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Title: Ambient illumination revisited: A new adaptation-based approach for optimizing medical imaging reading environments

Abstract

Ambient lighting in soft-copy reading rooms is currently kept at low values to preserve contrast rendition in the dark regions of a medical image. Low illuminance levels, however, create inadequate viewing conditions and may also cause eye strain. This eye strain may be potentially attributed to notable variations in the luminance adaptation state of the reader's eyes when moving the gaze intermittently between the brighter display and darker surrounding surfaces. This paper presents a methodology to minimize this variation and optimize the lighting conditions of reading rooms by exploiting the properties of liquid crystal displays (LCDs) with low diffuse reflection coefficients and high luminance ratio. First, a computational model was developed to determine a global luminance adaptation value, L{sub adp}, when viewing a medical image on display. The model is based on the diameter of the pupil size, which depends on the luminance of the observed object. Second, this value was compared with the luminance reflected off surrounding surfaces, L{sub s}, under various conditions of room illuminance, E, different values of diffuse reflection coefficients of surrounding surfaces, R{sub s}, and calibration settings of a typical LCD. The results suggest that for typical luminance settings of current LCDs, it is possiblemore » to raise ambient illumination to minimize differences in eye adaptation, potentially reducing visual fatigue while also complying with the TG18 specifications for controlled contrast rendition. Specifically, room illumination in the 75-150 lux range and surface diffuse reflection coefficients in the practical range of 0.13-0.22 sr{sup -1} provide an ideal setup for typical LCDs. Future LCDs with lower diffuse reflectivity and with higher inherent luminance ratios can provide further improvement of ergonomic viewing conditions in reading rooms.« less

Authors:
;  [1];  [2]
  1. Duke Advanced Imaging Laboratories, Departments of Radiology and Biomedical Engineering, Duke University, Durham, North Carolina 27705 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20853937
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 34; Journal Issue: 1; Other Information: DOI: 10.1118/1.2402583; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BRIGHTNESS; CALIBRATION; EYES; ILLUMINANCE; IMAGE PROCESSING; IMAGES; LIQUID CRYSTALS; REFLECTION; REFLECTIVITY

Citation Formats

Chawla, Amarpreet S., Samei, Ehsan, and Duke Advanced Imaging Laboratories, Departments of Radiology, Physics, Medical Physics, and Biomedical Engineering, Duke University, Durham, North Carolina 27705. Ambient illumination revisited: A new adaptation-based approach for optimizing medical imaging reading environments. United States: N. p., 2007. Web. doi:10.1118/1.2402583.
Chawla, Amarpreet S., Samei, Ehsan, & Duke Advanced Imaging Laboratories, Departments of Radiology, Physics, Medical Physics, and Biomedical Engineering, Duke University, Durham, North Carolina 27705. Ambient illumination revisited: A new adaptation-based approach for optimizing medical imaging reading environments. United States. doi:10.1118/1.2402583.
Chawla, Amarpreet S., Samei, Ehsan, and Duke Advanced Imaging Laboratories, Departments of Radiology, Physics, Medical Physics, and Biomedical Engineering, Duke University, Durham, North Carolina 27705. Mon . "Ambient illumination revisited: A new adaptation-based approach for optimizing medical imaging reading environments". United States. doi:10.1118/1.2402583.
@article{osti_20853937,
title = {Ambient illumination revisited: A new adaptation-based approach for optimizing medical imaging reading environments},
author = {Chawla, Amarpreet S. and Samei, Ehsan and Duke Advanced Imaging Laboratories, Departments of Radiology, Physics, Medical Physics, and Biomedical Engineering, Duke University, Durham, North Carolina 27705},
abstractNote = {Ambient lighting in soft-copy reading rooms is currently kept at low values to preserve contrast rendition in the dark regions of a medical image. Low illuminance levels, however, create inadequate viewing conditions and may also cause eye strain. This eye strain may be potentially attributed to notable variations in the luminance adaptation state of the reader's eyes when moving the gaze intermittently between the brighter display and darker surrounding surfaces. This paper presents a methodology to minimize this variation and optimize the lighting conditions of reading rooms by exploiting the properties of liquid crystal displays (LCDs) with low diffuse reflection coefficients and high luminance ratio. First, a computational model was developed to determine a global luminance adaptation value, L{sub adp}, when viewing a medical image on display. The model is based on the diameter of the pupil size, which depends on the luminance of the observed object. Second, this value was compared with the luminance reflected off surrounding surfaces, L{sub s}, under various conditions of room illuminance, E, different values of diffuse reflection coefficients of surrounding surfaces, R{sub s}, and calibration settings of a typical LCD. The results suggest that for typical luminance settings of current LCDs, it is possible to raise ambient illumination to minimize differences in eye adaptation, potentially reducing visual fatigue while also complying with the TG18 specifications for controlled contrast rendition. Specifically, room illumination in the 75-150 lux range and surface diffuse reflection coefficients in the practical range of 0.13-0.22 sr{sup -1} provide an ideal setup for typical LCDs. Future LCDs with lower diffuse reflectivity and with higher inherent luminance ratios can provide further improvement of ergonomic viewing conditions in reading rooms.},
doi = {10.1118/1.2402583},
journal = {Medical Physics},
number = 1,
volume = 34,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
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