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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]

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: 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]

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]

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]

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]

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]

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]

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]

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]

In this work, dose measurements were performed to evaluate an external radiotherapy treatment plan and, particularly, to validate dose calculations for a lung lesion case. Doses were calculated by the Varian Eclipse treatment planning system using the AAA anisotropic analytical algorithm. The measurements were performed using a Rando anthropomorphic phantom and TLD700 thermoluminescent dosimeters. The comparison between doses calculated and doses measured by means of thermoluminescence (TL) shows compatibility except for a few points, due to the limitations in the heterogeneity correction used for the case studied here. The deviation between the calculated and measured doses is about 6.5% for low (< 0.5 Gy) doses and about 1% for higher doses (> 0.5 Gy).The deviation between AAA-calculated and TL-measured doses was also found to be higher in proximity to heterogeneous tissue interfaces. [ABSTRACT FROM AUTHOR]

This study presumably reports the dosimetric properties of MgB4O7 glass system. A series of MgB4O7 glass samples with nominal compositions XMgO-(100-X) B2O3, with X = 35, 40 and 45 mol% was successfully synthesied using conventional melt quenching method. The presence of broad humps and absence of any sharp peak in typical X-ray diffraction patterns confirm the amorphous nature of the synthesised glass samples. Good glass forming ability, 0.55, of the mixture resulting in a glass with excellent glass stability, 1.4, was observed. Thermoluminescence glow curve was observed to be simple with a single well defined dosimetric peak around 200°C. The dose response was found to be linear from 6 µGy to 0.5 kGy when irradiated to Cs-137 gamma rays. Considerably satisfying thermoluminescent (TL) characteristics suggests that the MgB4O7 glass could be recommended as a TL dosimeter. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aims: To evaluate the underdosing of the maxillary sinus at its distal end produced by air cavity in the path of the 6 MV photon beam. Materials and Methods: A cubic solid water slab phantom of dimensions 18 cm x 18 cm x 18 cm with 4 cm x 4 cm x 4 cm air cavity 3 cm away from its anterior surface was used in this study. The percentage depth dose (PDD) for 6 MV X-rays along the central axis of the cubical air cavity was measured using thermoluminescent dosimeter-100 chips. The EGSnrc/DOSXYZnrc Monte Carlo (MC) code was used to estimate the PDD values in both homogeneous and inhomogeneous conditions. The dose data were generated for 1 cm x 1 cm, 2 cm x 2 cm, 3 cm x 3 cm, and 5 cm x 5 cm field sizes. Results: Average percentage dose reductions at 1 mm beyond the distal surface of the maxillary sinus for the field sizes 1 x 1, 2 x 2, and 3 x 3 cm2 are 42.4%, 39.5%, and 29.4%, respectively. However, for 5 cm x 5 cm field size, there is a dose enhancement (i.e., overdosing) at 1 mm from the distal surface of the maxillary sinus and the average percentage dose enhancement is 5.9%. Also, beyond 1 cm from the air-water interface, there is dose enhancement for all the field sizes. Conclusion: This study showed that the significant dose reduction occurs near the air-water interface for the treatment techniques using small photon fields such as intensity-modulated radiotherapy or other newer techniques. MC-based treatment planning calculation predicts realistic dose distribution while using small photon fields in the treatment of maxillary sinus. [ABSTRACT FROM AUTHOR]

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<0.05). Results: The mean effective doses of eyes and thyroid in three hospitals with codes of H1, H2 and H3 were obtained as 2.66±2.04 mSv and 0.03±0.009 mSv, 1.80±1.11 mSv and 0.03±0.02 mSv, 1.94±0.95 mSv, 0.04±0.01 mSv, respectively. We found significant differences between effective doses of the eyes and thyroid in the three hospitals (p<0.05). Despite the difference in effective doses between right and left sides of eyes and thyroid, we didn't find any other significant differences. Conclusion: The most important factor affecting patient radiation dose is the way CT scan examination is performed. [ABSTRACT FROM AUTHOR]

Background and Aim: The basic aim in radiography is to scan a clear image from the body organs, but the issue of the patient's protection against the harmful effects of ionizing radiation should never be neglected.The present study aimed at calculating the received drug to the perigonadic areas during radiography. Materials and Methods: In the current study thermoluminescence dosimeter was used to measure the dose absorbed by the skin.Dap values for each examination and also the patients demographic information such as age, body size, weight; and radiographic setting like mA, time, kVp , and focal spot distance from thefilm were recorded. Gonadal doses were calculated using PCXMC software (V: 2). Results: Maximum dose received by the testicles in the pelvis AP projection was 0.45 mGy and for the ovaries in abdomen PA it was, 0.306 mGy. Minimum dose received by the testicles and ovaries in lumbar LAT was 0.065 and 0.101, respectively. Conclusion: One of the ways for patients' gonadal dose reduction is to use appropriate shields for radiosensitive organs such as gonads. Hence,it is recommended to use appropriate shields for testicles because of their high radiosensitivity. [ABSTRACT FROM AUTHOR]

Abstract: With the purpose of reducing stray radiation dose (SRD) in out‐of‐field region (OFR) during radiotherapy with 6 MV intensity‐modulated radiation therapy (IMRT), a body‐shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investigated along the medial axis of a phantom using thermoluminescent dosimeters (TLDs). The SRDs at distances from field edge were then measured and analyzed for a clinical IMRT treatment plan for nasopharyngeal carcinoma before and after shielding using the BSD. In addition, SRDs in anterior, posterior, left and right directions of phantom were investigated with and without shielding, respectively. Also, the SRD at the bottom of treatment couch was measured. SRD decreased exponentially to a constant value with increasing distance from field edge. The shielding rate was 50%–80%; however, there were no significant differences in SRDs when shielded by 1 mm lead, 2 mm lead, or 1 mm lead plus 10 mm bolus (P>0.05). Importantly, the 10 mm bolus absorbed back‐scattering radiation due to the interaction between photons and lead. As a result, 1 mm lead plus 10 mm bolus was selected to prepare the BSD. After shielding with BSD, total SRDs in the OFR decreased to almost 50% of those without shielding when irradiated with IMRT beams. Due to the effects of treatment couch and gantry angle, SRDs at distances were not identical in anterior, posterior, left and right direction of phantom without BSD. As higher dose in anterior and lower dose in posterior, SRDs were substantial similarities after shielding. There was no significant difference in SRDs for left and right directions with or without shielding. Interestingly, SRDs in the four directions were similar after shielding. From these results, the BSD developed in this study may significantly reduce SRD in the OFR during radiotherapy, thus decreasing the risk of secondary cancers. [ABSTRACT FROM AUTHOR]

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Introduction: Professional radiation exposure cannot be avoided in nuclear medicine practices. It can only be minimized up to some extent by implementing good work practices. Aim and Objectives: The aim of our study was to audit the professional radiation exposure and exposure rate of radiation worker working in and around Department of nuclear medicine and molecular imaging, Tata Memorial Hospital. Materials and Methods: We calculated the total number of nuclear medicine and positron emission tomography/computed tomography (PET/CT) procedures performed in our department and the radiation exposure to the radiation professionals from year 2009 to 2012. Results: We performed an average of 6478 PET/CT scans and 3856 nuclear medicine scans/year from January 2009 to December 2012. The average annual whole body radiation exposure to nuclear medicine physician, technologist and nursing staff are 1.74 mSv, 2.93 mSv and 4.03 mSv respectively. Conclusion: Effi cient management and deployment of personnel is of utmost importance to optimize radiation exposure in a high volume nuclear medicine setup in order to work without anxiety of high radiation exposure. [ABSTRACT FROM AUTHOR]

PurposesTo design, construct and evaluate an anthropomorphic head and neck phantom for the dosimetric evaluation of 3D-conformal radiotherapy (3D-CRT) dose planning and delivery, for protocols developed by the Radiation Therapy Oncology Group (RTOG).Materials and methodsAn anthropomorphic head and neck phantom was designed and fabricated using Perspex material with delineated planning target volumes (PTVs) and organs at risk (OARs) regions. The phantom was imaged, planned and irradiated conformally by a 3D-CRT plan. Dosimetry within the phantom was assessed using thermoluminescent dosimeters (TLDs). The reproducibility of phantoms and TLD readings were checked by three repeated identical irradiations. Subsequent three clinical 3D-CRT plans for nasopharyngeal patients have been verified using the phantom. Measured doses from each dosimeter were compared with those acquired from the treatment planning system (TPS).ResultsPhantom's measured doses were reproducible with <3·5% standard deviation between the three TLDs’ repeated measurements. Verification of three head and neck 3D-CRT patients’ plans was implemented, and good agreement between measured values and those predicted by TPS was found. The percentage dose difference for TLD readings matched those corresponding to the calculated dose to within 4%.ConclusionThe good agreement between predicted and measured dose shows that the phantom is a useful and efficient tool for 3D-CRT technique dosimetric verification. [ABSTRACT FROM PUBLISHER]

This work is the first evaluation of environmental gamma exposure rates by the Nuclear Medicine Department at Lin Shin Hospital (LSH) in Taichung with Thermoluminescent dosimeter (TLD-100H) during the Fukushima Nuclear Power Plant (FNPP) accident. After the 9.0 M strong earthquake hit northern Japan on March 11, 2011, a TLD-100H was used to monitor environmental kerma rate at Taichung (2,500 km away from northern Japan) from Mar-08 to Apr-09, 2011 and evaluated kerma rate due to global fallout of the sever FNPP accidents. Exposure rates varied widely among positions close to the PET/CT facility. Observed kerma rates of up to 4.12 ± 0.62 mSv mo indicated an explicit, heavy leakage of photon through the PET/CT facility. No significant contributions were detected at Taichung, Taiwan. Hence, the health effect cause by the 'extra radiation' from FNPP accidents is negligible. As this was a rare case of environmental monitoring during a nuclear power plant accident, its findings are of considerable significance. [ABSTRACT FROM AUTHOR]

Second cancer induction in the contralateral breast (CB) is an issue of some concern in breast radiotherapy especially for women under the age of 45 years at the time of treatment. The CB dose from 2-field and 3-field techniques in post-mastectomy chest wall irradiations in an anthropomorphic phantom as well as in patients were measured using thermoluminescent dosimeters (TLDs) at the local radiotherapy center. Breast and chest wall radiotherapy treatments were planned conformally (3D-CRT) and delivered using 6-MV photons. The measured CB dose at the surface fell sharply with distance from the field edge. However, the average ratio of the measured to the calculated CB dose using the pencil beam algorithm at the surface was approximately 53%. The mean and median measured internal dose at the posterior border of CB in a phantom was 5.47 ± 0.22 cGy and 5.44 cGy, respectively. The internal CB dose was relatively independent of depth. In the present study the internal CB dose is 2.1–4.1% of the prescribed dose which is comparable to the values reported by other authors. [ABSTRACT FROM AUTHOR]

Introduction: Patients administered with a therapeutic dose of 131I for thyroid cancer treatment are potential sources of unacceptably high radiation exposure to other individuals, particularly the patient's immediate family members. The aim of this study is to investigate effects of early liothyronine consumption after radio-iodine therapy on accumulated dose and exposure rate in patients with thyroid carcinoma. This study was also undertaken to provide specific guidelines as to when 131I treated thyroid cancer patients may be safe to resume close contact with their family members. Methods: Forty patients treated postoperatively by 131I for the first time were studied. These patients were divided into two groups of twenty (group 1 with liothyronine and group 2 without liothyronine). The administered dose was 100 mCi for all patients. Thermoluminescent dosimeter chips were placed on the neck of the patients to measure thyroid dose. Liothyronine was administered 24 h after iodine therapy. Accumulated dose was measured at 12, 24, 36 and 48 h after iodine therapy. Exposure rate was also measured at 0.5, 1 and 1.5 meters from the patient's body axis with Geiger-Muller detectors at discharge time and one week later. Results: The findings indicated that liothyronine reduces accumulated dose of thyroid and stimulates rapid washout from the body after 48 h. The patient exposure rate was significantly higher in group 2 during or one week following discharge from the hospital. Conclusion: This study shows that liothyronine consumption decreases the exposure rate of patients at discharge time to the levels lower than that recommended by regulatory organizations. [ABSTRACT FROM AUTHOR]

Introduction Previous studies reported that the radiation exposure to the hands of orthopaedic surgeons was far below the acceptable limit. However, the risk could have been underestimated as some factors were overlooked, namely monitoring trainees during average workload, placing dosimeters over the most susceptible locations, measuring the cumulative dosage of radiation and considering the dose limit for non-classified workers. Materials and methods We performed a prospective study in two centres to estimate the radiation dose to the hands of two consultant trauma surgeons and two trainees (one assisting and one operating) while performing 47 fluoroscopy-assisted procedures. We used validated thermoluminescent dosimeters (TLDs) rings and fingerstalls for monitoring the cumulative dosage. Results Trainees were at higher risk while performing intramedullary nailing and during assistance. Higher radiation doses were recorded from dominant index fingers and particularly fingertips. Conclusion The risk of radiation exposure appears to be higher than previously reported. Fingertips are more susceptible to radiation exposure and should therefore be monitored in forthcoming studies. [ABSTRACT FROM AUTHOR]

A new manufacturing process using sol-gel method to obtain thermoluminescent dosimeters—TLDs is described. A LiF/SiO2 thermoluminescent dosimeter in the form of reusable solid chip was prepared using an acid-catalyzed sol-gel process, with tetramethoxysilane (TMOS) and LiF powder as precursors. In comparison with the manufacturing process of typical lithium fluoride based dosimeters, the method optimizes the manufacturing process. The new dosimeter has a dose response over a dose range varying from 0.1 Gy to ∼160 Gy and can be used to detect higher doses using the typical commercial TLD readers without special adjustments. Furthermore, the process may be used for the preparation of other TLDs using a simple chemical processing. [ABSTRACT FROM AUTHOR]

SUMMARY A small but growing proportion of patients requiring radiotherapy for prostate cancer have one or two hip prostheses which may shadow the target and affect the dose distribution. Approximately 10 such patients are treated at the Illawarra Cancer Care Centre per year. Hence a study was undertaken to examine the accuracy of various treatment methods that involve some of the treatment fields travelling through the prosthesis. A fixed-field measurement showed a dose reduction of 52% in the shadow of the prosthesis. A Monte Carlo simulation confirmed an increase in dose on the distal surface of the prosthesis of 35%. Of more clinical relevance, however, is the dose distribution due to the overall combined field treatment. Using a power law correction benchmarked against thermoluminescent dosimeters and Gafchromic film, three different beam set-ups for patient treatment were planned and the dose variation analysed. A four-field brick technique gave a dose variation across the target volume of ± 15% whereas a dual arc technique gave a dose variation of only ± 5%. A four-field oblique technique gave a dose variation of only ± 2% across the target volume but the oblique field technique included extra dose to the rectum. [ABSTRACT FROM AUTHOR]

Purpose: Thermoluminescent dosimeters (TLDs) are routinely used for dosimetric measurements of high energy photon and electron fields. However, TLD response in combined fields of photon and electron beam qualities has not been characterized. This work investigates the response of TLD-100 (LiF:Mg,Ti) to sequential irradiation by high-energy photon and electron beam qualities. Methods: TLDs were irradiated to a known dose by a linear accelerator with a 6 MV photon beam, a 6 MeV electron beam, and a NIST-traceable 60Co beam. TLDs were also irradiated in a mixed field of the 6 MeV electron beam and the 6 MV photon beam. The average TLD response per unit dose of the TLDs for each linac beam quality was normalized to the average response per unit dose of the TLDs irradiated by the 60Co beam. Irradiations were performed in water and in a Virtual Water™ phantom. The 6 MV photon beam and 6 MeV electron beam were used to create dose calibration curves relating TLD response to absorbed dose to water, which were applied to the TLDs irradiated in the mixed field. Results: TLD relative response per unit dose in the mixed field was less sensitive than the relative response in the photon field and more sensitive than the relative response in the electron field. Application of the photon dose calibration curve to the TLDs irradiated in a mixed field resulted in an underestimation of the delivered dose, while application of the electron dose calibration curve resulted in an overestimation of the dose. Conclusions: The relative response of TLD-100 in mixed fields fell between the relative response in the photon-only and electron-only fields. TLD-100 dosimetry of mixed fields must account for this intermediate response to minimize the estimation errors associated with calibration factors obtained from a single beam quality. [ABSTRACT FROM AUTHOR]