An Approach to Establishing Diagnostic Reference Levels in Interventional Pediatric Cardiology from Different Regions of Brazil.

Diagnostic reference levels (DRLs) are a pivotal strategy to be implemented since pediatric interventional cardiology procedures are increasing. This work aimed to propose an initial set of Brazilian DRLs for pediatric interventional diagnostic and therapeutic (D&T) procedures. A retrospective study was carried out in four Brazilian states, distributed across the three regions of the country. Data were collected from pediatric patients undergoing cardiac interventional procedures (CIPs), including their age and anthropometric characteristics, and at least four parameters (number of images, exposure time, air kerma-area product-PKA, and cumulative air kerma). Data from 279 patients undergoing CIPs were gathered (147 diagnostic and 132 therapeutic procedures). There were no significant differences in exposure time and the number of images between the D&T procedures. A wide range of PKA was observed when the therapeutic procedures were compared to diagnostics for all age groups. There were significant differences between the D&T procedures, whether grouping data by patient weight or age. In terms of cumulative air kerma, it was noted that no value exceeded the level to trigger a monitoring process for patients. This study shows that it is possible to adopt them as the first proposal to establish national DRLs considering pediatric patient groups.

Occupational radiation exposure in anesthesia for hepatic chemoembolization: a prospective study

Introduction Anesthetists play an important role during interventional radiology procedures. Like the main operator, anesthetists may also be subject to significant radiation levels in the fluoroscopy suite. Due to its complexity, hepatic chemoembolization procedures demand high fluoroscopic times and digital subtraction angiography images, exposing patients and medical staff to high radiation doses. Objective To assess and quantify the radiation to which one anesthetist was exposed over the course of seven consecutive hepatic chemoembolization procedures, and compare it to the exposure received by the main operator. Methods Medical staff dosimetry was evaluated during seven consecutive hepatic chemoembolization procedures conducted in a private hospital in Recife (Brazil), using thermoluminiscent dosimeters placed in regions of the head and torso. Results For the seven procedures evaluated in this study, the anesthetist received, on average, absorbed doses to the glabella, left eyebrow, right eyebrow and effective dose of 142.4 ± 72 µSv, 117.3 ± 66 µSv, 137.8 ± 71 µSv and 12.4 ± 8.4 µSv, respectively. Conclusions In some cases, ocular dose and effective dose received by the anesthetist may be 4 and 4.7 times greater, respectively, when compared to the main operator. According to the results of this study, the current occupational annual dose limit to the lens of the eye of 20 mSv can be exceeded with only two hepatic chemoembolization procedures per week if adequate radiation protection conditions are not guaranteed.

Introducción El anestesiólogo desempeña un papel importante durante los procedimientos de radiología intervencionista. Al igual que el operador principal, el anestesiólogo también puede estar expuesto a niveles significativos de radiación en la sala de fluoroscopía. Debido a su complejidad, durante los procedimientos de quimioembolización hepática se deben utilizar imágenes de fluoroscopía y angiografía de sustracción digital por períodos prolongados, exponiendo a los pacientes y al personal médico a dosis elevadas de radiación. Objetivo Evaluar y cuantificar la radiación a la cual se expuso un anestesiólogo durante el transcurso de siete procedimientos consecutivos de quimioembolización hepática, y comparar con la exposición recibida por el operador principal. Métodos Evaluación de la dosimetría ocupacional durante siete procedimientos consecutivos de quimioembolización hepática realizados en un hospital privado de Recife (Brasil) por medio de dosímetros termoluminiscentes ubicados en regiones de la cabeza y el torso. Resultados Para los siete procedimientos evaluados en este estudio, el anestesiólogo recibió, en promedio, dosis absorbidas en el entrecejo, la ceja izquierda, la ceja derecha y dosis efectivas de 142,4 ± 72 µSv, 117,3 ± 66 µSv, 137,8 ± 71 µSv y 12,4 ± 8,4 µSv, respectivamente. Conclusiones En algunos casos, la dosis ocular y la dosis efectiva que recibe el anestesiólogo puede ser, respectivamente, entre 4 y 4,7 veces más alta que la que recibe el operador principal. De acuerdo con los resultados de este estudio, el límite ocupacional anual de dosis en cristalino (20 mSv) se puede superar con apenas dos procedimientos de quimioembolización hepática a la semana en caso de no garantizarse las condiciones adecuadas de protección contra la radiación.

Development of ring radiation dosemeters using 3D printing.

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.

Radiation Exposure of Patients and Interventional Radiologists during Prostatic Artery Embolization: A Prospective Single-Operator Study.

PURPOSE: To prospectively analyze the radiation exposure of patients and interventional radiologists during prostatic artery embolization (PAE). MATERIALS AND METHODS: Twenty-five consecutive PAE procedures performed with an Artis zee system in a single center by an interventional radiologist were prospectively monitored. The mean age, weight, and prostate volume of the patients were 65.7 year (range, 43-85 y), 71.4 kg (range, 54-88 kg), and 79 cm3 (range, 36-157 cm3), respectively. In addition to Digital Imaging and Communications in Medicine radiation data, direct measures were also obtained. Radiochromic film was used to evaluate peak skin dose (PSD). The radiologist wore a protective apron and a thyroid collar, and a ceiling-suspended screen and a table curtain were used. To estimate the absorbed doses, nine pairs of dosimeters were attached to the operator's body. RESULTS: The average fluoroscopy time was 30.9 minutes (range, 15.5-48.3 min). The mean total dose-area product (DAP) was 450.7 Gy·cm2 (range, 248.3-791.73 Gy·cm2) per procedure. Digital subtraction angiography was responsible for 71.5% of the total DAP, followed by fluoroscopy and cone-beam computed tomography. The mean PSD was 2,420.3 mGy (range, 1,390-3,616 mGy). The average effective dose for the interventional radiologist was 17 µSv (range, 4-47 µSv); values for the eyes, hands, and feet were obtained, and were all greater on the left side. CONCLUSIONS: PAE may lead to high x-ray exposures to patients and interventional radiologists.

PiN photodiode performance comparison for dosimetry in radiology applications.

Performance comparison of selected photodiodes for usage as radiation detectors for radio-protection is presented. In this study, based on the criteria of minimum sensitive area of 5mm2, minimum half angle 60° and low cost, four commercial photodiodes are selected for evaluation: SFH205, SFH206, BPW34, and BPX90F. Photodiodes are low cost, small volume and lightweight detectors. As an electronic transducer, photodiode detector is an attractive approach for the development of low power portable electronic dosimeter for direct-reading real-time radiation dose measurement. The devices have been studied with respect to sensitivity (efficiency) in X-rays and gamma rays detection, repeatability and linearity in air kerma.

Dosimetric study of mandible examinations performed with three cone-beam computed tomography scanners.

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.

OSL and photo-transferred TL of quartz single crystals sensitized by high-dose of gamma-radiation and moderate heat-treatments.

This study investigates the optically stimulated luminescence (OSL) and the photo-transferred thermoluminescence (PTTL) signals in quartz single crystals showing a strong TL peak near 300°C after being sensitized by irradiation with 25kGy of gamma rays and heating at 400°C. Natural and sensitized samples were prepared from two crystals with different sensitivity levels in the 300°C TL region. Continuous-wave (CW) and linearly-modulated (LM) OSL signals were stimulated with blue light-emitting diodes during 40 and 1000s, respectively. Two components were isolated from the CW-OSL signals of sensitized samples. These components were clearly seen in LM-OSL measurements together with two long-term components. LM-OSL showed that the sensitization process considered in this study sensitized an ultrafast OSL component of these crystals. The similar behavior found for the thermal stabilities of OSL and TL signals and the dependence of these signals with sample origins suggested that the trapping site related to the ultrafast component is also related to the TL process of the sensitized peak. The PTTL signal induced by blue LEDs increased the intensity of the sensitized glow peak. On the other hand, a remarkable reduction in the intensity of this peak as a result of the accumulated effect of blue light exposure was clearly seen in both kinds of crystals. These results were explained by a mechanism of competition between optically unstable deep traps and trap levels responsible to the sensitized TL peak.

Dosimetric evaluation of dental implant planning examinations with cone-beam computed tomography.

The aim of this work was to perform a dosimetric evaluation of two cone-beam computed tomography scanners. The study was performed with two scanners: i-CAT classic and PreXion 3D. Air kerma-area product (PKA) was measured for all full-arch dental implant planning protocols. Surface air kerma was also estimated at the region of the eyes, salivary glands and thyroid using thermoluminescence dosemeters positioned on an anthropomorphic phantom. The PKA values for the i-CAT classic ranged from 24 to 180 µGy m(2) and, for the PreXion, from 70 to 138 µGy m(2). The large variation of these values was mainly caused by acquisition time and field of views. The surface air kerma values were from 0.08 to 3.39 mGy at the eyes, 0.50 to 3.96 mGy at the parotids, 0.11 to 2.95 mGy at the submandibular glands and 0.05 to 1.32 mGy at the thyroid. These values are comparable with those found in the literature.

Archeometric studies in the Franciscan Convent of "Santo Antônio" (Recife, PE).

The purpose of this paper is to characterize the tiles placed on the walls of the Franciscan convent of "Santo Antônio" (Recife-PE) and to obtain information about the several expansions and structural reforms performed on the convent by dating the bricks. For this purpose, a portable energy dispersive x-ray fluorescence (EDXRF) was used to characterize the tiles. The dating of the bricks was performed using the Thermoluminescence (TL) technique. The results of the EDXRF analysis show that the dominant component of the white pigment is lead [2PbCO(3)·Pb(OH)(2)], used since the ancient times until the 20th century, while the dominant element of the blue pigment is cobalt (CoO·Al(2)O(3)), that has been used from 1807 until nowadays. The TL dating of bricks indicate that there were walls with different periods of construction, being one built around 1765, with a deviation of 28 years, whereas other was built later, around 1874, with a deviation of 15 years. These results provide new data towards understanding how and when the Recife Franciscan convent of "Santo Antônio" was designed and built, contributing to other research works presently underway on site.

Volume computed tomography air kerma index and image quality evaluation in Brazil.

The aim of this study was to evaluate the image quality of 29 computed tomography (CT) scanners in Brazil and to perform estimations of patient dose and image quality of common CT examinations at these equipment. The volume CT air kerma indexes (C(VOL)) were estimated, using normalised weighted air kerma indexes, supplied by the ImPACT group. The image quality tests were performed using the phantom and accreditation protocol from the American College of Radiology (ACR). The C(VOL) values for head scans varied between 8.7 and 108 mGy. The Hi-res chest examinations presented C(VOL) values varying from 0.4 to 32 mGy. For abdominal scans, the estimated C(VOL) values varied between 4.1 and 94 mGy. This wide variation of air kerma between different centres is related to the scanner type and also to the scanning parameters. The results also showed that the image quality did not attend all ACR CT accreditation requirements.

Characterization of a homemade ionization chamber for radiotherapy beams.

A homemade cylindrical ionization chamber was studied for routine use in therapy beams of (60)Co and X-rays. Several characterization tests were performed: leakage current, saturation, ion collection efficiency, polarity effect, stability, stabilization time, chamber orientation and energy dependence. All results obtained were within international recommendations. Therefore the homemade ionization chamber presents usefulness for routine dosimetric procedures in radiotherapy beams.

Characterization of a CT ionization chamber for radiation field mapping.

A pencil-type ionization chamber, developed at Instituto de Pesquisas Energéticas e Nucleares (IPEN), was characterized with the objective to verify the possibility of its application in radiation field mapping procedures. The characterization tests were evaluated, and the results were satisfactory. The results obtained for the X radiation field mapping with the homemade chamber were compared with those of a PTW Farmer-type chamber (TN 30011-1). The maximum difference observed in this comparison was only 1.25%, showing good agreement.

Qualidade de imagens radiográficas processadas em consultórios odontológicos e em laboratório / Quality of radiographic image processed in dental offices and laboratory

Objetivos: Este estudo avaliou a qualidade de imagens radiográficas expostas em consultórios odontológicos e processadas nos próprios consultórios por cirurgiões-dentistas e/ou auxiliares ou em laboratório, por pesquisadores. Métodos: Dezoito consultórios odontológicos participaram da pesquisa. Cada um recebeu um par de caixas de filmes periapicais Kodak Ektaspeed, os quais foram expostos conjuntamente, com um molar inferior extraído. O tempo de exposição variou em função do consultório odontológico. A auxiliar e/ou o cirurgião-dentista realizaram o processamento de um dos filmes, com as mesmas técnicas e recursos utilizados habitualmente (Grupo 1). O outro filme foi processado por pesquisadores em no Laboratório de Metrologia da Universidade de Pernambuco (Grupo 2). Por meio de questionário, dois radiologistas avaliaram a nitidez, densidade, contraste, definição do esmalte, dentina e junção amelodentinária, erros presentes nas imagens e se cada imagem podia ser suficiente para um bom diagnóstico. A análise estatística foi analisada utilizando o teste do Qui-quadrado e o teste exato de Fisher. Resultados: O Grupo 2 demonstrou maior número de radiografias com baixa densidade e radiografias escuras (p<0,05). O Grupo 1 apresentou maior número de radiografias claras, com pontos escuros, pontos marrons e radiografias arranhadas (p<0,05). Não houve diferença estatística significante em relação à nitidez, contraste, definição do esmalte, dentina e junção amelodentinária, presença de pontos claros e capacidade de levar a um bom diagnóstico (p>0,05). Conclusões: Este estudo sugeriu que imagens radiográficas produzidas em consultórios odontológicos apresentam imperfeições na técnica de execução e no processamento. Entretanto, apesar da importância do correto processamento radiográfico, a sobre-exposição de filmes foi a maior causa de falhas na qualidade da imagem.

This work aims evaluate subjectively the quality of radiographic images exposed in dental offices and processed in proper dental offices by surgeon-dentists and/or assistants or in laboratory, by researchers. Methods: Eighteen dental offices integrated the research. Each one received a pair of Kodak Ektaspeed periapical films which was exposed together with an extracted inferior molar. The exposition time varied in function of each dental office. The assistant and/or surgeon dentist carried through the processing of one of the films, with the same technique and resources used habitually (Group 1). The other film was processed by researchers in the Laboratory of Metrology of Federal University of Pernambuco (Group 2). Through a questionnaire, two radiologists evaluated the sharpness, density, contrast, definition of enamel, dentine and amelodentinary junction, errors present in the images and if each image would be enough for a good diagnosis. Results: Through Chi-Square or Fisher´s Exact test, it was observed that Group 2 got a bigger number of radiographs with low density and dark radiographs (p-value<0,05). Group 1 presented a bigger number of clear radiographs, with dark spots, brown spots and scratch radiographs (p-value<0,05). There wasn?t statistical significant difference in relation to sharpness, contrast, definition of enamel, dentine, and amelodentinary junction, presence of clear spots and the capacity of carrying through a good diagnosis (p-value> 0.05). Conclusions: This study suggested that radiographic images produced in dental office present imperfections in technique execution and in the processing. However, despite the importance of a correct radiographic processing, the overexposure of the films was the major cause of flaws in image quality.

Avaliaçäo dos equipamentos de radiodiagnóstico da cidade do Recife / Evaluation of radiodiagnostic equipment of the Recife city

Um estudo preliminar das condições de funcionamento dos equipamentos de raios-X que operam nas clínicas e hospitais de Recife é apresentado neste trabalho. Os resultados mostraram que 78,2 por cento dos equipamentos testados apresentam coincidência de 1 a 2 por cento entre o campo luminoso e o feixe de radiação. Com relação à exatidão do valor da kV e do tempo de irradiação, os resultados indicaram que 84,6 por cento dos equipamentos analisados apresentam uma divergência maior que 10 por cento entre o tempo real de irradiação e o valor prefixado no painel e que 46,2 por cento paresentam variações maiores que 10 por cento com relação ao potencial do tubo.

This k paper reports the preliminary results of a survey aiming to determine the working conditions of x-ray units operating in hospitais and clinics in the city of Recife, Pernambuco. The results show that the discrepancy between the light field and the x-ray field stayed in the 1 to 2% interval in 78.2% of the equipments tested . The results show also that there is only a fair accuracy regarding kilovoltage and inadiation time. The discrepancy between the preset time and the "true" irradiation time was higher than 10% in 84.6% of the cases. The discrepancy between the preset and the applied kilovoltage, on the other hand, was higher than 10% in 46.2% of the inspected units.