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The main purpose of this study was to compare the parameters of computed tomography (CT) and the corresponding patient doses undergoing chest CT scan examinations in different regions of Brazil, providing the current scenario of how these procedures are being carried out in the country as well as the patient dose distribution. Thirty institutions, across 17 states and the Federal District participated in the survey. The evaluation included 30 multislice CTs of seven different models, manufactured by General Electric healthcare (GE). For each institution, data from 10 adult chest CT examinations, performed without contrast, were collected remotely. The analysis of the results showed a significant difference of the CTDIvol values, ranging from 1.1 mGy to 46.6 mGy. In 7 institutions. The mean value of CTDIvol was higher than values found in the literature and the UK Reference Levels. It was also observed that, regardless of the region of the country, for the same CT model, different scanning parameters were used, which resulted in CTDIvol up to five times higher among these institutions. Repetitions of CT acquisitions and scouts with radiation field dimensions larger than the region of interest were found in 25% of chest examinations, resulting in higher absorbed doses. The results of this work show a mapping of the chest CT procedures, which enable to establish strategic plans for the country. In addition, each institution will be able to implement an appropriate optimization program and establish institutional reference levels.

This study examines the thermoluminescent emission of quartz whose existence can be registered with 1 mGy test-doses. Samples originated from three crystals were sensitized using the combined effect of gamma radiation and heat-treatments. The glow curves were registered under five optical setups to collect emissions from ultraviolet to yellow-orange bands. The emissions were scrutinized using a computerized deconvolution method. After sensitization, the activation energies of trapping states increased, and the violet/blue emissions exceeded the near-ultraviolet emission in the whole glow curve. The possibility to remove and restore the sensitization effect and the existence of strong emissions above 350 °C indicates that the rise in TL sensitivity occurs when competition between active and deep traps is annihilated. The narrow distribution of activation energies and the subtle changes in band emissions suggest that TL production in quartz consist of localized transitions involving different energetic levels of the same traps and recombination centers.

This work demonstrates the use of high-resolution 3D printing to fine-tune the low energy dependence of an eye lens dosimeter holder associated to a BeO OSL detector element (ezClip). Five geometries of the denominated iBe dosimeter were developed, three with a variation in the thickness of the wall in front of the sensitive element that tailor the response at low radiation energies; and three with variations of width and curvature in order to vary the angular response of the dosimeter badges. Additive manufacturing was accomplished using stereolithography which gave a high degree of accuracy and precision. The optimised dosimeter badges showed a low energy and angular dependence, within −20% to +20% in the energy range of 24 keV to 662 keV and from 0 to 60° incidence; and within −10% to +10% in the energy range of 24 keV to 164 keV and from 0 to 60° incidence. In contrast to other dosimeters with higher effective atomic numbers, the use of BeO as the sensitive element resulted in a flat energy and angular dependence response at low energies. A significant reduction in the measurement uncertainty in the diagnostic radiology energy range was achieved.

The aim of this multi-centre study was to evaluate the irradiation parameters and the radiation dose of abdomen CT exams without contrast, performed in adults In Brazil, in order to provide an overview of the CT installed base in the country and contribute for the establishment of optimization programs. Equipment of seven different models, with 16 and 64 channels, installed in 17 Brazilian states, plus the Federal District, were analyzed. The results show that the mean CTDIvol ranged from 6.60 mGy to 34.64 mGy. The results also showed that different irradiation parameters are used in equipment of the same model, resulting, in some cases, in three times higher CTDIvol values. These characteristics are not restricted to a given region of the country but distributed throughout the national territory. Repetitions of acquisitions and topograms with scan length larger than the region of interest were found in 13.5% of abdomen examinations, resulting in considerably higher absorbed doses than expected. This survey of the abdomen tomography exams, performed in about 74% of the Brazilian states, showed that in many clinics the procedures are not optimized. This study can be used for the planning of dose optimization programs and will contribute to the establishment of local diagnostic reference levels (DRL) for CT.

Recent epidemiological studies suggested to lower the threshold dose for radiation induced cataract in the eye lens. Therefore, eye lens radiation protection became to play a more important role in personal dosimetry. The main objective of this work is to propose a new methodology for prototyping and benchmarking of an eye lens dosiemter based on the equivalent dose to the sensitive part of the eye lens, using CAD Software and Geant 4 Monte Carlo simulations with mesh modeling and 3D printing. A 3D printed dosimeter was type tested based on IEC 62387:2012, in terms of energy and angular dependence for the measurements of Hp(3). The results show that the methodology employed is suitable for the development of new eye lens dosimeters.

A comparison exercise of Latin American and Caribbean Secondary Standards Dosimetry Laboratories (SSDLs) was jointly organized by the International Atomic Energy Agency (IAEA) and the Ionizing Radiation Metrology Laboratory at the Federal University of Pernambuco (LMRI-DEN/UFPE). This exercise was organized during an IAEA regional meeting on the review and update of calibration capabilities in Latin America, held in Recife, during the period from 23 to 27 April 2018 under the technical cooperation project ME-RLA 9085-170572. Fifteen participating SSDLs were required to irradiate optically stimulated personal dosimeters in terms of the personal dose equivalent Hp(10) in 137Cs radiation quality. In addition, the IAEA Dosimetry Laboratory in Seibersdorf, Austria, and the National Physical Laboratory in Teddington, Middlesex, UK participated in this exercise as reference institutes. Each participant received 10 dosimeters that were hand-carried directly to the SSDL. Two nominal dose values of 2 mSv and 4 mSv were selected for this exercise. The participants irradiated the dosimeters using the setup and the procedures which are normally used in their standard laboratory for Hp(10) dosimeter irradiations. The dosimeters were evaluated as they were received by the coordinating laboratory, using a single BeOSL Reader. The results show that, except for one laboratory, the differences between the dosimeter reading and the assigned values were within 10%; this is consistent with the expanded uncertainty. The results indicate that most of the participant laboratories have a good capability to irradiate personal dosimeters in the quantity Hp(10).

Optically Stimulated Luminescence (OSL) is the luminescence emitted from a previously irradiated with ionizing radiation material by exposure to light. The aim of this paper is to evaluate the Blue Stimulation Luminescence (BSL) and Infra-Red Stimulation Luminescence (IRSL) for CaF2:Ce produced by the Solution Combustion Synthesis (SCS) method. The results showed that the OSL response of CaF2:Ce is strongly influenced by post-combustion thermal sintering temperature and dopant concentration. OSL response to dose are of the same order of magnitude of Al2O3:C, indicating the possibility of use of this material for radiation dosimetry.

Nanocrystalline powder samples of barium sulfate doped with Europium (BaSO4:Eu2+) were prepared, at a dopant concentration of 0.02 mol%, by the combustion solid-state technique in air atmospheres. Thermoluminescence (TL) response and dosimetric studies have been carried out for this phosphor in order to characterize it as a radiation dosimeter. The results showed that the TL glow curve of BaSO4:Eu2+present an intense TL peak at 200 °C accompanied by a small shoulder peak at 270 °C. The TL low detection limit for BaSO4:Eu (0.02 mol%) was found to be 17.8 μ G y for the gamma radiation emitted by 137Cs . The comparative study with the LiF:Mg, Ti (TLD-100) and calcium fluoride doped with thulium CaF2:Tm dosimeters showed that the TL response of the BaSO4:Eu(0.02 mol%) synthesized by the combustion solid-state technique is highly sensitive: it is 5.8 times higher than the response of the CaF2:Tm pellets and 9.4 times higher than the response of TLD-100. The high sensitivity of BaSO4:Eu and its linear dose response indicate that it can be used as sensor for gamma ionizing radiations.

This paper presents the results of X-ray fluorescence (XRF) analysis of bricks sampled from historical places in Pernambuco, a state in the northeastern region of Brazil. In this study, twenty bricks found in historical sites were analyzed. Two bricks made in the 17th century, presumably used as ballast in ships coming from Holland, five locally manufactured bricks: one from 18th century, three from 19th century, and one from 20th century, and thirteen bricks collected from a recent Archeological investigation of Alto da Se, in the town of Olinda. Qualitative determination of the chemical elements present in the samples was undertaken using a self-assembled portable XRF system based on a compact X-ray tube and a thermoelectrically cooled Si-PIN photodiode system, both commercially available. X-ray diffraction analysis was also carried out to assess the crystalline mineral phases present in the bricks. The results showed that quartz (SiO2) is the major mineral content in all bricks. Although less expressive in the XRD patterns, mineral phases of illite, kaolinite, anorthite, and rutile are also identified. The trace element distribution patterns of the bricks, determined by the XRF technique, is dominated by Fe and, in decreasing order, by K, Ti, Ca, Mn, Zr, Rb, Sr, Cr, and Y with slight differences among them. Analyses of the chemical compositional features of the bricks, evaluated by principal component analysis of the XRF datasets, allowed the samples to be grouped into five clusters with similar chemical composition. These cluster groups were able to identify both age and manufacturing sites. Dutch bricks prepared with different geological clays compositions were defined.

Excavations in the Lagoa Uri de Cima Archaeological Site (Salgueiro, Pernambuco, Brazil) revealed considerable Pleistocene mammalian fossils and lithics in multiple sedimentary layers of the ancient lake, currently dry. The site was found in 2010 during the construction of an open-air system of canals to connect water sheds of the semi-arid regions with the Sao Francisco River. The coexistence of a variety of extinct mammals and archaeological remains suggested the possibility of further light on the question of overlapping occupation of Northeastern Brazil by megafauna and humans in the Late Pleistocene. Electron spin resonance (ESR) dating of tooth enamel of mammal fossils can provide valuable information on the chronology of this site. This work presents the ESR dating of four teeth of two mammal species: Toxodon platensis (2) and Haplomastodon waringi (2). Dose-response curves were constructed using T1-B1 and T1-B2 amplitudes of the ESR signal of the hydroxyapatite CO2−radical, measured with a Bruker EMX-10+ X-band spectrometer. To verify the experimental protocol and the reliability of the exponential fittings for additive-doses and ESR signal intensities, the dose-response curve of one Toxodon platensis sample was independently obtained with a Jeol FA-200 X-band spectrometer. Equivalent dose to age conversions were carried out with the ROSY ESR dating program, with the external dose rate given by the environment and cosmic radiation and the internal dose rate given by probable uranium uptake models. The results show ages varying from 12,000 to 19,000 years for the four samples. The stratigraphical consistency is sub-optimal, but can be explained by the overall geomorphology of the site. These results place the creation of the lowest sedimentary levels of Lagoa Uri de Cima within the Late Pleistocene.

The results obtained with a standard float zone (FZ) silicon diode, processed at the Helsinki Institute of Physics, used as on-line diagnostic X-ray dosimeter are described in this work. The device was connected in the short-circuit current mode to the input of an integrating electrometer. The response repeatability and the current sensitivity coefficient of the diode were measured with diagnostic X-ray beams in the range of 40-80 kV. The dose-response of the device, evaluated from 10 mGy up to 500 mGy, was linear with high charge sensitivity. Nevertheless, significant energy dependence was observed in the charge sensitivity of FZ device for energies below 70 kV. The dosimetric characteristics of this FZ diode were compared to those of an XRA-50 commercial Si diode, specially designed to X-ray dosimetry. The results obtained with the FZ diode evidenced that it can be an alternative choice for diagnostic X-ray dosimetry, although it needs to be calibrated for individual X-ray beam energies. The studies of long-term stability and the radiation hardness of these diodes are under way.

The response of thin diodes (SFH206k) as dosimeters has been investigated employing the beam of an electron accelerator within the dose rate range of 2–8 kGy/s and accumulated doses up to 100 kGy. These devices, operating in the short-circuit mode and under industrial irradiation conditions, deliver current signals nonlinearly dependent on the dose rate, whichever the dose history of the diodes, due to the high density of the generated electron-hole pairs herein achieved. Despite this nonlinearity, the dose rate response is stable and characterized by current signals with repeatability better than 2.0%, regardless of the accumulated dose. It is also found that the dose responses are quite linear with sensitivities slightly dependent on the accumulated dose at a constant dose rate. The decrease in the charge sensitivity, taking as reference that obtained before any radiation damage, reaches only 9% (k = 2) at 100 kGy, which is much smaller than the values reported in the literature. From this low aging and the repeatability of both dose rate and dose responses, it seems that the photodiode under investigation is a low budget alternative, good enough for routine dosimetry, provided it has been previously calibrated in the same processing facility.

Calcium Fluoride is one of the oldest known thermoluminescent materials and is considered to be one of the most sensitive. This work presents the dosimetric properties results of CaF2:Tm produced by combustion synthesis. The X-ray diffraction confirmed that CaF2 was successfully produced. TL emission spectra, obtained using a Hammamatsu optical spectrometer, have the same lines of commercial CaF2:Tm, although transitions 3P0→3F4 (455 nm) and 1G4→3H6 (482 nm) are shown to be proportionally more intense. The deconvolution technique was employed and seven glow peaks were found similar to the commercial CaF2:Tm. A linear dose response curve was obtained for the range 0.1 mGy to 100 Gy, with the onset of a supralinear behavior at 50 Gy up to 100 Gy. The minimum measurable dose for gamma was around 100 μGy for a 6.0 mm diameter by 1.0 mm in thickness pellet. No significant fading was observed in 60 days of storage, within experimental uncertainties, showing that the main dosimetric peak is stable.

This work presents the results on the Blue Stimulation Luminescence (BSL) and Infra-Red Stimulation Luminescence (IRSL) of CaF2:Tm produced by the Solution Combustion Synthesis (SCS) method. XRD confirmed the formation of calcium fluoride. BSL showed a dose independent signal due to excitation-emission of Tm bands which was not observed for IRSL. A linear dose response curves was obtained for both Blue-OSL and IR-OSL. IRSL was found approximately three times higher sensitivity than Blue-OSL. The minimum measurable dose (MMD) for BSL was found to be around 1.0 mGy. For IRSL a MMD of around 100 μGy was obtained. The results demonstrated that CaF2:Tm produced by SCS has a strong potential for OSL dosimetry.

The thermoluminescence (TL) and infrared stimulated luminescence (IRSL) responses of in-house produced CaF2:Tm dosimeters are investigated in this work, envisaging their application in electron beam (EB) radiation processing. The irradiations were performed at an industrial EB accelerator (1.5 MeV) covering a dose rate range of 2–8 kGy/s and dose up to 10 kGy. In general, the TL glow curves display four peaks, termed as peaks 2, 3, 4, and 5, corresponding to temperatures at ~150, 200, 240, and 300 °C, respectively. The intensity of the low-temperature peaks (2 and 3) grows with the dose, while the others remain constant (saturated). Nevertheless, an evident dose effect on the glow curves manifests in decreased peak3/peak2 ratio with increasing doses. The CW-IRSL curves exhibit similar patterns with an initial signal increase, followed by an exponential decay. Instead of the normal monotonic decays, these peak-shaped curves might be due to the charge capture competition between empty shallow traps and recombination centers. Both TL and IRSL intensities increase linearly with doses up to 6 kGy, and for higher doses, they become sub-linear with a saturation trend around 10 kGy. Another common feature of TL/IRSL response is its dose rate dependence, being more sensitive at higher dose rates. Despite being dose-rate dependent, the CaF2:Tm dosimeters might be suitable for EB processing dosimetry. However, for their use as routine dosimeters, relevant dosimetric characteristics, such as fading and response reproducibility, have to be investigated. Work in this direction is underway.

The aim of this paper is to characterize the IRSL response of rare earth doped CaF2 and co-doped with Al or Li, produced by the solution combustion synthesis (SCS). The results showed a high intensity of the infrared optically stimulated luminescence (IRSL) response for the samples of CaF2 doped with Tb and co-doped with Li. For the samples of CaF2 doped with Ce and co-doped with Li present better IRSL response than the samples co-doped with Al. It was also observed that the samples of CaF2:Ce,Li present a high fading with 50% reduction of the IRSL signal in a period of 60 min. In case of the CaF2:Tb,Li there is no significant fading during this period. For clinical dosimetry the fast fading of the dosimeter is not adequate. However, this feature can be exploited for other applications such as tamper-proof passive systems that detect and timestamp the movement of undeclared nuclear materials, by the estimation of the OSL response of materials with different fading rates.

The purpose of this paper is to evaluate the use of alanine-EPR as a transfer standard dosimetry system for low energy X radiation, such as that in RS-2400, which operates in the range from 25 to 150 kV and 2 to 45 mA. Two types of alanine dosimeters were investigated. One is a commercial alanine pellets from Aerial-Centre de Ressources Technologiques, France and one was prepared in our laboratory (LMRI-DEN/UFPE). The EPR spectra of the irradiated dosimeters were recorded in the Nuclear Energy Department of UFPE, using a Bruker EMX10 EPR spectrometer operating in the X-band. The alanine-EPR dosimetry system was calibrated in the range of 20–220 Gy in this X-ray field, against an ionization chamber calibrated at the relevant X-ray energy with traceability to PTB. The results showed that both alanine dosimeters presented a linear dose response the same sensitivity, when the EPR signal was normalized to alanine mass. The total uncertainty in the measured dose was estimated to be about 3%. The results indicate that it is possible to use the alanine-EPR dosimetry system for validation of a low-energy X ray irradiator, such as RS-2400.

The dosimetric response of a multi guard ring structure (MGR) diode has been studied with clinical electron beam energies from 5 MeV to 15 MeV. The results showed that the MGR dose response is linear in the range of 5–320 cGy and presents reproducibility with variation coefficients less than 0.4%. The field output factors measured with the MGR agreed within 2% with those measured with an ionization chamber. This study evidences that this diode can be used for clinical electron beam dosimetry.

Doped Calcium fluoride (CaF2) is a well known dosimetric material used for measurement of ionizing radiation. In the literature we can find several synthetic routes to prepare this materials, however the majority of the methods present disadvantages such as long time for preparation, use of hazardous materials or crystal growth infrastructure. In order to overcome these problems, in this paper we present a simple wet chemical process by which calcium fluoride doped with thulium was fabricated. The crystal structure and particle size of the synthesized material was characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The thermoluminesce response for samples irradiated with 60Co gamma radiation showed a linear response up to 10 kGy. Additionally, the TL emission spectra shows spectroscopic emission lines characteristic of Tm3+, where the relative intensity of each line depend on the fabrication parameters.

The 110 °C TL glow peak of quartz has been used in dating and retrospective dosimetry due to the pre-dose effect and the sensitivity changes caused by heating. One of the main difficulties related to TL dating is the sureness that the geological signal was completely zeroed by firing. In this study, the sensitivity change of the 110 °C peak and the EPR signal intensity of the E 1 ′ center were combined to account for the burning status of archaeological pebbles. For this, a quartz pebble was sawn into many pieces and each piece was heat-treated at different temperatures from 200 to 800 °C. Powdered aliquots were γ-irradiated and stored into an ice-bath before the TL readout. Peak-maximum temperature, TL intensity and activation energy of the 110 °C peak were determined by glow curve deconvolution methods. The thermal activation characteristic obtained in this study showed a peak maximum at 500 °C and a sensitization ratio higher than 200. The heating temperature also affected the intensity of the E 1 ′ center. The usefulness of the burning pattern was tested by measuring the TL and EPR signals of several archaeological pebbles, initially classified as “burnt”, “unburnt” or “unidentified”, and also from two specimens burnt in a campfire. The main achievement of this study was the possibility to infer the temperature in which a pebble was heated in the past independent of visual signs.

This study evaluates the dose received by veterinarians and assistants involved in portable digital veterinary radiology procedures and checks the dose reduction obtained with the use of individual protection equipment. For this evaluation measurements were made using thermoluminescent dosimeters TLD-100, positioned at different parts of the body: hands, thorax, thyroids, gonads, left and right eye corners and at the center of the eyes. The dose was evaluated through 65 procedures performed with 55 animals. The results showed that in the case of assistants the received dose is significantly larger than that of the veterinarian. The most likely reason of this effect is that they are closer to the primary beam and thus are exposed to higher level of primary radiation first of all in regions of eyes and thyroids. The doses received by various body parts of the assistant are close to the annual limit recommended by International Commission on Radiological Protection.

This work reports the dating of a fossil human tooth and shell found at the archaeological site Toca do Enoque located in Serra das Confusões National Park (Piauí, Brazil). Many prehistoric paintings have been found at this site. An archaeological excavation unearthed three sepulchers with human skeletons and some shells. Two Brazilian laboratories, in Ribeirão Preto (USP) and Recife (UFPE), independently performed Electron Spin Resonance (ESR) measurements to date the tooth and the shell and obtain the equivalent dose received by each sample. The laboratories determined similar ages for the tooth and the shell (~4.8 kyBP). The results agreed with C-14 dating of the shell and other samples (charcoal) collected in the same sepulcher. Therefore, this work provides a valid inter-comparison of results by two independent ESR-dating laboratories and between two dating methods; i.e., C-14 and ESR, showing the validity of ESR dating for this range of ages. RESUMO Este trabalho relata a datação de um dente humano e concha fóssil encontrados no sítio arqueológico Toca do Enoque, localizado no Parque Nacional da Serra das Confusões (Piauí, Brasil), onde muitas pinturas pré-históricas foram encontradas. Durante uma escavação arqueológica, três enterramentos com esqueletos humanos e algumas conchas foram encontrados. Para a determinação da dose equivalente recebida por cada amostra, as medidas de Espectroscopia por Ressonância do Spin Eletrônico (ESR) para as datações do dente e da concha foram realizadas de forma independente por dois laboratórios brasileiros, em Ribeirão Preto (USP) e em Recife (UFPE). As idades obtidas para o dente e a concha por ambos os laboratórios são semelhantes (~ 4.8kyBP). Estes resultados estão de acordo com a datação por C-14 da concha e outras amostras (carvão) encontradas no mesmo sepultamento. Assim, este trabalho oferece uma comparação válida de resultados de datação por ESR de dois laboratórios independentes e entre dois métodos de datação, ou seja, C-14 e ESR com resultados que mostram a validade para a datação por ESR para essa faixa de idades.

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.

This work shows results of type testing of a ring radiation dosimeter system under IEC 62387:2012. The personal dosimeter investigated in this work consists of a commercial one element plastic ring which contains an LiF:Mg,Ti thermoluminescent pellet. By applying requirements for statistical fluctuations and linearity, a minimum measurable dose in Hp(0.07) was established. Energy and angular dependence aided in determining energy correction factors and fading requirements were used to select the most appropriate preheat scheme. Type testing of passive radiation monitors was performed in the Radiation Metrology Laboratory (LMRI-DEN/UFPE) of the Federal University of Pernambuco and is a major step in Brazil for the independent evaluation of these dosimeters, currently not available in the country.

The aim of this paper is to evaluate the thermoluminescent (TL) response of a larimar, a variety of pectolite (NaCa 2 Si 3 O 8 [OH]). It is a blue pectolite only found on the terrestrial crust of the province of Barahona, in the south-western region of the Dominican Republic. The larimar rock used in this study, presented a light-blue color with brown areas. X-ray powder diffractometry (XRD), showed that the light-blue portion of the rock is composed essentially by pectolite and the brown portion is composed by a mixture of minerals. Aliquots of 5 mg of light-blue portions were irradiated with gamma rays with doses from 10 to 10 4 Gy and the TL glow curves were obtained from 50 to 400 °C. The glow curve showed a broad peak around 150 °C and a peak near 280 °C. Different pre-heat condition were used to remove the broad peak. The TL emission of the main peak appeared in the region of 580 nm. The TL response of the main peak showed a linear behavior up to 2500 Gy and a sub-linear behavior above this dose value. Studies of the 30 day fading effects in TL signal using a pre-heating temperature around 180 °C during 15 min were carried out and fading near 25% was observed.

In this paper, we describe the results obtained for the evaluation of a multi-guard ring (MGR) structure diode as diagnostic X-ray dosimeter. This device was developed in the framework of R&D programs for the future CMS experiment at the Large Hadron Collider (LHC) with high radiation hardness to fulfill the requirements from this accelerator environment. In order to use the MGR diode as a dosimeter, it was connected in the photovoltaic mode to the input of an integrating electrometer and positioned at the center of an X-ray beam, beside a previously calibrated ionization chamber. The dependence of the diode response on the X-ray beam doses was evaluated for 35–90 kV X-ray generator bias supply, with doses in the range of 50 μGy–5 mGy. The good linearity of the dose–response curve obtained showed the MGR diode dosimeter to be a reliable alternative method for diagnostic X-ray dosimetry.

Dissolved gas analysis (DGA) is one of the most useful techniques do detect the incipient faults of power transformer. However, the identification of the faulted location by the traditional method is not always an easy task due to the variability of gas data and operational natures. This work aims to develop an intelligent system of preventive maintenance for automatically detecting incipient fault in power transformers through analysis of dissolved gases in transformer insulating oil by introducing the IEC 599 standard (International Electrotechnical Commission). The data used to model the system are taken from chromatographic analysis of CELPE (Electrical Company from Pernambuco). The results show a system with high accuracy when compared with other papers approaching the same problem. Moreover, the results also proved the ability of multiple incipient faults detection.