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- 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.
- 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.
- Impact of the background Region of Interest in the relative renal functionPublication . Sousa, Eva; Raminhas Carapinha, Maria João; Vaz, Tânia; Lucena, Filipa; Vieira, Lina OliveiraRenal scintigraphy with 99mTc-dimercaptosuccinic acid (99mTc-DMSA) is performed with the aim of detect cortical abnormalities related to urinary tract infection and accurately quantify relative renal function (RRF). For this quantitative assessment Nuclear Medicine Technologist should draw regions of interest (ROI) around each kidney (KROI) and peri-renal background (BKG) ROI although controversy still exists about BKG-ROI. The aim of this work was to evaluate the effect of the normalization procedure, number and location of BKG-ROI on the RRF in 99mTc-DMSA scintigraphy.
- MUGA processing: intra and interoperator variability impact using manual and automated methodsPublication . Belo, Rita; Alves, Cláudia; Carvalhal, Cristiana; Figueiredo, Sérgio; Carolino, Elisabete; Vieira, Lina OliveiraIntroduction – Multigated acquisition (MUGA) scan is mainly used for the assessment of left ventricular ejection fraction (LVEF) in patients who undergo cardiotoxic chemotherapy drugs. When applying automatic (A) or manual (M) processing methods, some biases in the quantitative metrics can be obtained. The aim of this study is to evaluate the influence of A and M methods, specifically, the inter and intraoperative variability in accordance with the professional experience. Methods – A retrospective study was performed with 14 MUGA exams available in ESTeSL’s Xeleris™ Functional Imaging Workstation v. 1.0628 database. Three operators (OP) with no professional experience and two with more than 10 years of experience, processed every study five times for each method, using the EF Analysis™ and the Peak Filling Rate™. To perform the multiple comparisons, the Repeated Measures ANOVA, Friedman, t-test and Wilcoxon tests were used, considering α=0.05. Results – Four of the OP presented statistically significant differences between methods in one or more parameters; similar values between experienced OP and between the non-experienced were observed when the A method was applied, and higher discrepancies were present for all parameters obtained by the M mode; higher LVEF, peak filling rate, and peak empying rate values were observed for the M method. Conclusion – Variability was found when comparing M and A processing methods, as well as interoperator variability associated with their level of experience. Despite that, there was a trend of less variability between the two experienced OP and in the A method.
- 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.
- Radiotherapy-customized head immobilization masks: from modeling and analysis to 3D printingPublication . Loja, Amélia; Craveiro, D. S.; Vieira, Lina Oliveira; Sousa, Eva; Rodrigues, J. A.; Portal, R. J. F.Immobilization devices may be a valuable aid to ensure the improved effectiveness of radiotherapy treatments where constraining the movements of specific anatomical segments is crucial. This need is also present in other situations, specifically when the superposition of various medical images is required for fine identification and characterization of some pathologies. Because of their structural characteristics, existing head immobilization systems may be claustrophobic and very uncomfortable for patients, during both the modeling and usage stages. Because of this, it is important to minimize all the discomforts related to the mask to alleviate patients’ distress and to simultaneously guarantee and maximize the restraint effectiveness of the mask. In the present work, various head immobilization mask models are proposed based on geometrical information extracted from computerized tomography images and from 3D laser scanning point clouds. These models also consider the corresponding connection to a radiotherapy table, as this connection is easily altered to accommodate various manufacturers’ solutions. A set of materials used in the radiotherapy field is considered to allow the assessment of the stiffness and strength of the masks when submitted to typical loadings.
- Hydrogen peroxide as a key player in bystander effectsPublication . Pinto, V.; Carmona, Bruno; Antunes, F.; Marinho, H. Susana; Vieira, Lina Oliveira; Soares, Helena
- Using 3D anthropometric data for the modelling of customised head immobilisation masksPublication . Loja, Amélia; Sousa, E.; Vieira, Lina Oliveira; Craveiro, D.S.; Parafita, Rui; C. Costa, Durval; Costa, DMSHead immobilization thermoplastic masks for radiotherapy purposes involve a distressful modelling procedure for the patient. To assess the possibility of using different acquisition and reconstruction methods to obtain a 3Dskin surface model of PIXY-phantom-head and to present a proposal of an alternative head immobilisation mask prototype. Phantom head geometry acquisitions using: computed tomography (reconstructed with ImageJ and Osirix); and 3DLaserScanner (reconstructed with SolidWorks). From these reconstructed surface models a set of landmarks was measured and subsequently compared with physical measurements obtained with a Rosscraft-Calliper. For statistical evaluation, relative deviations graphics and Friedman-test for non-parametrical paired samples were used, with a significance level of 5%. For a first assessment of the proposed mask performance, a radiotransparent material was considered, the strength and stiffness evaluation being performed using the finite element method. There are small differences between all the acquisitions and reconstructions methods and the physical measurements, statistically significant differences (X2F(6)) = 6.863, p=0.334) were not found. The proposed mask performed well from the strength and stiffness perspectives, leading to the desired immobilisation aim. The immobilisation mask design proposal may be an effective alternative to the present completely hand-made situation, which presents a high-degree of discomfort and stress to the patients.
- Exposição dos técnicos de medicina nuclear durante testes de ventilação pulmonarPublication . Alves, M.; Duarte, Ana Cristina; Mylkivska, A.; Pereira, E.; Jerónimo, V.; Carolino, Elisabete; Vieira, Lina OliveiraIntrodução – O teste da ventilação requer a inalação de um radiofármaco pelo paciente, o que pode conduzir a contaminações dos técnicos de medicina nuclear (TMN) pelo gás radioativo. Objetivo – Avaliar a exposição à radiação ionizante do TMN durante testes de ventilação pulmonar com 99mTc-Technegas® através da monitorização de contaminações externas das mãos e rosto. Métodos – Monitorização de quatro TMN de dois serviços diferentes durante a realização de estudos de ventilação pulmonar, utilizando para o efeito o monitor de radiação Geiger-Müller. Foram medidos os valores de radiação de fundo da sala onde é realizado o teste de ventilação pulmonar antes e após o procedimento, com e sem a presença do paciente; foi medida a taxa de dose nas mãos (com e sem as luvas utilizadas no procedimento) e no rosto (com e sem a máscara utilizada no procedimento). Os dados foram analisados no software estatístico SPSS, v. 22.0 para Windows. Resultados – Verificou-se que em ambos os serviços de medicina nuclear estudados os valores de taxa de dose mais elevados foram medidos após o teste de ventilação, com o paciente dentro da sala. O serviço Y apresentou valores de taxa de dose superiores ao nível de significância de 5% nas mãos com as respetivas luvas, nas luvas usadas durante o procedimento, no rosto com a respetiva máscara e na máscara. Conclusão – A contaminação na sala é tanto maior quanto maior o número de estudos de ventilação realizados. As luvas constituem uma barreira externa contra a contaminação direta nas mãos. As máscaras reduzem o risco de contaminação do rosto do TMN.
- Evaluation of the attenuation correction on myocardial perfusion imaging: a phantom studyPublication . Machado, Marisa; Oliveira, Francisco P. M.; Vieira, Lina Oliveira; Costa, Durval C.Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is important for risk stratification of coronary artery disease. MPI quantification obtained from available images may not be accurate due to several potential sources of error, being photon attenuation, especially in overweight patients, a significant problem. Attenuation maps derived from X-ray computed tomography (CT) may be used to correct for photon attenuation. The aim of this study was to evaluate the effects of non-attenuation correction (NAC) and attenuation correction (AC) in MPI SPECT imaging using anthropomorphic phantoms simulating patients with different attenuation profiles. Forty-nine SPECT and CT studies of Heart/Thorax phantoms with different attenuation layers were acquired. All SPECT imaging data were reconstructed with and without AC. Quantification of the myocardial signal (uptake) was performed in four regions of interest: septum, anterior wall, inferior wall, and apex. This was done both in NAC and AC SPECT images. A qualitative evaluation was performed by a nuclear medicine physician also in NAC and AC SPECT images. The results demonstrated, as expected, statistically lower counts when the thickness of the phantom attenuating material increased and attenuation correction was lacking. On the other hand, when attenuation correction was applied, there were no statistically significant count differences whatever the thickness of the phantom attenuating material. In the qualitative evaluation, the nuclear medicine physician observed small variations in the anterior wall uptake according to the various conditions under test. However, the changes were not statistically significant. In conclusion, there is no evidence that the effects of attenuation in overweight patients are not properly corrected when the MPI SPECT images are reconstructed with CT-based AC. In terms of qualitative visual assessment, there is no significant variation in the classification of myocardial walls uptake with and without AC when the evaluation is done by an experienced physician.
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