The radiation exposure data of participants were collected using Polimaster®electronic pocket dosimeters, ring dosimeters and thermoluminescent dosimeters. The participants’ workflow was tracked and the tasks that led to the highest radiation exposure were identified. Results: Radiopharmacists had 129 dispensing days with the resultant daily radiation exposure ranging between 0.01 µSv and 0.32 µSv. The radiographers’ daily radiation exposure ranged between 7.08 µSv and 19.14 µSv. Radiographers received the highest radiation dose during radiopharmaceutical injection (average = 1.86 µSv). Conclusion: The study found that staff working at a new PET/CT facility in Gauteng were not at risk of radiation exposure above the accepted annual limits, which are 20 mSv per annum, averaged over 5 years, and with no more than 50 mSv in 1 year. Contribution: The findings revealed the need for continuous training in radiation protection measures for all staff working in the PET/CT facility.

Background: Radiation protection plays a key role in medicine, due to the considerable usage of radiation in diagnosis and treatment. The protection against radiation exposure with inappropriate equipment is concerning. Objective: The current study aimed to investigate the efficiency and quality of the radiation protection gowns with multi-layered nanoparticles compositions of Bismuth, Tungsten, Barium, and Copper, and light non-lead commercial gowns in angiography departments for approval of the manufacturers' declarations and improve the quality of gowns. Material and Methods: In this case study, physicians, physician assistants, radiology technologists, and nurses were asked to wear two commercial and proposed gowns in the angiography departments. Dosimetry of personnel was conducted using a Thermoluminescent Dosimeter (TLD) (GR-200), and the radiation dose received by personnel was compared in both cases. The participants were asked to fill out a questionnaire about the quality and comfort of two radiation protection gowns. Results: However, both gowns provide the necessary radiation protection; the multi-layer proposed gown has better radiation protection than the commercial sample (2 to 14 percent reduction in effective dose). The proposed gown has higher flexibility and efficiency than the commercial sample due to the use of nanoparticles and multilayers (2.3 percent increase in personnel satisfaction according to the questionnaires). Conclusion: However, the multi-layer gown containing nanoparticles of Bismuth, Tungsten, Barium, and Copper has no significant difference from the non-lead commercial sample in terms of radiation protection, it has higher flexibility and comfort with more satisfaction for the personnel. [ABSTRACT FROM AUTHOR]

Background: Positron emission tomography/computed tomography (PET/CT) is an imaging modality that combines images from high-energy gamma rays emitted by a positron emitting radiopharmaceutical and those from the CT component. The images are then used in the diagnosis of severe diseases. Procedures with PET radiopharmaceuticals introduce a risk of high occupational radiation exposure to staff handling them. 18 Fluorine-Fluorodeoxyglucose ([18F] FDG) is the most commonly used PET radiopharmaceutical. Aim: To determine the radiation exposure of staff working at the PET/CT facility. Setting: Academic hospital in Gauteng. Methods: The study was quantitative and descriptive. The radiation exposure data of participants were collected using Polimaster®electronic pocket dosimeters, ring dosimeters and thermoluminescent dosimeters. The participants' workflow was tracked and the tasks that led to the highest radiation exposure were identified. Results: Radiopharmacists had 129 dispensing days with the resultant daily radiation exposure ranging between 0.01 μSv and 0.32 μSv. The radiographers' daily radiation exposure ranged between 7.08 μSv and 19.14 μSv. Radiographers received the highest radiation dose during radiopharmaceutical injection (average = 1.86 μSv). Conclusion: The study found that staff working at a new PET/CT facility in Gauteng were not at risk of radiation exposure above the accepted annual limits, which are 20 mSv per annum, averaged over 5 years, and with no more than 50 mSv in 1 year. Contribution: The findings revealed the need for continuous training in radiation protection measures for all staff working in the PET/CT facility. [ABSTRACT FROM AUTHOR]

This study investigates pediatric Computed Tomography (CT) dosimetry, specifically in the thoracic and head regions, using thermoluminescent dosimeters (TLD). The investigation, conducted at the Imaging Diagnostic Center of the Dom Vicente Scherer Hospital, involved two CT machines, the GE Optima 540 and Revolution EVO models. It aims to correlate in vivo TLD analysis with experimental CT Dose Index Volume (CTDIvol) values. The research reveals a maximum variation between machine-indicated CTDI values of 5.7% for the Optima 540 model and 6.8% for the Revolution EVO model at a voltage of 120 kV. Comparison with dose reference levels (DRL) from the United Kingdom and the United States indicates that the obtained values are below these standards, suggesting safe practices in the participating hospital. However, a larger sample size is recommended to establish local standards securely. In the thoracic region, nominal CTDI vol values indicate measurements around 150% lower than the dose values measured by TLD's, however, no correlation was found between the two variables (p-value = 0.09). In the head, nominal CTDI vol values varied on average 21% above the doses measured by TDL's, showing a strong correlation between the two quantities (p-value = 0.0002). The study highlights the importance of cautious interpretation of the CTDI vol and the need for continuous optimization of procedures to ensure safe practices and minimize the risks of radiation exposure in pediatric patients. • In vivo pediatric CT measurements were done with TLDs. • It finds a maximum variation in machine-indicated CTDI values of 5.7% and 6.8%. • Dose values obtained are below relative to UK/USA DRL values. • Significant head TLD-CTDI vol correlation; not in thoracic. • Emphasizes cautious CTDIvol interpretation and continuous procedure optimization for safety. [ABSTRACT FROM AUTHOR]

Epidemiological research has revealed that radiation exposure can cause cataracts. The Korean nuclear regulatory body has proposed the reduction of the occupational dose limit for the lens of the eye from 150 mSv/y to 100 mSv/5y, with an additional limitation of not exceeding 50 mSv/y for a specific year, taking into account the recommendations of the International Commission on Radiological Protection, and the International Atomic Energy Agency. This means that radiation workers should receive the same level of radiation safety for the lens of the eye as for whole-body protection. Korean nuclear power plants (NPPs) are conducting research to establish the radiation protection program for the lens of the eye. In terms of the preliminary results of the implementation of the radiation protection program for the lens of the eye dedicated to Korean NPPs, this review article summarizes the current state of understanding of the regulations, technical guidance, eye lens dosimeters, and radiation field conditions resulting in lens dose.

The aim of this work is to analyze existing detectors for the relative dosimetry of small radiation fields in external beam radiation therapy and the requirements for them, consider the problems in carrying out dosimetry of small radiation fields, determine the physical conditions under which an external photon beam can be designated as a small field. In modern radiation therapy, there is an increase in the use of small static fields, which is facilitated by the general availability of standard and optional multileaf collimators and new generation treatment machines of various designs. There is growing interest in the use of such radiation techniques as stereotactic radiosurgery, stereotactic body radiotherapy, intensity modulated radiotherapy, which are widely used small fields. This has increased the uncertainties in clinical dosimetry, especially for small fields. Accurate dosimetry of small fields is important when commissioning linear accelerators and is a difficult task, especially for very small fields used in stereotactic radiotherapy. In the course of the work, a study of topical problems in the dosimetry of small radiation fields in external beam radiation therapy has been carried out. The physical conditions under which the external photon beam can be designated as a small field are considered. A review and analysis of existing detectors for the relative dosimetry of small radiation fields, as well as an analysis of the requirements for the character. The analysis revealed that liquid ionization chambers, silicon diodes, diamond detectors, organic scintillators, radiochromic films, thermoluminescent dosimeters and optically stimulated luminescence detectors are considered suitable for relative dosimetry of small photon fields and are recommended for use in clinics where radiotherapy is performed.

The Sterile Insect Technique, or SIT, is an environment-friendly insect pest control method and uses gamma rays or X-rays to sterilize insects, remaining sexually competitive but cannot produce offspring. The dose control during the SIT procedures is essential for the quality of the irradiated product or material. Insects that receive too low a dose are not sufficiently sterile and those that receive too high a dose may be uncompetitive. There are few dosimetric systems used for the dose control during the irradiation procedure. The aim of this paper is to characterize the Optically Stimulated (OSL) response of Li2B4O7:Cu,Ag, synthesized by the Nuclear Energy Department of the Federal University of Pernambuco and the MTS-N dosimeters to be used for SIT dosimetry and applied in Moscamed Brazil’s pest and vector control programs. The results were evaluated using the student’s t-test. Applying the hypothesis that the results obtained with the three types of dosimeters are similar, the test showed that with 99% confidentiality the hypothesis is accepted, that is, the results of the three types of dosimeters are similar. It is possible to conclude that the OSL Li2B4O7:Cu,Ag, and the TL MTS-N can be used for dose control during the SIT irradiation procedures.

Abstract Background The use of X-ray as a diagnostic tool for complication and anomaly in the neonatal patient has been helpful, but the effect of radiation on newborn stands to increase their cancer risk. This study aims to determine the mean, 50th percentile (quartile 2 (Q2)), and 75th percentile (quartile 3 (Q3)) entrance surface dose (ESD) from anteroposterior (AP) chest X-ray and to compare our findings with other relevant studies. The study used calibrated thermoluminescent dosimeters (TLDs), which was positioned on the central axis of the patient. The encapsulated TLD chips were held to the patients’ body using paper tape. The mean kilovoltage peak (kVp) and milliampere seconds (mAs) used was 56.63(52–60) and 5.7 (5–6.3). The mean background TLD counts were subtracted from the exposed TLD counts and a calibration factor was applied to determine ESD. Results The mean ESDs of the newborn between 1 and 7, 8 and 14, 15 and 21, and 22 and 28 days were 1.09 ± 0.43, 1.15 ± 0.50, 1.19 ± 0.45, and 1.32 ± 0.47 mGy respectively. A one-way ANOVA test shows that there were no differences in the mean doses for the 4 age groups (P = 0.597). The 50th percentile for the 4 age groups was 1.07, 1.26, 1.09, and 1.29 mGy respectively, and 75th percentile were 1.41, 1.55, 1.55, and 1.69 mGy respectively. The mean effective dose (ED) in this study was 0.74 mSv, and the estimated cancer risk was 20.7 × 10−6. Conclusion ESD was primarily affected by the film-focus distance (FFD) and the patient field size. The ESD at 75th percentile and ED in this study was higher compared to other national and international studies. The estimated cancer risk to a newborn was below the International Commission on Radiological Protection (ICRP) limit for fatal childhood cancer (2.8 × 10−2Sv−1).

Federal Regulations of the United States require that installations possessing sufficient quantities of fissile material to potentially constitute a critical mass, such that the excessive exposure of individuals to radiation from a nuclear accident is possible, shall provide appropriate nuclear accident dosimetry. The American National Standard ANSl/HPS N13.3–2013 Dosimetry for Criticality Accidents provides technical, quality assurance, and performance requirements for nuclear accident dosimeters (NAD). In 2023 the U.S. Navy operated 82 nuclear-powered ships, with the fleet being composed of 11 aircraft carriers, 68 submarines, having a total number of 98 reactors. Since 1968 the U.S. Navy has used fixed nuclear accident dosimeters (FNAD) mounted to the bulkheads surrounding naval nuclear propulsion reactors. Since 1968 the US Navy has used two nuclear accident criticality dosimeters. The first Navy accident dosimeter DT-518/PD was introduced in 1968. It was developed by the Naval Radiological Defense Laboratory in San Francisco, California under leadership of Eugene Tochilin. This dosimeter contains two indium foils for quick dose assessments using shipboard gamma instruments available on nuclear powered vessels and two sulfur pellets/LiF TLD-700 powder for final dose determination at the Naval Dosimetry Center. The newest Navy NAD is the DT-723/PD, which contains indium foil, gold foil, cadmium shielded gold foil, sulfur pellet and a LiF TLD-700 chip. This paper provides a brief description of the measurement procedures, results of the testing of both NADs and comparison of their performance. • United States Navy nuclear fleet and number of nuclear reactors. • History United States Navy accident dosimetry program. • Nuclear accident dosimeter DT-518/PD. • Nuclear accident dosimeter DT-723/PD. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the skin dose of total body irradiation (TBI) with Helical Tomotherapy and the need to use a bolus to achieve an adequate skin dose. To simulate the RANDO phantom geometrically, arms and legs created from rice were added to the RANDO phantom and it was immobilized in a vacuum bed. Computed tomography (CT) images of the lower and upper parts of the phantom with a slice thickness of 3 mm were acquired with and without bolus. Fifteen thermoluminescent dosimeters (TLDs) were placed on the skin line of the RANDO phantom. Treatment plans were prepared, and the phantom was irradiated both with and without bolus by the Helical Tomotherapy technique. Results of the measurements and treatment planning system (TPS) doses were compared by the non-parametric Wilcoxon signed-rank test. All procedures were repeated three times and results were evaluated. At the end of the study, it was proven that even when no bolus is used, the skin receives an adequate dose in TBI with Helical Tomotherapy while achieving homogeneous dose distribution and saving critical organs at the same time. • The skin dose in TBI should not be under 90% of the given dose. • The skin-sparing effect of the photon beam is not desired in TBI. • In old TBI techniques beam spoiler or bolus is needed to reach desired skin dose. • In Tomotherapy, there is no need to use a bolus to enhance the skin dose. • TLD is an important part of treatment planning and QA in radiation therapy for TBI. [ABSTRACT FROM AUTHOR]

Surface brachytherapy (BT) lacks standard quality assurance (QA) protocols. Commercially available treatment planning systems (TPSs) are based on a dose calculation formalism that assumes the patient is made of water, resulting in potential deviations between planned and delivered doses. Here, a method for treatment plan verification for skin surface BT is reported. Chips of thermoluminescent dosimeters (TLDs) were used for dose point measurements. High-dose-rate treatments were simulated and delivered through a custom-flap applicator provided with four fixed catheters to guide the Iridium-192 (Ir-192) source by way of a remote afterloading system. A flat water-equivalent phantom was used to simulate patient skin. Elekta TPS Oncentra Brachy was used for planning. TLDs were calibrated to Ir-192 through an indirect method of linear interpolation between calibration factors (CFs) measured for 250 kV X-rays, Cesium-137, and Cobalt-60. Subsequently, plans were designed and delivered to test the reproducibility of the irradiation set-up and to make comparisons between planned and delivered dose. The obtained CF for Ir-192 was (4.96 ± 0.25) μC/Gy. Deviations between measured and TPS calculated doses for multi-catheter treatment configuration ranged from −8.4% to 13.3% with an average of 0.6%. TLDs could be included in clinical practice for QA in skin BT with a customized flap applicator.

Nuclear medicine technicians would receive unavoidable exposures during the preparation and administration of radiopharmaceuticals. Based on the staff dose monitoring, the dose reduction efficiencies of the radiation protection shields and the need to implement additional strategies to reduce the staff doses could be evaluated. In this study, medical staff doses during the preparation and administration of Tc-99 m, I-131, and Kr-81 radiopharmaceuticals were evaluated. The dose reduction efficiencies of the lead apron and thyroid shield were also investigated. GR-207 thermoluminescent dosimeter (TLD) chips were used for quantifying the medical staff doses. The occupational dose magnitudes were determined in five organs at risk including eye lens, thyroid, fingers, chest, and gonads. TLDs were located under and over the protective shields for evaluating the dose reduction efficiencies of the lead apron and thyroid shield. The occupational doses were normalized to the activities used in the working shifts. During preparation and injection of Tc-99 m radiopharmaceutical, the average annual doses were higher in the chest (4.49 mGy) and eye lenses (4 mGy). For I-131 radiopharmaceutical, the average annual doses of the point-finger (15.8 mGy) and eye lenses (1.23 mGy) were significantly higher than other organs. During the preparation and administration of Kr-81, the average annual doses of the point-finger (0.65 mGy) and chest (0.44 mGy) were higher. The significant dose reductions were achieved using the lead apron and thyroid shield. The radiation protection shields and minimum contact with the radioactive sources, including patients, are recommended to reduce the staff doses. [ABSTRACT FROM AUTHOR]

Thermoluminescent dosimeter (TLD) is still in use for many applications such as radiation protection, medical dosimetry, environmental research, and personnel dosimetry, with the overall aim of estimating radiation dose within a given medium or material. The aim of this study was to determine the coefficient of variation (CV) for thermoluminescent (TL) element within the same bar-coded slide and to establish calibration factors (CFs) at dose equivalent of 0.07 mm depth in tissue (Hp [0.07]) and dose equivalent of 10 mm depth in tissue (Hp [10]) for newly purchased TL elements alongside a new RadPro TLD manual reader and annealing oven. Annealed TL elements were taken to a Secondary Standard Dosimetry Laboratory (SSDL) for irradiation using a cesium-137 source at known doses (0.2–2 mGy). A RadPro Cube 400 manual TLD Reader was used to determine corresponding TL signal. The CV between two identical TL element within a bar-coded slide for (Hp [10]) and (Hp [0.07]) was determined and a graph of dose (mGy) against TL signal (Coulomb) was plotted to determine the elements CF. CVs from the raw data for 40 TL elements for Hp (10) and Hp (0.07) were 14.6% and 15.02%, respectively. Further selection of sensitive TL elements reduced the CVs of Hp (10) and Hp (0.07) to 3.73% and 3.21%, respectively, which was seen to be within ±10% accepted limit. The maximum percentage deviation for the calculated and actual dose for Hp (10) and Hp (0.07) was 16.7% and 14.3%, respectively. The CFs were power of 10 − 6 and the Coefficient of determination (R2) for Hp (10) and Hp (0.07) was 0.9998 and 0.9981, respectively, after adjustments were made on the initial graphs. Although large deviations were observed at low doses from the results of the raw data. Re-selected “golden Chips” had R2 close to unity and CV was within recommended standards.

Background: A monitoring for radiological technologists and radiation workers must be implemented to ensure the radiation safety. Aims: The aim of our study was to measure the occupational radiation dose for medical workers from the Department of Diagnostic Radiology, Cardiac Catheterization Laboratory, Nuclear Medicine, Dental Services, Endoscopy, and Surgery at King Abdulaziz Medical City (KAMC), Riyadh, Saudi Arabia. Materials & Methods: This study was conducted at KAMC, Ministry of National Guard-Health Affairs, Riyadh, Saudi Arabia. Across-sectional study and a suitably and structured questionnaire was adapted from the previous similar studies and monitored radiation doses designed in line with the study's objectives were collected among the different medical workers. A total of 223 medical radiation workers were involved in this study, and descriptive statistics were used to analyze the data. Results: It is noted that the diagnostic radiology department recorded the highest value of effective dose followed by cardiac catheterization laboratory and nuclear medicine and so on. The measured amount of effective dose for diagnostic radiology, cardiac catheterization laboratory, nuclear medicine, dental services, endoscopy, and surgery at KAMC was found to be 14.35, 5.23, 4.56, 3.88, 3.52, and 1.87 mSv, respectively. Conclusions: This study provide an evidence that the occupational radiation dose for all the monitored departments at KAMC are well below the international recommended dose limit (20 mSv). [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the occupational radiation exposure levels of veterinary staff during fluoroscopic examination using thermoluminescent dosimeters (TLDs). A prospective study was conducted to measure radiation doses in three positioned persons (two restrainers and one observer) using TLDs. The TLDs were placed on the inside and outside of the lead-equivalent protective devices of the panorama mask, thyroid shield, apron and arm shield. The TLDs were placed at five anatomic sites (eye, thyroid, breast, gonad and hand). Radiation exposure was measured in 65 fluoroscopic examinations at 80 kVp and 100 mAs. The doses (mSv) (outside/inside the shield) measured in restrainers A and B and observer C were 3.09/0.59, 3.80/0.65 and 0.63/0.44 in the eye; 2.20/0.73, 1.88/1.10 and 0.79/0.45 in the thyroid; 3.42/0.44, 3.94/2.35 and 0.61/0.34 in the breast; 1.84/0.45, 1.69/0.23 and 0.46/0.36 in the gonad; and 5.56/3.16, 8.29/2.99 and 0.79/0.34 in the hand, respectively. Out of all the lead protection devices, the radiation dose of the hand was the highest in all three participants, with the thyroid radiation dose value being the same as the hand in the observer C. Radiation doses received by the eyes of all three participants were also not negligible. Veterinary workers exposed to radiation through not only radiography but also fluoroscopy should wear protective gear, especially for the eyes.

Thyroid exposure to radiation in brain computed tomography (CT) scan is of great value since it is considered as a vital organ. This study aimed to investigate the absorbed dose of thyroid by various protocols of head CT in patients referring to 64-slice CT scan center and to compare the values with the calculated dose by imaging performance and assessment of CT (ImPACT) method. Also, the values of CT scan dose index (CTDI) were calculated with semiconductor detector. In this cross-sectional study, 120 outpatients including three groups of forty individuals over 40 years old referring to the hospital radiology centers in Tehran for head CT were chosen and 3 thermo-luminescence dosimeter (TLD-GR200) were applied on thyroid gland of each patient. For brain CT, Absorbed and effective doses of thyroid gland were calculated by ImPACT software. In addition, semiconductor detector in head CTDI phantom calculated CTDI for the applied protocols. Mean effective dose of thyroid gland in brain scan group was calculated by TLD and ImPACT software which showed no significant difference (P < 0.001). Mean effective dose of thyroid gland in unidirectional and bi-directional sinus scan by TLD and ImPACT software were different significantly (P < 0.001). Also, the differences between CTDI values shown by brain and sinus scan protocol with semiconductor detector and those CTDI were significant (P < 0.001). The calculated values of absorbed dose and effective doses of thyroid by TLD and ImPACT software were not significantly different. Mean effective dose calculated for thyroid gland in head scans by TLD and ImPACT was less than the annual permissive level for thyroid gland suggested by International Committee on Radiological Protection. In this study, calculated values of thyroid effective dose in brain scan with 64-slice scanner were less than the calculated values in a similar study.

Background: Estimating organ dose from computed tomography (CT) procedures is still ongoing. The aim is to reduce induced cancer risk associated with over dose. Aim and Objectives: The aim of this study was to estimate organ dose using CT-Expo software, to compare obtained values with thermoluminescent dosimeter (TLD) measurements from validated in-house phantoms, and to compare the CT-Expo results with other related studies. Materials and Methods: Four CT diagnostic centers denoted as A, B, C, and D were randomly selected for this study. A CT-Expo software (version 2.5 Germany) was used. A preliminary study was carried out to determine organ dose from the in-house phantoms using bovine tissues. The CT dose parameters used with the in-house phantoms were retrieved from the CT monitor and were used with CT-Expo worksheet to estimate organ dose as well. Results: The CT-Expo mean organ dose to the brain, eye lens, esophagus, and thyroid were 29.05 ± 10.78, 35.65 ± 15.1, 12.45 ± 10.13, and 4.25 ± 2.78 mGy, respectively; to the heart and lungs were 13.08 ± 9.84 and 11.5 ± 7.26 mGy, respectively; and to the liver, stomach, and kidney were 14.42 ± 9.07, 12.78 ± 7.97, and 11.73 ± 7.92 mGy, respectively. There was no statistically significant difference between the TLD measurements and CT-Expo (P = 0.361). The relative difference between CT-Expo and TLD measurements for brain, eye lens, heart, lungs, kidney, liver, and stomach were ≤21%. Investigated organ doses from the software were between 4.25 and 35.65 mGy. There was no difference in mean organ dose when compared to the studies in Thailand, Tanzania, Japan, USA (cadavers 1 and 2), and Nigeria. Conclusion: Large percentage differences were noticed in the thyroid and esophagus which was as a result of the software not recognizing them as organs in the head/neck but rather as organs in the chest; however, there was no difference in organ dose between the CT-Expo and TLD measurement from the in-house-validated phantom.

Purpose: This study aimed to evaluate the dosimetric properties of a newly developed thermoluminescent sheet‐type dosimeter (TLD‐sheet) for clinical proton beams. Materials and Methods: The TLD‐sheet is composed mainly of manganese doped lithium triborate, with a physical size and thickness of 150 mm × 150 mm and 0.15 mm respectively. It is flexible and can be cut freely for usage. The TLD‐sheet has an effective atomic number of 7.3 and tissue‐equivalent properties. We tested the reproducibility, fading effect, dose linearity, homogeneity, energy dependence, and water equivalent thickness (WET) of the TLD‐sheet for clinical proton beams. We conducted tests with both unmodulated and modulated proton beams at energies of 150 and 210 MeV. Results: The measurement reproducibility was within 4%, which included the inhomogeneity of the TLD‐sheet. The fading rates were approximately 20% and 30% after 2 and 7 days respectively. The TLD‐sheet showed notable energy dependence in the Bragg peak and distal end of the spread‐out Bragg peak regions. However, the dose–response characteristics of the TLD‐sheet remained linear up to a physical dose of 10 Gy in this study. This linearity was highly superior to those of commonly used radiochromic film. The thin WET of the TLD‐sheet had little effect on the range. Conclusion: Although notable energy dependences were observed in Bragg peak region, the response characteristics examined in this study, such as reproducibility, fading effects, dose linearity, dose homogeneity and WET, showed that the TLD‐sheet can be a useful and effective dosimetry tool. With its flexible and reusable characteristics, it may also be an excellent in vivo skin dosimetry tool for proton therapy. [ABSTRACT FROM AUTHOR]

Background: The use of X-ray as a diagnostic tool for complication and anomaly in the neonatal patient has been helpful, but the effect of radiation on newborn stands to increase their cancer risk. This study aims to determine the mean, 50th percentile (quartile 2 (Q2)), and 75th percentile (quartile 3 (Q3)) entrance surface dose (ESD) from anteroposterior (AP) chest X-ray and to compare our findings with other relevant studies. The study used calibrated thermoluminescent dosimeters (TLDs), which was positioned on the central axis of the patient. The encapsulated TLD chips were held to the patients' body using paper tape. The mean kilovoltage peak (kVp) and milliampere seconds (mAs) used was 56.63(52–60) and 5.7 (5–6.3). The mean background TLD counts were subtracted from the exposed TLD counts and a calibration factor was applied to determine ESD. Results: The mean ESDs of the newborn between 1 and 7, 8 and 14, 15 and 21, and 22 and 28 days were 1.09 ± 0.43, 1.15 ± 0.50, 1.19 ± 0.45, and 1.32 ± 0.47 mGy respectively. A one-way ANOVA test shows that there were no differences in the mean doses for the 4 age groups (P = 0.597). The 50th percentile for the 4 age groups was 1.07, 1.26, 1.09, and 1.29 mGy respectively, and 75th percentile were 1.41, 1.55, 1.55, and 1.69 mGy respectively. The mean effective dose (ED) in this study was 0.74 mSv, and the estimated cancer risk was 20.7 × 10−6. Conclusion: ESD was primarily affected by the film-focus distance (FFD) and the patient field size. The ESD at 75th percentile and ED in this study was higher compared to other national and international studies. The estimated cancer risk to a newborn was below the International Commission on Radiological Protection (ICRP) limit for fatal childhood cancer (2.8 × 10−2Sv−1). [ABSTRACT FROM AUTHOR]

The health risk of staying in space is a well-known fact, and the radiation doses to the astronauts must be monitored. The Pille-ISS thermoluminescent dosimeter system is present on the International Space Station (ISS) since 2003. We present an analysis of 60000 data points over 19 years from the 90 min automatic measurements and show a 4-day-long segment of 15 min measurements. In the case of the 15 min we show that the mapping of the radiation environment for the orbit of the ISS is possible with the Pille system. From our results the dose rates inside the South Atlantic Anomaly (SAA) are at least 1 magnitude higher than outside. From the 90 min data, we select orbits passing through the SAA. A statistical correlation in the SAA between the ISS altitude and monthly mean dose rate is presented with the Spearman correlation value of ρ SAA =0.56. The dose rate and the sunspot number show strong inverse Pearson correlation (R 2 =-0.90) at a given altitude., 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 © 2024 The Committee on Space Research (COSPAR). Published by Elsevier B.V. All rights reserved.)

This study was aimed at estimating restrainer exposure to scatter radiation in veterinary radiography using thermoluminescent dosimeters (TLDs) in different positions, and at different anatomic regions. A prospective study was conducted to measure exposure dose of two restrainers: A (cathode side) and B (anode side), and an observer C (at a 1-meter distance from the X-ray table) over two months. Protective devices included panorama mask, thyroid shield and arm shield. TLDs were placed on the inside and outside of the protective gear at five different anatomic sites (eye, thyroid, breast, gonad and arm). The study data consisted of 778 exposures, 82 patients (78 dogs, four cats), a mean kVp of 58.7 and a mean mAs of 11.4. The doses (outside the shield/inside the shield, in mSv) measured by restrainers A, B and C were eye (3.04/0.42), (2.29/0.17), (0.55/0.01), thyroid (2.93/0.01), (1.97/0.01), (0.19/0.01), breast (1.01/0.04), (0.73/0.01), (0.32/0.01), gonad (0.07/0.01), (0.01/0.01), (0.16/0.01) and arm (2.81/1.43), (1.17/0.01), (0.08/0.01), respectively. This study describes the extent of occupational radiation exposure in small animal radiography. The exposure dose for eyes outside lead protection showed the highest value in all participants. With lead protection, the reduction in the exposure dose of eyes was significant (A: 86%, B: 93%, C: 98%), and the highest reduction was 99% in the thyroid region. These results suggest the necessity of radiation shields in manual restraint, particularly for eye protection.

Background and Aim: CT scan as a medical imaging modality delivers high radiation dose to the patients. Since eye and thyroid are two radiosensitive organs in this study, those effective doses were evaluated in brain CT scan. Using TLD as dosimeter. Materials and Methods: This cross-sectional study was carried out in three selective hospitals in Rasht in September and October in year 2016.TLD was used as personal dosimeter. To measure the effective dose, TLDs were put on the patient’s eyes and thyroid and the mean effective dose was evaluated in brain CT scan. Results were analytical using SPSS software and Anova (P

This analysis estimated secondary cancer risks after volumetric modulated arc therapy (VMAT) and compared those risks to the risks associated with other modalities of head-and-neck (H&N) radiotherapy. Images of H&N anthropomorphic phantom were acquired with a computed tomography scanner and exported via digital imaging and communications in medicine (DICOM) standards to a treatment planning system. Treatment plans were performed using a VMAT dual-arc technique, a nine-field intensity-modulated radiation therapy (IMRT) technique, and a four-field three-dimensional conformal therapy (3DCRT) technique. The prescription dose was 66.0 Gy for all three techniques, but to accommodate the range of dosimeter responses, we delivered a single dose of 6.60 Gy to the isocenter. The lifetime risk for secondary cancers was estimated according to National Council on Radiation Protection and Measurements (NCRP) Report 116. VMAT delivered the lowest maximum doses to esophagus (23 Gy), and normal brain (40 Gy). In comparison, maximum doses for 3DCRT were 74% and 40%, higher than those for VMAT for the esophagus, and normal brain, respectively. The normal tissue complication probability and equivalent uniform dose for the brain (2.1%, 0.9%, 0.8% and 3.8 Gy, 2.6 Gy, 2.3 Gy) and esophagus (4.2%, 0.7%, 0.4% and 3.7 Gy, 2.2 Gy, 1.8 Gy) were calculated for the 3DCRT, IMRT and VMAT respectively. Fractional esophagus OAR volumes receiving more than 20 Gy were 3.6% for VMAT, 23.6% for IMRT, and 100% for 3DCRT. The calculations for mean doses, NTCP, EUD and OAR volumes suggest that the risk of secondary cancer induction after VMAT is lower than after IMRT and 3DCRT.

Background. The use of ionisation chamber and thermoluminescent dosimeter (TLD) for patient dosimetry are well established. Aim and objectives. The aim was to compare the entrance surface air kerma (ESAK) between MTS-N (LiF: Mg, Ti) chips and ionisation chamber by exposing them to same dose. The purpose is to use the TL chips as a tool for patient dosimetry/audit in diagnostic radiology. In addition, homogeneity and element correction factor (ECF) of the selected chips were determined. Material and methods. TL chips were annealed at 400°c for one hour and allowed to cool and were further heated to a temperature of 100°c for another two hour usings a TLD Furnace Type LAB-01/400. The calibrated DCT-10mm ionisation chamber was positioned on a plastic container filled with water, 10cm thick at source to image distance (SID) of 1m for a 10 × 10cm2 field size. The same procedure was used for the TL chips, which were carefully placed in a transparent nylon on the plastic container as well. Exposures were made to 10mGy. MagicMax software was used to display the ion-chamber ESAK. A RadPro Cube 400 manual TLD reader was used to determine corresponding TL signal and predetermined calibration factor (CF). The unexposed chips were subtracted from exposed ones and were multiplied with the appropriate backscatter factor (BSF) to determine TL ESAK. Results. There was good exposure reproducibility from the X-ray unit, with coefficient of variation (CV) of 0.12%. The maximum uniformity index of the chips was 24.18%, which was below the 30% limit. The ECF for the ten (10) selected TL chips ranged from 0.9-1.1, which was within accepted limit (0.8-1.2). The maximum deviation of the TL chips to the ion-chamber was -9%, which was < ± 10%, while 70% of the % deviation were < ± 5%. The mean dose of TL chips was 10.02±0.48mGy, with accuracy of 0.2%. Conclusion. The MTS-N (LiF: Mg, Ti) chips from this study yielded positive results when compared to ionisation chamber measurement at low dose. [ABSTRACT FROM AUTHOR]

Aims: In central nervous system (CNS) tumors, surgery combined with radiotherapy may cure many tumors. The basic technique in conventional radiotherapy is craniospinal radiotherapy; in this technique, spinal cord can be treated with electron or photon beams. This study was aimed to compare two radiotherapy techniques in craniospinal radiotherapy, (a) treatment of spine with a single photon beam and (b) with a combination of photon and electron beams. Materials and Methods: The two techniques were planned. In the first technique, both brain and spine were irradiated with 6 MV photon beams. In the second technique, brain was irradiated with 6 MV photon and spine with 18 MeV electron beams. To compensate the dose deficiency in lumbar area, an anterior field of 15 MV photon beam was also applied in the second technique. The dose to target volume and organ at risks (OARs) were measured by thermoluminescent dosimeter and compared with the corresponding values calculated by Isogray treatment planning system. Results: OARs including heart, mandible, thyroid, and lungs received lower dose from technique 2 compared with technique 1; kidneys were exceptions which received higher dose in the technique 2. Conclusions: The dose to thyroid, mandible, heart, and lungs were lower in technique 2, while kidneys received higher dose in technique 2. This was caused by using the anterior 15 MV photon beam. Based on these results, for children, instead of photon beam for treatment of spinal cord, it is wiser to use electron beam. [ABSTRACT FROM AUTHOR]

Aim: Liver volume measurement is a mandatory test before measure liver surgeries and transplantation. We aimed a study on the difference in volume measurement and radiation dose to an anthropomorphic liver phantom using high-dose and low-dose diagnostic computed tomography (CT). Materials and Methods: Several measurements of the manual total volume measurement done on an anthropomorphic liver phantom mounted with thermoluminescent dosimeter. We exposed the phantom with diagnostic CT, low-dose CT, and a low-dose CT with copper filter. Results: Phantom underwent ten scanning for each exposure. There was no significant difference in the total volume measurement in comparison to the phantom volume. The volume of phantom measured by low-dose CT, low-dose CT with copper phantom, and high-dose CT were 1869 ± 18 cm3, 1852 ± 24 cm³, and 1908 ± 12 cm³, (P = 0.3), respectively. However, the radiation dose delivered was significantly different (1.54 mGy, 0.77 mGy, and 5.84 mGy [P = 0.001], respectively). Conclusion: Total liver volume measurement provides essential clinical information in several clinical conditions. We recommended that the volume measured by a low-dose CT has an excellent correlation with the diagnostic quality CT and should be a routine in the routine clinical practice. CT volumetry achieves the same result while using very less radiation exposure. It may also be used with functional imaging to give complete information. [ABSTRACT FROM AUTHOR]

Thermoluminescent dosimeter (TLD) is still in use for many applications such as radiation protection, medical dosimetry, environmental research, and personnel dosimetry, with the overall aim of estimating radiation dose within a given medium or material. The aim of this study was to determine the coefficient of variation (CV) for thermoluminescent (TL) element within the same bar-coded slide and to establish calibration factors (CFs) at dose equivalent of 0.07 mm depth in tissue (Hp [0.07]) and dose equivalent of 10 mm depth in tissue (Hp [10]) for newly purchased TL elements alongside a new RadPro TLD manual reader and annealing oven. Annealed TL elements were taken to a Secondary Standard Dosimetry Laboratory (SSDL) for irradiation using a cesium-137 source at known doses (0.2–2 mGy). A RadPro Cube 400 manual TLD Reader was used to determine corresponding TL signal. The CV between two identical TL element within a bar-coded slide for (Hp [10]) and (Hp [0.07]) was determined and a graph of dose (mGy) against TL signal (Coulomb) was plotted to determine the elements CF. CVs from the raw data for 40 TL elements for Hp (10) and Hp (0.07) were 14.6% and 15.02%, respectively. Further selection of sensitive TL elements reduced the CVs of Hp (10) and Hp (0.07) to 3.73% and 3.21%, respectively, which was seen to be within ±10% accepted limit. The maximum percentage deviation for the calculated and actual dose for Hp (10) and Hp (0.07) was 16.7% and 14.3%, respectively. The CFs were power of 10 − 6 and the Coefficient of determination (R2) for Hp (10) and Hp (0.07) was 0.9998 and 0.9981, respectively, after adjustments were made on the initial graphs. Although large deviations were observed at low doses from the results of the raw data. Re-selected "golden Chips" had R2 close to unity and CV was within recommended standards. [ABSTRACT FROM AUTHOR]

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 R2 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. [ABSTRACT FROM AUTHOR]

Background: The use of X-ray in dental procedures causes exposure of the patient to ionizing radiation. This exposure depends primarily on the parameters used in tooth examination. The aim of the study was to determine the patients exposure and to assess the technical condition of X-ray tubes. Material and Methods: Seventeen hundred dental offices were covered by the questionnaire survey and 740 questionnaires were sent back. Direct measurements were performed in 100 units by using the thermoluminescent detectors and X-ray films. Results: The results showed that the most commonly used exposure time is 0.22±0.16 s. The average entrance dose for the parameters used most commonly by dentists is 1.7±1.4 mGy. The average efficiency of X-ray tube estimated on the basis of exposures is 46.5±23.7 μGy/mAs. Conclusions: The study results indicate that the vast majority of X-ray tubes meet the requirements specified in the binding regulations. Med Pr 2017;67(4):491–496

Background and Aim: The basic aim in radiography is to acquire a good image from the body organs, but never the issue of the patient's protection against the harmful effects of ionizing radiation should be neglected. One of the most important factors for assessing the radiation risk is the dose received by sensitive organs such as gonads. Radiation damage to the gonads can be lead to genetic damages at the progeny of the radiated individuals, and that damage can be transmitted to the next generation. Materials and Methods: In this study the thermoluminescence dosimeters were used to measure the entrance skin dose. DAP values for each examination and also the patients information such as age, size, weight and machine setting like that mA, time, kVp and focal spot to film distance were recorded. By means of PCXMC software version 2 gonadal doses were calculated. Results: The maximum dose received by the testicles was for the pelvis AP projection, 0.45mGy and for the ovaries maximum dose was for abdomen PA, 0.306 mGy. The minimum dose received by the testicles and ovaries was for lumbar LAT 0.065, 0.101 respectively. Conclusion: One of the ways for patient and gonadal dose reduction is to use appropriate shields for radiosensitive organs such as gonads. Hence its recommended to use appropriate shields for gonads because of their high radiosensitivity.

The use of multi-detector row computed tomography in cardiac examinations is increasing globally. Several hospitals are yet to establish a practical method for evaluating the extra scattering dose in the lungs (Dlung) of male examinees with different body-weights undergoing cardiac computed tomography. To measure the dose in each slice of a lung (Dlung,i), thermoluminescent dosimeters are inserted into Rando and tissue-equivalent phantoms made of polymethylmethacrylate and derived from ICRU 48 with masses from 10 to 90 kg. Dlung was evaluated by weighing the scanned volume of each slice. A practical method for determining Dlung involves 64-slice computed tomography scans using a Philips Brilliance computed tomography at 120 kV and 200 mAs, with a thickness of 1.0 mm. Dlung,i increased with distance from the scanning region. This experiment yielded Dlung values from 12.1 ± 2.1 mSv (90 kg) to 23.0 ± 3.8 mSv (10 kg). Finally, a simple equation can be used to derive the relationship between Dlung and the body-weights of a male examinee. Experimental results are compared with others in the literature.

Introduction: Owing to the abundance of head and neck epithelial tumors and their treatment by radiotherapy and the complications of ionizing rays on the organs that may be in the radiation field and/or in the vicinity of radiation field during radiotherapy as well as the sensitive organs such as gonads to the radiation, to be aware of the absorbed dose of such organs in radiotherapy of head and neck tumors and to reduce the absorbed dose of these organs seem a very crucial issue. This study aims to measure the absorbed dose of thyroid, parathyroid, eye lens and gonads (ovaries and testicles) in radiotherapy of head and neck epithelial tumors and to compare it with the tolerance dose values (TD5/5) of each organ. Materials and Methods: In this research, the received dose to the thyroid, parathyroid, eye lens and gonads in designing a 2-D treatment was measured by TLD-100 for curing the head and neck cancers by Cobalt-60 Device on a tissue-equivalent human phantom and on 20 patients (10 men, 10 women) with head and neck epithelial cancer. The values of absorbed dose were compared using T-test at various depths in phantom and in the area of intended organs. Then, the results were analyzed on Excel®-2010. Results: According to the measurements on phantom, the results of absorbed dose are 176.5±17.3cGy, 6.22±0.14 cGy, 0.37±0.07 cGy and 0.12±0.08 cGy for thyroid-parathyroid, eye lens, ovaries, and testicles, respectively. Meanwhile, the values of average absorbed dose based on measurements on patients are 145.4±12.7 cGy, 7.79±0.36 cGy, 0.26±0.03 cGy and 0.18±0.08 cGy for thyroid-parathyroid, eye lens, ovaries, and testicles, respectively. Discussion and Conclusion: The measurements on phantom at various depths and the analysis of results showed that the absorbed dose does not entail a significant difference in the thyroid and parathyroid regions during the radiotherapy of head and neck epithelial tumors and in the assumed treatment fields (P-Value

Purpose: The aim of this study was to determine the mean volume computed tomography dose index (CTDIvol) for the standard head and body phantoms and locally designed head and body phantoms respectively. Similarly, this study determined and compared the displayed mean CTDIvol and Dose Length Product (DLP) for the above phantoms from the CT monitor. In addition, the percentage deviations of both phantoms were compared with the recommended limits from the International Atomic Energy Agency (IAEA) and the American College of Radiologists (ACR). Materials and Methods: Dose measurements were made using a standard polymethymethacrylate (PMMA) phantom for head and body as well as a locally designed phantom with four CT scanners using thermoluminescence dosimeters (TLDs). The locally designed phantoms were made using a PMMA sheet, which was bent to give the desired cylindrical shape and was made like the standard phantoms. The constructed phantom was filled with water and the TLD chips were inserted into the center and peripheries of the phantoms to obtain the absorbed doses. Results: The CTDIvol for the standard head and body phantom for center A was 66.97 and 21.85mGy and for B was 23.39 and 6.29mGy respectively. Similarly, the CTDIvol for the constructed head and body phantom for center A was 63.91 and 19.84mGy and for B was 24.67 and 6.30mGy respectively. The uncertainty between the standard and constructed head phantoms for centers A and B was 4.6 and 5.5% respectively, while that of the standard and constructed body phantoms for centers A and B was 9.2 and 0.0% respectively. The maximum percent deviation from the console CTDIvol and DLP values with the four phantoms for centers A and B was within ±20%. The mean correction factors for the head and body were 0.998 and 1.05 respectively. Conclusion: The uncertainties obtained in this study were within the IAEA and ACR recommended value of ±20%. The constructed phantom proved useful for CT dose measurements.

Purpose: The purpose of this study was to compare calibration factors for deep dose equivalent Hp (10) and shallow dose equivalent Hp (0.07) between Cesium (Cs)-137 and X-ray sources when they are exposed to same dose and to determine uncertainties with MTS-N (LiF: Mg, Ti) chips when they are exposed to low dose ≤ 2mGy. Material and Methods: Thermoluminescent (TL) chips were annealed at 400oC for one hour and allowed to cool and were subjected to a temperature of 100oC for another two hours using a TLD Furnace Type LAB-01/400. They were then taken to a Secondary Standard Dosimetry Laboratory (SSDL) for irradiation using a Cs-137 source at known doses (0.2-2mGy). A RadPro Cube 400 manual TLD Reader was used to determine corresponding TL signal. The above process was replicated but with a calibrated X-ray unit as the source for calibration. Results: The calibration factors (CF) from the line graph of dose (mGy) against TL signal (count) for Cs-137 source with Hp (10) and Hp (0.07) were 3.72 x 10-6 and 5.97x10-6 mGy/count respectively. Those with X-ray source for Hp (10) and Hp (0.07) were 3.44x10-6 and 4.05x10-6 mGy/count respectively with an overall coefficient of determination (R2) = 0.99. The adjusted maximum percentage deviation between the actual and calculated dose for both sources was -2.74%. The percent (%) deviation of the mean with both sources for Hp (10) and Hp (0.07) was 3.9% and 19% respectively. Conclusion: Adjusted percent deviation from both sources were within the recommended dose limit of ±30% by the Radiological Protection Institute of Ireland (RPII) and within the International Commission on Radiological Protection (ICRP) limit respectively. Better accuracy was seen for Hp (10) with both sources compared to Hp (0.07). Calibration of the MTS-N chips using both sources was successful and can be used for personal dosimetry.

A total body irradiation (TBI) protocol was developed to support a bone marrow transplant (BMT) program for the treatment of canine hematologic malignancies. The purpose of this prospective study is to describe implementation of the protocol and resultant dosimetry. Nongraphic manual treatment planning using 6 MV photons, isocentric delivery, 40 × 40 cm field size, wall‐mounted lasers to verify positioning, a lucite beam spoiler (without use of bolus material), a dose rate of 8.75 cGy/min at patient isocenter, and a source‐to‐axis distance of 338 cm were used for TBI. A monitor unit calculation formula was derived using ion chamber measurements and a solid water phantom. Five thermoluminescent dosimeters (TLDs) were used at various anatomic locations in each of four cadaver dogs, to verify fidelity of the monitor unit formula prior to clinical implementation. In vivo dosimetric data were then collected with five TLDs at various anatomic locations in six patients treated with TBI. A total dose of 10 Gy divided into two 5 Gy fractions was delivered approximately 16 h apart, immediately followed by autologous stem cell transplant. The mean difference between prescribed and delivered doses ranged from 99% to 109% for various sites in cadavers, and from 83% to 121% in clinical patients. The mean total body dose in cadavers and clinical patients when whole body dose was estimated by averaging doses measured by variably placed TLDs ranged from 98% to 108% and 93% to 102% of the prescribed dose, respectively, which was considered acceptable. This protocol could be used for institutional implementation of TBI. [ABSTRACT FROM AUTHOR]

Thyroid exposure to radiation in brain computed tomography (CT) scan is of great value since it is considered as a vital organ. This study aimed to investigate the absorbed dose of thyroid by various protocols of head CT in patients referring to 64-slice CT scan center and to compare the values with the calculated dose by imaging performance and assessment of CT (ImPACT) method. Also, the values of CT scan dose index (CTDI) were calculated with semiconductor detector. In this cross-sectional study, 120 outpatients including three groups of forty individuals over 40 years old referring to the hospital radiology centers in Tehran for head CT were chosen and 3 thermo-luminescence dosimeter (TLD-GR200) were applied on thyroid gland of each patient. For brain CT, Absorbed and effective doses of thyroid gland were calculated by ImPACT software. In addition, semiconductor detector in head CTDI phantom calculated CTDI for the applied protocols. Mean effective dose of thyroid gland in brain scan group was calculated by TLD and ImPACT software which showed no significant difference (P < 0.001). Mean effective dose of thyroid gland in unidirectional and bi-directional sinus scan by TLD and ImPACT software were different significantly (P < 0.001). Also, the differences between CTDI values shown by brain and sinus scan protocol with semiconductor detector and those CTDI were significant (P < 0.001). The calculated values of absorbed dose and effective doses of thyroid by TLD and ImPACT software were not significantly different. Mean effective dose calculated for thyroid gland in head scans by TLD and ImPACT was less than the annual permissive level for thyroid gland suggested by International Committee on Radiological Protection. In this study, calculated values of thyroid effective dose in brain scan with 64-slice scanner were less than the calculated values in a similar study. [ABSTRACT FROM AUTHOR]

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The purpose of this study was to evaluate the occupational radiation exposure levels of veterinary staff during fluoroscopic examination using thermoluminescent dosimeters (TLDs). A prospective study was conducted to measure radiation doses in three positioned persons (two restrainers and one observer) using TLDs. The TLDs were placed on the inside and outside of the lead-equivalent protective devices of the panorama mask, thyroid shield, apron and arm shield. The TLDs were placed at five anatomic sites (eye, thyroid, breast, gonad and hand). Radiation exposure was measured in 65 fluoroscopic examinations at 80 kVp and 100 mAs. The doses (mSv) (outside/inside the shield) measured in restrainers A and B and observer C were 3.09/0.59, 3.80/0.65 and 0.63/0.44 in the eye; 2.20/0.73, 1.88/1.10 and 0.79/0.45 in the thyroid; 3.42/0.44, 3.94/2.35 and 0.61/0.34 in the breast; 1.84/0.45, 1.69/0.23 and 0.46/0.36 in the gonad; and 5.56/3.16, 8.29/2.99 and 0.79/0.34 in the hand, respectively. Out of all the lead protection devices, the radiation dose of the hand was the highest in all three participants, with the thyroid radiation dose value being the same as the hand in the observer C. Radiation doses received by the eyes of all three participants were also not negligible. Veterinary workers exposed to radiation through not only radiography but also fluoroscopy should wear protective gear, especially for the eyes. [ABSTRACT FROM AUTHOR]

Aim: By necessity of dosimeters calibration for evaluating delivered dose accuracy to organs out of the radiation field in patients undergoing gamma knife radiosurgery, we calibrated thermoluminescence dosimeters in gamma knife and 60Co instruments, and then, compared both results to investigate when one of these devices was out of reach, can we use one of this instruments instead of the ther. Materials and Methods: To individual calibration by 60Co, thermoluminescent dosimeters (TLDs) were placed in a Perspex sheet with conditions of source-skin distance = 80 cm, field size = 10 cm × 10 cm, and dose = 100 cGy. For individual calibration by Gamma knife, TLDs placed in flat Perspex were located in a special sphere and were exposed with conditions of source to axis distance = 40 cm, field size = 18 mm, and dose = 100 cGy, and for group calibration, TLDs were divided into six groups and were exposed with doses of 0-1000 cGy in both devices. Results: According to Fisher's exact test, calculated P = 0.27, so the difference is not significant. Conclusions: The result showed despite differences in calibration conditions, 60Co unit can be used to calibrate TLD dosimeter for estimating the accuracy of measurement of delivered dose to organs of patients undergoing Gamma Knife 4C radiosurgery treatment. [ABSTRACT FROM AUTHOR]

Abstract Electron paramagnetic resonance (EPR) dosimetry is a physical method for the retrospective dose assessment for radiation accident. It can be used to detect and measure free radical concentration proportional to the absorbed dose of the sample. The purpose of the work is to establish the conversion coefficients between the absorbed dose of tooth/fingernail and the whole body effective dose. The calibration curves of signal-dose for EPR and electric charge-dose for thermoluminescent dosimeter (TLD) were first established. Linear regression of the relationship has a high R-squared (>0.99) for different radiation modalities with different amounts of energy. The Rando phantom with embedded TLDs at each critical organ was irradiated using the photon beams (6, 10 MV) and the electron beams (6, 9, and 12 MeV) from the linear accelerator. Accordingly, the conversion coefficients between tooth/fingernail dose and whole-body effective dose or between tooth/fingernail dose and the organ dose were derived based on the measurements of TLDs. The effective dose and the absorbed dose of organs can be roughly and quickly estimated by employing the proposed conversion coefficients based on the EPR measurements of teeth and fingernails in case of a radiation accident. As such, the radiation injuries those exposed suffer can be identified for categorization using the EPR measurements. Highlights • EPR dosimetry and TL dosimetry were used. • Good linear relationships of EPR signals-dose and TLD signals-dose are presented. • Conversion coefficients from the tooth/fingernail dose to the effective dose. • EPR measurement of teeth and fingernails for predicting the effective/organ dose. [ABSTRACT FROM AUTHOR]

According to results of in-depth studies, the risk of the radiation-induced cataract is higher than it was considered earlier. In April 2011, ICRP released a statement on the tissue reactions. The statement recommends that for the case of for occupational exposure in planned exposure situations, an equivalent dose for the lens of the eye should be less than 20 mSv in a year, averaged over the defined periods of 5 years, with no single year exceeding the value of 50 mSv. In this regard, the new standard IAEA № GSR Part 3 provides the dose limit of 20 mSv in a year for occupational exposure for the lens of the eye. The dosimetric data on levels of exposure for personnel in the Russian Federation is practically absent. This paper performs a preliminary evaluation of equivalent dose for the lens of the eye for personnel working in X-ray operating rooms of medical facilities in Saint Petersburg and Kazan. This group of personnel was selected because of the fact that methodic of carrying out procedures forces medical staff to be not only in the zone of scattered radiation but also in the X-ray beam. This fact significantly increases exposure doses for the personnel. It is shown that actual annual dose can exceed the new dose limit (the highest recorded value Нр(3) in 3 months of work was 8,6 mSv). We made a conclusion on the necessity of the lens of the eye dose monitoring amongst interventional specialists on conditions that new limits will be established in the Russian Federation. The Russian and foreign dosimeters for measurement of individual dose equivalent for the lens of the eye Нр(3) which have been registered in the Russian State Register of Measuring Instruments, are descrivebed in the paper.