Observer Performance of Reduced X-Ray Images on Liquid Crystal Displays

Akiko Ihori¹*, Chihiro Kataoka², Daigo Yokoyama², Naotoshi Fujita³, Naruomi Yasuda⁴, Akihiro Sugiura⁴ and Yoshie Kodera²

¹Graduate School of Medical Sciences, Nagoya University, Nagoya 461-8673, Japan
²School of Health Sciences, Nagoya University, Nagoya 461-8673, Japan
³Department of Radiological Technology, Nagoya University Hospital, Nagoya 466-8560, Japan
⁴School of Health Sciences, Gifu University of Medical Science, Seki 501-3892, Japan
*E-mail address: aihori0312@gmail.com

(Received November 14, 2010; Accepted April 10, 2011)

Abstract. In soft-copy diagnosis, each pixel of an X-ray detector is displayed as the corresponding pixel of a liquid crystal display (LCD). However, when a mammographic image is displayed on an LCD for the first time, the entire image is reduced. We examined the influence of differences in LCD image-reduction rates on the signaldetection performance by observational experiments. We created a simulated image similar to Burger’s phantom and reduced it by using the nearest neighbor, bilinear, and bicubic interpolation methods. We displayed the reduced images on LCDs with different numbers of pixels and examined the signal-detection performance with each interpolation method. The signal-detection performance deteriorated as the image-reduction rate increased irrespective of the interpolation method. Among the interpolation methods, the nearest neighbor method resulted in the worst signal-detection performance, and the bilinear method was the most suitable for image reduction. Mammographic images are mostly reduced for viewing on an LCD. Such reduction changes the appearance of microcalcifications. Therefore, depending on their size and distribution, microcalcifications observed in these images may be missed on an LCD.

Keywords: Liquid Crystal Display, Interpolation Method, Phase-Contrast Mammography, Simulation Image