A new grid-based Boltzmann equation solver, Acuros, was developed specifically for performing accurate and rapid radiotherapy dose calculations. In this study we benchmarked its performance against Monte Carlo for 6 and 18 MV photon beams in heterogeneous media. Acuros solves the coupled Boltzmann transport equations for neutral and charged particles on a locally adaptive Cartesian grid. The Ac...

Introduction Low dose rate brachytherapy sources have been widely used for interstitial implants in tumor sites, particularly in prostate. Dosimetric characteristics of a new IrSeed 125I brachytherapy source have been determined using the LiF thermoluminescent dosimeter (TLD) chips. Materials and Methods Dose rate constant, radial dose function, and anisotropy function around the IrSeed 125I so...

Bioluminescence imaging has shown great potential for studying and monitoring disease progression in small animal pre-clinical imaging. However, absolute bioluminescence source recovery through tomographic multi-wavelength measurements is often hindered through the lack of quantitative accuracy and suffers from both poor localisation and quantitative recovery. In this work a method to incorpora...

Introduction: For RF-spoiled gradient echo imaging (ie SPGR, FLASH, T1-FFE), the combination of spoiling gradients and quadratic phase cycling eliminates net transverse magnetization within a voxel [1-4] to enable pure T1 contrast. Generally, many RF excitations are required to attain steady state magnetization levels. Therefore, when unsaturated spins are flowing into the imaging volume, inflo...

PURPOSE The Valencia HDR applicators are accessories of the microSelectron HDR afterloading system (Nucletron) shaped as truncated cones. The base of the cone is either 2 or 3 cm diameter. They are intended to treat skin lesions, being the typical prescription depth 3 mm. In patients with eyelid lesions, an internal shielding is very useful to reduce the dose to the ocular globe. The purpose of...

The objective of calibrating TLD badges and radiation survey meters demand that accurate dose gets to the TLDs and radiation survey meters. A lead block mould and an ICRU slab phantom had been designed and constructed to collimate the panoramic Cs-137 source at the secondary standards dosimetry laboratory (SSDL) by experts at the National Nuclear Research Institute (NNRI) workshop of the Ghana ...

Time-resolved transmittance spectroscopy was performed in the wavelength range of 610 or 700 to 1050 nm on phantom parallelepipeds and bone tissue cubes of different sizes. The data were best fitted with solutions of the diffusion equation for a laterally infinite slab and for a parallelepiped to investigate how size and optical properties of the samples affect the results obtained with the two...

OBJECTIVES To assess the feasibility of an objective approach for the evaluation of low-contrast detectability in multidetector computed-tomography (MDCT) by combining a virtual phantom containing simulated lesions with an image quality metric. MATERIALS AND METHODS A low-contrast phantom containing hypodense spheric lesions (-20 HU) was scanned on a 64-slice MDCT scanner at 4 different dose ...

A method of generating images through highly scattering media is presented that involves comparing measurements of the time-dependent intensity of transmitted light with an analytical model describing the sensitivity of that intensity on localized changes in optical properties. A least-squares fitting procedure is employed to derive the amplitudes of the measurement perturbations caused by embe...

The authors studied the direct conversion of syngas to light paraffins in a dual-bed fixed-bed reactor. A catalyst composed three catalysts, physically mixed methanol synthesis (CZA), and dehydration dimethyl ether (DME) (Al2O3(C)) were put upper bed for DME, while SAPO-34 (SP34-C) zeolite was lower DME conversion. effects mass ratio CZA Al2O3(C), H2/CO molar ratio, space velocity on catalytic ...