Browsing by Author "Vieira, Lina Oliveira"
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- 3D printing of abdominal immobilization masks for therapeutics: dosimetric, mechanical and financial analysisPublication . Duarte, Jessica; Loja, Maria Amélia Ramos; Portal, Ricardo; Vieira, Lina OliveiraMolding immobilization masks is a time-consuming process, strongly dependent on the healthcare professional, and potentially uncomfortable for the patient. Thus, an alternative sustainable automated production process is proposed for abdominal masks, using fused deposition modelling (FDM) 3D printing with polylactic acid (PLA). Radiological properties of PLA were evaluated by submitting a set of PLA plates to photon beam radiation, while estimations of their mechanical characteristics were assessed through numerical simulation. Based on the obtained results, the abdominal mask was 3D printed and process costs and times were analyzed. The plates revealed dose transmissions similar to the conventional mask at all energies, and mechanical deformation guarantees the required immobilization, with a 66% final cost reduction. PLA proved to be an excellent material for this purpose. Despite the increase in labour costs, a significant reduction in material costs is observed with the proposed process. However, the time results are not favorable, mainly due to the printing technique used in this study.
- 3D printing of abdominal immobilization masks for therapeutics: dosimetric, mechanical and financial analysisPublication . Duarte, Jessica; Loja, M.A.R.; Portal, Ricardo; Vieira, Lina OliveiraMolding immobilization masks is a time-consuming process, strongly dependent on the healthcare professional, and potentially uncomfortable for the patient. Thus, an alternative sustainable automated production process is proposed for abdominal masks, using fused deposition modelling (FDM) 3D printing with polylactic acid (PLA). Radiological properties of PLA were evaluated by submitting a set of PLA plates to photon beam radiation, while estimations of their mechanical characteristics were assessed through numerical simulation. Based on the obtained results, the abdominal mask was 3D printed and process costs and times were analyzed. The plates revealed dose transmissions similar to the conventional mask at all energies, and mechanical deformation guarantees the required immobilization, with a 66% final cost reduction. PLA proved to be an excellent material for this purpose. Despite the increase in labour costs, a significant reduction in material costs is observed with the proposed process. However, the time results are not favorable, mainly due to the printing technique used in this study.
- An optimization strategy for customized radiotherapy head immobilization masksPublication . Craveiro, D. S.; Loja, M.A.R.; Vieira, Lina Oliveira; Vinyas, M.An effective head immobilization is an important requirement in radiotherapy treatment sessions, although it may also be thought in the future as a precious aid in brain medical imaging. Thus, the present work is focused on the stiffness optimization of a customized head immobilization mask, modeled upon the head reconstruction surface based on computerized tomography images. This paper proposes a strategy supported by a metaheuristic optimization technique and a metamodeling approach for the whole mask, illustrated at its most unfavorable region occurring in the gnathion region.
- An optimization strategy for customized radiotherapy head immobilization masksPublication . Craveiro, D.S.; Loja, Amélia; Vieira, Lina Oliveira; Vinyas, M.An effective head immobilization is an important requirement in radiotherapy treatment sessions, although it may also be thought in the future as a precious aid in brain medical imaging. Thus, the present work is focused on the stiffness optimization of a customized head immobilization mask, modelled upon the head reconstruction surface based on computerized tomography images. This paper proposes a strategy supported by a metaheuristic optimization technique and a metamodeling approach for the whole mask, illustrated at its most unfavorable region occurring in the gnathion region.
- Analysis of the interference of endogenous circadian rhythms on 3'- deoxy- 3'- [18F]Fluorothymidine physiological uptake at the human bone marrowPublication . Varela, N. M.; Lucena, Filipa; Raminhas Carapinha, Maria João; Vieira, Lina OliveiraThe main purpose of the present study is to determine if the circadian rhythms present in the human bone marrow are likely to influence 3’- deoxy- 3’-[18F] Fluorothymidine (18F-FLT) uptake in the same organ. The 18F-FLT is a Thymidine analogous proliferation agent. The relatively high physiological uptake of this tracer in the bone marrow diminishes the Tumor/Background (T/B) ratio, decreasing the detection accuracy of PET/CT and possibly affecting SUV quantifications.
- Anxiety experienced by oncological patients who undergo 18F-FDG PET CT: a systematic reviewPublication . Vieira, Lina Oliveira; Pires, A.; Grilo, Ana MonteiroIntroduction: Anxiety is an emotional reaction often experienced by patients who undergo Positron Emission Tomography/Computed Tomography (PET/CT) with 18F-2-fluoro-2-deoxy-d-glucose (18F-FDG). This systematic review aimed to summarise the evidence currently available considering the anxiety experienced by adult oncological patients concerning pre and post 18F-FDG PET/CT examination and the factors contributing to anxiety. Methods: A systematic review search of CINAHL, PsycINFO, PubMed, Scopus, and Web Science databases and other manual search sources, was conducted from November to February 2021. The research included articles published from January 2000 to December 2020. It included quantitative studies, which analyzed the anxiety experienced by oncological patients who had undergone 18F-FDG PET/CT. Results: Ten articles met the inclusion criteria for this systematic review. The studies selected were published between 2011 and 2020 and carried out in five countries. Anxiety experienced by patients was evaluated at the various stages of the 18F-FDG PET/CT, eight studies assessed it in the pre-examination, seven studies in the post-examination, and five studies at both times. Four main anxiety factors were found: patients' clinical situation, first-time patients’ examination, scan procedure, and patients' concern with the examination result. Conclusion: Moderate to high levels of anxiety are present in most of the patients who undergo the examination. This review also highlights several factors related to the anxiety levels through different procedure moments. Implications for practice: The results of this research will allow health professionals to adjust non-pharmacological strategies to decrease anxiety levels in oncological patients undergoing 18F-FDG PET/CT.
- Assessment of the potential of convolutional neuronal networks in the differential diagnosis of Parkinson’s disease based on brain imaging [123I]FP-CIT SPECTPublication . Valador, N.; Oliveira, F. P.; Ferreira, P. M.; Vieira, Lina Oliveira; Costa, D. C.Aim/Introduction: To evaluate the potential of convolutional neural networks (CNN) in the differential diagnosis of Parkinson’s disease (PD) based on [123I]FP-CIT single-photon emission computed tomography (SPECT) images, compared to other machine learning-based classifiers. Materials and Methods: This work included 806 [123I]FP-CIT SPECT brain images (208 health controls and 598 with PD). Data were obtained from the Parkinson’s Progression Markers Initiative (PPMI) database (www.ppmi-info.org/data). For each subject, only the first scan was considered (baseline or screening). The protocol of image acquisition and pre-processing is available at http://www.ppmi-info.org/study-design/research-documentsand-sops/. CNN was compared against k-nearest neighbor (kNN), logistic regression (LG), decision trees (DT), support vector machines (SVM), and artificial neural networks (ANN) classifiers. The CNN classifier was trained with 2-dimensional image patches (dimensions: 88 mm x 82 mm) containing the striatal region, extracted from the head superior-inferior maximum intensity projection. The remaining classifiers were trained with five features extracted from the 3-dimensional striatal region: caudate binding potential, putamen binding potential, putamen to caudate ratio, the volume of the striatal region with “normal uptake”, and the major axis of that region. The minimum values extracted from each cerebral hemisphere were used. The split ratio of the dataset was 75:25 (75% for training and 25% for testing). Each of the five features was also considered individually to assess its potential for classification in terms of performance (accuracy, sensitivity, and specificity). Results: In the test dataset, the accuracy, sensitivity, and specificity of the CNN were 96%, 98%, and 91%, respectively. This finding was very similar to what we obtained with the other classifiers (kNN: 95%, 99%, 85%; LG: 94%, 97%, 86%, DT: 94%, 97%, 84%, SVM: 94%, 98%, 88%, and ANN: 94%, 97%, 86%). The accuracy differences are not statistically significant (Cochran Q test, p = 0.592). Individually, the feature that best differentiates PD from normal scans was the putamen binding potential with 93% accuracy, 93% sensitivity, and 94% specificity in the test dataset, based on the optimal cutoff (1.716) that maximizes Younden’s coefficient in the training dataset. Conclusion: CNN classifier proved to be as robust and accurate as the other classifiers frequently used in the type of problems as in this work, with the great advantage of using images as direct input. All machine learning-based classifiers tested are robust and very accurate in the classification of brain [123I]FP-CIT SPECT scans. Standard visual clinical evaluation should be complemented with quantification classification used also as a training tool.
- Cancer patient experience in a nuclear medicine department: comparison between bone scintigraphy and 18F-FDG PET/CTPublication . Grilo, Ana Monteiro; Vieira, Lina Oliveira; Carolino, Elisabete; Costa, Melissa; Galaio, Salomé; Melo, Inês; Geão, Ana; Santos, Andrea; Colarinha, PaulaObjective: To assess the emotional impact on cancer patients undergoing Nuclear Medicine scans and identify how professionals can improve patient experience. Methods: 94 patients undergoing a Bone Scan (BS) or a Positron emission tomography/Computed Tomography (18F-FDG PET/CT) completed two Scan Experience Questionnaires and the State Anxiety Inventory (STAI-S) prior to the scan and after image acquisition. Results: Before the exam, the mean anxiety levels were higher for the BS patients compared to the 18F-FDG PET/CT group. For the post-scan STAI-S mean score, the opposite is true. Both groups experienced a reduction in levels of anxiety after the scan (BS - STAI score pre-scan = 51.75, and post-scan = 36.70; 18F-FDG PET/CT - STAI score pre-scan = 44.67, and post-scan = 38.82). The greatest anxiety factor for the BS group was the duration of the exam - 5.34 ± 2.08 (mean ± SD), while for the 18F-FDG PET/CT group it was the result - 5.40±1.80 (mean ± SD). Conclusion: Patients undergoing NM exams in an oncological context revealed significant anxiety levels prior to and after their scans. However, the BS and 18F-FDG PET/CT have different triggers. It is of extreme importance that healthcare professionals are aware of these peculiarities and adjust their procedures accordingly.
- Developments on finite element methods for medical image supported diagnosticsPublication . Almeida, Ana; Barbosa, Joaquim; Carvalho, André; Loja, Amélia; Portal, Ricardo; Rodrigues, José Alberto; Vieira, Lina OliveiraVariational image-processing models offer high-quality processing capabilities for imaging. They have been widely developed and used in the last two decades, enriching the fields of mathematics as well as information science. Mathematically, several tools are needed: energy optimization, regularization, partial differential equations, level set functions, and numerical algorithms. For this work we consider a second-order variational model for solving medical image problems. The aim is to obtain as far as possible fine features of the initial image and identify medical pathologies. The approach consists of constructing a regularized functional and to locally analyse the obtained solution. Some parameters selection is performed at the discrete level in the framework of the finite element method. We present several numerical simulations to test the efficiency of the proposed approach.
- Effectiveness of educational videos on patient’s preparation for diagnostic procedures: systematic review and meta-analysisPublication . Grilo, Ana; Ferreira, Ana Catarina; Ramos, Marta Pedro; Carolino, Elisabete; Pires, Ana Filipa; Vieira, Lina OliveiraAlthough diagnostic procedures are crucial for secondary prevention and patient disease control, they often trigger fear and anxiety. These reactions highlight the need to adopt effective interventions to improve patients' experience and satisfaction. Recently, educational videos have been employed in preparing diagnostic procedures; however, there is no integrated understanding of their effects. This systematic review and meta-analysis aimed to assess the effectiveness of educational videos on patients' anxiety and satisfaction regarding preparation for diagnostic procedures. Three scientific databases (PubMed; Web of Science, Scopus), were used in this systematic review. Studies about educational videos as a form of preparation for patients undergoing diagnostic procedures published between 2000 and 2021 were included. A meta-analysis was also conducted. Sixteen studies met the inclusion criteria for systematic review, and seven were included in the meta-analysis. Nine studies of the total sample were about vascular procedures and seven studies about other medical image procedures. Of the fourteen studies that evaluated the use of educational videos on patients' anxiety, nine proved to reduce it significantly. Of the thirteen studies that evaluated satisfaction, seven showed a significant increase in the experimental group. Studies included in the meta-analysis show that educational video patient groups had lower anxiety levels than the control groups after the procedure. Although future studies are required, the results suggest that educational videos effectively prepare patients for diagnostic procedures, improving care quality.
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