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X-Ray Imaging Innovations

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Heaven T.J.,University of Alabama at Birmingham | White S.L.,University of Alabama at Birmingham | Gauntt D.M.,X-Ray Imaging Innovations | Weems R.A.,University of Alabama at Birmingham | Litaker M.S.,University of Alabama at Birmingham
Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology | Year: 2010

Objectives: The aim of this study was to apply the dual-energy radiographic technique to teeth and to soft tissue simulated with Lucite and report the visual and quantitative results. Study design: High- and low-energy image pairs were exposed of aluminum and Lucite calibration wedges and human teeth sections. Reconstructed images of the calibration wedges and teeth sections were viewed and measured. Results: The aluminum reconstruction images accentuated the aluminum wedge and the teeth, whereas the Lucite reconstruction images minimized them. Correlations between the nominal direct and dual-energy measurements of the wedges and teeth thicknesses were found to be very good. The root-mean-square deviation of the dual-energy reconstructions from the measured nominal thicknesses was found to be no greater than 0.6 mm. Conclusion: These results demonstrate the feasibility of using dual energy as a means of selective cancellation of unwanted tissues and the measurement of posterior tooth density. © 2010 Mosby, Inc. All rights reserved.


Scott A.W.,University of Alabama at Birmingham | Gauntt D.M.,University of Alabama at Birmingham | Gauntt D.M.,X-Ray Imaging Innovations | Yester M.V.,University of Alabama at Birmingham | And 2 more authors.
Medical Physics | Year: 2012

Purpose: Grids are often not used in mobile chest radiography, and when used, they have a low ratio and are often inaccurately aligned. Recently, a mobile radiography automatic grid alignment system (MRAGA) was developed that accurately and automatically aligns the focal spot with the grid. The objective of this study is to investigate high-ratio grid tradeoffs in mobile chest radiography at fixed patient dose when the focal spot lies on the focal axis of the grid. Methods: The chest phantoms (medium and large) used in this study were modifications of the ANSI (American National Standards Institute) chest phantom and consisted of layers of Lucite™, aluminum, and air. For the large chest phantom, the amount of Lucite and aluminum was increased by 50 over the medium phantom. Further modifications included a mediastinum insert and the addition of contrast targets in the lung and mediastinum regions. Five high-ratio grids were evaluated and compared to the nongrid results at x-ray tube potentials of 80, 90, 100, and 110 kVp for both phantoms. The grids investigated were from two manufacturers: 12:1 and 15:1 aluminum interspace grids from one and 10:1, 13:1, and 15:1 fiber interspace grids from another. MRAGA was employed to align the focal spot with the grid. All exposures for a given kVp and phantom size were made using the same current-time product (CTP). The phantom images were acquired using computed radiography, and contrast-to-noise ratios (CNR) and CNR improvement factors (kCNR) were determined from the resultant images. The noise in the targets and the contrast between the targets and their backgrounds were calculated using a local detrending correction, and the CNR was calculated as the ratio of the target contrast to the background noise. kCNR was defined as the ratio of the CNR imaged with the grid divided by the CNR imaged without a grid. Results: The CNR values obtained with a high-ratio grid were 4-65 higher than those obtained without a grid at the same phantom dose. The improvement was greater for the large chest phantom than the medium chest phantom and greater for the mediastinum targets than for the lung targets. In general, the fiber interspace grids performed better than the aluminum interspace grids. In the lung, k CNR for both types of grids exhibited little dependence on kVp or grid ratio. In the mediastinum, kCNR decreased 4-10 with increasing kVp, and varied up to 5.3 with grid ratio. Conclusions: When the focal spot is accurately aligned with the grid, the use of a high-ratio grid in mobile chest radiography improves image quality with no increase in dose to the phantom. For the grids studied, the performance of the fiber interspace grids was superior to the performance of the aluminum interspace grids, with the fiber interspace 13:1 grid producing the best overall results for the medium chest phantom and the fiber interspace 15:1 producing the best overall results for the large chest phantom. © 2012 American Association of Physicists in Medicine.


Gauntt D.M.,X-Ray Imaging Innovations | Barnes G.T.,X-Ray Imaging Innovations
Medical Physics | Year: 2010

Purpose: A mobile radiography automatic grid alignment system (AGAS) has been developed by modifying a commercially available mobile unit. The objectives of this article are to describe the modifications and operation and to report on the accuracy with which the focal spot is aligned to the grid and the time required to achieve the alignment. Methods: The modifications include an optical target arm attached to the grid tunnel, a video camera attached to the collimator, a motion control system with six degrees of freedom to position the collimator and x-ray tube, and a computer to control the system. The video camera and computer determine the grid position, and then the motion control system drives the x-ray focal spot to the center of the grid focal axis. The accuracy of the alignment of the focal spot with the grid and the time required to achieve alignment were measured both in laboratory tests and in clinical use. Results: For a typical exam, the modified unit automatically aligns the focal spot with the grid in less than 10 s, with an accuracy of better than 4 mm. The results of the speed and accuracy tests in clinical use were similar to the results in laboratory tests. Comparison patient chest images are presented-one obtained with a standard mobile radiographic unit without a grid and the other obtained with the modified unit and a 15:1 grid. The 15:1 grid images demonstrate a marked improvement in image quality compared to the nongrid images with no increase in patient dose. Conclusions: The mobile radiography AGAS produces images of significantly improved quality compared to nongrid images with alignment times of less than 10 s and no increase in patient dose. © 2010 American Association of Physicists in Medicine.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 300.41K | Year: 2011

DESCRIPTION (provided by applicant): Antiscatter grids currently employed on fluoroscopic systems are limited in their capability to control scatter. As a result, fluoroscopic radiation levels are higher for the average patient than they would be with a more efficient grid system, and higher still for large patients. Poor image quality often increases the beam-on time required to successfully perform interventional procedures, increasing the radiation dose still further. This problem is critical in interventional exams, where skin doses are occasionally high enough to induce radiation burns1-3, and effective doses often exceed those of CT exams4 and contribute about 14% of the nationwide effective dose from medical imaging procedures5. Our proposal is to develop a high efficiency antiscatter grid system that will result in a significant improvement in fluoroscopy system dose efficiency. The results of our benchmarked Monte Carlo modeling indicate that a factor of 1.5 to 2.0 or more improvement is achievable.Cardiologists and radiologists can use this improvement either to produce higher quality images at current fluoroscopic radiation levels, allowing them to shorten exams, or to produce images comparable to today's image quality standards at markedly lower dose rates. The proposed innovative antiscatter grid system will incorporate a coarse strip density, air interspaced grid and a reciprocating grid drive with innovative approaches to suppress vibrations and grid artifacts. In Phase I we will build a grid and drive system and demonstrate: 1) the use of the system in fluorographic (digital spot) imaging; 2) the robust suppression of grid artifacts; and 3) a dose efficiency at least 1.5 times greater than that of commonly used grids. In Phase II we will build avibration-free reciprocating drive system suitable for fluoroscopic imaging, a compact x-ray tube grid bias supply to perform fast x-ray switching for short x-ray pulses, and with our manufacturing partner we will modify a commercially available clinicalfluoroscopy unit to demonstrate the use and performance of the grid system. Of practical importance is that the domestic manufacturer has already expressed interest in evaluating the grid system for inclusion in their product line and in commercializing the technology. PUBLIC HEALTH RELEVANCE: Millions of fluoroscopic examinations are performed each year, and these exams often result in high patient radiation doses and injury1-3, are among the highest dose exams in medical imaging4, and account for 14% of the effective dose from medical imaging in the United States5. We propose to improve the dose efficiency of fluoroscopy by a factor of 1.5 to 2.0 or more. This significant improvement will be accomplished by building an innovative high efficiency antiscatter grid system; clinical fluoroscopic systems using this grid system will be able to achieve markedly improved image quality at current radiation dose levels, or alternatively will be able to achieve image quality comparable to that obtained on today's fluoroscopic systems at a fraction of the radiation dose.


PubMed | X-Ray Imaging Innovations
Type: Journal Article | Journal: Medical physics | Year: 2011

A mobile radiography automatic grid alignment system (AGAS) has been developed by modifying a commercially available mobile unit. The objectives of this article are to describe the modifications and operation and to report on the accuracy with which the focal spot is aligned to the grid and the time required to achieve the alignment.The modifications include an optical target arm attached to the grid tunnel, a video camera attached to the collimator, a motion control system with six degrees of freedom to position the collimator and x-ray tube, and a computer to control the system. The video camera and computer determine the grid position, and then the motion control system drives the x-ray focal spot to the center of the grid focal axis. The accuracy of the alignment of the focal spot with the grid and the time required to achieve alignment were measured both in laboratory tests and in clinical use.For a typical exam, the modified unit automatically aligns the focal spot with the grid in less than 10 s, with an accuracy of better than 4 mm. The results of the speed and accuracy tests in clinical use were similar to the results in laboratory tests. Comparison patient chest images are presented--one obtained with a standard mobile radiographic unit without a grid and the other obtained with the modified unit and a 15:1 grid. The 15:1 grid images demonstrate a marked improvement in image quality compared to the nongrid images with no increase in patient dose.The mobile radiography AGAS produces images of significantly improved quality compared to nongrid images with alignment times of less than 10 s and no increase in patient dose.

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