Publications by authors named "N Alsbou"

Introduction: Although many studies have investigated small electron fields, there are several dosimetric issues that are not well understood. This includes lack of charged particle equilibrium, lateral scatter, source occlusion and volume averaging of the detectors used in the measurement of the commissioning data. High energy electron beams are also associated with bremsstrahlung production that contributes to dose deposition, which is not well investigated, particularly for small electron fields.

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Article Synopsis
  • The study focuses on electron beam radiation therapy and examines dosimetric uncertainties tied to different factors like heterogeneities and various detectors.
  • Measurements and calculations were done using electron Monte Carlo (eMC) algorithms and a MapCheck2 detector across various cone sizes (6 to 25 cm).
  • Results revealed significant discrepancies in dose estimations, with eMC underestimating doses in the umbra region by 3 times and overestimating in the penumbra region by 40%, due to issues like lateral bremsstrahlung and inconsistencies in CT image quality.
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The goal of this project is to investigate quantitatively the performance of different deformable image registration algorithms (DIR) with helical (HCT), axial (ACT), and cone-beam CT (CBCT). The variations in the CT-number values and lengths of well-known targets moving with controlled motion were evaluated. Four DIR algorithms: Demons, Fast-Demons, Horn-Schunck and Lucas-Kanade were used to register intramodality CT images of a mobile phantom scanned with different imaging techniques.

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The objective of this study is to quantitatively evaluate variations of dose distributions deposited in mobile target by measurement and modeling. The effects of variation in dose distribution induced by motion on tumor dose coverage and sparing of normal tissues were investigated quantitatively. The dose distributions with motion artifacts were modeled considering different motion patterns that include (a) motion with constant speed and (b) sinusoidal motion.

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Purpose: To quantify the variations in the length and position of fiducial markers induced by motion in axial (ACT), helical (HCT) and cone-beam CT (CBCT) imaging and associated uncertainty in image-guided radiotherapy (IGRT) by measurement and modeling.

Methods: A mobile thorax phantom containing markers of various lengths was imaged using ACT, HCT and CBCT imaging. The phantom was imaged while stationary and moving where it was moved sinusoidally with different motion amplitudes and frequency.

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