Imaging phantom

About: Imaging phantom is a research topic. Over the lifetime, 28170 publications have been published within this topic receiving 510003 citations. The topic is also known as: phantom.

Real-time in vivo photoacoustic and ultrasound imaging.

Abstract: A real-time photoacoustic imaging system is designed and built. This system is based on a commercially available ultrasound imaging system. It can achieve a frame rate of 8 frames/sec. Vasculature in the hand of a human volunteer is imaged, and the resulting photoacoustic image is combined with the ultrasound image. The real-time photo acoustic imaging system with a hybrid ultrasound probe is demonstrated by imaging the branching of subcutaneous blood vessels in the hand

Contrast-to-Noise Ratio and Low-Contrast Object Resolution on Full- and Low-Dose MDCT: SAFIRE Versus Filtered Back Projection in a Low-Contrast Object Phantom and in the Liver

Abstract: OBJECTIVE. The purpose of this article is to evaluate the effect of sinogram-affirmed iterative reconstruction (SAFIRE) on contrast-to-noise ratio (CNR) compared with filtered back projection (FBP) and to determine whether SAFIRE improves low-contrast object detection or conspicuity in a low-contrast object phantom and in the liver on full- and low-dose examinations. SUBJECTS AND METHODS. A low-contrast object phantom was scanned at 100%, 70%, 50%, and 30% dose using a single-source made of a dual-source MDCT scanner, with the raw data reconstructed with SAFIRE and FBP. Unenhanced liver CT scans in 22 patients were performed using a dual-source MDCT. The raw data from both tubes (100% dose) were reconstructed using FBP, and data from one tube (50% dose) were reconstructed using both FBP and SAFIRE. CNR was measured in the phantom and in the liver. Noise, contrast, and CNR were compared using paired Student t tests. Six readers assessed sphere detection and conspicuity in the phantom and liver–inferior ven...

DOSXYZnrc Users Manual

Abstract: DOSXYZnrc is an EGSnrc-based Monte Carlo simulation code for calculating dose distributions in a rectilinear voxel phantom and is based directly on the DOSXYZ code developed for the EGS4 code system (see NRC Report PIRS-509B). DOSXYZnrc is part of the OMEGABEAM system of codes developed at NRC. Density and material in every voxel may vary. A variety of beams may be incident on the phantom, including full phase-space files from BEAMnrc and beams characterized using Beam Characterization models. The companion program ctcreate is capable of reading in a CT data set of Hounsfield numbers and converting it into the information needed by DOSXYZnrc to simulate transport in a phantom (i.e. the appropriate material and density are specified in each voxel). Any of the available beams can be incident on this CT phantom. The code includes a restart facility and can be run on parallel computing platforms. The statistical analysis is based on a history by history method as opposed to the batch method used in DOSXYZ. This user’s manual covers general DOSXYZnrc inputs, geometries and outputs. It contains information on how to compile and run DOSXYZnrc using the EGSnrcMP system. It also describes the use of ctcreate. The figure on the front page shows a PAW visualisation of the isodose curves from a DOSXYZ simulation in which a Clinac 2100c 18MeV electron beam (simulated using a multiple-source model–with 35 million initial histories) was incident on the head and neck of a CT phantom. The visualisation was implemented by Daryoush Sheikh-Bagheri. NRCC Report PIRS-794(revB) 3

Segmentation of dynamic PET images using cluster analysis

Abstract: Quantitative positron emission tomography (PET) studies provide in vivo measurements of dynamic physiological and biochemical processes in humans. A limitation of PET is an inability to provide precise anatomic localization due to relatively poor spatial resolution when compared to magnetic resonance (MR) imaging. Manual placement of region-of-interest (ROI) is commonly used in clinical and research settings in analysis of PET datasets. However, this approach is operator dependent and time-consuming. A semi- or fully-automated ROI delineation (or segmentation) method offers advantages by reducing operator error/subjectivity and thereby improving reproducibility. In this work, we describe an approach to automatically segment dynamic PET images using cluster analysis and we validate our approach with a simulated phantom study and assess its performance with real dynamic PET data. Our preliminary results suggest that cluster analysis can automatically segment tissues in dynamic PET studies and has the potential to replace manual ROI delineation for some applications.

3-D FLASH imaging using a single surface coil and a new adiabatic pulse, BIR-4.

Abstract: A new adiabatic pulse, which can induce uniform and arbitrary flip angles despite the presence of transmitter coil magnetic field (B1) inhomogeneities, is employed for 3-D fast imaging using a single surface coil for pulse transmission and signal detection. Computer calculations and phantom, rat, and human surface coil imaging experiments demonstrate the utility of this adiabatic pulse for T1-weighted imaging with a transmitter coil which generates a highly inhomogeneous B1 field profile.