The Monte Carlo method is used to analyse the dose fall-off at the exit surface of a megavoltage photon beam. The convolution/superposition method of dose calculation using Monte-Carlo-generated homogeneous photon kernels is shown to be in error for exit dose calculation. Instead, photon kernels that incorporate modelling of the exit surface were generated, also using Monte Carlo, to analyse the problem, and the calculated dose fall-off using these kernels agrees well with measured data. In addition, the physics underlying the characteristics of the dose fall-off is analysed based on complete Monte Carlo modelling. Practical improvements to the convolution/superposition method are suggested.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1088/0031-9155/39/4/003 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Residence time of particles in indoor surface networks.
J Hazard Mater
January 2025
Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, PR China; Faculty of Architecture, The University of Hong Kong, Hong Kong, PR China. Electronic address:
Infectious microbes can spread rapidly from fomites (contaminated surfaces) via hand touch, with prolonged residence time on surfaces increasing transmission risk by extending exposure periods and/or involving more susceptible individuals. Existing studies have focused on decreasing microbial contamination, but not on the need for rapid removal from surface systems. This study introduces residence time as the time that a microbe spends within the surface system.
View Article and Find Full Text PDFA comparison of energy dispersive spectroscopy in transmission scanning electron microscopy with scanning transmission electron microscopy.
Ultramicroscopy
January 2025
Mechanical Engineering, University of Michigan, USA.
The objective of this work was to explore the capabilities of a field emission gun scanning electron microscope (FEG-SEM) equipped with a transmission scanning electron detector (TSEM) and energy dispersive spectroscopy (EDS) to identify nanoscale chemical heterogeneities in a gas atomization reaction synthesis (GARS) steel sample. The results of this analysis were compared to the same study conducted with scanning transmission electron microscopy (STEM) with EDS mapping. TSEM-EDS was performed using the standard spectral analysis approach, i.
View Article and Find Full Text PDFSynergizing Monte Carlo simulations and experimental insights for efficient cationic dye removal using natural fluorapatite.
J Mol Model
January 2025
Processes, Materials and Environment Laboratory (LPME), Faculty of Sciences and Technology of Fez, Sidi Mohamed Ben Abdellah University, B.P. 2202, Fez, Morocco.
Context: Natural fluorapatite (FAP) has been investigated as an adsorbent for the removal of dyes such as methylene blue (MB) and crystal violet (CV) from aqueous solutions. Effective dye removal is crucial for water treatment, particularly for industrial wastewater containing toxic dyes. FAP, a naturally abundant material, was characterized using XRD, FTIR, and SEM analysis.
View Article and Find Full Text PDFQuantitative Evaluation of Multiple Treatment Regimens for Treatment-Resistant Depression.
Int J Neuropsychopharmacol
January 2025
Center for Drug Clinical Research, Shanghai University of Traditional Chinese Medicine, No.1200 Cailun Road, Shanghai 201203, China.
Objective: This study aims to quantitatively evaluate the efficacy and safety of various treatment regimens for treatment-resistant depression (TRD) across oral, intravenous, and intranasal routes to inform clinical guidelines.
Methods: A systematic review identified randomized controlled trials on TRD, with efficacy measured by changes in the Montgomery-Åsberg Depression Rating Scale (MADRS). We developed pharmacodynamic and covariate models for different administration routes, using Monte Carlo simulations to estimate efficacy distribution.
High-Purity Ethylene Production from Ethane/Ethylene Mixtures at Ambient Conditions by Ethane-Selective Fluorine-Doped Activated Carbon Adsorbents.
ACS Appl Mater Interfaces
January 2025
Department of Chemical Engineering, University of Patras, Patras 26504, Greece.
Energy-efficient separation of light alkanes from alkenes is considered as one of the most important separations of the chemical industry today due to the high energy penalty associated with the applied conventional cryogenic technologies. This study introduces fluorine-doped activated carbon adsorbents, where elemental fluorine incorporation into the carbon matrix plays a unique role in achieving high ethane selectivity. This enhanced selectivity arises from specific interactions between surface-doped fluorine atoms and ethane molecules, coupled with porosity modulation.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!