Repository logo

Browsing by Author "Teles, P"

Now showing 1 - 2 of 2
  • Assessment of Patient Dose Reduction by Bismuth Shielding in CT Using Measurements, GEANT4 and MCNPX Simulations
    Publication . Mendes, M; Costa, F; Figueira, C; Madeira, P; Teles, P; Vaz, P
    This work reports on the use of two different Monte Carlo codes (GEANT4 and MCNPX) for assessing the dose reduction using bismuth shields in computer tomography (CT) procedures in order to protect radiosensitive organs such as eye lens, thyroid and breast. Measurements were performed using head and body PMMA phantoms and an ionisation chamber placed in five different positions of the phantom. Simulations were performed to estimate Computed Tomography Dose Index values using GEANT4 and MCNPX. The relative differences between measurements and simulations were <10 %. The dose reduction arising from the use of bismuth shielding ranges from 2 to 45 %, depending on the position of the bismuth shield. The percentage of dose reduction was more significant for the area covered by the bismuth shielding (36 % for eye lens, 39 % for thyroid and 45 % for breast shields).
    2015-07Journal article Open access Show more
  • Case Report: Rare Convexity Meningeal Chondroma Mimicking a Meningioma
    Publication . Abreu, PG; Pappamikail, L; Pontinha, C; Drago, J; Lourenço, JA; Romero, C; Teles, P; Correia, JP
    Background: Intracranial chondromas account for 0.2-0.3% of all intracranial neoplastic lesions and less than a quarter arise in the convexity or falx. Despite its benign nature, exceedingly rare malignant transformations exist. The misdiagnosis with meningiomas is frequent and may be related with chondromas' similar insidious clinical presentation and imaging features. Standalone surgery is advised and complete resection provides the definitive treatment. Case description: A 44-year-old female presents with insidious headache, visual disturbances, and papilledema. The imaging studies were compatible with frontal parasagittal meningioma. Surgery revealed a meningeal based mass, mostly avascular and with a well-demarked surgical plane from the brain parenchyma. Complete resection with meningeal margins was achieved and the histopathologic examination revealed a chondroma. The patient symptoms subsided and no surgical complications existed. Conclusion: Intracranial convexity chondromas constitute a rare differential diagnosis for meningiomas. The present case reinforces the current scarce data and serves as reminder for clinicians diagnosing and treating intracranial tumors.
    2021Journal article Open access Show more