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1.
Biomed Phys Eng Express ; 10(5)2024 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-39094590

RESUMO

Purpose. Secondary skin collimation (SSC) is essential for shielding normal tissues near tumors during electron and orthovoltage radiation treatments. Traditional SSC fabrication methods, such as crafting in-house lead sheets, are labor-intensive and produce SSCs with low geometric accuracy. This study introduces a workflow that integrated 3D scanning and 3D printing technologies with an in-house mold process, enabling the production of patient-specific SSCs within six hours.Methods. An anthropomorphic head phantom was scanned with a handheld 3D scanner. The resulting scan data was imported into 3D modeling software for design. The completed model was exported to a 3D printer as a printable file. Subsequently, molten Cerrobend was poured into the mold and allowed to set, completing the SSC production. Geometric accuracy was assessed using CT images, and the shielding effectiveness was evaluated through film dosimetry.Results. The 3D printed mold achieved submillimeter accuracy (0.5 mm) and exhibited high conformity to the phantom surface. It successfully endured the weight and heat of the Cerrobend during pouring and curing. Dosimetric analysis conducted with radiochromic film demonstrated good agreement between the measured and expected attenuation values of the SSC slab, within ±3%.Conclusions. This study presents a proof of concept for novel mold room workflows that produce patient-specific SSCs within six hours, a significant improvement over the traditional SSC fabrication process, which takes 2-3 days. The submillimeter accuracy and versatility of 3D scanning and printing technologies afford greater design freedom and enhanced delivery accuracy for cases involving irregular geometries.


Assuntos
Imagens de Fantasmas , Impressão Tridimensional , Pele , Humanos , Tomografia Computadorizada por Raios X/métodos , Software , Cabeça , Desenho de Equipamento , Proteção Radiológica/métodos , Proteção Radiológica/instrumentação , Dosimetria Fotográfica/métodos , Dosimetria Fotográfica/instrumentação
2.
Radiat Prot Dosimetry ; 200(11-12): 1167-1172, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016473

RESUMO

There has been an increase in the use of high energy photon beam for container scanners in many countries for multi purposes such as detecting high atomic number materials which might be nuclear materials, drugs, high explosive materials and other contrabands etc. High energy photon beams generally 6 and 9 MV can be used for scanning such materials. However, it is important to ensure that radiation level beyond the container scanner installation is within the permissible dose limit specified by the national competent authority for the protection of public and radiation workers. In this paper, challenges in the biological shielding during the installation of high energy X-ray system for scanning vehicles containing suspected materials are discussed. The purpose of the present study is to develop a methodology for shielding design and evaluation for container scanner installations. The basic concept pertaining to shielding evaluation of radiotherapy installations provided in National Council on Radiation Protection and Measurements (NCRP)/International Atomic Energy Agency (IAEA) reports are referred, and appropriately used to calculate optimized shielding thicknesses requirements for container scanner installation. Workload is estimated based on number of containers scanned, machine ON time and dose rate at 1 m. The shielding evaluation includes use of beam stopper in the primary beam, scattering by heterogeneous metallic scrap materials or any other suspected materials contained in the vehicle and their impact on the thickness of shielding walls. A model lay out plan to be used for installation of container scanner is developed. A methodology for shielding evaluation for various protective walls and ceiling of this model is also discussed. The study provides basic requirement for designing a structural room for installing 9MV container scanner from radiological safety view point.


Assuntos
Desenho de Equipamento , Proteção Radiológica , Proteção Radiológica/instrumentação , Proteção Radiológica/normas , Humanos , Doses de Radiação , Fótons , Raios X
3.
Radiat Prot Dosimetry ; 200(11-12): 1178-1182, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016485

RESUMO

Polydimethyl silicone rubber-based polymer composites filled with molybdenum and bismuth were fabricated using simple open mold cast technique. The physical and chemical structure and gamma shielding parameters like attenuation coefficient, half-value layer (HVL) thickness and relaxation length have been investigated for the said novel materials using X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FTIR) and gamma ray spectrometer. XRD study reveals the crystalline nature of the composites. It is evident from FTIR studies that there is no chemical interaction between the polymer matrix and filler particles. The results of attenuation studies reveal that the linear attenuation coefficient increases with addition of Bi and Mo and is found to be 0.653, 1.341 and 1.017, 1.793 and 0.102, 0.152 cm-1 for 1MMB and 2MMB polymer composites at 80, 356 and 662 keV gamma rays, respectively. The HVL thickness of the materials is found to be 1.06, 0.51 and 0.68, 0.38 and 6.73, 4.532 cm for 1MMB (20Mo + 10Bi phr) and 2MMB (40Mo + 20Bi phr) at these energies, respectively. The mass attenuation coefficient of the novel composites 1MMB and 2MMB is found to be higher than the conventional materials like lead and barite for 356 keV gamma rays. In addition, the material is found to be light weight and flexible enabling to be molded in required forms, thus being a substitute for the material lead that is known to be heavy and toxic by nature.


Assuntos
Bismuto , Molibdênio , Polímeros , Polímeros/química , Molibdênio/química , Molibdênio/efeitos da radiação , Bismuto/química , Raios gama , Radiação Ionizante , Proteção Radiológica/métodos , Proteção Radiológica/instrumentação , Teste de Materiais , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , Humanos
4.
Radiat Prot Dosimetry ; 200(11-12): 1153-1157, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016490

RESUMO

To shield people from dangerous gamma radiation, it is imperative to fabricate inexpensive and environmentally friendly materials. In the present work, suitability of concrete with various % concentrations of ceramics as gamma-ray shielding material has been studied. In this regard, concrete mixture using M-sand and cement with ceramic as filler in different concentrations has been prepared. The mass attenuation coefficients of the prepared samples were measured for different concentrations of ceramics such as 15, 30, 45 and 60%. The mass attenuation coefficients, half value layer (HVL) and tenth vale layer (TVL) of the prepared samples were determined using gamma-ray spectrometer with NaI(Tl) detector at 511, 661.6, 1173, 1332 keV gamma energies. Experimentally obtained mass attenuation coefficients varied from 0.080 to 0.090, 0.074 to 0.086, 0.056 to 0.072 and 0.054 to 0.055 cm2 g-1 at 511, 662, 1173 and 1332 keV, respectively. Therefore concrete mixture with ceramics filler could be a promising shielding material than the bare concrete.


Assuntos
Cerâmica , Materiais de Construção , Raios gama , Proteção Radiológica , Cerâmica/química , Materiais de Construção/análise , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Espectrometria gama , Teste de Materiais , Doses de Radiação , Humanos
5.
Radiat Prot Dosimetry ; 200(11-12): 1132-1137, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016493

RESUMO

KAlpakkam MINI reactor (KAMINI) is a 233U fuelled research reactor has various neutron irradiation locations for experimental purposes. The pit at the south beam end of KAMINI reactor is being extensively utilised for neutron attenuation experiments in prospective shielding materials as well as for neutron radiography. During reactor operation, it will be closed by a movable shield. A vault door is located above the shield and the movable shield is used to attenuate streaming neutrons and gamma-rays during reactor operation. Even with the shield, there exists significant dose because of streaming neutrons and gamma rays. Its variation depends on the power of the reactor. The neutron and gamma dose rates close to the south beam vault door have recently been found to be 275-300 µSv/h and 175-200 µSv/h, respectively, when the reactor is operating at 10 kW. In order to characterise the streaming neutron spectra of vault door place for the first time, measurements are done using the Nested Neutron Spectrometer. Along with the neutron flux, neutron mean energy and ambient dose-equivalent rate are also measured and compared with earlier measurements carried out inside the south beam pit. It is observed that the presence of paraffin shield reduces the neutron average energy from 370 to 178 keV. Apart from energy reduction, 10 kW normalised neutron flux of south beam pit is also attenuated by the shield by 25 000 times and it is found that the neutron spectrum of the measured location is also more thermalized. Neutron reference data of the location are generated.


Assuntos
Raios gama , Nêutrons , Reatores Nucleares , Doses de Radiação , Proteção Radiológica , Proteção Radiológica/métodos , Proteção Radiológica/instrumentação , Monitoramento de Radiação/métodos , Monitoramento de Radiação/instrumentação , Desenho de Equipamento , Análise Espectral/instrumentação , Análise Espectral/métodos , Humanos , Tório/análise , Urânio
6.
Radiat Prot Dosimetry ; 200(11-12): 1233-1236, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016503

RESUMO

The shielding of gamma radiation is of the utmost importance in industries, such as nuclear power plants, medical imaging, and space exploration. For the purpose of shielding objects in such an environment, it is essential to design materials with flexibility as well as high shielding capability. In order to enhance the radiation attenuation effectiveness of polymers, such as polyvinyl alcohol (PVA), glass has been blended with varying percentages. The fabricated composite has been subjected to gamma-ray interaction studies. The radiation shielding parameter, such as mass attenuation coefficient (µ/ρ), has been determined for various energies, such as 137Cs (661.6 keV) and 60Co (1173 and 1332 keV). It is observed that the PVA composite with glass exhibits improved gamma radiation shielding properties compared to PVA. Therefore, the present work paves the way for the utility of PVA polymer with glass, offering a cost-effective and sustainable approach to gamma radiation shielding in radiation environments.


Assuntos
Raios gama , Vidro , Álcool de Polivinil , Proteção Radiológica , Vidro/química , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Álcool de Polivinil/química , Álcool de Polivinil/efeitos da radiação , Polímeros/química , Radioisótopos de Césio , Radioisótopos de Cobalto , Doses de Radiação , Teste de Materiais
7.
Radiat Prot Dosimetry ; 200(11-12): 1197-1201, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39016512

RESUMO

Improved imaging techniques and modern radiotherapy treatment delivery in the treatment field are reduced to the precise size of the tumor, which necessitates the need for small-field dosimetry. Dosimetry in small-field dosimetry is challenging because most of the available code of practice for dosimetry is based on the cavity theory concept. Some small-sized detectors show good spatial resolution and sensitivity. Of the available small detectors, the diamond detector's performance is remarkably good. Most of the centers for radiotherapy lack diamond detectors. In this situation, if a diode detector is available, we can use it for small-field dosimetry by applying the Daisy Chaining method correction methods. In this study, the diode detector's response is not over-responding because of the defective diode. So this diode cannot be used for further measurements, and we have to regularly check the performance of the diode before using it for measurements.


Assuntos
Estudos de Viabilidade , Radiometria , Radiometria/instrumentação , Radiometria/métodos , Humanos , Desenho de Equipamento , Dosagem Radioterapêutica , Semicondutores , Proteção Radiológica/instrumentação
8.
Radiat Prot Dosimetry ; 200(13): 1306-1315, 2024 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-38992982

RESUMO

In India, the prevailing approach to eye lens dosimetry is the placement of an existing dosemeter on the forehead region after slight modification serves as a dedicated Eye Lens Dosemeter. A methodology for estimating the eye lens dose in terms of the Hp(3) has been previously explored employing an algorithm based on the response characteristics of this dosemeter using ISO slab phantom. It was observed that the performance of the dosemeter in terms of Hp(3) using previous algorithm showed under response at higher angles of incidence and photon beams of energy < 200 keV. Further, study was conducted to modify the algorithm following the latest ISO recommendations. This involved generation of data from the response of existing dosemeter on a cylindrical phantom. The results of this study revealed better performance of the newly established algorithm in estimating eye lens dose in terms of Hp(3) when compared to the earlier algorithm.


Assuntos
Algoritmos , Cristalino , Imagens de Fantasmas , Dosimetria Termoluminescente , Humanos , Calibragem , Cristalino/efeitos da radiação , Dosimetria Termoluminescente/instrumentação , Dosimetria Termoluminescente/métodos , Doses de Radiação , Fótons , Cabeça/efeitos da radiação , Índia , Proteção Radiológica/normas , Proteção Radiológica/instrumentação
9.
Brachytherapy ; 23(5): 595-603, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38942713

RESUMO

BACKGROUND: To protect the rectum and bladder from high dose exposure, the Japanese guidelines for managing uterine cervical carcinoma recommend pelvic irradiation with central shielding (CS). Conversely, the European Society for Radiotherapy and Oncology (ESTRO) and the American Brachytherapy Society (ABS) guidelines recommend delivering ≥85 Gy to high-risk clinical target volume D90 (CTVHR D90%). In this study, we investigated whether a gel spacer can enable the safe delivery of the ESTRO/ABS-recommended doses to the target while observing dose constraints for the OARs without using CS in external beam radiation therapy (EBRT). MATERIALS AND METHODS: Twenty patients who received definitive radiation therapy without CS and were treated by brachytherapy with a gel spacer between 2017 and 2022 were retrospectively reviewed. The cumulative doses of EBRT and brachytherapy treatment outcomes and incidence of adverse events were also examined. RESULTS: The median cumulative CTVHR D90%, rectum D2cm3, and bladder D2cm3 were 86.6 Gy, 62.9 Gy, and 72.0 Gy, respectively. The 2-year local control rate was 95%. There were no CTCAE ≥Grade 3 late gastrointestinal or genitourinary adverse events. CONCLUSIONS: The use of gel spacer can enable ESTRO/ABS-recommended dose constraints even without using CS in EBRT, with favorable outcomes and low adverse event rates.


Assuntos
Braquiterapia , Géis , Dosagem Radioterapêutica , Radioterapia Guiada por Imagem , Neoplasias do Colo do Útero , Humanos , Feminino , Braquiterapia/métodos , Braquiterapia/instrumentação , Neoplasias do Colo do Útero/radioterapia , Neoplasias do Colo do Útero/diagnóstico por imagem , Pessoa de Meia-Idade , Estudos Retrospectivos , Idoso , Radioterapia Guiada por Imagem/métodos , Adulto , Tomografia Computadorizada por Raios X , Órgãos em Risco/efeitos da radiação , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Bexiga Urinária/efeitos da radiação , Reto , Idoso de 80 Anos ou mais , Lesões por Radiação/prevenção & controle , Lesões por Radiação/etiologia , Pelve
10.
J Appl Clin Med Phys ; 25(7): e14377, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38695845

RESUMO

PURPOSE: A computational method based on Monte-Carlo calculations is presented and used to calculate isodose curves for a new upright and tilting CT scanner useful for radiation protection purposes. METHODS: The TOPAS code platform with imported CAD files for key components was used to construct a calculation space for the scanner. A sphere of water acts as the patient would by creating scatter out of the bore. Maximum intensity dose maps are calculated for various possible tilt angles to make sure radiation protection for site planning uses the maximum possible dose everywhere. RESULTS: The resulting maximum intensity isodose lines are more rounded than ones for just a single tilt angle and so closer to isotropic. These maximum intensity curves are closer to the isotropic assumption used in CTDI or DLP based methods of site planning and radiation protection. The isodose lines are similar to those of a standard CT scanner, just tilted upwards. There is more metal above the beam that lessens the dose above versus below isocenter. CONCLUSION: Aside from the orientation, this upright scanner is very similar to a typical CT scanner, and nothing different for shielding needs to be done for this new upright tilting CT scanner, because an isotropic scatter source is often assumed for any CT scanner.


Assuntos
Método de Monte Carlo , Tomógrafos Computadorizados , Tomografia Computadorizada por Raios X , Humanos , Tomografia Computadorizada por Raios X/métodos , Tomografia Computadorizada por Raios X/instrumentação , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Imagens de Fantasmas , Doses de Radiação , Algoritmos , Planejamento da Radioterapia Assistida por Computador/métodos , Processamento de Imagem Assistida por Computador/métodos
11.
Radiat Prot Dosimetry ; 200(8): 745-754, 2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38702838

RESUMO

This study analysed the occupational dose in Korean pressurized heavy-water reactors (PHWRs) and identified tasks involving high radiation exposure. The average individual dose was sufficiently low to be below the annual effective dose limit for radiation workers and is even lower than the dose limit for the general public. However, some workers received relatively higher doses than others. Furthermore, most PHWR workers are exposed to radiation during planned maintenance periods. In this study, the radiation dose was normalized (radiation dose per unit time) to determine the high-radiation-exposure tasks in Korean PHWRs. Consequently, end-fitting lapping, delayed neutron tube work and fuel channel fixed-end change tasks were identified as high-radiation-exposure tasks in Korean PHWRs. If appropriate radiation protection measures are prioritized for the identified high-dose exposure tasks, optimization of radiological protection will be effectively achieved by reducing the dose that is relatively higher than the average.


Assuntos
Exposição Ocupacional , Doses de Radiação , Monitoramento de Radiação , Exposição Ocupacional/análise , Exposição Ocupacional/prevenção & controle , Humanos , República da Coreia , Monitoramento de Radiação/métodos , Monitoramento de Radiação/instrumentação , Proteção Radiológica/instrumentação , Exposição à Radiação/análise , Reatores Nucleares , Água
12.
Med Phys ; 51(6): 4423-4433, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38695760

RESUMO

BACKGROUND: The newly available ZAP-X stereotactic radiosurgical system is designed for the treatment of intracranial lesions, with several unique features that include a self-shielding, gyroscopic gantry, wheel collimation, non-orthogonal kV imaging, short source-axis distance, and low-energy megavoltage beam. Systematic characterization of its radiation as well as other properties is imperative to ensure its safe and effective clinical application. PURPOSE: To accurately determine the radiation output of the ZAP-X with a special focus on the smaller diameter cones and an aim to provide useful recommendations on quantification of small field dosimetry. METHODS: Six different types of detectors were used to measure relative output factors at field sizes ranging from 4 to 25 mm, including the PTW microSilicon and microdiamond diodes, Exradin W2 plastic scintillator, Exradin A16 and A1SL ionization chambers, and the alanine dosimeter. The 25 mm cone served as the reference field size. Absolute dose was determined with both TG-51-based dosimetry using a calibrated PTW Semiflex ion chamber and measurements using alanine dosimeters. RESULTS: The average radiation output factors (maximum deviation from the average) measured with the microDiamond, microSilicon, and W2 detectors were: for the 4 mm cone, 0.741 (1.0%); for the 5 mm cone: 0.817 (1.0%); for the 7.5 mm cone: 0.908 (1.0%); for the 10 mm cone: 0.946 (0.4%); for the 12.5 mm cone: 0.964 (0.2%); for the 15 mm cone: 0.976 (0.1%); for the 20 mm cone: 0.990 (0.1%). For field sizes larger than 10 mm, the A1SL and A16 micro-chambers also yielded consistent output factors within 1.5% of those obtained using the microSilicon, microdiamond, and W2 detectors. The absolute dose measurement obtained with alanine was within 1.2%, consistent with combined uncertainties, compared to the PTW Semiflex chamber for the 25 mm reference cone. CONCLUSION: For field sizes less than 10 mm, the microSilicon diode, microDiamond detector, and W2 scintillator are suitable devices for accurate small field dosimetry of the ZAP-X system. For larger fields, the A1SL and A16 micro-chambers can also be used. Furthermore, alanine dosimetry can be an accurate verification of reference and absolute dose typically measured with ion chambers. Use of multiple suitable detectors and uncertainty analyses were recommended for reliable determination of small field radiation outputs.


Assuntos
Radiometria , Radiocirurgia , Radiocirurgia/instrumentação , Radiometria/instrumentação , Proteção Radiológica/instrumentação , Padrões de Referência
13.
Sci Rep ; 14(1): 10719, 2024 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-38729975

RESUMO

The shielding parameters can vary depending on the geometrical structure of the linear accelerators (LINAC), treatment techniques, and beam energies. Recently, the introduction of O-ring type linear accelerators is increasing. The objective of this study is to evaluate the shielding parameters of new type of linac using a dedicated program developed by us named ORSE (O-ring type Radiation therapy equipment Shielding Evaluation). The shielding evaluation was conducted for a total of four treatment rooms including Elekta Unity, Varian Halcyon, and Accuray Tomotherapy. The developed program possesses the capability to calculate transmitted dose, maximum treatable patient capacity, and shielding wall thickness based on patient data. The doses were measured for five days using glass dosimeters to compare with the results of program. The IMRT factors and use factors obtained from patient data showed differences of up to 65.0% and 33.8%, respectively, compared to safety management report. The shielding evaluation conducted in each treatment room showed that the transmitted dose at every location was below 1% of the dose limit. The results of program and measurements showed a maximum difference of 0.003 mSv/week in transmitted dose. The ORSE program allows for the shielding evaluation results to the clinical environment of each institution based on patient data.


Assuntos
Aceleradores de Partículas , Proteção Radiológica , Aceleradores de Partículas/instrumentação , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Humanos , Radioterapia de Intensidade Modulada/métodos , Doses de Radiação
14.
Biomed Phys Eng Express ; 10(4)2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38697045

RESUMO

Whole-body counters (WBC) are used in internal dosimetry forin vivomonitoring in radiation protection. The calibration processes of a WBC set-up include the measurement of a physical phantom filled with a certificate radioactive source that usually is referred to a standard set of individuals determined by the International Commission on Radiological Protection (ICRP). The aim of this study was to develop an anthropomorphic and anthropometric female physical phantom for the calibration of the WBC systems. The reference female computational phantom of the ICRP, now called RFPID (Reference Female Phantom for Internal Dosimetry) was printed using PLA filament and with an empty interior. The goal is to use the RFPID to reduce the uncertainties associated within vivomonitoring system. The images which generated the phantom were manipulated using ImageJ®, Amide®, GIMP®and the 3D Slicer®software. RFPID was split into several parts and printed using a 3D printer in order to print the whole-body phantom. The newly printed physical phantom RFPID was successfully fabricated, and it is suitable to mimic human tissue, anatomically similar to a human body i.e., size, shape, material composition, and density.


Assuntos
Imagens de Fantasmas , Impressão Tridimensional , Contagem Corporal Total , Humanos , Feminino , Contagem Corporal Total/métodos , Calibragem , Proteção Radiológica/métodos , Proteção Radiológica/instrumentação , Radiometria/métodos , Radiometria/instrumentação , Antropometria
16.
Ann Vasc Surg ; 106: 16-24, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38641000

RESUMO

BACKGROUND: The risk of radiation exposure in the surgical operating room (OR) and/or catheterization laboratory is now well established. Complex endovascular procedures often require multiple approaches and different positioning of the staff members around the patient, potentially increasing the levels of radiations exposure. Our goal was to evaluate the levels of radiation exposure of the members of the staff during endovascular aortic procedures in order to propose radioprotection optimization. METHODS: We included 41 aortic endovascular procedures out of 114 procedures performed between January 12, 2014, and August 31, 2015, including 24 standard endovascular aortic aneurysm repair (EVAR), 7 EVAR with iliac branch (EVARib), 8 complex fenestrated/branched EVAR (F/B EVAR), and 2 thoracic EVAR (TEVAR). Procedures were performed in an OR equipped with a carbon fiber table and a mobile fluoroscopy C-arm. We collected the usual dosimetry data given by the C-arm as well as the patient's peak skin dose (PSD). In all staff members, radiation exposure was measured with thermoluminescent chip dosimeters placed on both temples, on posterior sides of both hands, and on both lower legs. RESULTS: PSD levels were low for EVAR because 24 patients had values below the reading threshold. PSD significantly increased with more complex procedures. Main operator (MO) received the higher level of irradiation on whole body, hands, and ankles. Eye lenses irradiation was higher on both assistant operators (AOs). Other members received low levels of irradiation. We found a high ranges of radiation exposure with a high risk of exposure for the AO, mainly for F/B EVAR and EVARib. CONCLUSIONS: Even if all personal protections are used, staff positioning is a major point that must be considered. If MO is supposed to be the most exposed to X-rays, specific conditions of positioning of the AO may be at risk of exposure.


Assuntos
Procedimentos Endovasculares , Exposição Ocupacional , Saúde Ocupacional , Salas Cirúrgicas , Doses de Radiação , Exposição à Radiação , Radiografia Intervencionista , Humanos , Exposição Ocupacional/prevenção & controle , Exposição Ocupacional/efeitos adversos , Procedimentos Endovasculares/efeitos adversos , Procedimentos Endovasculares/instrumentação , Exposição à Radiação/prevenção & controle , Exposição à Radiação/efeitos adversos , Fatores de Risco , Radiografia Intervencionista/efeitos adversos , Medição de Risco , Feminino , Masculino , Implante de Prótese Vascular/efeitos adversos , Implante de Prótese Vascular/instrumentação , Dosimetria Termoluminescente , Monitoramento de Radiação , Idoso , Lesões por Radiação/prevenção & controle , Lesões por Radiação/etiologia , Proteção Radiológica/instrumentação , Pessoa de Meia-Idade
17.
Life Sci Space Res (Amst) ; 41: 119-126, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38670638

RESUMO

The risk posed by prolonged exposure to space radiation represents a significant obstacle to long-duration human space exploration. Of the ion species present in the galactic cosmic ray spectrum, relativistic protons are the most abundant and as such are a relevant point of interest with regard to the radiation protection of space crews involved in future long-term missions to the Moon, Mars, and beyond. This work compared the shielding effectiveness of a number of standard and composite materials relevant to the design and development of future spacecraft or planetary surface habitats. Absorbed dose was measured using Al2O3:C optically stimulated luminescence dosimeters behind shielding targets of varying composition and depth using the 1 GeV nominal energy proton beam available at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory in New York. Absorbed dose scored from computer simulations performed using the multi-purpose Monte Carlo radiation transport code FLUKA agrees well with measurements obtained via the shielding experiments. All shielding materials tested and modeled in this study were unable to reduce absorbed dose below that measured by the (unshielded) front detector, even after depths as large as 30 g/cm2. These results could be noteworthy given the broad range of proton energies present in the galactic cosmic ray spectrum, and the potential health and safety hazard such space radiation could represent to future human space exploration.


Assuntos
Radiação Cósmica , Método de Monte Carlo , Prótons , Proteção Radiológica , Voo Espacial , Proteção Radiológica/instrumentação , Proteção Radiológica/métodos , Humanos , Radiação Cósmica/efeitos adversos , Doses de Radiação , Astronave , Simulação por Computador
18.
Radiat Res ; 201(5): 499-503, 2024 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-38471522

RESUMO

Despite the large variety of high-voltage semiconductor components for medium and high voltage switching and pulse-forming applications as well as for high-power high-frequency generation, the use of vacuum electron tubes still prevails to a considerable degree. Due to the common design incorporating a high energy electron beam which finally is dumped into an anode or a resonator cavity, these tubes are also considered as sources of X rays produced as bremsstrahlung and characteristic radiation, which are referred to as parasitic X rays. Here three types of vacuum-electron tubes, diode, tetrode, and thyratron, with glass housings are investigated. They are predominantly operated in the high voltage range below 30 kV and are not subject to licensing laws. The measurements of the dose rate and X-ray-spectra were performed in the laboratory without complex electrical circuitry usually used in making practical measurements for occupational radiation protection. For the diode tube, where a parasitic X-ray emission is observed only in the reverse operation as a blocking diode, a broad distribution of dose rates of electrically equivalent specimens was observed. This is attributed to field emission from the electrodes. For the tetrode and the thyratron tubes, field emission from the electrodes is identified as the dominant mechanism for the generation of parasitic X rays. Thus, technical radiation protection must focus on shielding of the glass tube rather than optimization of the electrical circuitry.


Assuntos
Elétrons , Vidro , Exposição Ocupacional , Raios X , Vácuo , Vidro/química , Exposição Ocupacional/análise , Doses de Radiação , Proteção Radiológica/instrumentação
19.
Cardiovasc Revasc Med ; 64: 70-75, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38538447

RESUMO

OBJECTIVES: This study evaluated the efficacy of a novel comprehensive shield designed to minimize radiation exposure (RE) to Physicians performing coronary and structural heart procedures. BACKGROUND: The Protego™ radiation shielding system (Image Diagnostics Inc., Fitchburg, Ma) is designed to provide comprehensive protection from RE and has been State certified sufficient to allow operators to perform procedures without orthopedically burdensome lead aprons. METHODS: This single center two-group cohort study assessed the efficacy of this shield in a large number of cardiac procedures (coronary and structural), comparing operator RE compared to standard protection methods (personal lead apparel and "drop down" shield). RESULTS: The Protego™ system reduced operator RE by 99 % compared to Standard Protection. RE was significantly lower at both "Head" level by thyroid median dose 0.0 (0.0, 0,0) vs 5.7 (2.9, 8.2) µSv (p < 0.001), as well as waist dose 0.0 (0.0, 0.0) vs 10.0 (5.0, 16.6) µSv (p < 0.001). "Zero" Total RE was documented by Raysafe™ in 64 % (n = 32) of TAVR cases and 73.2 % (n = 183) of the coronary cases utilizing Protego™. In contrast, standard protection did not achieve "Zero" exposure in a single case. These dramatic differences in RE were achieved despite higher fluoroscopy times in the Protego™ arm (11.9 ± 8.6 vs 14.3 ± 12.5 min, p = 0.015). Per case procedural exposure measured by Dose Area Product was higher in the Protego™ group compared to standard protection (115.4 ± 139.2 vs 74.9 ± 69.3, p < 0.001). CONCLUSION: The Protego™ shield provides total body RE protection for operators performing both coronary and structural heart procedures. This shield allows procedural performance without the need for personal lead aprons and has potential to reduce catheterization laboratory occupational health hazards.


Assuntos
Exposição Ocupacional , Saúde Ocupacional , Doses de Radiação , Exposição à Radiação , Proteção Radiológica , Radiografia Intervencionista , Humanos , Exposição Ocupacional/prevenção & controle , Exposição Ocupacional/efeitos adversos , Exposição à Radiação/prevenção & controle , Exposição à Radiação/efeitos adversos , Proteção Radiológica/instrumentação , Radiografia Intervencionista/efeitos adversos , Radiografia Intervencionista/normas , Fatores de Risco , Medição de Risco , Lesões por Radiação/prevenção & controle , Lesões por Radiação/etiologia , Desenho de Equipamento , Cateterismo Cardíaco/efeitos adversos , Cateterismo Cardíaco/instrumentação , Masculino , Monitoramento de Radiação , Feminino
20.
Magn Reson Med ; 92(1): 406-415, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38411281

RESUMO

PURPOSE: To utilize the transmit radiofrequency (RF) field in MRI as a power source, near or within the field of view but without affecting image quality or safety. METHODS: Power harvesting is performed by RF induction in a resonant coil. Resulting RF field distortion in the subject is canceled by a selective shield that couples to the harvester while being transparent to the RF transmitter. Such shielding is designed with the help of electromagnetic simulation. A shielded harvester of 3 cm diameter is implemented, assessed on the bench, and tested in a 3T MRI system, recording power yield during typical scans. RESULTS: The concept of selective shielding is confirmed by simulation. Bench tests show effective power harvesting in the presence of the shield. In the MRI system, it is confirmed that selective shielding virtually eliminates RF perturbation. In scans with the harvester immediately adjacent to a phantom, up to 100 mW of average power are harvested without affecting image quality. CONCLUSION: Selective shielding enables stealthy RF harvesting which can be used to supply wireless power to on-body devices during MRI.


Assuntos
Desenho de Equipamento , Imageamento por Ressonância Magnética , Imagens de Fantasmas , Ondas de Rádio , Imageamento por Ressonância Magnética/instrumentação , Proteção Radiológica/instrumentação , Humanos , Análise de Falha de Equipamento
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