Dr. Lynn M. Fletcher-Heath Profile

Dr. Lynn M. Fletcher-Heath

at Carestream Health Inc

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Publications (6)

Proceedings Article | 21 March 2007 Paper

Clinical evaluation of new workflow-efficient image processing for digital radiography

Lori Barski, Mary Couwenhoven, Xiaohui Wang, Lynn Fletcher-Heath, Michael Dupin, Douglas Katz, Anita Price, Anca Kranz, A. Orlando Ortiz, Betty Motroni, Lily Belfi, David Foos

Proceedings Volume 6515, 65151R (2007) https://doi.org/10.1117/12.710191

KEYWORDS: Image processing, Chromium, Image quality, Diagnostics, Radiography, Signal processing, Image segmentation, Process control, Radiology, Image enhancement

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Proceedings Article | 20 March 2007 Paper

Technology assessment: observer study directly compares screen/film to CR mammography

Lynn Fletcher-Heath, Anne Richards, Susan Ryan-Kron

Proceedings Volume 6515, 65151F (2007) https://doi.org/10.1117/12.712702

KEYWORDS: Chromium, Breast, Mammography, Image quality, Cancer, Diagnostics, Tissues, Image compression, Digital mammography, Architectural distortion

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Proceedings Article | 3 March 2006 Paper

Investigation of diagnostic and image quality attributes: comparison of screen-film to CR mammography

Lynn Fletcher-Heath, Anne Richards, Susan Ryan-Kron

Proceedings Volume 6142, 614230 (2006) https://doi.org/10.1117/12.655708

KEYWORDS: Chromium, Diagnostics, Image quality, Mammography, Digital mammography, Breast, Architectural distortion, Image compression, Image processing, Digital imaging

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Digital mammography is advancing into an arena where analog has long been the gold standard. Direct digital systems may not be the favored solution for a particular site while computed radiography (CR) mammography, remains unproven worldwide. This pilot study responds to the growing desire to acquire and display digital mammographic images by exploring the acceptability of CR mammography. Images representing a range of breast tissue types were collected from 49 subjects (17 screening; 32 diagnostic) at four clinical sites. Comparison views were collected on the same breast, under the same compression, using automatic exposure control on state-of-the-art film systems followed by CR. CR images were processed and printed to a mammography printer for hard copy feature comparison. Each image pair in the study was evaluated according to 13 image quality attributes covering noise, contrast, sharpness, and image quality in the overall captured images as well as in each of several particular breast regions (periphery and skin-line, parenchyma and fatty tissue). A rating scale from 1 to 5 was used (strong preference for film=1, strong preference for CR=5). Twelve experienced mammographers at four clinical sites scored a subset of the 49 cases for a total of 64 image pair readings. There were 64 ratings for each of 13 image quality attributes for all cases and, an additional series of scores (four or five attribute ratings) for each abnormality in the category of mass, architectural distortion and microcalcification, for a total of 1069 scores. Based on the pilot study results, it was suggested that CR was equivalent or preferred to conventional screen-film for overall image quality (38% scored 3; 46% scored >3), image contrast (27% scored 3; 59% scored >3) and sharpness (28% scored 3; 50% scored >3). No preference was found when assessing noise. This pilot study also suggested that diagnostic quality was maintained in assessing abnormalities for attributes necessary to evaluate masses and microcalcifications as compared to screen-film.

Proceedings Article | 2 March 2006 Paper

Applying the European protocol for the quality control of the physical and technical aspects of mammography screening threshold contrast visibility assessment to digital systems

Richard Van Metter, Michael Heath, Lynn Fletcher-Heath

Proceedings Volume 6142, 614205 (2006) https://doi.org/10.1117/12.650141

KEYWORDS: Failure analysis, Digital mammography, Visualization, Gold, Target detection, Visibility, Statistical analysis, Error analysis, Image quality, Mammography

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The need to assure the image quality of digital systems for mammography screening applications is now widely recognized. One approach is embodied in Part B of the European Protocol for the Quality Control of the Physical and Technical Aspects of Mammography Screening (EPQCM), which prescribes criteria for several interconnected image quality metrics. The focus of this study is on the "threshold contrast visibility" (TCV) protocol (section 2.4.1 of the EPQCM), in which human observers score images of a CDMAM or similar 4-AFC phantom. This section of the EPQCM currently omits many critical experimental details, which must be gleaned from ancillary documents. Given these, the purpose of this study is to quantify the effects of several remaining experimental variables, including phantom design, and the methods used for scoring and analysis, on the measured results. Preliminary studies of two CDMAM version 3.4 (CDMAM 3.4) phantoms have revealed a 17% difference in TCV when averaged over all target diameters from 0.1 to 2.0 mm. This indicates phantom variability may affect results at some sites. More importantly, we have shown that the current CDMAM phantom design, methods for scoring, and analysis, substantially limit the ability to measure system performance accurately and precisely. An improved phantom design has been shown to avoid these limitations. Viewing environment and presentation context affect the performance and efficiency of visual scoring of phantom images. An automated display tool has been developed that isolates individual 4-AFC targets of CDMAM phantom images, automatically optimizes window/level, and automatically records observers' scores. While not substantially changing TCV, the tool has increased scoring efficiency while mitigating several of the limitations associated with unassisted visual scoring. For example, learning bias and navigational issues are completely avoided. Ultimately, software-based ideal observer scoring will likely prove to be a better approach. Statistical-decision-theory-based (SDT) analysis has been shown to mitigate limitations associated with the current CDMAM phantom and the ad hoc nearest-neighbor correcting (NNC) scoring method. NNC analysis is sensitive to the degree of incomplete scoring (stopping criteria). However, SDT substantially mitigates this problem, using all of the available data to derive thresholds that are more interpretable. Bootstrap sampling was used to provide an estimate of the standard error for SDT analysis. In conclusion, the current EPQCM section 2.4.1 protocol fails to measure TCV accurately and precisely enough to qualify digital mammography systems. This paper presents a series of recommendations that supplement section 2.4.1 of the EPQCM and that provide a stable and accurate measure of TCV.

Proceedings Article | 20 April 2005 Paper

Quantifying the performance of human and software CDMAM phantom image observers for the qualification of digital mammography systems

Lynn Fletcher-Heath, Richard Van Metter

Proceedings Volume 5745, (2005) https://doi.org/10.1117/12.595510

KEYWORDS: Visualization, Statistical analysis, Electronic design automation, Visual analytics, Digital mammography, Error analysis, Image quality, Data modeling, Digital imaging, Contrast sensitivity

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Proceedings Article | 24 June 1998 Paper

Segmenting nonenhancing brain tumors from normal tissues in magnetic resonance images

Lynn Fletcher-Heath, Lawrence Hall, Dmitry Goldgof

Proceedings Volume 3338, (1998) https://doi.org/10.1117/12.310939

KEYWORDS: Tumors, Image segmentation, Tissues, Brain, Magnetic resonance imaging, Neuroimaging, Image processing, Magnetism, Binary data, Head

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