Computational Methods for Shape Restoration of Buried Objects in Compton Backscatter Imaging

Watanabe, Yoichi; Monroe, James; Keshavmurthy, Shyam P.; Jacobs, Alan M.; Dugan, Edward T.

doi:10.13182/nse96-a28547

Cited by 9 publications

(2 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The purpose of this investigation is to present and explain the different approaches that have been taken to develop a Modulation Transfer Function adapted to the Radiography by Selective Detection RSD imaging system [1][2][3][4][5][6][7][8][9][10][11][12] for the purpose of defining a process to measure system response by evaluating the image quality. Figure 1 shows a picture of the RSD system in which an X-ray tube is at a center of four detectors.…”

Section: Introductionmentioning

confidence: 99%

An adapted modulation transfer function for x-ray backscatter radiography by selective detection

et al. 2007

Self Cite

View full text Add to dashboard Cite

The Modulation Transfer Function (MTF) is a quantitative function based on frequency resolution that characterizes imaging system performance. In this study, a new MTF methodology is investigated for application to Radiography by Selective Detection (RSD), an enhanced single-side x-ray Compton backscatter imaging (CBI) technique which detects selected scatter components. The RSD imaging modality is a unique type of real-time radiography that uses a set of fin and sleeve collimators to preferentially select different components of the x-ray backscattered field. Radiography by selective detection has performed successfully in different non-destructive evaluation (NDE) applications. A customized RSD imaging system was built at the University of Florida for inspection of the space shuttle external tank spray-on foam insulation (SOFI). The x-ray backscatter RSD imaging system has been successfully used for crack and corrosion detection in a variety of materials. The conventional transmission x-ray image quality characterization tools do not apply for RSD because of the different physical process involved. Thus, the main objective of this project is to provide an adapted tool for dynamic evaluation of RSD system image quality. For this purpose, an analytical model of the RSD imaging system response is developed and supported. Two approaches are taken for the MTF calculations: one using the Fourier Transform of a line spread function and the other one using a sine function pattern. Calibration and test targets are then designed according to this proposed model. A customized Matlab code using image contrast and digital curve recognition is developed to support the experimental data and provide the Modulation Transfer Functions for RSD.

show abstract

Section: Introductionmentioning

confidence: 99%

An adapted modulation transfer function for x-ray backscatter radiography by selective detection

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…Lateral migration radiography (LMR), a type of backscatter x-ray radiography based upon selective detection of scatter field velocity components, was first applied at the University of Florida (UF) to the detection of buried land mines [1][2][3][4][5][6][7][8][9][10] . The resulting images were stunning in their definitive detail.…”

Section: Introductionmentioning

confidence: 99%

Detection of defects in foam thermal insulation using lateral migration backscatter x-ray radiography

et al. 2004

Self Cite

View full text Add to dashboard Cite

A new Compton x-ray backscatter imaging technique called lateral migration radiography (LMR) has been successfully applied to the detection of voids and delaminations in the foam thermal insulation used on the shuttle external tank. LMR employs detection of selected scatter field velocity components, by using specially designed detectors and detector collimators, to achieve high image contrast.LMR is based on image contrast generated by migration of probe x-ray radiation in directions transverse to the illumination radiation beam. Because LMR is sensitive to electron density variations in these directions, thin, but large density variations, such as cracks and delaminations, generate signal-to-background ratios sufficient to produce images of features which are not even detectable in the usually interrogated thin dimension.The examined foam thermal insulation test panels consist of aluminum plates onto which the sprayed-on foam insulation (SOFI) is applied. Some of the test panels include structural features bolted to the base plate. The SOFI was layed down over the base plate and structure with a thickness varying from a few tens of mm up to a few hundred mm. The test panels included voids and simulated delaminations in the SOFI ranging in cross-sectional size from 6 x 6 mm to 50 x 50 mm. High quality images were acquired using pixels of 2 to 3 mm and irradiation times of as low as 0.05 s per pixel.

show abstract

Lateral Migration Radiography

et al. 1998

View full text Add to dashboard Cite

Lateral migration radiography (LMR) is a new form of Compton backscatter imaging (CBI) that utilizes both multiple-scatter and single-scatter photons. The LMR imaging modality uses two pairs of detectors. Each set has a detector that is uncollimated to predominantly image single-scatter photons and the other collimated to image predominantly multiple-scattered photons. This allows generation of two separate images, one containing primarily surface features and the other containing primarily subsurface features. These two images make LMR useful for imaging and identifying objects to a depth of several X-ray photon mean free paths even in the presence of unknown surface clutter or surface imperfections.The principles of LMR are demonstrated through Monte Carlo simulation of the photon transport. The Monte Carlo simulation results are verified with experimental measurements from an LMR system used for landmine detection. The presented research demonstrates the methodology for designing an LMR system, identifies methods for restoring and enhancing LMR images, and lays the foundation for the development of other applications of LMR, including, for example, the nondestructive examination of welds, castings, and composites.

show abstract

Computational Methods for Shape Restoration of Buried Objects in Compton Backscatter Imaging

Cited by 9 publications

References 6 publications

An adapted modulation transfer function for x-ray backscatter radiography by selective detection

An adapted modulation transfer function for x-ray backscatter radiography by selective detection

Detection of defects in foam thermal insulation using lateral migration backscatter x-ray radiography

Lateral Migration Radiography

Contact Info

Product

Resources

About