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Proceedings Paper

Shape determination of microcalcifications in simulated digital mammography images with varying pixel size
Author(s): Mark Ruschin; Magnus Bath; Bengt Hemdal; Anders Tingberg
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Paper Abstract

The purpose of this work was to study how the pixel size of digital detectors can affect shape determination of microcalcifications in mammography. Screen-film mammograms containing microcalcifications clinically proven to be indicative of malignancy were digitised at 100 lines/mm using a high-resolution Tango drum scanner. Forty microcalcifications were selected to cover an appropriate range of sizes, shapes and contrasts typically found of malignant cases. Based on the measured MTF and NPS of the combined screen-film and scanner system, these digitised images were filtered to simulate images acquired with a square sampling pixel size of 10 μm x 10 μm and a fill factor of one. To simulate images acquired with larger pixel sizes, these finely sampled images were re-binned to yield a range of effective pixel sizes from 20 μm up to 140 μm. An alternative forced-choice (AFC) observer experiment was conducted with eleven observers for this set of digitised microcalcifications to determine how pixel size affects the ability to discriminate shape. It was found that observer score increased with decreasing pixel size down to 60 μm (p<0.01), at which point no significant advantage was obtained by using smaller pixel sizes due to the excessive relative noise-per-pixel. The relative gain in shape discrimination ability at smaller pixel sizes was larger for microcalcifications that were smaller than 500 μm and circular.

Paper Details

Date Published: 6 April 2005
PDF: 12 pages
Proc. SPIE 5749, Medical Imaging 2005: Image Perception, Observer Performance, and Technology Assessment, (6 April 2005); doi: 10.1117/12.595377
Show Author Affiliations
Mark Ruschin, Lund Univ. (Sweden)
Malmo Univ. Hospital (Sweden)
Magnus Bath, Sahlgrenska Univ. Hospital (Sweden)
Bengt Hemdal, Lund Univ. (Sweden)
Malmo Univ. Hospital (Sweden)
Anders Tingberg, Lund Univ. (Sweden)
Malmo Univ. Hospital (Sweden)

Published in SPIE Proceedings Vol. 5749:
Medical Imaging 2005: Image Perception, Observer Performance, and Technology Assessment
Miguel P. Eckstein; Yulei Jiang, Editor(s)

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