Dr. Francisca R. Sugiro Profile

Dr. Francisca R. Sugiro

at Eastman Kodak Co

SPIE Involvement:

Author

Publications (6)

Proceedings Article | 20 March 2007 Paper

Advanced system model for the prediction of the clinical task performance of radiographic systems

Karin Töpfer, Brian Keelan, Francisca Sugiro

Proceedings Volume 6515, 651512 (2007) https://doi.org/10.1117/12.709570

KEYWORDS: Sensors, Lung, Systems modeling, Dual energy imaging, Modulation transfer functions, Image processing, Visual process modeling, Radiography, Interference (communication), Target detection

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A flexible software tool was developed that combines predictive models for detector noise and blur with image simulation and an improved human observer model to predict the clinical task performance of existing and future radiographic systems. The model starts with high-fidelity images from a database and mathematical models of common disease features, which may be added to the images at desired contrast levels. These images are processed through the entire imaging chain including capture, the detector, image processing, and hardcopy or softcopy display. The simulated images and the viewing conditions are passed to a human observer model, which calculates the detectability index d' of the signal (disease or target feature). The visual model incorporates a channelized Hotelling observer with a luminance-dependent contrast sensitivity function and two types of internal visual system noise (intrinsic and image background-induced). It was optimized based on three independent human observer studies of target detection, and is able to predict d' over a wide range of viewing conditions, background complexities, and target spatial frequency content. A more intuitive metric of system performance, Task-Specific Detective Efficiency (TSDE), is defined to indicate how much detector improvements would translate to better radiologist performance. The TSDE is calculated as the squared ratio of d' for a system with the actual detector and a hypothetical system containing an ideal detector. A low TSDE, e.g., 5% for the detection of 0.1 mm microcalcifications in typical mammography systems, indicates that improvements in the detector characteristics are likely to translate to better detection performance. The TSDE of lung nodule detection is as high as 75% even with the detective quantum efficiency (DQE) of the detector not exceeding 24%. Applications of the model to system optimizations for flat-panel detectors, in mammography and dual energy digital radiography, are discussed.

Proceedings Article | 3 November 2004 Paper

Source-optic-crystal optimization for compact monochromatic imaging

Danhong Li, Francisca Sugiro, Carolyn MacDonald

Proceedings Volume 5537, (2004) https://doi.org/10.1117/12.562649

KEYWORDS: Crystals, X-ray optics, Crystal optics, Silicon, Molybdenum, X-rays, Diffraction, Laser induced fluorescence, Mica, Spatial resolution

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Proceedings Article | 7 January 2004 Paper

Monochromatic applications of polycapillary optics

Carolyn MacDonald, Noor Mail, D. Li, M. Roy, Francisca Sugiro

Proceedings Volume 5196, (2004) https://doi.org/10.1117/12.509683

KEYWORDS: Crystals, X-ray optics, Radio optics, Sensors, Laser crystals, X-ray sources, Monochromators, Channel projecting optics, Crystal optics, X-rays

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Proceedings Article | 6 December 2001 Paper

Improved radiography with polycapillary x-ray optics

Carolyn MacDonald, Francisca Sugiro, Walter Gibson

Proceedings Volume 4502, (2001) https://doi.org/10.1117/12.449871

KEYWORDS: X-ray optics, Crystals, Optics manufacturing, X-rays, Capillaries, Spatial resolution, Sensors, Radio optics, Optical testing, Laser crystals

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Polycapillary x-ray optics provide an innovative new way to control x-ray beams. Placing these optics after the object to be imaged provides very efficient rejection of Compton scatter, while allowing image magnification without loss of resolution, image demagnification, or image shaping to match with digital detectors. An extensive study of the effects of surface and profile defects have greatly enhanced the understanding of the manufacturing process and lead to improved reproducibility and manufacturability of the optics. Measurements were performed on magnifying tapers. The optics had measured primary transmissions greater than 50% and scatter transmission of less than 1%. For a 5-cm thick Lucite phantom, this resulted in a contrast enhancement compared to a conventional grid of nearly a factor of two. The magnification from the tapered capillary optics improved the MTF at all frequencies out to 1.9 times the original system resolution. Increases below the system resolution are most important because clinically relevant structures generally occupy lower spatial frequencies. Alternatively, placing a collimating optic and diffracting crystal before the patient provides sufficient monochromatic beam intensity for medical imaging. Contrast, resolution, and intensity measurements were performed with both high and low angular acceptance crystals. At 8 keV, contrast enhancement was a factor of 5 relative to the polychromatic case, in good agreement with theoretical values. At 17.5 keV, monochromatic subject contrast was more than a factor of 2 times greater than the conventional polychromatic contrast. An additional factor of two increase in contrast is expected from the removal of scatter obtained from using the air gap which is allowable from the parallel beam. The measured angular resolution after the crystal was 0.4 mrad for a silicon crystal. The realization of these applications has been advanced by the recent marked improvement in available optic quality and reproducibility. Manufacturing progress has been assisted by the development of simulation analyses which allow for increasingly accurate assessment of optics defects. Optics performance over the whole range of energy from 10 to 80 keV can often be matched with one or two fitting parameters. Continuing optics manufacturing challenges include the advance of applications at energies above 40 keV and the production of optics for imaging which are of adequate clinical size. Multioptic jigs designed to increase imaging area have been tested.