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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Analysis of Breast Lesions using a Simplified Rubber Band Straightening Transform and the Onion Transform

Lee, Matthew Allen 05 May 2007 (has links)
This thesis compares different methods that could be used to construct a computer aided diagnosis (CAD) system that analyzes mammograms. Such systems have many steps, but this thesis focuses on feature extraction, feature selection, and classification. The main comparison is between the simplified Rubber Band Straightening Transform (SRBST) and the Onion Transform, which are used to extract texture features. Another comparison is between 2D and 3D co-occurrence matrices. Next, features are selected using a greedy algorithm. This section mainly compares the effectiveness of Receiver Operating Characteristic (ROC) and Class Overlap Rating (COR). Also evaluated are the effectiveness of Linear Discriminate Analysis (LDA) and the sort order of features. Then the selected features are used to classify the lesions. In this part, Nearest Mean, Nearest Neighbor, and Maximum Likelihood are compared. The results are then used to determine the best combination of methods to use in a CAD system.
32

The Effects of Bcl-2 and Bcl-XL Expression on the Radiation Response of MCF-10A Cells

Mills, Caitlin E. 10 1900 (has links)
<p>Ionizing radiation is used to screen for, diagnose, and treat breast cancer. Noncancerous breast cells are exposed to a range of doses as a result of these procedures in addition to the low levels of natural background radiation that they are always exposed to. With the consistent increase in medical radiation procedures, and the climbing rates of breast cancer in most populations, understanding the effects of these exposures is of interest and importance. Radiation exposure results in DNA double strand breaks which can trigger various cellular responses including cell cycle arrest, and cell death. Apoptosis is a form of highly regulated cell death that is controlled by the Bcl-2 family of proteins. Bcl-2 and Bcl-XL are anti-apoptotic proteins that are commonly overexpressed in human cancers including breast cancer. This thesis was focused on investigating the effects of Bcl-2 and Bcl-XL expression on the radiation response of human mammary epithelial cells. Bcl-2 and Bcl-XL were exogenously expressed in MCF-10A cells, and Bcl-XL expression was knocked down. Cytogenetic techniques were used to characterize the MCF-10A cells used. Automated image based assays were used to validate the anti-apoptotic effects of the exogenous proteins against known apoptotic stimuli, and to probe the effects of radiation exposure. The influence of Bcl-2 and Bcl-XL expression on the immediate and short term effects of radiation exposure was investigated using cell growth assays, flow cytometry, and</p> / Doctor of Philosophy (PhD)
33

Krūties vėžio atrankinės mamografinės patikros rezultatų ir pacienčių išgyvenamumo įvertinimas / Evaluation of mammography screening results and survival of breast cancer patients

Jonaitienė, Eglė 20 September 2010 (has links)
Darbo tikslas - įvertinti krūties vėžio mamografinės patikros rezultatus ir pacienčių išgyvenamumą. Darbo uždaviniai: 1. Išanalizuoti mamografinių pakitimų struktūrą skirtingose amžiaus grupėse bei įvertinti jų sąsają su krūties vėžio rizikos veiksniais tarp mamografinėje patikroje dalyvavusių moterų. 2. Palyginti dviejų nepriklausomų radiologų mamografinio tyrimo vertinimo patikimumą. 3. Įvertinti mamografinės diagnostikos tikslumą, palyginant mamografinių ir patologinių–morfologinių tyrimų duomenis. 4. Įvertinti moterų, kurioms buvo nustatytas krūties vėžys, penkerių metų išgyvenamumą ir jo ryšį su prognostiniais veiksniais. / The aim of the study - to evaluate the results of mammography screening and survival of breast cancer patients. Objectives: 1. To analyse mammography findings structure in different age groups and evaluate their correlation with breast cancer risk factors in women participants of mammography screening. 2. To evaluate the benefit of independent double reading in mammography screening 3. To evaluate the accuracy of mammography diagnostics by comparing radiological and histological findings. 4. To estimate five year survival of breast cancer patients and establish its correlation with prognostic indicators of the tumour.
34

Développement et mise en place au BIPM d’un systéme international de comparaison et d’étalonnage pour la dosimétrie en mammographie / Development and impementation of an international comparison and calibration facility for mamography dosimetry at the BIPM

Kessler, Cecilia 23 April 2013 (has links)
La mammographie est une technique d’imagerie par rayons x, considérée comme la technique actuelle la plus efficace pour dépister le cancer du sein à un stade précoce. A cause des risques de carcinogenèse induite par les rayonnements associés à l’examen par rayons x, il est donc essentiel de réaliser un étalonnage précis du faisceau de rayonnements afin de réduire au maximum la dose de rayonnement délivrée au sein du patient et d’obtenir la meilleure qualité d’image possible. L’étalonnage du faisceau de rayons x est effectué avec des chambres d’ionisation, instruments du commerce qui doivent être préalablement étalonnées dans des laboratoires d’étalonnage de référence, de préférence dans le même type de faisceaux de rayonnements que celui utilisé pour le diagnostic.Dans un pays donné, les laboratoires d’étalonnage de référence en dosimétrie des rayonnements sont généralement rattachés au laboratoire national de métrologie ; ce sont des laboratoires de référence primaires ou secondaires de dosimétrie. Les laboratoires primaires vérifient l’exactitude de leurs mesures conduites avec des étalons primaires en participant à des comparaisons internationales alors que les laboratoires secondaires, détenteurs d’étalons secondaires, doivent procéder à la caractérisation de leurs instruments de référence.Afin de répondre aux besoins des laboratoires nationaux de métrologie le Bureau international des poids et mesures (BIPM) maintient des étalons de référence stables pour la dosimétrie des rayonnements ionisants et met à disposition de ses États Membres des équipements internationaux pour la comparaison des étalons primaires et la caractérisation des étalons nationaux secondaires afin d’assurer l’unification mondiale des mesures et leur traçabilité au Système international d’unités (SI).Le Département des rayonnements ionisants du BIPM a effectué les premières comparaisons internationales dans des faisceaux de rayons x aux basses énergies en 1966 et, en 2001, les Instituts nationaux de métrologie (INM) ont pour la première fois proposé que le BIPM étende ses activités à la mammographie.Une description du travail que j’ai entrepris au BIPM pour répondre aux besoins des laboratoires nationaux de métrologie en matière de comparaisons et d’étalonnages dans ce domaine est présentée dans cette thèse et distribuée en quatre parties : l’établissement de sept faisceaux de rayonnement en utilisant un tube à rayons x à anode en tungstène et filtre en molybdène (faisceau W/Mo); l’installation d’un tube à rayons x à anode en molybdène avec filtre en molybdène et l’établissement de quatre faisceaux de rayonnement (faisceau Mo/Mo); conception et fabrication d’un nouvel étalon primaire pour la dosimétrie dans les faisceaux mammographiques. la création d’une nouvelle série de comparaisons en continu du BIPM, identifiées dans la base de données du BIPM sur les comparaisons clés KCDB sous la référence BIPM.RI(I)-K7 et un programme pour l’étalonnage des étalons nationaux secondaires qui inclut le nouveau dispositif expérimental dans le système managérial de la qualité du département des rayonnements ionisants (RI) du BIPM.L’expertise acquise lors de ce travail est maintenant transféré aux INM pour les aider dans le développement de leurs propres étalons primaires et à améliorer leurs dispositifs expérimentaux existants. Jusqu’à aujourd’hui 6 comparaisons ont été menées à bien dans le nouveau dispositif expérimental établi au BIPM ; la participation à la nouvelle comparaison–clé continue permet aux INM de soutenir leurs capacités d’étalonnages et de mesures (CMC). La caractérisation et l’étalonnage des étalons nationaux secondaires ont été réalisés pour l’heure pour 5 INM. / Mammography is an x-ray examination of the breast, considered to be the most sensitive technique currently available for early detection of breast cancer. Because of risks of radiation-induced carcinogenesis associated with the use of x rays, accurate calibration of the x-ray unit is essential in order to minimize the radiation dose delivered to the patient breast but having a good image quality. The beam calibration is made using ionization chambers, commercial instruments that need to be characterized at standard reference dosimetry laboratories in well-defined x-ray beams similar to those used in the diagnostic institutes.Standard reference laboratories for radiation dosimetry are usually part of the National Metrology Institute of each country; they can either be Primary or Secondary Standard Dosimetry Laboratories. Primary Laboratories verify the accuracy of their measurements using the primary standards by taking part in international comparisons while the Secondary Laboratories, holding secondary standards, need the characterization of their reference instruments. In order to fulfil these requirements of the National Metrology Institutes (NMIs), the Bureau International des Poids et Mesures (BIPM) maintains stable reference standards for radiation dosimetry and provides to the its Member States an international facility for comparisons of primary standards and characterization of secondary standards to ensure world-wide uniformity of measurements and their traceability to the International System of Units (SI).The Ionizing Radiation Department of the BIPM started international comparisons and characterizations in low-energy x-ray beams in 1966 and in 2001, the NMIs required the BIPM to extend these activities to mammography beams. A description of the work I carried out at the BIPM to provide an international facility for comparisons and calibrations in the mammography field is presented in this thesis, divided into four stages:  establishment of seven reference radiation beams using the combination tungsten-anode x-ray tube and molybdenum filtration (W/Mo beams);  installation of a molybdenum-anode x-ray tube with molybdenum filtration and establishment of four reference radiation beams (Mo/Mo beams);  design and construction of a new primary standard free-air chamber for the dosimetry of the mammography beams;  establishment of a new ongoing international comparison in the new reference mammography beams, registered in the BIPM key comparison database KCDB as BIPM.RI(I)-K7 and a programme for the calibration of national secondary standards by including the new facility in the quality management system of the Ionizing Radiation (IR) Department of the BIPM.The experience obtained during this work is now transferred to the NMIs to help them in the development of primary standards and to improve their existing facilities.To date, six successfully comparisons have been carried out in the new facility established at the BIPM; the participation in the new ongoing key comparison allow the NMIs to support their calibration and measurement capabilities (CMCs). Characterization and calibration of national secondary standards have been done for five NMIs.
35

Microcalcificações amorfas agrupadas na mamografia digital de campo total: correlação anatomopatológica / Grouped amorphous microcalcifications in full-field digital mamography: anatomopathologic correlation

Ferreira, Vera Christina Camargo de Siqueira 08 March 2012 (has links)
INTRODUÇÃO: O objetivo deste estudo é determinar a correlação anatomopatológica das calcificações amorfas agrupadas diagnosticadas na mamografia digital de campo total, ou seja, das calcificações suspeitas mais tênues, uma vez que houve aumento da caracterização de calcificações na mamografia digital. MÉTODOS: Estudo retrospectivo baseado nos laudos mamográficos classificados como categoria BI-RADS 4 no primeiro ano de introdução da técnica digital, com análise dos diagnósticos anatomopatológicos das microcalcificações amorfas agrupadas submetidas à biópsia de fragmento assistida à vácuo no serviço. Calculou-se: os achados anatomopatológicos que se associaram ao achado radiológico de microcalcificações amorfas agrupadas e o valor preditivo positivo destas calcificações biopsiadas. RESULTADOS: Dos 219 achados por microcalcificações amorfas agrupadas, 78 foram submetidos à biópsia de fragmento assistida à vácuo com seguimento conhecido ou cirurgia subsequente. O diagnóstico anatomopatológico correspondeu a oito (10%) casos malignos, 36 (46%) casos benignos, e 34 (44%) diagnósticos de lesões de risco, das quais oito (10%) do subgrupo cicatriz radiada/lesões papilíferas (sete cicatrizes radiadas e um papiloma) e 26 (33%) do subgrupo atipias/ neoplasias lobulares, correspondendo a 14 (18%) hiperplasias ductais atípicas, quatro (5%) neoplasias lobulares e oito (10%) lesões de células colunares com atipia (atipia epitelial plana). A ampliação cirúrgica foi recomendada para as lesões com potencial incerto de malignidade à biópsia e realizada em 65% do subgrupo atipias/neoplasias lobulares, com taxa de subestimação nula (0/18). O tempo médio de seguimento das pacientes com diagnóstico benigno ou de lesão de risco foi 22 meses. CONCLUSÕES: Um terço das microcalcificações amorfas agrupadas em mamografia digital de campo total corresponderam a lesões precursoras representadas pelas atipias (ductais e colunares) e neoplasias lobulares. Essas lesões se associaram às calcificações amorfas agrupadas numa proporção de cerca de 3:1 em relação às lesões malignas, cujo VPP 3 foi 10% / PURPOSE: To determine the anatomopathological correlation of grouped amorphous calcifications (the most tenuous of suspicious calcifications) disclosed on full-field digital mammography, given the enhanced characterization of calcifications provided by digital mammography. METHODS: A retrospective study of mammographic reports classified as BI-RADS® category 4 at a private diagnostic service specialized in breast imaging was carried out on exams performed during the first year of introducing the digital technique. The investigation entailed analysis of the anatomopathological diagnoses of BI-RADS® category 4 for grouped amorphous microcalcifications submitted to vacuum-assisted breast biopsy (VABB). Anatomopathological findings correlated to this radiological finding were determined and positive predictive value of these calcifications submitted to biopsy (PPV 3) was calculated. RESULTS: Of the 219 findings of grouped amorphous microcalcifications, 78 were submitted to VABB with known follow-up or subsequent surgery. The anatomopathological results included eight (10%) malignant cases, 36 (46%) benign cases and 34 (44%) diagnoses of high-risk lesions, eight of which belonged to the radial scar/papillary lesion subgroup (seven radial scars and one papilloma) and 26 (33% of all cases) to the atypia/lobular neoplasia subgroup, comprising 14 atypical ductal hyperplasias, four lobular neoplasias and eight flat epithelial atypia. Extended surgery was recommended for lesions with uncertain malignant potential at biopsy and performed in 65% of the atypia/lobular neoplasia subgroup, with an underestimation rate of zero (0/18). Mean follow-up time of patients diagnosed with benign or high-risk lesions was 22 months. CONCLUSIONS: One-third of grouped amorphous calcifications on full-field digital mammography corresponded to precursory lesions in the form of atypia (ductal and columnar) or lobular neoplasias. These lesions were associated to grouped amorphous calcifications at a ratio of 3:1 compared to malignant lesions,whose PPV 3 was 10%
36

Microcalcificações amorfas agrupadas na mamografia digital de campo total: correlação anatomopatológica / Grouped amorphous microcalcifications in full-field digital mamography: anatomopathologic correlation

Vera Christina Camargo de Siqueira Ferreira 08 March 2012 (has links)
INTRODUÇÃO: O objetivo deste estudo é determinar a correlação anatomopatológica das calcificações amorfas agrupadas diagnosticadas na mamografia digital de campo total, ou seja, das calcificações suspeitas mais tênues, uma vez que houve aumento da caracterização de calcificações na mamografia digital. MÉTODOS: Estudo retrospectivo baseado nos laudos mamográficos classificados como categoria BI-RADS 4 no primeiro ano de introdução da técnica digital, com análise dos diagnósticos anatomopatológicos das microcalcificações amorfas agrupadas submetidas à biópsia de fragmento assistida à vácuo no serviço. Calculou-se: os achados anatomopatológicos que se associaram ao achado radiológico de microcalcificações amorfas agrupadas e o valor preditivo positivo destas calcificações biopsiadas. RESULTADOS: Dos 219 achados por microcalcificações amorfas agrupadas, 78 foram submetidos à biópsia de fragmento assistida à vácuo com seguimento conhecido ou cirurgia subsequente. O diagnóstico anatomopatológico correspondeu a oito (10%) casos malignos, 36 (46%) casos benignos, e 34 (44%) diagnósticos de lesões de risco, das quais oito (10%) do subgrupo cicatriz radiada/lesões papilíferas (sete cicatrizes radiadas e um papiloma) e 26 (33%) do subgrupo atipias/ neoplasias lobulares, correspondendo a 14 (18%) hiperplasias ductais atípicas, quatro (5%) neoplasias lobulares e oito (10%) lesões de células colunares com atipia (atipia epitelial plana). A ampliação cirúrgica foi recomendada para as lesões com potencial incerto de malignidade à biópsia e realizada em 65% do subgrupo atipias/neoplasias lobulares, com taxa de subestimação nula (0/18). O tempo médio de seguimento das pacientes com diagnóstico benigno ou de lesão de risco foi 22 meses. CONCLUSÕES: Um terço das microcalcificações amorfas agrupadas em mamografia digital de campo total corresponderam a lesões precursoras representadas pelas atipias (ductais e colunares) e neoplasias lobulares. Essas lesões se associaram às calcificações amorfas agrupadas numa proporção de cerca de 3:1 em relação às lesões malignas, cujo VPP 3 foi 10% / PURPOSE: To determine the anatomopathological correlation of grouped amorphous calcifications (the most tenuous of suspicious calcifications) disclosed on full-field digital mammography, given the enhanced characterization of calcifications provided by digital mammography. METHODS: A retrospective study of mammographic reports classified as BI-RADS® category 4 at a private diagnostic service specialized in breast imaging was carried out on exams performed during the first year of introducing the digital technique. The investigation entailed analysis of the anatomopathological diagnoses of BI-RADS® category 4 for grouped amorphous microcalcifications submitted to vacuum-assisted breast biopsy (VABB). Anatomopathological findings correlated to this radiological finding were determined and positive predictive value of these calcifications submitted to biopsy (PPV 3) was calculated. RESULTS: Of the 219 findings of grouped amorphous microcalcifications, 78 were submitted to VABB with known follow-up or subsequent surgery. The anatomopathological results included eight (10%) malignant cases, 36 (46%) benign cases and 34 (44%) diagnoses of high-risk lesions, eight of which belonged to the radial scar/papillary lesion subgroup (seven radial scars and one papilloma) and 26 (33% of all cases) to the atypia/lobular neoplasia subgroup, comprising 14 atypical ductal hyperplasias, four lobular neoplasias and eight flat epithelial atypia. Extended surgery was recommended for lesions with uncertain malignant potential at biopsy and performed in 65% of the atypia/lobular neoplasia subgroup, with an underestimation rate of zero (0/18). Mean follow-up time of patients diagnosed with benign or high-risk lesions was 22 months. CONCLUSIONS: One-third of grouped amorphous calcifications on full-field digital mammography corresponded to precursory lesions in the form of atypia (ductal and columnar) or lobular neoplasias. These lesions were associated to grouped amorphous calcifications at a ratio of 3:1 compared to malignant lesions,whose PPV 3 was 10%
37

Breast Abnormalities: Identification of Indicators that Facilitate Use of Health Services for Diagnosis and Treatment of Breast Cancer

DeBoard, Ruth Ann January 2010 (has links)
Problem: There is a lack of knowledge about women who are screened for breast cancer, have an abnormal finding on mammogram, and then do not return in a timely manner for diagnostics and treatment. Lack of follow- up likely constitutes delayed treatment and poorer outcomes. Delays may result in later entry into the health system with advanced disease, more extensive and expensive care, burdening resources. Late stage breast cancer likely results in poorer health outcomes or early death.Purpose and Aims: The purpose of this research is to describe contextual characteristics at the health delivery level as well as individual characteristics of women with abnormal mammography, and their association with use of follow- up health services. Particularly, this research examines the differences between women who are early and late responders after an abnormal mammogram.Population: The participants were a convenience sample of 380 women who participated in mobile breast cancer screening. A subset of women with inconclusive or abnormal mammogram findings was the focus of analysis.Methods: This research utilized a descriptive design with quantitative data collection through participant survey at mobile mammogram screening events in multiple urban and rural Arizona sites. Participants requiring further health care were followed by chart review. Analysis of correlations with the outcome variable: time to first follow- up appointment for recommended health care in women with abnormal mammograms was conducted.Findings: Data indicated the time to the first follow- up appointment ranged from 1- 110 days with follow- up for 77.4% of participants within 60 days, 6.5% within 60-90 days, and 16.1% without follow- up after 90 days. Significant relationships between contextual and individual characteristics and follow- up were found. Categories included organizational health system characteristics of geographic location, clinical breast exam and shared case management; individual characteristics of beliefs including value of health care; finance including out of pocket costs and perceptions of financial assistance; perceived needs including breast symptoms; and satisfaction with the last health visit and mammograms in general.Implications: Recognition of barriers to follow- up after breast cancer screening is important for development of interventions to improve outcomes and has implications for screening and treatment management programs, community health centers and private practice. Health disparity related to screening without adequate options for access to health care is ethically untenable. Nurses are well positioned to reduce barriers to health care.
38

Avaliação dos achados mamográficos classificados na categoria 4 do sistema BI_RADS® e sua correlação histopatológia /

Teixeira, Marta de Betânia Rabelo. January 2011 (has links)
Orientador: Gilberto Uemura / Banca: Maria de Fátima Brito Vogt / Banca: Eduardo Carvalho Pessoa / Resumo: Objetivo: Determinar o valor preditivo positivo para malignidade de lesões mamárias classificadas nas subcategorias 4A, 4B e 4C do sistema BI-RADS® pela correlação entre os achados mamográficos e histopatológicos. Sujeitos e métodos: Estudo analítico-descritivo de 89 pacientes submetidas à core biopsy e biópsia cirúrgica com e sem estereotaxia, que possuíam mamografias classificadas nas subcategorias 4A, 4B e 4C do BI-RADS® 4ª edição. Os achados mamográficos foram correlacionados com os diagnósticos histológicos das lesões, calculando-se o valor preditivo positivo para malignidade em cada subcategoria. Resultados: Dentre as 89 pacientes avaliadas foram diagnosticados 50 casos de câncer de mama (56,2%), sendo 9 na subcategoria 4A, 21 na 4B e 20 na 4C. Os valores preditivos positivos encontrados foram, respectivamente, 25,7 %, 63,6 % e 95,2 % para as subcategorias 4A, B e C. O nódulo espiculado foi o achado mais relacionado à doença maligna. Conclusão: Houve elevação progressiva do VPP nas subcategorias 4A, 4B e 4C do BIRADS ® / Abstract: Objective: To determine the positive predictive value for malignancy of mammary lesions classified in the subcategories 4A, 4B and 4C of the BI-RADS® system based on the correlation between the mammographic and histopathological findings. Subjects and methods: Analytical-descriptive study of 89 patients submittted to core biopsy and surgical biopsy with and without stereotatic localization, that possessed mammograms classified as subcategories 4A, 4B and 4C of the BI-RADS® 4th edition. The mammographic findings were correlated to the histological diagnosis of the lesions, then calculating the positive predictive value for malignancy in each subcategory. Results: Among the 89 evaluated patients, 50 were diagnosed as breast cancer cases (56.2%), of which 9 in subcategory 4A, 21 in 4B and 20 in 4C. The positive predictive values found were, respectively, 25.7%, 63.6% and 95,2% for the 4A, B and C subcategories. The spiculated nodule was the finding most related to the malignant disease. Conclusion: There has been progressive elevation of the PPV in subcategories 4A, 4B and 4C of BI-RADS® / Mestre
39

Avaliação dos critérios de qualidade de imagem e estudo das doses em um departamento de mamografia / Evaluation of the image quality criteria and study of dosis in a mammography department

Alcântara, Marcela Costa 30 October 2009 (has links)
Os critérios de qualidade de imagem mamógrafica publicados pela European Commission foram implementados em três mamógrafos de um mesmo departamento de radiologia de um hospital na cidade de São Paulo. Dentre os mamógrafos dois apresentam o sistema tela-filme e um deles apresenta o sistema digital indireto. Durante o período de coleta de dados, foi observada a necessidade de realizar um estudo sobre índice de rejeição de imagem em cada mamógrafo. Portanto, este estudo foi realizado e, em seguida, foram feitas comparações, entre os mamógrafos, do índice de rejeição de imagem e da porcentagem de imagens que atendiam a cada critério de qualidade de imagem. Paralelamente a esses estudos, foi realizado o estudo das doses na entrada da pele e glandular média. Essas doses foram estimadas, baseando-se em diferentes metodologias apresentadas por diferentes grupos de estudiosos, para todas as combinações anodo-filtro apresentadas pelo equipamento. Para estimar a dose na entrada da pele pelo método publicado no guia da ANVISA e a dose glandular média pelo método de Wu, foi desenvolvido um manequim no formato bem próximo ao de uma mama, em diferentes espessuras de PMMA. Por fim, associou-se a qualidade da imagem com a dose recebida pela paciente. O equipamento digital apresentou melhores resultados na avaliação dos critérios de qualidade, menor índice de rejeição de imagem e menores valores de dose glandular média e na entrada da pele em todos os métodos estudados. Porém não é suficiente, pois não atende às pacientes que possuem mamas grandes. / The mammographic image quality criteria published by European Commission were implemented in three mammography equipments of a same radiology department in a hospital of Sao Paulo city. Among the mammography equipments, two use the screen-film system and one of them uses the indirect digital system. During the data collection, it was noted the need to conduct a study about image rejection in each mammography equipment. Therefore, this study was realized and, after that, the results in each mammography equipment of image rejection and image percentage that present each quality criterion it were compared. At the same time of this studies, it was realized other study about surface entrance dose and average glandular dose. These doses it was estimated based on different methods published by different groups of researcher, for all combinations anodefilter available in the equipment. To estimate the surface entrance dose following the methodology published in ANVISA guide and the average glandular dose following the Wu methodology, it was developed a phantom, in different thicknesses of acrylic, to simulate a breast. Finally, the image quality it was associated with the dose received by patient. The digital equipment shows better results in the evaluation of quality criteria, lower rate of image rejection and lower values of average glandular dose and surface entrance dose in all methods studied. But it is not sufficient, because is not adequate for patients with great breast.
40

Avaliação dos critérios de qualidade de imagem e estudo das doses em um departamento de mamografia / Evaluation of the image quality criteria and study of dosis in a mammography department

Marcela Costa Alcântara 30 October 2009 (has links)
Os critérios de qualidade de imagem mamógrafica publicados pela European Commission foram implementados em três mamógrafos de um mesmo departamento de radiologia de um hospital na cidade de São Paulo. Dentre os mamógrafos dois apresentam o sistema tela-filme e um deles apresenta o sistema digital indireto. Durante o período de coleta de dados, foi observada a necessidade de realizar um estudo sobre índice de rejeição de imagem em cada mamógrafo. Portanto, este estudo foi realizado e, em seguida, foram feitas comparações, entre os mamógrafos, do índice de rejeição de imagem e da porcentagem de imagens que atendiam a cada critério de qualidade de imagem. Paralelamente a esses estudos, foi realizado o estudo das doses na entrada da pele e glandular média. Essas doses foram estimadas, baseando-se em diferentes metodologias apresentadas por diferentes grupos de estudiosos, para todas as combinações anodo-filtro apresentadas pelo equipamento. Para estimar a dose na entrada da pele pelo método publicado no guia da ANVISA e a dose glandular média pelo método de Wu, foi desenvolvido um manequim no formato bem próximo ao de uma mama, em diferentes espessuras de PMMA. Por fim, associou-se a qualidade da imagem com a dose recebida pela paciente. O equipamento digital apresentou melhores resultados na avaliação dos critérios de qualidade, menor índice de rejeição de imagem e menores valores de dose glandular média e na entrada da pele em todos os métodos estudados. Porém não é suficiente, pois não atende às pacientes que possuem mamas grandes. / The mammographic image quality criteria published by European Commission were implemented in three mammography equipments of a same radiology department in a hospital of Sao Paulo city. Among the mammography equipments, two use the screen-film system and one of them uses the indirect digital system. During the data collection, it was noted the need to conduct a study about image rejection in each mammography equipment. Therefore, this study was realized and, after that, the results in each mammography equipment of image rejection and image percentage that present each quality criterion it were compared. At the same time of this studies, it was realized other study about surface entrance dose and average glandular dose. These doses it was estimated based on different methods published by different groups of researcher, for all combinations anodefilter available in the equipment. To estimate the surface entrance dose following the methodology published in ANVISA guide and the average glandular dose following the Wu methodology, it was developed a phantom, in different thicknesses of acrylic, to simulate a breast. Finally, the image quality it was associated with the dose received by patient. The digital equipment shows better results in the evaluation of quality criteria, lower rate of image rejection and lower values of average glandular dose and surface entrance dose in all methods studied. But it is not sufficient, because is not adequate for patients with great breast.

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