Percorrer por autor "Pereira, Norberto"
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- The impact of a rectal spacer in VMAT Dosimetry in the treatment of Prostate CancerPublication . Oliveira, Susana; Fernandes, Ruben; Baylina, Pilar; Santos, João; Vieira, Guy; Faria, Isabel; Pereira, Norberto; Fernandes, Rúben; BAYLINA MACHADO, PILAR; Sousa Pinho Faria, Isabel MariaAlthough the dosimetric advantages of rectal spacers in prostate cancer radiotherapy have been demonstrated in selected clinical trials, real-world data from routine clinical practice remain limited—particularly within the Portuguese healthcare system. This study offers a detailed dosimetric comparison of Volumetric Modulated Arc Therapy (VMAT), with and without rectal spacer use, in a real-world patient cohort, aiming to assess the clinical relevance of spacer insertion under standard treatment protocols. A retrospective dosimetric evaluation was performed on 80 prostate cancer patients treated at a radiotherapy centre in southern Portugal. Patients were equally divided into two matched groups (n = 40): one receiving VMAT alone, the other receiving VMAT with hydrogel rectal spacer placement. Dose-volume histograms (DVHs) were analysed for the planning target volume (PTV) and key organs at risk (OARs). Standard dosimetric metrics, such as V50–V75 for the rectum and bladder, V50 for femoral heads, and mean dose for the penile bulb, were assessed. PTV coverage was evaluated using conformity and homogeneity indices. Spacer use significantly decreased rectal dose exposure across all evaluated parameters without compromising PTV coverage or increasing dose to other OARs. These findings support routine rectal spacer applications to enhance treatment safety and patient outcomes.
- Integrating cognitive factors and eye movement data in reading predictive models for children with Dyslexia and ADHD-IPublication . Pereira, Norberto; Costa, Maria Armanda; Guerreiro, ManuelaThis study reports on several specific neurocognitive processes and eye-tracking predictors of reading outcomes for a sample of children with Developmental Dyslexia (DD) and Attention-Deficit/Hyperactivity Disorder – inattentive subtype (ADHD-I) compared to typical readers. Participants included 19 typical readers, 21 children diagnosed with ADHD-I and 19 children with DD. All participants were attending 4th grade and had a mean age of 9.08 years. The psycholinguistic profile of each group was assessed using a battery of neuropsychological and linguistic tests. Participants were submitted to a silent reading task with lexical manipulation of the text. Multinomial logistic regression was conducted to evaluate the predictive capability of developing dyslexia or ADHD-I based on the following measures: (a) a linguistic model that included measures of phonological awareness, rapid naming, and reading fluency and accuracy; (b) a cognitive neuropsychological model that included measures of memory, attention, visual processes, and cognitive or intellectual functioning, and (c) an additive model of lexical word properties with manipulation of word-frequency and word-length effects through eye-tracking. The additive model in conjunction with the neuropsychological model classification improved the prediction of who develops dyslexia or ADHD-I having as baseline normal readers. Several of the neuropsychological and eyetracking variables have power to predict the degree of reading outcomes in children with learning disabilities.