RESUMEN

Extremity radiation monitoring is an important tool for the assessment of occupational exposures to staff at a variety of workplaces where ionising radiation is used. This work shows the feasibility of applying 3D printing for the development of customisable ring dosemeters. The rings were developed using two types of resin, hard and flexible and has the possibility of sterilisation using different techniques. The printed ring dosemeter was associated with BeO optically stimulated dosemeters. The energy and angular response were found within ±20% in the energy range from 24 to 662 keV and from 0° to 60° angle of incidence. This contributes to the reduction of measurement uncertainty when compared with currently used thermoluminescent detectors dosemeters. The new ring dosemeter showed a satisfactory response with respect to the performance criteria of the IEC 62387 Standard, in addition to providing improved ergonomics in relation to the commercial ring dosemeter.

Asunto(s)

Exposición Profesional , Monitoreo de Radiación , Humanos , Dosis de Radiación , Monitoreo de Radiación/métodos , Dosímetros de Radiación , Equipos de Seguridad , Exposición Profesional/análisis , Impresión Tridimensional , Dosimetría Termoluminiscente/métodos

RESUMEN

Significant research is being conducted on new materials suitable for dosimetry in recent decades with particular focus on their luminescent properties. For instance, a new ceramic detector, aluminum oxide 520 (ALOX-520), was developed at CDTN in 2011 using the sol-gel method. The detectors were doped with C, Fe, Mg, Ca, Cr, Ni, and Mo impurities that generated the necessary dosimetric trap levels to enhance the luminescence effects. Consequently, the resultant material was appropriate for the quantification of ionizing radiation fields by both thermally and optically stimulated luminescence techniques. Originally, ALOX 520 was sintered at 2023 K under a highly reducing atmosphere. At the end of this process, it exhibited important dosimetric properties, as already described in existing literature. The objective of this study is to conduct tests at higher temperatures in vacuum to investigate the effect of thermal treatments under these conditions on the structural and dosimetric properties of the material. Accordingly, ALOX-520 was re-sintered at high temperatures and the changes in its physical, morphological, and dosimetric properties were analyzed. ALOX 520T exhibited better dosimetric properties in terms of homogeneity, reproducibility, linearity, and signal fading. Physically, an increase in the detection threshold value of ALOX-520T could be linked to a decrease in the sensitivity of this detector. The energy dependence, the thermal quenching correction, and kinetic studies for ALOX-520T conducted as part of this work are original. However, the obtained results are consistent with those reported in the literature for α-Al2O3 ceramic detectors. XRD and XRF analyses demonstrated that the thermal treatment did not change the crystalline structure or composition of the material. All the results indicate that an appropriate thermal treatment could improve the dosimetric properties of the ALOX-520 detector without causing significant changes in its crystalline structure.

Asunto(s)

Óxido de Aluminio , Radiometría , Óxido de Aluminio/química , Reproducibilidad de los Resultados , Cinética , Mediciones Luminiscentes , Dosimetría Termoluminiscente/métodos

RESUMEN

The increasing use of thermoluminescence (TL) materials as radiation detectors with application in different areas of ionizing radiation has motivated research on new materials with adequate luminescent characteristics. In this work, experimental results gadolinium aluminate (GdAlO3) analyzed by thermoluminescent phenomenon under beta irradiation effect are studied. To prepare GdAlO3 powders the coprecipitation method was used. TL glow curve and other luminescent characteristics were analyzed using an automatic Lexsig Smart TL/OSL luminescent reader. TL glow curve showed four peaks with three prominent and well-defined peaks centered at 140, 230, and 270 °C. TL response as a function of beta radiation dose was linearity in the range from 1.1 up to 44 Gy. Kinetic parameters such as activation energy (E), frequency factor (s), and order of kinetics after the deconvolution of the TL glow curve were also determined using Chen's peak shape method. Experimental results show GdAlO3 as a potential luminescent host material for TL studies.

Asunto(s)

Mediciones Luminiscentes , Dosimetría Termoluminiscente , Cinética , Luminiscencia , Polvos , Dosimetría Termoluminiscente/métodos

RESUMEN

This work presents the results obtained from the dosimetric properties of the new radiation detectors of KMgF3:Tb + PTFE. The thermoluminescent material was obtained by microwave technique. The polycrystalline powder obtained was mixed with polytetrafluoroethylene resin powder in the ratio 2:3 to make dosimeters in pellet form. The thermoluminescent response of these new detectors presented a linear behavior, in the dose range between 1 and 1000 Gy 60Co gamma radiation, the repeatability test in the measurements, during ten cycles of heat treatment, irradiation and readouts, showed ±â€¯3.7% DS, the stability test of thermoluminescent signal, during two months showed that the fading is practically null. For the results obtained, this new detector could be very useful for radiation dosimetry, in clinical applications.

Asunto(s)

Dosimetría Termoluminiscente/métodos , Radioisótopos de Cobalto , Fluoruros , Rayos gamma , Humanos , Compuestos de Magnesio , Politetrafluoroetileno , Compuestos de Potasio , Terbio , Dosimetría Termoluminiscente/estadística & datos numéricos

RESUMEN

Interest in the study of the thermoluminescence of metallic oxides doped with various elements has been steadily increasing due to the characteristics of these materials and their possible applications in the dosimetry of ionizing radiation. Metal oxides such as zirconium oxide (ZrO2), aluminum oxide Al2O3, titanium oxide (TiO2), hafnium oxide (HfO2) and beryllium oxide (BeO) are very interesting semiconductor materials having a wide band gap with different important applications. Since 1998, in our country we have developed these materials un-doped and doped with various elements, using different preparation methods. These materials have been obtained in powder form, thin films or in pellets made by mixing the TL powder with PTFE. Thermoluminescent and dosimetric characteristics of these materials have been studied and have been used successfully in various applications. It is presented an overview of the development of these materials in Mexico for the past 20 years.

Asunto(s)

Metales , Dosimetría Termoluminiscente/métodos , Óxido de Aluminio , Berilio , Hafnio , Humanos , Luminiscencia , Metales/química , México , Microscopía de Fuerza Atómica , Óxidos/química , Polvos , Semiconductores , Titanio , Difracción de Rayos X , Circonio

RESUMEN

High levels of primordial radionuclides have been reported in soils and rocks of São José de Espinharas, in the state of Paraiba, Brazil. These radionuclides are derived from high concentrations of natural uranium and thorium from a mine in the region. Thus, there is a need for a dosimetric evaluation in the area near the mine and the surrounding cities. In this study, the annual effective dose was analyzed in 178 points of five cities. The measurements were performed using thermoluminescent dosimetry with LiF:Mg, Ti (TLD-100). The annual effective dose from environmental exposure varied from 0.71 to 2.07 mSv, with an arithmetic mean of 0.99 mSv. This average is more than twice the estimated value for indoor environments adopted by the UNSCEAR, which is 0.41 mSv. These results will allow establishing reference values for background radiation of the region and criteria to infer a stochastic risk for the local population.

Asunto(s)

Radiación de Fondo , Contaminantes Radiactivos del Suelo/análisis , Dosimetría Termoluminiscente/métodos , Uranio/análisis , Brasil , Humanos , Dosis de Radiación , Torio/análisis

RESUMEN

As the ionizing radiation to which workers are exposed is related to possible harmful biological effect, its dose evaluation gains relevance. Although the effects of low doses are still controversial, the radiation protection authorities assume that any dose of ionizing radiation is potentially harmful to the human health and adopt the linear non-threshold model for the dose-effect relation. The Dosimetry Laboratory of the Institute of Physics of the University of São Paulo performs the external individual monitoring of workers exposed to X- and gamma-rays since 1981, with the technique of thermoluminescence. Currently, ~500 badges are provided to the university professionals mostly working in research laboratories and hospitals. Data of individual annual dose equivalent collected from 1995 to 2015 and the performance of the monitoring service are presented in this paper.

Asunto(s)

Exposición Profesional/análisis , Dosimetría Termoluminiscente/métodos , Brasil , Diseño de Equipo , Rayos gamma , Humanos , Enfermedades Profesionales/prevención & control , Dosis de Radiación , Traumatismos por Radiación/prevención & control , Radiación Ionizante , Medición de Riesgo , Dosimetría Termoluminiscente/instrumentación , Universidades , Rayos X

RESUMEN

A new regulatory statement was issued concerning the eye lens radiation protection of persons in planned exposures. A debate was raised on the adequacy of the dosimetric quantity and on its method of measurement. The aim of this work was to establish the individual monitoring procedure with the EYE-D™ holder and a MCP-N LiF:Mg,Cu,P thermoluminescent chip detector for measuring the personal dose equivalent Hp(3) in workers of a Positron Emission Tomography Radiopharmaceutical Production Facility.

Asunto(s)

Cristalino/fisiología , Cristalino/efectos de la radiación , Exposición Profesional/análisis , Tomografía de Emisión de Positrones/métodos , Exposición a la Radiación/análisis , Dosimetría Termoluminiscente/instrumentación , Brasil/epidemiología , Diseño de Equipo , Análisis de Falla de Equipo , Humanos , Radiofármacos , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Dosimetría Termoluminiscente/métodos

RESUMEN

The Brazilian Instituto de Radioproteção e Dosimetria (IRD) runs a neutron individual monitoring system with a home-made TLD albedo dosemeter. It has already been characterised and calibrated in some reference fields. However, the complete energy response of this dosemeter is not known, and the calibration factors for all monitored workplace neutron fields are difficult to be obtained experimentally. Therefore, to overcome such difficulties, Monte Carlo simulations have been used. This paper describes the simulation of the HP(10) neutron response of the IRD TLD albedo dosemeter using the MCNPX transport code, for energies from thermal to 20 MeV. The validation of the MCNPX modelling is done comparing the simulated results with the experimental measurements for ISO standard neutron fields of (241)Am-Be, (252)Cf, (241)Am-B and (252)Cf(D2O) and also for (241)Am-Be source moderated with paraffin and silicone. Bare (252)Cf are used for normalisation.

Asunto(s)

Dosis de Radiación , Dosímetros de Radiación , Monitoreo de Radiación/instrumentación , Protección Radiológica/instrumentación , Dosimetría Termoluminiscente/métodos , Algoritmos , Americio/análisis , Berilio/análisis , Boro/análisis , Brasil , Calibración , Californio/análisis , Simulación por Computador , Humanos , Ensayo de Materiales , Método de Montecarlo , Neutrones , Exposición Profesional/análisis , Parafina/química , Monitoreo de Radiación/métodos , Protección Radiológica/métodos , Sensibilidad y Especificidad , Silicio/química , Programas Informáticos

RESUMEN

This paper aims to evaluate the feasibility of applying LiF:Mg,Ti microdosimeters as a new method of dosimetry to volumetric-modulated arc therapy (VMAT) RapidArc. The response of microdosimeters presented a maximum variation of ±3.18% and ±0.510% using optically stimulated luminescence (OSL) and thermoluminescence (TL) techniques, respectively. Although studies were conducted on LiF:Mg,Ti microdosimeters previously, the microdosimeters in this study showed precision and high potential of application in VMAT dosimetry and in the verification of treatment planning using the VMAT technique.

Asunto(s)

Radiometría/métodos , Radioterapia de Intensidad Modulada/normas , Fluoruros , Humanos , Compuestos de Litio , Luminiscencia , Magnesio , Fantasmas de Imagen , Polimetil Metacrilato , Control de Calidad , Radiometría/instrumentación , Radiometría/estadística & datos numéricos , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada/estadística & datos numéricos , Dosimetría Termoluminiscente/instrumentación , Dosimetría Termoluminiscente/métodos , Dosimetría Termoluminiscente/estadística & datos numéricos , Titanio

RESUMEN

The objective of this work was to evaluate the air kerma-area product (PKA) and the skin absorbed dose in the region of the eyes, salivary glands and thyroid of the patient from mandible examinations performed with three cone-beam computed tomography (CBCT) scanners, i.e. i-CAT classic, Gendex CB-500 and PreXion 3D. For the dosimetric evaluation, an anthropomorphic head phantom (model RS-250) was used to simulate an adult patient. The CBCT examinations were performed using standard and high-resolution protocols for mandible acquisitions for adult patients. During the phantom's exposure, the PKA was measured using an ionising chamber and the absorbed doses to the skin in the region of the eyes, thyroid and salivary glands were estimated using thermoluminescence dosemeters (TLDs) positioned on the phantom's surface. The PKA values estimated with the CBCT scanners varied from 26 to 138 µGy m(2). Skin absorbed doses in the region of the eyes varied from 0.07 to 0.34 mGy; at the parotid glands, from 1.31 to 5.93 mGy; at the submandibular glands, from 1.41 to 6.86 mGy; and at the thyroid, from 0.18 to 2.45 mGy. PKA and absorbed doses showed the highest values for the PreXion 3D scanner due to the use of the continuous exposure mode and a high current-time product.

Asunto(s)

Tomografía Computarizada de Haz Cónico/normas , Mandíbula/diagnóstico por imagen , Dosis de Radiación , Radiometría/normas , Aire , Antropometría , Tomografía Computarizada de Haz Cónico/métodos , Diseño de Equipo , Ojo/efectos de la radiación , Cabeza/efectos de la radiación , Humanos , Imagenología Tridimensional/métodos , Glándula Parótida/diagnóstico por imagen , Fantasmas de Imagen , Piel/efectos de la radiación , Glándula Submandibular/diagnóstico por imagen , Dosimetría Termoluminiscente/métodos , Glándula Tiroides/diagnóstico por imagen , Tomógrafos Computarizados por Rayos X

RESUMEN

We study the high- to low- temperature signal ratio (HLTR) of the CaF2:Tm glow curve as a function of beam quality for low-energy photon beams with effective energy between 15.2 and 33.6 keV, generated with W, Mo and Rh anodes. CaF2:Tm dosemeters (TLD-300) were exposed to x-rays and (60)Co gamma-rays. Glow curves were deconvoluted into 7 peaks, using computerized glow curve deconvolution and HLTR was evaluated. Air kerma and dose in water were between 2.1-15.0 mGy and 49.8-373.8 mGy, respectively. All peaks in the glow curve showed a linear response with respect to air kerma and dose in water. HLTR values decreased monotonically between 1.029 ± 0.010 (at 15.2 keV) and 0.821 ± 0.011 (33.6 keV), and no effects due to the use of different anode/filter combinations were observed. The results indicate a relatively high value of HLTR (about 1 for 17 keV effective energy, or 3 keV µm(-1) track-average LET) and a measurable dependence on the photon beam quality. Comparison of these photon data with HLTR for ions shows good quantitative agreement. The reported evolution of the CaF2:Tm glow curve could facilitate the estimation of the effective energy of unknown photon fields by this technique.

Asunto(s)

Fotones , Dosimetría Termoluminiscente/métodos , Fluoruro de Calcio/química , Rayos gamma , Dosis de Radiación , Talio/química , Dosimetría Termoluminiscente/instrumentación , Rayos X

RESUMEN

This work evaluates the radiological risk that patients treated with I for differentiated thyroid cancer could present to relatives and occupationally exposed workers. Recently, the International Atomic Energy Agency issued document K9010241, which recommends that patient discharge from the hospital must be based on the particular status of each patient. This work measures effective dose received by caregivers of patients treated with I at the Instituto Nacional de Cancerología, Mexico City. Thermoluminescent dosimeters were carried during a 15-d period by 40 family caregivers after patient release from hospital. Relatives were classified into two groups, ambulatory and hospitalized, according to the release mode of the patient, and three categories according to the individual patient home and transport facilities. Categories A, B, and C were defined going from most to least adequate concerning public exposure risk. Measurements were performed for 20 family caregivers in each group. The effective dose received by all caregivers participating in this study was found to be less than 5 mSv, the recommended limit per event for caregivers suggested by ICRP 103. In addition, 70 and 90% of ambulatory and hospitalized groups, respectively, received doses lower than 1 mSv. Caregivers belonging to category C, with home situations that are not appropriate for immediate release, received the highest average doses; i.e., 2.2 ± 1.3 and 3.1 ± 1.0 mSv for hospitalized and ambulatory patients, respectively. Results of this work have shown that the proper implementation of radiation protection instructions for relatives and patients can reduce significantly the risk that differentiated thyroid cancer patients treated with I can represent for surrounding individuals. The results also stress the relevance of the patient's particular lifestyle and transport conditions as the prevailing factors related to the dose received by the caregiver. Therefore, the patient's status should be the criterion used to decide his/her release modality. This work provides support to recommend the implementation of the "patient specific release criteria" in accordance with ICRP 94, IAEA Safety Report No. 63, and IAE document K9010241 A for patients treated with radiopharmaceuticals.

Asunto(s)

Cuidadores , Radioisótopos de Yodo/uso terapéutico , Protección Radiológica , Dosimetría Termoluminiscente/métodos , Neoplasias de la Tiroides/radioterapia , Adulto , Exposición a Riesgos Ambientales , Familia , Femenino , Hospitalización , Humanos , Masculino , México , Persona de Mediana Edad , Alta del Paciente , Factores de Tiempo , Adulto Joven

RESUMEN

The feasibility of Durolon as a thermal neutron dosimeter was studied. As experimentally determined the proposed methodology covers a wide range of doses, from 0.1 mSv

Asunto(s)

Neutrones , Cemento de Policarboxilato/química , Dosimetría Termoluminiscente/instrumentación , Dosimetría Termoluminiscente/métodos , Estudios de Factibilidad , Reproducibilidad de los Resultados

RESUMEN

The glow curve of Al2O3:C compounds has been analyzed by employing a model consisting of two active traps, thermally disconnected traps and one recombination centre. The analysis takes into account interaction among traps and the thermal quenching of the thermoluminescent emission.

Asunto(s)

Óxido de Aluminio/química , Óxido de Aluminio/efectos de la radiación , Modelos Químicos , Dosimetría Termoluminiscente/instrumentación , Dosimetría Termoluminiscente/métodos , Simulación por Computador , Relación Dosis-Respuesta en la Radiación , Electrones , Diseño de Equipo , Análisis de Falla de Equipo , Ensayo de Materiales , Fotones , Dosis de Radiación

RESUMEN

The characteristics of the thermoluminescence glow curve and dosimetric peak of LiF:Mg,Ti (TLD-100) crystals are studied, with emphasis on the evaluation of the influence of the irradiation dose and heating rate on the dosimetric peak (peak 5) trapping parameters. These parameters were obtained using a computerized deconvolution routine that assumed first-order kinetics for each peak composing the glow curve. This routine was able to fit accurately (1.2% < FOM < 3.4%) all measured glow curves. It was found that for the evaluated range of photon doses (0.2 to 20 cGy) and heating rates (7 to 25 K/s), the behavior of the dosimetric peak was consistent with the predictions of the Randall-Wilkins first-order kinetic model. In particular, it was confirmed that the activation energy of the dosimetric peak is independent of the heating rate and irradiation dose, as expected from this model. The mean activation energy obtained for peak 5 was 2.27 ± 0.08 eV. The area under the experimental glow curves for the same dose remained stable regardless of the heating rate used, indicating that the thermal quenching effect did not have a significant influence within the studied range. By fixing the heating rate and varying the dose, it was found that the integral was proportional to the irradiation dose, as expected.

Asunto(s)

Fluoruros/química , Calor , Compuestos de Litio/química , Magnesio/química , Dosimetría Termoluminiscente/métodos , Titanio/química , Cinética

RESUMEN

The aim of this paper was to develop a thermoluminescent dosimetry method for the absorbed dose determination of 6 MeV high-energy electron beams by thermoluminescent dosimetry. Total body irradiation (TBI) was performed using four dual fields angled at 252° and 285° in high-dose rate (HDR) mode. TBI measurements were investigated to estimate the absorbed dose in different anatomical parts of the patient. Experimental results were obtained using thermoluminescent detectors and solid water phantoms. The TL response of the dosimeters, as a function of the high-energy electron beam (HEEB) absorbed dose, was linear, from 0.1 to 500 cGy. The entrance skin dose (ESD) and isodose distribution on the surface of the treatment were investigated graphically.

Asunto(s)

Dosimetría Termoluminiscente/métodos , Irradiación Corporal Total/métodos , Electrones/uso terapéutico , Humanos , Micosis Fungoide/radioterapia , Fantasmas de Imagen , Dosificación Radioterapéutica

RESUMEN

This paper presents the results of Environmental and Personnel Dosimetry made in a radiology area of a veterinary hospital. Dosimetry was realized using thermoluminescent (TL) materials. Environmental Dosimetry results show that areas closer to the X-ray equipment are safe. Personnel Dosimetry shows important measurements of daily workday in some persons near to the limit established by ICRP. TL results of radiation measurement suggest TLDs are good candidates as a dosimeter to radiation dosimetry in veterinary radiology.

Asunto(s)

Protección Radiológica/métodos , Radiometría/métodos , Tecnología Radiológica/veterinaria , Dosimetría Termoluminiscente/métodos , Humanos , Exposición Profesional/análisis , Radiometría/instrumentación , Dosimetría Termoluminiscente/instrumentación

RESUMEN

Thermoluminescence dosimetry (TLD) is applied worldwide for personal and medical dosimetry. TLD method has resulted in many interesting findings in medicine as TL dosimeters have many relevant advantages such as high sensitivity, small physical size, tissue equivalence, etc. The main characteristics of various TL materials used in radiation measurements and their practical consequences are overviewed: well defined TL glow curve, batch homogeneity, signal stability after irradiation, precision and accuracy, response with dose, and influence of energy. In this paper a brief summary of the advances in the application of thermally stimulated luminescence (TSL) to dosimetry in radiation therapy application is presented.

Asunto(s)

Dosimetría Termoluminiscente/métodos , Humanos , Radiometría/métodos , Reproducibilidad de los Resultados

RESUMEN

The presence of caretakers/comforters during nuclear medicine examinations is relatively common. These caretakers receive higher doses than the general public, who receive only environmental/background exposure. The aim of this research was to know about the doses received by two significant groups of caretakers: comforters of cancer patients (Group I) and mothers of small children (Group II). The patients were scheduled to undergo two different diagnostic studies: Inmuno-Scintigraphy using a monoclonal antibody bound to (99m)Tc (for adults) and Renal Scintigraphy using (99m)Tc-dimercaptosuccinic acid (for children). The average effective doses were 0.27 and 0.29 mSv for Groups I and II, respectively. Additionally, environmental monitoring was performed in the waiting room for injected patients (Room I) and inside the procedure room (Room II). Equivalent environmental doses of 0.28 and 0.24 mSv for Rooms 1 and II, respectively, were found, which are similar to values reported by other authors.

Asunto(s)

Cuidadores/estadística & datos numéricos , Exposición a Riesgos Ambientales/estadística & datos numéricos , Madres/estadística & datos numéricos , Neoplasias/diagnóstico por imagen , Dosis de Radiación , Radiofármacos/análisis , Dosimetría Termoluminiscente/métodos , Adolescente , Adulto , Niño , Exposición a Riesgos Ambientales/análisis , Femenino , Humanos , Masculino , Protección Radiológica/métodos , Cintigrafía , Adulto Joven