Reference Phantom Design for the Birmingham BNCT Project

2001 ◽  
pp. 681-686
Author(s):  
C. Wojnecki ◽  
S. Green
Keyword(s):  
Reference Phantom ◽  
Phantom Design

Interventional Mr imaging

1997 ◽  
Vol 38 (1) ◽  
pp. 43-46
Author(s):  
R. P. J. Joensuu ◽  
R. E. Sepponen ◽  
A. E. Lamminen ◽  
C.-G. M. Standertskjöld-Nordenstam
Keyword(s):  
Mr Imaging ◽  
Signal To Noise Ratio ◽  
Coaxial Cable ◽  
High Signal ◽  
The Poor ◽  
Imaging Sequence ◽  
Reference Phantom ◽  
Interventional Mr ◽  
Interventional Devices ◽  
Interventional Mr Imaging

Purpose: The poor localization facility of interventional instruments in MR imaging has been one of the major obstacles to the popularization of interventional MR imaging. It has been suggested that the Overhauser enhancement be used to generate markers of small size and high visibility. This article studies the feasibility of a localization marker based on this method. Material and Methods: A small Overhauser marker was constructed on the tip of a coaxial cable and comparative images were taken by a 0.23 T imager with and without electron spin irradiation. Results: During irradiation an enhanced signal intensity from the marker was observed. The signal from the marker also exceeded the signal from a 0.25 mmol MnCl2 reference phantom. Conclusion: Its small size and high signal-to-noise ratio, together with immunity to most system nonlinearities and imaging errors, makes the Overhauser marker a promising localization method for the accurate positioning of interventional devices. The method may be applied at any field strength, and markers are visible in images obtained with any practical imaging sequence.

CT evaluation of solitary pulmonary nodules: value of 185-H reference phantom.

1991 ◽  
Vol 156 (5) ◽  
pp. 925-929 ◽  
Author(s):  
S J Swensen ◽  
G F Harms ◽  
R L Morin ◽  
J L Myers
Keyword(s):  
Pulmonary Nodules ◽  
Solitary Pulmonary Nodules ◽  
Reference Phantom ◽  
Ct Evaluation

Backscatter Coefficient Measurements Using a Reference Phantom to Extract Depth-Dependent Instrumentation Factors

1990 ◽  
Vol 12 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Lin Xin Yao ◽  
James A. Zagzebski ◽  
Ernest L. Madsen
Keyword(s):  
Attenuation Coefficient ◽  
Time Domain ◽  
Reduction Method ◽  
Processing Technique ◽  
Processing Method ◽  
Backscatter Coefficient ◽  
Attenuation Coefficients ◽  
Reference Phantom ◽  
Dependent Signal ◽  
Data Reduction Method

In previous work, we demonstrated that accurate backscatter coefficient measurements are obtained with a data reduction method that explicitly accounts for experimental factors involved in recording echo data. An alternative, relative processing method for determining the backscatter coefficient and the attenuation coefficient is presented here. This method involves comparison of echo data from a sample with data recorded from a reference phantom whose backscatter and attenuation coefficients are known. A time domain processing technique is used to extract depth and frequency dependent signal ratios for the sample and the reference phantom. The attenuation coefficient and backscatter coefficient of the sample are found from these ratios. The method is tested using tissue-mimicking phantoms with known scattering and attenuation properties.

scholarly journals EM Estimation of the X-Ray Spectrum With a Genetically Optimized Step-Wedge Phantom

2021 ◽  
Vol 9 ◽  
Author(s):  
Mengzhou Li ◽  
Feng-Lei Fan ◽  
Wenxiang Cong ◽  
Ge Wang
Keyword(s):  
Energy Spectrum ◽  
Condition Number ◽  
Linear Equations ◽  
Spectrum Estimation ◽  
Genetic Optimization ◽  
System Matrix ◽  
X Ray ◽  
Phantom Design ◽  
Selection Of ◽  
Spectrum Inversion

The energy spectrum of an X-ray tube plays an important role in computed tomography (CT), and is often estimated from physical measurement of dedicated phantoms. Usually, this estimation problem is reduced to solving a system of linear equations, which is generally ill-conditioned. In this paper, we optimize a phantom design to find the most effective combinations of thicknesses for different materials. First, we analyze the ill-posedness of the energy spectrum inversion when the number of unknown variables (N) and measurements (M) are equal, and show the condition number of the system matrix increases exponentially with N if the transmission thicknesses are linearly changed. Then, we present a genetic optimization algorithm to minimize the condition number of the system matrix in a general case (M < N) with respect to the selection of thicknesses and types of phantom materials. Finally, in the simulation with Poisson noise we study the accuracy of the spectrum estimation using the expectation-maximum algorithm. Our results indicate that the proposed method allows high-quality spectrum estimation, and the number of measurements is reduced over two thirds of that required by the widely-used method using a phantom with linearly-changed thicknesses.

Solitary pulmonary nodules: comparison of classification with standard, thin-section, and reference phantom CT.

Radiology ◽  
1991 ◽  
Vol 179 (2) ◽  
pp. 477-481 ◽  
Author(s):  
A Khan ◽  
P G Herman ◽  
P Vorwerk ◽  
P Stevens ◽  
K A Rojas ◽  
...  
Keyword(s):  
Thin Section ◽  
Pulmonary Nodules ◽  
Solitary Pulmonary Nodules ◽  
Reference Phantom

PO-1628 Pre-treatment verification using portal images. Could them substitute our reference phantom?

2021 ◽  
Vol 161 ◽  
pp. S1348-S1350
Author(s):  
J.D. García Fuentes ◽  
P. Retorta ◽  
R. Colmenares ◽  
D. Sevillano ◽  
F. Orozco ◽  
...  
Keyword(s):  
Treatment Verification ◽  
Reference Phantom ◽  
Pre Treatment ◽  
Portal Images
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