Dr. Amarpreet S. Chawla Profile

Dr. Amarpreet S. Chawla

at Duke Univ Medical Ctr

SPIE Involvement:

Author

Publications (15)

Proceedings Article | 6 March 2013 Paper

Monte-Carlo simulations of a coded-aperture x-ray scatter imaging system for molecular imaging

Anuj Kapadia, Manu Lakshmanan, Kalyani Krishnamurthy, Pooyan Sahbaee, Amarpreet Chawla, Scott Wolter, Ken Maccabe, David Brady, Ehsan Samei

Proceedings Volume 8668, 86680B (2013) https://doi.org/10.1117/12.2008484

KEYWORDS: Diffraction, X-rays, Monte Carlo methods, X-ray imaging, Coded apertures, Imaging systems, Sensors, X-ray diffraction, Aluminum, Scattering

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Proceedings Article | 14 March 2009 Paper

Optimized lesion detection in digital breast tomosynthesis

Amarpreet Chawla, Ehsan Samei, Joseph Lo

Proceedings Volume 7258, 72580P (2009) https://doi.org/10.1117/12.813964

KEYWORDS: Mammography, Breast, Diagnostics, Image quality, Image acquisition, 3D acquisition, Reconstruction algorithms, Data acquisition, Digital mammography, Prototyping

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While diagnostic improvement via breast tomosynthesis has been notable, the full potential of tomosynthesis has not yet been realized. This is because of the complex task of optimizing multiple parameters that constitute image acquisition and thus affect tomosynthesis performance. Those parameters include dose, number of angular projections, and the total angular span of those projections. In this study, we investigated the effects of acquisition parameters, independent of each other, on the overall diagnostic image quality of tomosynthesis. Five mastectomy specimens were imaged using a prototype tomosynthesis system. 25 angular projections of each specimen were acquired at 6.2 times typical single-view mammographic dose level. Images at lower dose levels were then simulated using a noise modification routine. Each projection image was supplemented with 84 simulated 3 mm 3D lesions embedded at the center of 84 non-overlapping ROIs. The projection images were then reconstructed using a filtered-back projection (FBP) algorithm at 224 different combinations of acquisition parameters to investigate which one of the many possible combinations maximized performance. Performance was evaluated in terms of a Laguerre-Gauss channelized Hotelling observer model-based measure of lesion detectability. Results showed that performance improved with an increase in the total acquisition dose level and the angular span. At a constant dose level and angular span, the performance rolled-off beyond a certain number of projections, indicating that simply increasing the number of projections in tomosynthesis may not necessarily improve its performance. The best performance was obtained with 15-17 projections spanning an angular arc of ~45° - the maximum tested in our study, and for an acquisition dose equal to single-view mammography. The optimization framework developed in this framework is applicable to other reconstruction techniques and other multi-projection systems.

Proceedings Article | 27 March 2008 Paper

Optimized acquisition scheme for multi-projection correlation imaging of breast cancer

Amarpreet Chawla, Ehsan Samei, Robert Saunders, Joseph Lo, Swatee Singh

Proceedings Volume 6915, 691528 (2008) https://doi.org/10.1117/12.773174

KEYWORDS: Computer aided diagnosis and therapy, Image processing, Imaging systems, Diagnostics, Image segmentation, Breast, Mammography, Image analysis, Data acquisition, Mathematical modeling

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Proceedings Article | 17 March 2008 Paper

Computer-aided detection of breast masses in tomosynthesis reconstructed volumes using information-theoretic similarity measures

Swatee Singh, Georgia Tourassi, Amarpreet Chawla, Robert Saunders, Ehsan Samei, Joseph Lo

Proceedings Volume 6915, 691505 (2008) https://doi.org/10.1117/12.772978

KEYWORDS: Computer aided diagnosis and therapy, Breast, Reconstruction algorithms, Databases, Computer aided design, Computing systems, Image filtering, Breast cancer, Human subjects, Gaussian filters

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Proceedings Article | 13 March 2008 Paper

The effect of increased ambient lighting on detection accuracy in uniform and anatomical backgrounds

Benjamin Pollard, Amarpreet Chawla, Noriyuki Hashimoto, Ehsan Samei

Proceedings Volume 6919, 69190R (2008) https://doi.org/10.1117/12.772932

KEYWORDS: Light sources and illumination, LCDs, Mammography, Chest imaging, Visualization, Chest, Diagnostics, Radiology, Calibration, Image segmentation

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Proceedings Article | 30 March 2007 Paper

Effect of increased ambient lighting on detectability: a psychophysical study

Amarpreet Chawla, Benjamin Pollard, Ehsan Samei, Noriyuki Hashimoto

Proceedings Volume 6516, 651617 (2007) https://doi.org/10.1117/12.713559

KEYWORDS: Light sources and illumination, Target detection, Mammography, LCDs, Eye, Calibration, Medical imaging, Diagnostics, Radiology, Statistical analysis

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Last year in this conference, we presented a theoretical analysis of how ambient lighting in dark reading rooms could be moderately increased without compromising the interpretation of images displayed on LCDs. Based on that analysis, in this paper we present results of two psychophysical experiments which were designed to verify those theoretical predictions. The first experiment was designed to test how an increase in ambient lighting affects the detection of subtle objects at different luminance levels, particularly at lower luminance levels. Towards that end, images of targets consisting of low-contrast objects were shown to seven observers, first under a dark room illumination condition of 1 lux and then under a higher room illumination condition of 50 lux. The targets had three base luminance values of 1, 12 and 35 cd/m² and were embedded in a uniform background. The uniform background was set to 12 cd/m² which enabled fixing L_adp, the visual adaptation luminance value when looking at the display, to 12 cd/m². This value also matched the luminance value of about 12 cd/m² reflected off the wall surrounding the LCD at the higher ambient lighting condition. The task of the observers was to detect and classify the displayed objects under the two room lighting conditions. The results indicated that the detection rate in dark area (base luminance of 1 cd/m²) increased by 15% when the ambient illumination is increased from 1 to 50 lux. The increase was not conclusive for targets embedded in higher luminance regions, but there was no evidence to the contrary either. The second experiment was designed to investigate the adaptation luminance value of the eye when viewing typical mammograms. It was found that, for a typical display luminance calibration, this value might lie between 12 and 20 cd/m². Findings from the two experiments provide justification for a controlled increase of ambient lighting to improve ergonomic viewing conditions in darkly lit reading rooms while potentially improving diagnostic performance.

Proceedings Article | 28 March 2007 Paper

A mathematical model approach toward combining information from multiple image projections of the same patient

Amarpreet Chawla, Ehsan Samei, Craig Abbey

Proceedings Volume 6510, 65101K (2007) https://doi.org/10.1117/12.713651

KEYWORDS: Breast, Sensors, Mathematical modeling, Performance modeling, 3D modeling, Imaging systems, Digital breast tomosynthesis, Mammography, Image processing, Binary data

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Proceedings Article | 17 March 2006 Paper

Analyzing the effect of dose reduction on the detection of mammographic lesions using mathematical observer models

Amarpreet Chawla, Robert Saunders, Craig Abbey, David Delong, Ehsan Samei

Proceedings Volume 6146, 61460I (2006) https://doi.org/10.1117/12.656378

KEYWORDS: Mammography, Signal to noise ratio, Breast, Mathematical modeling, Eye, Image quality, Performance modeling, Statistical analysis, Eye models, Visual process modeling

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Proceedings Article | 16 March 2006 Paper

A method for reduction of eye fatigue by optimizing the ambient light conditions in radiology reading rooms

Amarpreet Chawla, Ehsan Samei

Proceedings Volume 6145, 614503 (2006) https://doi.org/10.1117/12.655688

KEYWORDS: Lawrencium, LCDs, Light sources and illumination, Eye, Reflection, Medical imaging, Calibration, Radiology, CRTs, Visualization

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Proceedings Article | 20 April 2005 Paper

Physical evaluation of a high-frame-rate extended dynamic range flat panel detector for real-time cone beam computed tomography applications

Sarah Boyce, Amarpreet Chawla, Ehsan Samei

Proceedings Volume 5745, (2005) https://doi.org/10.1117/12.593881

KEYWORDS: Modulation transfer functions, Sensors, Computed tomography, Computing systems, Prototyping, X-rays, Imaging systems, Fluoroscopy, Angiography, Quantum efficiency

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Proceedings Article | 30 December 2003 Paper

Why should you calibrate your display?

Hans Roehrig, Amarpreet Chawla, Elizabeth Krupinski, Jiahua Fan, Kunal Gandhi

Proceedings Volume 5199, (2003) https://doi.org/10.1117/12.515317

KEYWORDS: LCDs, Calibration, CRTs, Liquid crystals, Radiology, Medical imaging, Control systems, Modulation, Diagnostics, Standards development

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Proceedings Article | 30 May 2003 Paper

Real-time MTF evaluation of displays in the clinical arena

Amarpreet Chawla, Hans Roehrig, Jiahua Fan, Kunal Gandhi

Proceedings Volume 5029, (2003) https://doi.org/10.1117/12.480369

KEYWORDS: Modulation transfer functions, CCD cameras, LCDs, Charge-coupled devices, Image acquisition, Data acquisition, CRTs, Fourier transforms, Image processing, Image quality

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Proceedings Article | 30 May 2003 Paper

Characterization of liquid-crystal displays for medical images: II

Hartwig Blume, Peter Steven, Anne Ho, Fred Stevens, Adi Abileah, Scott Robinson, Hans Roehrig, Jiahua Fan, Amarpreet Chawla, Kunal Gandhi

Proceedings Volume 5029, (2003) https://doi.org/10.1117/12.479774

KEYWORDS: LCDs, Modulation transfer functions, CRTs, Modulation, Liquid crystals, Calibration, Signal to noise ratio, Photometry, Displays, CCD cameras

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Proceedings Article | 22 May 2003 Paper

Spatial noise and threshold contrasts in LCD displays

Hans Roehrig, Elizabeth Krupinski, Amarpreet Chawla, Jiahua Fan, Kunal Gandhi

Proceedings Volume 5034, (2003) https://doi.org/10.1117/12.480358

KEYWORDS: LCDs, Signal to noise ratio, CCD cameras, CRTs, Charge-coupled devices, Contrast sensitivity, Modulation, Interference (communication), Calibration, Fourier transforms

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Proceedings Article | 26 November 2002 Paper

The liquid crystal display (LCD) for medical imaging in comparison with the cathode ray tube display (CRT)

Hans Roehrig, Jiahua Fan, Amarpreet Chawla, Kunal Gandhi

Proceedings Volume 4786, (2002) https://doi.org/10.1117/12.456332

KEYWORDS: LCDs, CRTs, Modulation transfer functions, Calibration, Liquid crystals, Medical imaging, Radiology, X-rays, Control systems, Spatial resolution

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Showing 5 of 15 publications

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