G T Barnes

University of Alabama at Birmingham

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Michael V. Yester

University of Alabama at Birmingham

Xizeng Wu

University of Alabama at Birmingham

D. Tucker

The University of Texas at Austin

M Yester

Birmingham VA Medical Center

R. Fräser

Emory University

Michael A. King

University of Massachusetts Chan Medical School

Miguel Souto

University of Minho

Eric L. Gingold

Thomas Jefferson University

D. R. Gustafson

Wayne State University

Richard A. Sones

Case Western Reserve University

Cooperative Institutions

University of Alabama at Birmingham

University of Alabama at Birmingham Hospital

University of Alabama

Birmingham VA Medical Center

Evangelismos Hospital

Taber International (United States)

National and Kapodistrian University of Athens

Johns Hopkins University

Universidade de Santiago de Compostela

University of Kansas

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

SU‐E‐I‐53: Optimal KVp for Image Quality and Noise in Iodine Contrast in Head CTA

Medical Physics (2012)

Lynne L. Johnson M Yester G T Barnes

Purpose: For brain CT perfusion it is well established that 80 kVp is optimal. Although neuro‐CT angiography is somewhat similar, emphasis is on the detection of aneurysms and related vascular pathologies throughout the brain. Thus it is necessary to visualize small and large blood vessels with contrast material, as well as form multi‐planar views and 3D images, so image quality and noise in addition to contrast are important for thin slices. A study was initiated to determine the optimal kVp for neuro‐CTA. Methods: A customized version of a commercial head phantom (CIRS 007TE‐27 medium adult head CT dose phantom) was purchased to facilitate quantitative measurements with iodinated contrast material, contrast for white and gray matter, and to maintain the ability to perform dosimetry. The customization consisted of adding four 25 mm holes, 35 mm from the center arranged at 45 degree angles from the center, with solid rods equivalent with brain, white, and gray matter, as well as four fillable vials were included for study of contrast agents. Dosimetry measurements were carried out with standard pencil chamber and with 0.6 cc ionization chamber. For study of the optimal kVp for a head CTA, the vials were filled with four different concentrations of contrast, approximating low to medium concentrations that would be expected in such a study. The standard CTA protocol was followed, 64 × 0.625, pitch 0.53, rotation speed 0.5 second, and CTDIvol was kept constant for each kVp. Results: The best contrast was observed at 80 kVp; however, in order to achieve noise in CTA low enough to be clinically useful there may be issues with tube current capability for a clinical technique. Clinical investigation is underway. Conclusions: The best balance of contrast and noise currently possible will be achieved at 100 kVp in a clinical scan.

10.1118/1.4734769

Cite

Citations (0)

Digital radiography of the chest: state of the art

European Radiology (1994)

Miguel Souto Katerina Malagari D. Tucker Pablo G. Tahoces J. Correa

Digital radiography

Interventional radiology

Digital Imaging

Computed radiography

Neuroradiology

10.1007/bf00599059

Cite

Citations (13)

Accounting 3B (Supp Exam)

G T Barnes B. Madikizela Z. Patel J. Wessels Kevan Heathcote

Source

Cite

Citations (0)

<title>Optimizing Computed Tomography (CT) Scanner Geometry</title>

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (1979)

G T Barnes Michael V. Yester Michael A. King

The effect of CT scanner geometry on spatial resolution, contrast sensitivity, and patient dose are considered and used to determine the limiting factor or factors for a particular scanner. To this end analytical expressions for the components of the system modulation transfer function (MTF) are identified, and a Geometrical Figure of Merit is introduced based on the information capacity per rad. This formalism is used to compare four commercial CT units representing the main types presently in use. Improvements in scanner geometry are suggested which will improve this Figure of Merit for a given design. A new geometry, which would be relatively inexpensive to manufacture, is introduced and considered in the context of the formalism presented. Such a geometry utilizing state of the art components is shown to be superior to present and improved versions of CT scanners currently available.

Figure of Merit

Formalism (music)

Limiting

Optical transfer function

10.1117/12.957146

Cite

Citations (1)

Investigation of self-irradiation damage in plutonium by positronium annihilation

Journal of Nuclear Materials (1973)

D. R. Gustafson G T Barnes

Positronium

Annihilation

Annihilation radiation

10.1016/0022-3115(73)90081-0

Cite

Citations (6)

Digital chest radiography: comparison of unprocessed and processed images in the detection of solitary pulmonary nodules.

Radiology (1995)

J. Correa Miguel Souto Pablo G. Tahoces Katerina Malagari D. Tucker

PURPOSE: To compare the accuracy with which simulated solitary pulmonary nodules can be identified on digital images of the chest that are unprocessed, processed with adaptive spatial filtering, or processed with global filtering. MATERIALS AND METHODS: Six experienced chest radiologists evaluated 408 test radiographs (136 from each of the three types, half with simulated nodules) and judged whether a nodule was present. Data from the 2,448 observations were evaluated by means of a receiver operating characteristic curve with location methods. RESULTS: Accuracy was significantly better with the adaptive filter technique than with the global technique (P < .05), and it was better with adaptive filtering than with no processing in the detection of pulmonary nodules in the mediastinal-subdiaphragmatic areas (P < .05). No significant difference was found between no processing and global filtering. CONCLUSION: Adaptive filtration is superior to global filtration in the identification of solitary pulmonary nodules and is superior to no processing in nodules projected over the radiopaque areas of the thorax on digital images.

Solitary pulmonary nodule

10.1148/radiology.195.1.7892481

Cite

Citations (21)

OPTIMIZING COMPUTED TOMOGRAPHY (CT) SCANNER GEOMETRY

Journal of Computer Assisted Tomography (1980)

G T Barnes Michael V. Yester Michael A. King Rodney A. Brooks

Department of Diagnostic Radiology, University of Alabama School of Medicine, Birmingham, Alabama 35233.

Industrial computed tomography

10.1097/00004728-198002000-00041

Cite

Citations (1)

Metastatic calcification of the heart and lungs in end-stage renal disease: detection and quantification by dual-energy digital chest radiography

American Journal of Roentgenology (1987)

Colleen Sanders MS Frank SG Rostand E.A. Rutsky G T Barnes

Metastatic calcification of the lung and heart can cause severe cardiopulmonary compromise and death. Although it is found in most end-stage renal disease patients at autopsy, it is only rarely detected during life. Using a prototype dual-energy digital chest radiographic unit, we measured calcium content (mg/cm2) over the lung and heart in 32 hemodialysis patients. Pulmonary calcium content was significantly greater in these patients than in sex-matched control subjects (men, 230 +/- 43 [mean +/- standard error] vs 166 +/- 7, p less than .05; women, 168 +/- 19 vs 110 +/- 7.5, p less than .001). Abnormal values were detected by dual-energy radiography in 44% of patients (vs 9% of patients studied by conventional radiography). Cardiac calcium content was also significantly greater in the hemodialysis patients than in the control subjects (259 +/- 14 vs 184 +/- 8, p less than .05). Metastatic calcification was significantly correlated with elevated phosphate and calcium-phosphate product levels. Patients with significantly elevated pulmonary calcium content had evidence of restrictive lung disease by functional testing. There was an inverse correlation between elevated cardiac calcium content and ejection fraction. We conclude that dual-energy digital radiography allows premortem diagnosis of metastatic visceral calcification and is more sensitive than current techniques.

Metastatic calcification

10.2214/ajr.149.5.881

Cite

Citations (63)

Signal‐to‐noise ratio considerations in radiographic imaging

Medical Physics (1983)

Dev P. Chakraborty G T Barnes

The methodology employed to calculate radiographic signal-to-noise ratio (SNR) for the commonly used disk-shaped test object is reviewed. Although the "matched" aperture yields the maximum SNR, its shape is difficult to achieve experimentally. On the other hand, a circular aperture having the same size as the object is much simpler to realize. We have performed a numerical analysis of the SNRs obtained with matched and circular apertures for two screen/film systems (a mammographic and a general purpose combination) for a range of test-object sizes. We find that for object sizes greater than 0.5 mm in diameter, there is a less than 4% difference between the SNRs obtained with the two apertures. The shapes of some of the matched apertures are also presented. We conclude that the SNR determined with the circular aperture is a simpler and more useful determinant of system performance for the screen/film combinations studied.

Aperture (computer memory)

Computed radiography

SIGNAL (programming language)

Coded aperture

10.1118/1.595310

Cite

Citations (4)

Bone mineral densitometry with x-ray and radionuclide sources: A theoretical comparison

Medical Physics (1991)

Dev P. Chakraborty G T Barnes

Two methods of dual‐photon absorptiometry (DPA) utilizing an x‐ray tube instead of a radionuclide source have recently been introduced. In one method kVp switching is employed and two transmitted intensities at each pixel are determined. In the other method, K ‐edge filtration combined with a single kVp spectrum is used, but photons in two energy windows are counted. We present a theoretical analysis of the two methods, focusing on a figure of merit which is essentially the exposure efficiency (the precision for a given entrance exposure) and tube loading. We also compare their exposure efficiencies to theoretical limits that no DPA system can exceed. Our study indicates that the K ‐edge‐filtered method is more exposure efficient by about a factor of 2. The switched‐kVp method requires less heat units per scan by about a factor of 3. A hybrid K ‐edge switched‐kVp method is suggested which achieves the same exposure efficiency as the K ‐edge‐filtered method at lesser tube loading. Our theoretical model is based on published x‐ray spectra and attenuation coefficients and is in good agreement with other simulation work. It is of interest that a point source of Gd‐153 would be even more exposure efficient, achieving about 90% of the theoretical limit. However, in practice, the Gd source is of finite size and limited strength, and consequently the radionuclide method cannot achieve as good a precision as either x‐ray method in similar scan times.

Effective atomic number

Filtration (mathematics)

10.1118/1.596613

Cite

Citations (14)