Dissertations / Theses on the topic 'Dose Reference Level'

Cardiac computed tomography angiography (CCTA) has become an invaluable tool for the detection of cardiac disease. However, radiation brings potential risks of radiation-induced cancers. Diagnostic Reference Levels (DRLs) identify unusually high radiation doses, which makes it a useful tool for targeting dose optimisation. The literature shows no established DRLs for CCTA in Saudi Arabia or Australia. This thesis aims to: 1) propose national DRLs (NDRLs) for CCTA in these countries; 2) identify the associated factors for dose variation in current CT centres. Methods: A structured survey was designed to record information about the CCTA protocols, patient parameters, volume CT dose index (CTDIvol) and dose-length product (DLP). The data were collected from 11 and nine CT centres in Saudi Arabia and Australia, respectively. A stepwise regression analysis was performed to assess the contribution of tube voltage (kV), padding time technique, cross-sectional area (CSA) of chest and weight to DLP. Results: The Saudi NDRL values in CTDIvol and DLP were 43 mGy and 808 mGy cm, respectively while the Australian NDRLs were 22 mGy and 268 mGy cm, respectively. The stepwise regression showed that kV was the most significant predictor of DLP followed by padding technique then CSA, while patient weight had no significant effect on DLP. Conclusions: The findings show that DRLs in both countries are comparable or lower than DRLs in published studies due to the implementation of dose-saving technologies such as prospective ECG gating mode. Additionally, a wide variation in median dose between CT centres, which indicated the potential for using DRLs to encourage dose optimisation in current departmental CCTA protocols. Associated factors for dose variation include employing the RGM protocol, high-kV, use of the padding time, and larger CSA of the chest. Findings should provide baseline guidance for optimising CCTA examinations in CT imaging centres in Saudi Arabia and Australia.

An investigation of clinical Abdominal Computed Tomography (CT)dose, and associated clinical diagnostic protocols, has been ndertaken. This research was carried out to study the pattern of CT dose from routine abdominal examinations in Malaysian practices. From this study it is hoped to establish a Dose Reference Level (DRL) to assist in optimising radiation dose for CT abdominal examination in Malaysia

Doctor of Health Science
An investigation of clinical Abdominal Computed Tomography (CT)dose, and associated clinical diagnostic protocols, has been ndertaken. This research was carried out to study the pattern of CT dose from routine abdominal examinations in Malaysian practices. From this study it is hoped to establish a Dose Reference Level (DRL) to assist in optimising radiation dose for CT abdominal examination in Malaysia

Abstract Fluoroscopically guided procedures are currently an area of special concern in relation to radiation protection, as they may produce a high radiation dose to patients and increase the risk of skin injury. ERCP is a gastrointestinal procedure used as a gold standard in the treatment of pancreatobiliary disorders. It is performed under endoscopic and fluoroscopic guidance. Recently, both the number and the complexity with associated increased technical difficulty of therapeutic ERCP procedures have significantly increased. The present study aimed to assess the medical use of radiation in ERCP, with special emphasis on optimisation of radiation protection of patients. For this purpose, the level of patient radiation exposure during ERCP was evaluated by registering the radiation dose indices in Finnish hospitals. The entrance surface dose was measured by thermoluminescent dosimeters and the effective dose was estimated using conversion coefficients. For dose optimisation and for quality assurance, the local diagnostic reference levels (DRL) for ERCP were established and reviewed after five years. A single centre prospective analysis was conducted to identify patient-, procedure- and operator-related factors affecting dose area product (DAP) and fluoroscopy time (FT). The results showed a large variation of dose indices in overall, as among participating hospitals due to differences in patient characteristics, operator, equipment and procedural complexity. The risk of radiation-induced skin injury and the lifetime cancer risk seems to be reasonably low, indicating ERCP to be a low-dose study. Local DRL is an effective tool in the optimisation process, as a certain degree of dose reduction was achieved during the years. Multiple factors were found to affect DAP and FT in ERCP. The awareness of these factors may help to predict possible prolonged procedures that cause a higher radiation dose to the patient and thus facilitate the use of appropriate precautions
Tiivistelmä Säteilysuojelun näkökulmasta läpivalaisuohjauksessa tehtävät toimenpiteet ovat erityisen huolen aiheena, koska ne voivat aiheuttaa potilaille suuria säteilyannoksia ja siten lisätä ihovaurion riskiä. ERCP on ruoansulatuskanavan endoskopiatoimenpide, jota käytetään haima- ja sappitiesairauksien hoidossa kultaisena standardina. ERCP suoritetaan duodenoskoopilla läpivalaisukontrollissa. Viime vuosina ERCP toimenpiteiden määrät ja toimenpiteiden monimutkaisuus ovat kasvaneet merkittävästi lisääntyneen teknisen haastavuuden vuoksi. Tutkimuksen tarkoituksena oli arvioida säteilyn lääketieteellistä käyttöä ERCP:ssa, kiinnittäen eritystä huomiota potilaan säteilysuojelun optimointiin. Potilaan säteilyaltistuksen tasoa ERCP:ssa arvioitiin keräämällä potilasannoksia suomalaisista sairaaloista, pinta-annokset mitattiin termoloistedosimetreilla ja efektiivinen annos laskettiin muuntokertoimilla. Säteilyaltistuksen optimointi- ja laadunvalvonnan työkaluksi ERCP:lle asetettiin paikalliset vertailutasot ja ne tarkistettiin 5 vuoden kuluttua. Potilaaseen, toimenpiteeseen ja toimenpiteen suorittajaan liittyvät tekijät, jotka vaikuttavat annoksen ja pinta-alan tuloon (DAP) sekä läpivalaisuaikaan, selvitettiin retrospektiivisesti yhdessä sairaalassa. Tutkimuksen tulokset osoittivat, että potilaan säteilyannoksissa oli suurta vaihtelua niin yleisesti, kuin osallistuvien sairaaloiden välillä. Vaihtelu johtui potilaan ominaisuuksista, erilaisista läpivalaisulaitteista, toimenpiteen suorittajista ja ERCP toimenpiteiden vaikeusasteesta. Säteilyn aiheuttaman ihovaurion riski ja elinikäinen syöpäriski näyttäisi tulosten perusteella olevan kohtuullisen alhainen, mikä osoittaa, että ERCP on matala-annostutkimus. Paikallinen vertailutaso osoittautui tehokkaaksi optimointityökaluksi, sillä annostason lasku ERCP:ssa saavutettiin vuosien kuluessa. Useiden tekijöiden todettiin vaikuttavan DAP:n ja läpivalaisuaikaan ERCP:ssa. Näiden tekijöiden tiedostaminen voi auttaa tunnistamaan etukäteen ne haastavat ERCP toimenpiteet, jotka voivat aiheuttaa suuria säteilyannoksia potilaille, ja siten mahdollistaa niihin varautumisen

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Diagnostic Radiography, Department of Nursing and Radiography in the Faculty of Health Wellness Sciences at Cape Peninsula University of Technology 2014
Aim: The aim of this study was to record the values of CTDIw and DLP displayed on the Computed Tomography (CT) scanner monitors of patients undergoing CT examinations of the head as Diagnostic Reference Levels (DRL) for dose optimisation in Northern Nigeria. Background: A brain CT scan is the most common CT examination performed, and this modality is recognized as delivering a high dose. CT, therefore, contributes significantly to the total collective effective dose to the population. Elimination of unnecessary or unproductive radiation exposure is necessary. To achieve this, practitioners must adhere to the principles of the justification of practices, and optimisation of radiation protection. Furthermore, the development of DRLs for the local context is advised. These reference doses are a guide to the expected exposure dose from a procedure and are useful as an investigation tool to identify incidences where patient doses are unusually high. Methodology: The study was conducted in three radiology departments with CT centres in Northern Nigeria. Data was collected, using a purposive sampling technique, from 60 consenting adult participants (weighing 70 ±3 kg) that had brain CT scans on seventh generations 4&16-slice GE and 16-slice Philips CT scanners. Prior to commencement of the study the CT scanners were certified by the medical physicists. For each brain scan, patient information, exposure factors, weighted computed tomography dose index (CTDIw), volume computed tomography dose index (CTDIvol) and dose length product (DLP) values were recorded. The data were analysed using SPSS version (16) statistical software. The mean, standard deviation and third quartile values of the CTDIw and DLP were calculated. An inter-comparison of the measured doses from the three research sites was conducted. A combined dose for the three centres was calculated, and compared with the reported data from the international communities where there are established DRLs. Results: The mean CTDIw and DLP values were: centre A (88 mGy and 713 mGy.cm), centre B (68 mGy and 1098 mGy.cm), and centre C (70 mGy and 59 mGy.cm). Comparison of CTDIw and DLP for the scanners of the same manufacturers showed statistically significant differences (p=0.003) and (p=0.03) respectively. In the case of the scanners of a different model but the same number of slices, the comparison of DLP was statistically significant (p=0.005) while no significant difference was noted in the measured CTDIw. Third quartile values of the cumulative doses of CTDIw and DLP, for Northern Nigeria were determined as 77 mGy and 985 mGy.cm respectively. Conclusion: The study has established Local DRLs (LDRLs) which are significantly higher than most of the reported data in the literature. Also dose variation between centres was noted. Optimization is thus recommended. Keywords: Head Imaging, Radiation Dose, Dose optimization, Computed Tomography, Local Diagnostic Reference Levels, Radiation Protection

Thesis (MSc.(Med)(Physics))--University of Limpopo, 2010.
Key words: Diagnostic reference levels (DRL), entrance surface dose (ESD), thermoluminescence dosimetry (TLD) Introduction: Diagnostic reference levels (DRL‟s) are defined as a dose level set for standard sized patients or standard phantoms and are not for individual exposures and individual patients and are an efficient standard for optimizing the radiation protection of patients and are practically useful for more common examinations. The International Atomic Energy Agency (IAEA) recommends entrance surface dose (ESD) as DRL‟s in diagnostic radiology and are establish using a TLD on a patient/phantom surface. Aim: To estimate entrance surface dose for different X-ray procedures. Objectives: The objective of this study is to develop the diagnostic reference levels by assessing the dose received by a patient in radiographic exposure. This was achieved using different X-ray techniques to estimate the entrance surface dose for different examinations. Method: The study was conducted at the Dr George Mukhari hospital using 5 different X-ray machines. Before the study commenced quality assurance was done on the machines. The following examinations were considered: Cervical spine (AP), cervical spine (LAT), Skull (AP), Skull (PA), Abdomen (AP), Pelvis (AP), Lumber spine (AP), Lumber spine (LAT), Chest (PA) and Chest (LAT). Thermoluminescence lithium fluoride (LiF) (TLD-100, 3.16 X 3.16 X 0.9 mm3, Harshaw) and the Rando phantom were used to estimate the ESD‟s in mGy. Three TLD‟s were mounted on the top of the phantom in the centre of X-ray beam, external to the organ/tissue being imaged. The average dose was calculated for each radiograph and for each examination. The following technique factors were recorded: tube kilovoltage, focus-to-surface distance, focus-to-film distance, time and mA. vi Results: The mean ESD‟s measured at the centre of X-ray beam on the surface of the phantom for the following examinations are: Cervical spine (AP), 2.99 (± 0.26) mGy; Cervical spine (LAT), 3.23 (± 0.34) mGy; Skull (PA), 3.50 (±0.37) mGy; Skull (LAT), 2.60 (± 0.26) mGy; Abdomen (AP), 4.18 (± 0.40) mGy; Pelvis (AP), 3.96 (± 0.33) mGy; Lumber spine (APS), 4.72 (± 0.39) mGy; Lumber spine (LAT), 8.56 (± 0.67) mGy Chest (PA), 0.72 (± 0.27) mGy and Chest (LAT), 1.03 (± 0.45) mGy. Conclusion: The results of the individual exposure and the overall results of each examination were lower than reported in the literature except for the chest (PA). The determination of patient dose and the comparison with the international DRL‟s are an important factor in the optimization process in diagnostic radiology and it is of special concern for the patient‟s protection. The baseline of diagnostic reference levels for the Dr George Mukhari hospital has been established and the results obtained could be useful for future patient dose measurements in diagnostic radiology Department at the Dr George Mukhari hospital.

Aims: In 3 phases, this thesis explores: radiation doses delivered to women during mammography, methods to estimate mean glandular dose (MGD), and the use of mammographic breast density (MBD) in MGD calculations. Firstly, it examines Diagnostic reference levels (DRLs) for digital mammography in Australia, with novel focus on the use of compressed breast thickness (CBT) and detector technologies as a guide when determining patient derived DRLs. Secondly, it analyses the agreement between Organ Dose estimated by different digital mammography units and calculated MGD for clinical data. Thirdly, it explores the novel use of MBD in MGD calculations, suggesting a new dose estimation called the actual glandular dose (AGD), and compares MGD to AGD. Methods: DICOM headers were extracted from 52405 anonymised mammograms using 3rd party software. Exposure and QA information were utilised to calculate MGD using 3 methods. LIBRA software was used to estimate MBD for 31097 mammograms. Median, 75th and 95th percentiles were calculated across MGDs obtained for all included data and according to 9 CBT ranges, average population CBT, and for 3 detector technologies. The significance of the differences, correlations, and agreement between MGDs for different CBT ranges, calculation methods, and different density estimation methods were analysed. Conclusions: This thesis have recommended DRLs for mammography in Australia, it shows that MGD is dependent upon CBT and detector technology, hence DRLs were presented as a table for different CBTs and detectors. The work also shows that Organ Doses reported by vendors vary from that calculated using established methodologies. Data produced also show that the use of MGD calculated using standardised glandularities underestimates dose at lower CBTs compared to AGD by up to 10%, hence, underestimating radiation risk. Finally, AGD was proposed; it considers differences in breast composition for individualised radiation-induced risk assessment.

The International Commission of Radiological Protection (ICRP) advises that in principle Diagnostic Reference Levels (DRL) could be used in fluoroscopically guided interventional procedures to avoid unnecessary stochastic radiation risk. The increase in complexity of interventional procedures, combined with a lack of specialist training on radiation techniques, poses a significant risk to patients. These risks have not gone unnoticed by government authorities worldwide and in 2015 the South African Department of Health: Directorate Radiation Control issued requirements to license holders of interventional fluoroscopy units, requiring that a medical physicist optimize their radiation usage using DRLs. The Dose Area Product (DAP) quantity measured for each patient represents a dosimetry index, the value of which for the purpose of improvement should be optimized against the DRL. In this dissertation, I aim to establish if DRLs in the South African private healthcare interventional theatres are high compared to international levels and whether DRLs will optimize the doses used.

Thesis (MSc (Radiography))--Cape Peninsula University of Technology, 2019
Background: The National Radiation Protection Authority (NRPA) of Namibia was tasked in 2005 by the IAEA under the project RAF9/033 to develop diagnostic reference levels for conventional radiographic examinations. To date, no study that examines the radiation dose in diagnostic radiology has been undertaken in Namibia and radiation protection of patients may not be optimised. Diagnostic reference levels acts as a quality assurance tool that identifies procedures or activities where patient doses are high. Objectives: The purpose of the study was to develop local Diagnostic Reference Levels (LDRL’s) for commonly performed conventional radiography projections in Windhoek, Namibia. The objectives of the study were to: • Measure KAP (Kerma Area Product) for postero-anterior (PA) and lateral (LAT) chest, antero-posterior (AP) and LAT lumbar spine, AP pelvis, and PA and LAT skull projections. • Calculate entrance skin and effective doses from the recorded KAP values. • To compare the KAP, entrance skin doses and effective doses with internationally established reference levels for the same procedure as well as similar studies in Africa. • Develop conversion coefficients from KAP values for estimation of effective and skin doses in clinical practice. Method: In this study, three (3) hospitals located in Windhoek, Khomas region were selected and KAP measurements were recorded on 218 patients with a mean weight of 70±5kg.The entrance skin, and effective doses were calculated through Monto Carlo simulations by entering the geometric data, exposure parameters and equipment specifications and KAP values into PCXMC 2.0 software (Finland). Diagnostic Reference levels (75th percentile), entrance skin doses (ESDs) and effective doses were calculated for anterior (PA) and lateral (LAT) chest, antero-posterior (AP) and LAT lumbar spine, AP pelvis, and PA and LAT skull projections. Results: The 75th percentiles of the entrance skin doses combined for PA and LAT chest, AP and LAT Lumbar spine, AP Pelvis and PA and LAT skull were, 0.0333 mSv, 0.0663 mSv, 0.1970 mSv, 0.2740 mSv, 0.2497 mSv, 0.0922 mSv, and 0.0584 mSv respectively. The effective doses for the same procedures were 0.0545 mSv, 0.0942, 0.3792, 0.2970 mSv, 0.3061 mSv, 0.0267 and 0.0283 respectively. The highest skin dose was recorded for the lateral lumbar spine projection while the highest effective dose was measured for AP lumbar spine projection. Conclusion: The ESD’s in this study were much lower than previously reported values. However the effective doses were generally similar and compare well with previous studies. On the basis of the results it can be concluded that the effective dose is a better dosimetry quantity than ESD to determine deterministic effects of radiation.

There has been considerable controversy and debate over recent years about the most appropriate method of measuring poverty. This debate has included, among other issues, the questions of absolute versus relative poverty, the merits of money income as a measure of the standard of living and the associated selection of poverty lines and equivalence scales, and the selection of alternative indices of poverty. A review of the literature indicates that the choice of differing approaches to poverty measurement can lead to differing estimates of poverty. In the face of such results an evaluation of the impact upon poverty estimates of alternative measurement methodology is appropriate. This thesis assesses the impact upon the estimated level of poverty of variations in some of the key poverty measurement parameters. The expenditure data derived from the 1975-76, 1984 and 1993-94 Household Expenditure Surveys have been analysed to assess the sensitivity of poverty estimates, derived from a range of poverty indices, to variations in the generosity of the equivalence scales, the level of the poverty line, and the choice of the indicator of the level of resources used. The sensitivity of each poverty index to variations in these parameters is assessed at both the aggregated level and for the specified household types, while those population subgroups particularly susceptible to poverty are also identified. The poverty distributions derived for each of the survey years are compared to evaluate the impact upon changes in the level of poverty over time of variations in the underlying parameters. The thesis concludes that both poverty estimates at a point in time, and poverty trends over time are sensitive to variations in the equivalence scales, in the level of the poverty line, in the selection of the indicator of the level of resources, and in the choice of poverty index itself. In light of these results, a review of recent Australian poverty research concludes that insufficient attention has been paid to the sensitivity issues associated with the measurement of poverty.

INTRODUÇÃO: A busca pelo diagnóstico cada vez mais precoce das demências traz a necessidade de estratégias mais eficientes na utilização dos testes cognitivos. A definição dos parâmetros de normalidade para esses testes é particularmente desafiadora no contexto brasileiro de baixa escolaridade e grande heterogeneidade sociocultural. OBJETIVO: Avaliar os efeitos de diferentes estratégias de ajuste de normas nas propriedades do Mini-Exame do Estado Mental (MEEM). MÉTODOS: Duzentos e trinta idosos encaminhados a um serviço de Geriatria por suspeita de comprometimento cognitivo foram recrutados sequencialmente e submetidos ao MEEM. Todos os pacientes passaram por uma segunda avaliação cega para o resultado do MEEM, constituída de testagem neuropsicológica e entrevista com um informante para obtenção de diagnóstico padrão-ouro. Para o ajuste de normas, quatro fatores preditores foram testados: (1) características sociodemográficas; (2) uma classificação simples de alfabetismo funcional com quatro níveis; (3) um questionário de habilidades cognitivas pré-morbidas respondido pelo informante; (4) um teste de leitura de palavras aplicado diretamente ao paciente. Três técnicas de predição foram testadas: (1) agrupamento em níveis; (2) regressão linear; (3) regressão não-linear por modelo polinomial fracional. As combinações de fatores preditores e técnicas de predição deram origem a vinte modelos que foram testados individualmente na comparação com o MEEM sem ajuste. Os desfechos avaliados foram a acurácia do modelo na detecção de comprometimento cognitivo e a variação da sensibilidade e da especificidade entre os níveis socioeconômicos. RESULTADOS: Entre os 230 idosos recrutados, 106 (46%) apresentavam envelhecimento cognitivo normal, 56 (24%) comprometimento cognitivo sem demência e 68 (29%) demência. A classificação de alfabetismo funcional, o questionário de habilidades cognitivas pré-mórbidas e o teste de leitura de palavras não apresentaram propriedades adequadas para ajuste de normas, mas as limitações podem estar relacionadas a problemas específicos dos instrumentos utilizados e não devem ser generalizadas. Alguns modelos baseados em fatores sociodemográficos foram capazes de melhorar a acurácia do MEEM, resultado que diverge da literatura atual e que deve ser confirmado em outros estudos com populações de baixa escolaridade. Um modelo polinomial fracional utilizando variáveis sociodemográficas apresentou propriedades ótimas de acurácia e promoveu estabilização da sensibilidade e da especificidade entre os níveis socioeconômicos. A partir das equações geradas por esse modelo podem ser construídas tabelas simples de uso clínico para converter o resultado bruto em escore z ou percentil. CONCLUSÕES: Nossos resultados apontam o modelo polinomial fracional baseado em variáveis sociodemográficas como a melhor opção para ajuste de normas de testes cognitivos em nosso meio
INTRODUCTION: The need for diagnosing dementia early demands effective strategies on the use of cognitive tests. Establishing criteria of normality for these tests is a challenging task in environments of low education and enormous sociocultural heterogeneity such as observed in Brazil. OBJETIVE: To evaluate how different strategies for adjusting norms can change the properties of the Mini-Mental Status Examination (MMSE). METHODS: Two hundred and thirty older adults referred for a geriatric service because of suspected cognitive impairment were recruited sequentially and completed the MMSE. All the patients underwent a second assessment, blind to the result of the MMSE, which was composed of a neuropsychological battery and an interview with a close informant for the establishment a gold-standard diagnosis. For the adjustment of the norms, four predictive factors were evaluated: (1) demographic characteristics; (2) a simple classification of functional literacy with four levels; (3) a premorbid abilities questionnaire; (4) a word-reading test. Three techniques of prediction were evaluated: (1) grouping in demographic or ability levels; (2) simple or multivariate linear regression; (3) nonlinear regression by using a fractional polynomial model. Some possible combinations of predictive factors and prediction techniques originated twenty models that were assessed individually in comparison with the raw MMSE scores. The endpoints assessed were accuracy of the model for detecting cognitive impairment and the variation of the sensibility and specificity across socioeconomic levels. RESULTS: Of the 230 older adults recruited, 106 (46%) had normal cognitive aging, 56 (24%) presented cognitive impairment no dementia (CIND) and 68 (29%) had dementia. The functional literacy classification, the premorbid cognitive abilities questionnaire and the word-reading test did not present adequate properties for the adjustment of norms, but the limitations may be associated to specific problems of the instruments an cannot be generalized. Some models based on the demographic characteristics were able to improve the accuracy of the MMSE. This finding diverges from the currently available literature and should be confirmed in further studies with low-educated populations. A fractional polynomial model employing demographic factors presented very good properties and was able to stabilize the sensibility and the specificity across the socioeconomic levels. The equations generated by this model can be employed to construct practical tables for converting raw scores into z scores and percentiles. CONCLUSIONS: Our results point to the fractional polynomial model based on demographic variables as the best choice to adjust norms for cognitive tests in our context

No
Introduction: The purpose was to determine if an age based, local diagnostic reference level for paediatric skeletal surveys could be established using retrospective data. Methods: All children below two years of age referred for a primary skeletal survey as a result of suspected physical abuse during 2017 or 2018 (n ¼ 45) were retrospectively included from a large Danish university hospital. The skeletal survey protocol included a total of 33 images. Dose Area Product (DAP) and acquisition parameters for all images were recorded from the Picture Archival and Communication System (PACS) and effective dose was estimated. The 75th percentile for DAP was considered as the diagnostic reference level (DRL). Results: The 75th percentile for DAP was 314 mGy*cm2 , 520 mGy*cm2 and 779 mGy*cm2 for children <1 month, 1e11 months and 12 < 24 months of age respectively. However, only the age group 1e11 months had a sufficient number of children (n ¼ 27) to establish a local DRL. Thus, for the other groups the DAP result must be interpreted with caution. Effective dose was 0.19, 0.26 and 0.18 mSv for children <1, 1e11 months and 12 < 24 months of age respectively. Conclusion: For children between 1 and 11 months of age, a local diagnostic reference level of 520 mGy*cm2 was determined. This may be used as an initial benchmark for primary skeletal surveys as a result of suspected physical abuse for comparison and future discussion. Implications for practice: While the data presented reflects the results of a single department, the suggested diagnostic reference level may be used as a benchmark for other departments when auditing skeletal survey radiation dose.

A Tomografia Computorizada (TC) é uma modalidade de imagem com crescente utilização em diagnóstico, tendo sofrido desenvolvimentos tecnológicos importantes nas últimas duas décadas. Na última década, em Portugal, verificou-se um crescimento anual do número de equipamentos de TC instalados e do número de exames realizados. Apesar do aumento da utilização, a TC constitui a fonte de radiodiagnóstico que mais contribui para a dose efectiva da população e para o aumento dos riscos, estocásticos, da exposição às radiações médicas, em especial em pacientes pediátricos, pois são considerados dez vezes mais radiossensíveis do que os adultos. A optimização dos protocolos utilizados e a definição de Níveis de Referência de Dose locais devem ser aplicadas localmente segundo os princípios da protecção radiológica e de acordo com o quadro legal nacional em vigor. Nesse sentido, este trabalho teve como objectivos a caracterização das práticas locais na realização de exames de TC em pacientes adultos e pediátricos e a análise do nível de adequação às recomendações da Comissão Europeia. Foram analisados os descritores de dose –Computed Tomography Dose Index (CTDIvol), Dose Length Product (DLP) e dose efectiva – para os exames de TC crânio-encefálica, TC dos seios perinasais, TC dos ouvidos, TC do tórax, TC do abdómen, TC abdominal e pélvica e TC do tórax, abdómen e pélvis. Concluiu-se existir uma inadequação dos protocolos standard, relativamente às recomendações europeias, nos exames de TC crânio-encefálica, TC dos seios perinasais, TC dos ouvidos. Nos casos pediátricos concluiu-se a imperatividade de criação de protocolos pediátricos específicos, uma vez que se observaram valores de DLP muito superiores aos recomendados pela Comissão Europeia para a população adulta. Estas observações, em particular nos casos pediátricos, alertam para a necessidade de optimização de procedimentos e criação de protocolos específicos para a população pediátrica. Espera-se que os resultados e conclusões deste trabalho contribuam para a melhoria das práticas locais, inseridas na problemática da protecção radiológica, e na definição de Níveis de Referência de Dose locais, optimizados.
Computed Tomography (CT) is an imaging modality with increasing diagnostic use, having undergone major technological developments in the last two decades. In the last decade, in Portugal, there was an annual increase in the number of CT scanners installed and in the number of exams performed. Despite the increased use, the CT represents the main source of medical radiation on effective dose to the population and is the main contributer to the increased risk of exposure to medical radiation, particularly in pediatric patients, because they are considered ten times more radiosensitive than adults. The optimization of the protocols used and the definition of local Reference Dose Levels should be applied locally according to the principles of radiological protection and in agreement with the national legal framework. In this way, this work focused on the characterization of local practices of CT examinations in adults and pediatric patients and analyzed the level of compliance with the recommendations of the European Commission. Dose descriptors – Computed Tomography Dose Index (CTDIvol), Dose Length Product (DLP) and effective dose – were analyzed for brain CT, sinuses CT, petrous bone CT, chest CT, abdominal CT, abdominal and pelvic CT and chest, abdominal and pelvic CT. We concluded that there is some inadequacy of standard protocols, regarding European recommendations, on brain CT, sinuses CT and petrous bone CT. In pediatric cases it was concluded the urgency of creating specific pediatric protocols, because DLP values registered were much higher than those recommended by the European Commission for the adult population. These remarks, particularly in pediatric cases, highlight the need to optimize procedures, and to build of specific protocols for the pediatric population. It is hoped that the results and conclusions of this study contribute to the improvement of local practices, embedded in the issue of radiation protection, and conduct to the definition of local optimized Reference Dose Levels.

RESUMO - A exposição a radiações ionizantes em tomografia computorizada (TC) pode constituir-se como um risco para a saúde dos utentes. A TC é utilizada no diagnóstico e follow-up de doentes com Linfoma não-Hodgkin, subtipo Linfoma Difuso das Grandes Células B (LDGCB). O objetivo deste estudo foi determinar a dose efetiva acumulada e o risco de segundas neoplasias nestes doentes, diagnosticados em 2011 no IPOLFG e seguidos na consulta de hematologia até 2013. Foram avaliados retrospetivamente 70 doentes com base nos registos de dose do “Patient Protocol” das TC efetuadas. Em média cada doente fez 12 TC e a dose efetiva acumulada foi de 64,76 mSv (percentil 75). Três doentes foram expostos a doses de radiação superiores 90 mSv e um atingiu 111,72 mSv. Os resultados demonstram ser necessário rever os parâmetros e protocolos de exames de TC: (i) TC crânio (DLP= 777 mGycm) e TC abdominal-pélvico (DLP= 628 mGycm). O aumento do número de exames de TC efetuados e a consequente dose parece corresponder a um aumento do risco de segundas neoplasias e risco de morte por doenças neoplásicas durante a vida destes doentes. Os resultados são aparentemente mais significativos para as mulheres, que apresentam o dobro do risco de cancro do pulmão e risco de mortalidade superior em 14% para todas as doenças neoplásicas. O elevado número de exames de TC realizados por cada doente contribui para o aumento da probabilidade de efeitos deletérios e também para o aumento dos níveis de dose efetiva coletiva na população em geral.
ABSTRACT - Exposure to ionizing radiation of computed tomography (CT) examination may be a risk to the patients’ health. CT is used in the diagnosis and follow-up of patients with non-Hodgkin's Lymphoma, subtype Diffuse Large B-Cell Lymphoma (DLBCL). This study’s objective was to establish the cumulative effective dose and the risk of second cancers diseases in these patients, diagnosed in 2011 at IPOLFG and followed in hematology appointment on this oncologic hospital, up to 2013. Seventy patients were retrospectively evaluated based on the dose data obtained from the "Protocol Patient" of CT scans performed. On average each patient underwent 12 CT, the cumulative effective dose per patient was 64.76 mSv (75th percentile). Three patients were exposed to higher doses of radiation 90 mSv and one reached 111.72 mSv. The results show the need to review the parameters and CT scans protocols: (i) TC skull (DLP = 777 mGycm) and abdominal-pelvic CT (DLP = 628 mGycm). The increase in the number of CT examinations performed and the subsequent dose may correspond to an increased risk of second cancers and risk of death from malignant disease during the life of these patients. The results seem to be more significant for women who have twice the risk of lung cancer and a risk of 14% higher mortality for all cancer diseases. The high number of CT examinations for each patient contributes to the increased probability of deleterious effects and also to increase the collective effective dose levels in the general population.

The practice in the department of nuclear medicine requires the involvement of radiation protection with care of patients and occupational safety of radiation workers. Nuclear medicine involves the handling of radioactive substances that may cause external or internal irradiation of workers. The amount of the dose depends on the type of radionuclide, the amount of energy, the work performed by the worker within the department. Patients or staff may be exposed to the external or internal irradiation. The topic of this thesis is the analysis of the current state of radiation protection in the department of nuclear medicine according to the new legislation. The part of the work is the evaluation of monitoring of workers and patients. The research results of the average annual effective dose of total body irradiation at radiation workers ranged from 1.35 to 1.73 mSv, monthly ranged from 0.1? 0.65 mSv. The average annual equivalent dose of Hp (0,07) ranged from 1.15 to 117.68 mSw. The lowest monthly Hp (0.07) was 0.07 mSw and the highest one was 19.92 mSw. At SSK-treated patients the doses applied were 4% lower than diagnostic reference level and the dose at DSSL-treated patients was 22% less than DRU. In conclusion, it was found that the values from personal dosimeters were below the limit and in the case of finger dosimeters in two cases the values were above the examination level. The values of other workers were below the monitoring level during the monitored period. The applied doses of radiopharmaceuticals were less in the observed group of patients than the established diagnostic reference level. On the basis of the presented results it can be stated that radiation protection is in the Department of Nuclear Medicine of Znojmo Hospital f.o, secured in accordance with the applicable legislation.

The aim of this study is to determination of local diagnostic reference levels for radiodiagnostic examination in the General Teaching Hospital in Prague. Local diagnostic reference levels are used for an evaluation of radiation load which patients receive during medical examinations of specific parts of the human body. The evaluation can be on the level of a hospital and its department or on the level of concrete X-ray machine. The theoretical part describes a ionizing radiation, including its interaction with matter, creating, formation of radiodiagnostic image, legislation during optimization of radiodiagnostic examination, radiological protection and determination of values for radiation dose. The practical part describes the determination of local diagnostic reference levels with the help of entrance surface kerma and the median dose in the mammary gland. Both of these variables are relevant for determination of the risk of adverse effects of ionizing radiation which is applied during radiographic examination. Data for this study was collected with the help of operating diaries and PACS system. It has been rated twenty-six kinds of examinations from twelve mobile and nine stationary (including two mammographs) X-ray machines. All resulting values were statistically processed and compared with...

Os Corpos de Bombeiros (CB) contam com uma rede de quartéis implantada em todo o território nacional, atualmente organizada por um modelo baseado nos limites territoriais das NUTS (Nomenclatura das Unidades Territoriais para Fins Estatísticos). Será, portanto, possível rentabilizar a rede de CB no patamar sub-regional, através da implementação de critérios de desempenho dos CB, entre eles, a população abrangida dentro dos tempos de resposta convencionados. O objetivo deste trabalho é propor uma reorganização operacional da rede de quartéis já implantada nas Sub-Regiões da Lezíria do Tejo e Médio Tejo, tendo como base um modelo da Rede Principal dos Serviços Operacionais dos Corpos de Bombeiros em Portugal Continental. Para tal, definiram-se critérios com vista à constituição de Agrupamentos de CB, que partilhando entre si áreas de atuação, permite priorizar o despacho de meios baseado no tempo de resposta dentro dos limites dos Agrupamentos. A aplicação dos critérios contemplando a rede viária existente e a distribuição da população residente, permitiu, recorrendo ao software QGIS®, aferir as zonas com necessidade de reforço da rede de quartéis. Aplicado o modelo à área de estudo, verificou-se um aumento de 18,4% (1.401 km2) de área e de 6,1% da população (30.524 habitantes) abrangidas dentro dos tempos de referência (10 e 20 minutos). Para garantir a atividade operacional nos 24 municípios abrangidos, a rede de CB contaria 24 quartéis sede e 22 postos avançados (reforço da atual rede com 8), guarnecidos no mínimo por um efetivo total de 1.897 bombeiros profissionais. O facto da rede de quartéis já se encontrar implantada no território alvo de estudo e apenas necessitar de reforços pontuais, deveria ser atualmente um fator desencadeador de interesse na sua rentabilização por parte das várias entidades envolvidas.
Fire Departments (CB) have a network of barracks deployed throughout the national territory, currently organized by a model based on the territorial limits of the NUTS (Nomenclature of Territorial Units for Statistical Purposes). Therefore, it will be possible to improve the fire department network at the sub-regional level, through the implementation of fire departments performance criteria, including the population coverage within the settled response times. The objective of this work is to propose an operational reorganization of the barracks network already implemented in the Sub-Regions of Lezíria do Tejo and Médio Tejo, based on a model of the Main Network of Operational Services for Fire Brigades in Mainland Portugal. To this end, criteria were defined with a view to the constitution of CB Groups, which sharing areas of activity among themselves, allows prioritizing the dispatch of means based on the response time within the limits of the Groups. The application of the criteria covering the existing road network and the distribution of the resident population, allowed, using the QGIS® software, to assess the areas in need of reinforcement of the barracks network. Applying the model to the Lezíria do Tejo and Médio Tejo sub-regions, there was an increase of 18,4% (1.401 km2) in area and 6,1% of the population (30.524 inhabitants) covered within the reference times (10 and 20 minutes). In order to guarantee operational activity in the 24 municipalities covered, the fire departments network would consist of a total of 24 headquarters and 22 outposts with a minimum of 1.897 professional firefighters. The fact that the barracks network is already implanted in the study target territory and only needs occasional reinforcements, should be a triggering factor of interest in its profitability by the various entities involved.