Browsing by Author "Borlinhas, Filipa"
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- Arms up vs. arms down: CT dose optimizationPublication . Borlinhas, Filipa; Vicente, Ana Cristina; Venâncio, JoséIntroduction - Computed Tomography (CT) technologies are evolving in terms radiation dose optimization. When a transition of CT technology takes place, every procedure should be revised and questioned in terms of radiation dose optimization. A procedure such as positioning a patient for a CT examination may be considered simple, but it may become radical concerning radiation dose. The CT examination of Neck+Thorax+Abdomen+Pelvis (NTAP) requires a large anatomical region to be irradiated and, in most of the cases, the patients have to be scanned regularly to evaluate oncologic disease. Radiographers gathered efforts in order to optimize the delivered radiation dose of this type of examinations, and positioning of the patient during the scout was found as a dose reduction parameter. The aim of this work is to emphasize the need to constantly revise CT examination protocols and clinical practice. Methods - Two different positioning to perform the NTAP CT examination scout were tested, one with a patient with arms up and the other with arms down. In the past, these examinations were performed with arms down so it was only necessary to do the new CT examination scouts with arms up. Dose estimations provided by the CT equipment were reported and compared between the two different positioning during the scout. Results - The radiation dose for the entire NTAP examination was lower when the scout was performed with arms up. Considering AEC technology, contrast media phases, anatomical regions specificities, and patient comfort, these tests were performed without compromising the diagnosis of the patient, but significant changes had to be applied to the protocol. Conclusions - The CT technology evolution implies changes in clinical practice and examination procedures. It is extremely important that the Radiology professionals revise their practices periodically in order to find procedures that can be optimized in terms of radiation dose.
- Contributo para o estabelecimento de níveis de referência de diagnóstico em equipamentos de TC multidetectoresPublication . Borlinhas, Filipa; Moura, Marta; Machado, Nuno; Lança, Luís; Madeira, Paula; Costa, João PauloActualmente a Tomografia Computorizada (TC) é um dos métodos de diagnóstico por imagem que tem uma maior contribuição para a dose de radiação X recebida pelos pacientes. Pretende-se com este estudo avaliar as doses praticadas em TC e contribuir para o estabelecimento de Níveis de Referência de Diagnóstico (NRD) na região da Grande Lisboa, Portugal. Foram efectuadas medições de dose em 5 equipamentos de TC multidetectores, considerando o abdómen como área anatómica de interesse. Recorreu-se a uma câmara de ionização e a um fantoma para obter o índice de dose de TC (CTDI) e o produto dose-comprimento (DLP), que permitem determinar os NRD. Estes valores foram comparados com os NRD propostos pela Guideline Europeia e com os estudos desenvolvidos em outros países, como o Reino Unido, Grécia e Taiwan. Os resultados revelaram que os valores de NRD obtidos neste estudo (16,7 mGy para o CTDIvol e 436,5 mGy·cm para o DLP) são discrepantes relativamente à Guideline Europeia (±50%), mas muito próximos relativamente aos NRD estabelecidos nos países considerados. Estes valores podem ser eventualmente explicados pelos equipamentos em análise e pela utilização de protocolos de exame adoptados pelos profissionais de Radiologia nas instituições analisadas. ABSTRACT - Nowadays Computed Tomography (CT) is one of the imaging techniques which have a large contribution to radiation dose received by patients. The purpose of this study is to evaluate CT doses and contribute to the establishment of Diagnostic Reference Levels (DRL) in Lisbon, Portugal. Dose measurements on 5 multidetector CT scanners have been performed, considering the abdomen as the anatomic region of interest. All measurements were performed using an ionization chamber and a phantom to obtain the index CT dose (CTDI) and the dose-length product (DLP), which are used to determine DRL. These values were compared not only with European reference dose values but also with DRL studies developed in other countries like United Kingdom, Greece and Taiwan. The results revealed that DRL values obtained in this study (CTDIvol is 16,7 mGy and DLP is 436,5 mGy·cm) have a higher discrepancy to European Guideline (±50%), while the DRL´s of other countries are nearest to values obtained in this study. Those differences may be eventually explained by the type of the evaluated equipments but also by the exam protocols used by the Radiology professionals on the analyzed institutions.
- CR radiation dose optimization strategies: clinical practice approachPublication . Borlinhas, Filipa; Afonso, José; Vicente, Ana Cristina; Venâncio, JoséIn medical radiation exposures, namely in Computed Tomography (CT), there is an inverse relationship between the image noise and radiation dose. Radiographers need to recognize the situations that require optimization and to apply optimization strategies, without compromise patient diagnosis. The purpose of this work, based on a literature review and on the analysis of routine CT procedures, is to provide an overview of CT optimization techniques feasible to implement in routine practice. The key parameters and the main situations that affect image quality and patient dose will be discussed. Several CT parameters can be adjusted such as potential and tube current, rotation time, Automatic Exposure Control (AEC), detectors configuration, slice thickness, Pitch, table speed, post-processing with the filter kernels, and so on. These parameters vary with patient anatomical region of interest, examination length, positioning, clinical information, and acquisition phases. Furthermore, there are new reconstruction algorithms developed by manufacturers that also help to optimize dose by reducing artifacts and image noise, and many studies state their superior results. Also, the knowledge on the CT parameters trade-offs between radiation dose and image quality is essential for dose optimization, so this will also be highlighted and described in this work. The solution for the excess of radiation dose problem is not only to reduce radiation dose in general but also to adequate and personalize this optimization to each patient and clinical situation. The literature points out some solutions to handle this problem and is very important that the Radiographers are familiar with those when performing CT examinations in practice.
- Quantificação da difusão na ressonância magnética da mama: ADC e KurtosisPublication . Borlinhas, Filipa; Ferreira, Hugo AlexandreObjectivo: Analisar quantitativamente a Difusão por RM da mama, através do Coeficiente de Difusão Aparente (ADC) em Imagem ponderada em Difusão (DWI) e Kurtosis Média (MK) em Imagem por Kurtosis de Difusão (DKI), de alguns tipos de lesões mamárias. Metodologia: Este estudo foi realizado com a autorização da Comissão de Ética e Comissão Científica do Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E. e as utentes deram o seu consentimento informado quanto à participação no estudo. Consideraram-se 20 utentes do sexo feminino, com idade média±desvio padrão de 58,78±12,27anos (dos 40 a 83anos) e 23 casos de lesões mamárias: 3 benignas - 3 Fibroadenomas (FA); e 20 malignas - 16 Carcinomas Ductais Invasivos (CDI), 2 Carcinomas Ductais In Situ (CDIS), 2 Carcinomas Lobulares Invasivos (ILC). Utilizou-se um equipamento de RM de 1,5T com uma bobina específica para a mama. Além do protocolo normal aplicou-se durante o exame uma sequência adicional de Difusão com 6 valores de b (0, 50, 250, 500, 750 e 1000s/mm2). Seleccionaram-se os melhores valores de b a utilizar na prática clínica, obteve-se o valor de ADC através do ajuste exponencial dos valores de intensidade de sinal das lesões estudadas (ADCajuste) e do valor de ADC produzido automaticamente pelo equipamento (mapa ADC). Obtiveram-se também os valores de difusividade média equivalente ao ADC no modelo não Gaussiano (MD) e MK para as mesmas lesões através de um ajuste não linear para um modelo de difusão não Gaussiana. Analisaram-se as diferenças entre as lesões estudadas quanto ao seu tipo e histologia de acordo com os parâmetros quantificadores de Difusão considerados. Resultados: Os resultados indicam que a exclusão dos valores b=0s/mm2 reflecte ajustes com qualidade superior (R2≈1) em 60,87% dos casos. O par b=50-1000s/mm2 constitui a combinação óptima mais frequente em 86.96% dos casos. O ADCajuste calculado foi de (1,43±0,25)x10-3mm2/s (média±desvio padrão) e (0,94±0,22)x10-3 mm2/s para as lesões benignas e lesões malignas, respectivamente. O ADC calculado a partir do Mapa ADC foi de (1,46±0,32)x10-3 mm2/s e (1,15±0,22)x10-3mm2/s, para as lesões benignas e para as malignas, respectivamente. No caso de MD o valor da média±desvio padrão obtido para as lesões benignas foi de (1,70±0,27)x10-3mm2/s e para as lesões malignas de (1,33±0,35)x10-3mm2/s. Para a MK, as lesões benignas atingiram o valor de 0,50±0,44 e as benignas de 1,18±0,43. Os parâmetros ADCajuste e MK apresentam diferenças estatisticamente significativas entre as lesões benignas e malignas (p<0,05). Observou-se ainda que os parâmetros ADCajuste, MD e MK têm potencial para diferenciar entre FA e CDI (p<0,05). A diferenciação entre CDI e CDIS é observada apenas com os parâmetros ADCajuste e ADC Mapa (p<0,05). Conclusões: O ADC tem potencialidades caracterizadoras de lesões da mama e a MK pode fornecer informação adicional nessa caracterização. ABSTRACT - Purpose: Quantitative assessment of breast MRI Diffusion, through Apparent Diffusion Coefficient (ADC) on Diffusion-Weighted Imaging (DWI) and Mean Kurtosis (MK) on Diffusional Kurtosis Imaging (DKI), of some types of breast lesions. Methodology: This study was performed with the acceptance of the Ethic's and Scientifics' Committee of Instituto Português de Oncologia de Lisboa Francisco Gentil, E.P.E., and informed consent was obtained from all the participants. Twenty female subjects, with mean age±standard deviation of 58,78±12,27years (from 40 to 83 years), with 23 mammary lesions, were considered: 3 benign - 3 Fibroadenomas (FA); e 20 malignant - 16 Invasive Ductal Carcinomas (CDI), 2 Ductal Carcinomas In Situ (CDIS), 2 Invasive Lobular Carcinoma (ILC). The study was performed with 1.5T MRI equipment and a specific breast coil was used. Besides the normal protocol the study required an extra DWI sequence with 6 b values (0, 50, 250, 500, 750 and 1000s/mm2). The best b values were selected to use in the clinical practice, the ADC value was obtained with the lesion signal intensity exponential adjustment (ADCadjust) but also through the ADC automatically produced by the equipment (ADC Map). The Mean Diffusivity equivalent to the ADC on the non Gaussian model (MD) and MK parameters were obtained as well for the same lesions considering, this time, taking into account a non linear adjustment to describe a non Gaussian Diffusion model. Differences between lesions types and histology were analyzed taking into account the Diffusion quantification parameters considered in this study. Results: The exclusion of b=0s/mm2 reflects adjustments with a superior quality (R2≈1) in 60,87% of the cases. The 50-1000s/mm2 b value pair was the most frequent optimal combination in 86.96% of the cases. ADCadjust results were (1,43±0,25) x103mm2/s (mean±standard deviation) and (0,94±0,22)x10-3mm2/s for benign and malignant lesions, respectively. ADC calculated through the ADC Map resulted in (1,46±0,32)x10-3mm2/s and (1,15±0,22)x10-3mm2/s for the benign and malignant lesions respectively. In the MD case, the value obtained for the benign lesions was (1,70±0,27) x10-3 mm2/s and for the malignant lesions was (1,33±0,35)x10-3mm2/s. The mean MK value for the benign lesions was 0,50±0,44 and for the malignant ones was 1,18±0,43. The ADCadjust and the MK parameters presented statistically significant differences between benign and malignant lesions (p<0,05). In reference to the histological lesion types, ADCadjust, MD and MK parameters have the potential to differentiate between FA and CDI (p<0,05). Only the ADCadjust and ADC Map were able to differentiate between CDI and CDIS (p<0,05). Conclusions: ADC has the potential to characterize breast lesions and MK can add information to it.
- Quantificação por imagem ponderada em difusão (DWI) das lesões tumorais da mamaPublication . Borlinhas, Filipa; Ferreira, Hugo AlexandreIntrodução – A técnica de Difusão por Ressonância Magnética (RM), ao avaliar o movimento das moléculas de água nos tecidos, permite inferir sobre a arquitetura dos mesmos, em particular relativamente à celularidade, volume celular e permeabilidade das membranas. O Coeficiente de Difusão Aparente (ADC) é um parâmetro quantificável da imagem ponderada em difusão (DWI). A sua análise poderá fornecer informação clínica adicional sobre estas lesões, sobretudo em relação à sua caracterização histológica. Objetivos – Caracterizar e diferenciar tipos e alguns subtipos de lesões mamárias através da análise do ADC. Metodologia – 20 Mulheres com 23 lesões mamárias foram submetidas a RM mamária: 3 lesões benignas (3 Fibroadenomas-FA) e 20 malignas (16 Carcinomas Ductais Invasivos-CDI, 2 Carcinomas Ductais In Situ-CDIS e 2 Carcinomas Invasivos Lobulares-CLI). Num equipamento 1.5T aplicou-se uma sequência de Difusão (b=0,50,250,500,750,1000 s/mm2). Obteve-se o ADC através do ajuste exponencial da intensidade de sinal das lesões em função do valor de b, fazendo-se corresponder os valores de ADC à respetiva caracterização histológica e posterior comparação com a literatura. Resultados e Discussão – As lesões malignas apresentaram ADCs significativamente (p=0,014) inferiores [(0,94±0,22)x10-3 mm2/s] aos das benignas [(1,43±0,25)x10-3 mm2/s]. A justificação pode residir no aumento da celularidade e consequente restrição da Difusão que se observa nas lesões malignas. Os CDI apresentaram ADCs baixos [(0,88±0,17)x10-3 mm2/s], enquanto que os CDIS apresentaram ADCs mais elevados [(1,33±0,29)x10-3 mm2/s]. Estes resultados estão de acordo com o facto dos CDIS estarem limitados aos ductos mamários, mantendo-se menos alterada a estrutura do tecido adjacente e resultando numa menor restrição à difusão que nos CDI. Verificaram-se diferenças significativas entre FA e CDI (p=0,010) e entre CDI e CDIS (p=0,049). Conclusões – O ADC possibilita a diferenciação entre lesões mamárias benignas e malignas, bem como entre alguns tipos histológicos. O desenvolvimento deste conceito pode representar um avanço no papel da RM na avaliação destas neoplasias. ABSTRACT - Introduction – The Magnetic Resonance (MR) diffusion technique measures the movement of water molecules in tissues. Therefore, it provides useful information about tissue architecture, specially regarding tissue cellularity, cell volume and membrane permeability. The quantification of diffusion weighted imaging (DWI) data is done by measuring the so-called. Apparent Diffusion Coefficient (ADC). This parameter provides additional clinical information about breast lesions, and potentially allows for in-vivo histological characterization. Purpose – To characterize and differentiate breast lesions through ADC analysis. Methodology – The study comprised 20 women, with 23 breast lesions: 3 benign lesions - 3 Fibroadenomas (FA); and 20 malignant - 16 Invasive Ductal Carcinomas (CDI), 2 Ductal Carcinomas In Situ (CDIS), 2 Invasive Lobular Carcinoma (CLI). On a 1.5T equipment a diffusion-weighted sequence with 6 b-values (b=0,50,250,500,750,1000 s/mm2) was used to examine the patients. ADC was obtained by fitting an exponential to data of lesion signal intensity vs. b values. A correspondence of ADC values to histological lesion characterization was done and finally, the results were comparison with the literature. Results and Discussion – Malignant lesions showed inferior ADCs significantly (p=0.014) lower ((0.94±0.22)x10-3 mm2/s) than the benign lesions ((1.43±0.25)x10-3 mm2/s). This may be associated to increasead cellularity in malignant lesions, which result in higher tissue restriction to diffusion. CDI showed low ADC values ((0.88±0.17)x10-3 mm2/s), while the CDIS showed higher ADCs ((1.33±0.29)x10-3 mm2/s). These results agree with the fact that CDIS are limited to mammary ducts, maintaining a less altered neighboring tissue structure, which results in a lower restriction to diffusion than observed in CDI. Significant differences between FA and CDI (p=0.010) and between CDI and CDIS (p=0.049) were observed. Conclusion – The ADC parameter is able to differentiate between malignant and benign breast lesions, as well as between some histological types.
- RM da mama: optimização dos valores de b em difusãoPublication . Borlinhas, Filipa; Ferreira, Hugo AlexandreA imagem por difusão em RM caracteriza o movimento microscópico e aleatório das moléculas de água no tecido e a sua quantificação através do ADC permite avaliar a celularidade e estrutura do mesmo. O valor b corresponde ao factor de sensibilização à difusão, sendo que as imagens podem ser mais ou menos ponderadas em difusão. Segundo vários autores torna-se importante a determinação dos valores de b mais adequados pois este parâmetro é variável com o tipo de equipamento utilizado, podendo influenciar a qualidade diagnóstica do método.
- The need for technological updating in radiology: a case study in CTPublication . Afonso, J.; Borlinhas, Filipa; Venâncio, JoséIntroduction - The exposure of the population to ionizing radiation following radiologic exams has become a topic of special concern due to its growing importance. Computed Tomography (CT) technology is well-known to be the main accountable for the significant increase verified. In this context and derived from the concerns of health personnel, as well as media highlight on this topic, manufacturers have been developing solutions that improve their scanners performance on radiation dose, being, therefore, a strong sales argument. Methods - Radiation dose measurements were obtained in similar technical conditions of real CT exams at the Radiology Department of IPOLFG, EPE, with a 32 cm circular Polymethylmethacrylate phantom, simulating an adult’s chest, abdomen, and pelvis. Comparisons were made between the performance of a CT scanner, developed and manufactured in 2002, equipped with the best technology available at the time, and similar measurements, gathered in the same circumstances were obtained with another CT scanner of the same manufacturer but developed and manufactured in 2014. Both devices have16 rows of detectors, but differ in hardware and software, as well as other characteristics related to their construction. The data collected using a Unfords dosimeter, model Xi with processing according to international guidelines, allows the dose comparison between these two devices that can be due, for example, to the dose optimization technology inherent to each equipment. Results - The dose/dose indicators comparison in devices supplied with the best available at the moment of their manufacture in 2002 and 2014 highlights the importance of the progress achieved in 12 years of technical evolution. Conclusions - Dosage control in radiation received by the population as a result of CT exams, whose growth has been verified in the last few years, results not only from the increasing number of requests for exams due to trivialization and reduced cost of these devices but also the celerity and commodity in performing them. An increase in awareness of the negative impact of this matter, not only individually but also publicly, has been countered by the manufacturers with a strong investment in technological development to keep their devices at the same level has the competition’s, which results in a shorter lifespan for the CT devices. Nowadays, a top-level device gets exceeded and obsolete in a decade. Therefore, has to be proven by this study, a frequent evaluation and analysis of the technology available, in addition to its impact in control and decrease of the dosage to which the patients are submitted during exams, is crucial.