Recursos de colección

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É um repositório para instituições de ensino e investigação produtoras de literatura científica cuja dimensão ainda não justifica a criação de um repositório próprio. Permite integrar instituições, grupos ou indivíduos na infra-estrutura do projecto, nomeadamente através das pesquisas do Portal RCAAP e da B-On.

Mostrando recursos 1 - 12 de 12

  1. Transition from screen-film to computed radiography in a paediatric hospital: the missing link towards optimisation

    Paulo, Graciano; Santos, Joana; Moreira, Ana; Figueiredo, Filipa
    In paediatrics, the risks associated with ionising radiation should be a major concern, due to children's higher susceptibility to radiation effects. Measure entrance skin dose (ESD) in chest and pelvis X-ray projections and compare the results with the 'European guidelines on quality criteria for diagnostic radiographer images in paediatrics' in order to optimise radiological practice. ESD values were obtained using an ionisation chamber Diamentor M4 KDK (PTW) in 429 children, who underwent chest X-ray or pelvis X-ray in a Computed Radiography system. In the first phase of the study, data were collected according to protocols used in the department; in...

  2. TLD measurements and Monte Carlo simulations for glandular dose and scatter fraction assessment in mammography: a comparative study

    Di Maria, Salvatore; Barros, Sílvia; Bento, Joana; Teles, Pedro; Figueira, Catarina; Pereira, Matheus; Vaz, P.; Paulo, Graciano
    The main purpose of this study was to validate and compare Mean Glandular Dose (MGD) values obtained using Monte Carlo simulations with experimental values obtained from Entrance Surface Dose (ESD) and depth dose measurements performed in a Hospital mammography unit. ESD and depth dose were measured using ThermoLuminescent Dosimeters (TLDs), and a tissue equivalent mammography phantom recommended by the American College of Radiology (ACR). Measurements and Monte Carlo simulations were also compared with the MGD calculated using the Automatic Exposure Control (AEC) system of the mammographic unit. In the simulations the Doppler energy broadening effect was also taken into account....

  3. Estimation of the collective dose in the Portuguese population due to medical procedures in 2010

    Teles, Pedro; De Sousa, Carmen; Paulo, Graciano; Santos, Joana; Pascoal, Ana; Cardoso, Gabriela; Lança, Isabel; Matela, Nuno; Janeiro, Luís; Sousa, Patrick; Carvoeiras, Pedro; Parafita, Rui; Santos, A. I.; Simaozinho, Paula; Vaz, P.
    In a wide range of medical fields, technological advancements have led to an increase in the average collective dose in national populations worldwide. Periodic estimations of the average collective population dose due to medical exposure is, therefore of utmost importance, and is now mandatory in countries within the European Union (article 12 of EURATOM directive 97/43). Presented in this work is a report on the estimation of the collective dose in the Portuguese population due to nuclear medicine diagnostic procedures and the Top 20 diagnostic radiology examinations, which represent the 20 exams that contribute the most to the total collective...

  4. Medical staff extremity dosimetry in CT fluoroscopy: an anthropomorphic hand voxel phantom study

    Figueira, Catarina; Becker, Frank; Blunck, Ch; DiMaria, S.; Baptista, Márcia; Esteves, B.; Paulo, Graciano; Santos, Joana; Teles, Pedro; Vaz, P.
    This work aims to contribute to the study of the radiation dose distribution delivered to the hands of medical staff members during a general computed tomographic (CT) fluoroscopic guided procedure. In this study, both Monte Carlo simulations and measurements were performed. For free-in-air and computed tomography dose index (CTDI) body phantom measurements, a standard pencil ionization chamber (IC) 100 mm long was used. The CT scanner model was implemented using MCNPX (Monte Carlo N-Particle eXtended) and was successfully validated by comparing the simulated results with measurements. Subsequently, CT images of a hand, together with an anthropomorphic phantom, were voxelized and...

  5. Paediatric CT optimisation utilising Catphanw 600 and age-specific anthropomorphic phantoms

    Santos, Joana; Batista, Maria; Foley, Shane; Paulo, Graciano; McEntee, Mark; Rainford, Loiuse
    The purpose of the study is to perform phantom-based optimisation of paediatric computed tomography (CT) protocols and quantify the impact upon radiation dose and image noise levels. The study involved three Portuguese paediatric centres. Currently employed scanning protocols for head and chest examinations and combinations of exposure parameters were applied to a Catphan(®)600 phantom to review the CT dose impact. Contrast-noise ratio (CNR) was quantified using Radia Diagnostic(®) tool. Imaging parameters, returning similar CNRs (<1) and dose savings were applied to three paediatric anthropomorphic phantoms. OsiriX software based on standard deviation pixel values facilitated image noise analysis. Currently employed protocols...

  6. Quadricipite architecture evaluation with ultrasound, in an elderly population

    Boieiro, A.; Mogas, F.; Moretto, D.; Tavares, P.; André, A.; Paulo, Graciano
    Aging is associated with a progressive loss of neuromuscular function that often leads to a progressive disability and loss of independence. Degenerative processes begin to limit autonomy and functionality. Those processes is sarcopenia, defined as a gradual decline in muscle mass The aim of this study was to evaluate the muscle architecture, in an elderly population that practice exercise and a sedentary group, with the purpose of investigate the process of sarcopenia. Methods: Elderly people were evaluated, this evaluation was performed with an ultrasound, with 12 Mhz transducer. We evaluate both quadricipite muscles in contraction and in rest. A questionnaire was...

  7. Management of patient and staff radiation dose in interventional radiology: current concepts

    Bartal, Gabriel; Vañó, Eliseo; Paulo, Graciano; Miller, Donald
    The increasing complexity and numbers of interventional fluoroscopy procedures have led to increasing patient doses of radiation and to increasing concern over staff doses. Hybrid rooms incorporate multiple imaging modalities and are used by multidisciplinary teams in interventional fluoroscopy suites and operating theaters. These rooms present additional radiation protection challenges. The new low annual exposure limit for the lens of the eye also requires specific measures to prevent cataracts in operators. The traditional attitude of radiation protection must be changed to one of proactive management of radiation dose and image quality. Incorporation of a comprehensive dose management program into the...

  8. The establishment of computed tomography diagnostic reference levels in Portugal

    Santos, Joana; Foley, Shane; Paulo, Graciano; McEntee, Mark; Rainford, Louise
    The aims of this study were to investigate the frequency of Portuguese computed tomography (CT) examinations, identify protocol application and establish diagnostic reference levels (DRLs). CT departments (n=5211) were surveyed nationally (June 2011-January 2012) and CT protocol information and dose data were collected, as were retrospective age-categorised paediatric CT data from three national paediatric centres. The proposed national CT DRLs (CTDIvol) for adults were 75, 18, 14, 18, 17, 36, 22, 27 and 16 mGy for head, neck, chest, abdomen, pelvis, cervical, dorsal, lumbar and joints, respectively. The levels for paediatric head and chest examinations were as follows: 48 and...

  9. The impact of pediatric-specific dose modulation curves on radiation dose and image quality in head computed tomography

    Santos, Joana; Foley, Shane; Paulo, Graciano; McEntee, Mark F.; Rainford, Louise
    The volume of CT examinations has increased with resultant increases in collective dose values over the last decade.Objective: To analyze the impact of the tube current and voltage modulation for dose values and image quality of pediatric head CT examinations. Materials and methods: Head CT examinations were performed on anthropomorphic phantoms and four pediatric age categories before and after the introduction of dedicated pediatric curves for tube voltage and current modulation. Local diagnostic reference levels were calculated. Visual grading characteristic image quality evaluation was performed by four pediatric neuroradiologists and image noise comparisons were performed. Results: Pediatric-specific modulation curves demonstrated...

  10. Diagnostic reference levels in plain radiography for paediatric imaging: a portuguese study

    Paulo, Graciano; Vañó, Eliseo; Rodrigues, Adriana
    Objective: To determine diagnostic reference levels (DRLs) for the most frequent paediatric plain radiography examinations in Portugal (chest, pelvis and abdomen) and to characterise a standard paediatric patient for each age group used in literature. Methods: Anthropometric data was collected from 9935 patients. Each age group (<1, 1-<5, 5-<10, 10-<16, ≥16) was categorised by the median values of weight, height and BMI, to define a standard patient. Exposure parameters, kerma-area product (KAP-mGy cm2) and entrance surface air kerma (ESAK-μGy) were collected. DRLs for KAP and ESAK were defined as the 75th percentile (P75) of dose values and presented by age...

  11. Call for implementing a radiation protection culture in fluoroscopically guided interventional procedures

    Bartal, Gabriel; Roguin, Ariel; Paulo, Graciano
    The purpose of this article is to discuss the first prospective study published to date that followed a large cohort of radiologic technologists; the authors examined the risks of cancer incidence and mortality in U.S. radiologic technologists (radiographers) assisting in fluoroscopically guided interventional procedures.

  12. As características e funcionamento das conexinas, a surdez hereditária e a mutação do gene da conexina 26 e a displasia oculodentodigital e a mutação do gene da conexina 43

    Martins, Diana Mafalda Miranda, 1991-; Cruz, Andreia,; Girão, Cristina,

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