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Physical Psychophysical Evaluation of a New Digital Specimen Radiography System for Use in Mammography

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Physical Psychophysical Evaluation of a New Digital Specimen Radiography System for Use in Mammography

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    1. Physical & Psychophysical Evaluation of a New Digital Specimen Radiography System for Use in Mammography Elizabeth Krupinski, PhD Hans Roehrig, PhD University of Arizona William Schempp, PhD MedOptics Corporation

    2. Rationale Specimen radiography of excised breast tissue is critical to ensure that an appropriate tissue sample has been obtained or that complete removal of the lesion has been successful.

    3. Objectives To physically characterize the new high-resolution digital specimen radiography system from MedOptics Corporation. To evaluate human observer detection performance using images acquired with the new system.

    4. The Digital System Camera 1024 x 1024, 1” x 1” large area high-res CCD 2:1 fiber optic taper bonded to CCD (2”x2” FOV) standard Lanex Regular screen coupled to large end of taper image data digitized at 500 Kpix/sec, 12-bits Faxitron MICRO 50 x-ray source 15-50 kVp range 1-90 sec time selection SID = 50 cm

    5. Faxitron HVL & Eeff

    6. Camera X-radiation Response

    7. Camera Dark Signal & Noise

    8. Noise Power Spectrum 25 kVp

    9. Noise Power Spectrum 30 kVp

    10. Comparison NPS & Square MTF

    11. MTF

    12. MTF from Square Wave Response

    13. Observer Performance Study 2 CDMAM contrast-detail phantoms Commercially available large version Small experimental version Imaging conditions Traditional plain film Fuji Computed Radiography (CR) MedOptics Digital System 25 kV & 30 kV @ High (3600 GL), medium (2400 GL) & low (1200 GL) exposures

    14. Film Image Optical Densities

    15. Viewing Conditions Traditional film & Fuji CR film standard viewbox @ 1100 ft-L extraneous light masked Fuji CR digital & MedOptics Digital DataRay DR110 1728 x 2304 140 ft-L Perceptually linearized with Barten curve

    16. Observers & Task 10 undergrad students in each condition On outline of phantom indicate location of all disks visible in the phantom(s) Window/Level & zoom available on monitor Ambient lights turned off in all conditions

    17. Large Phantom Results

    18. Small Phantom Results

    19. Performance Summary Increases monotonically low to high exposures 25 kV > 30 kV MedOptics Digital System Best Traditional plain film worst Fuji CR monitor & film in middle Minor differences between phantoms

    20. Conclusions MedOptics Digital Biopsy System yields high detection performance Currently mammographers image core biopsy samples with either traditional systems or stereotactic units Traditional takes too long Stereotactic requires patient to get out of unit to image sample Digital avoids these problems & is fast

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