1. Observer Performance Using Monitors With Different Phosphors Elizabeth A. Krupinski, PhD Hans Roehrig, PhD University of Arizona Tucson, AZ

2. P104 vs P45 b P104 bigger grain sizebigger grain size fewer grains per pixelfewer grains per pixel two componentstwo components more non-uniformitymore non-uniformity b Lower SNR for P104

3. Examples P45 Phosphor P104 Phosphor

4. Max SNR / CRT Pixel 020406080 Luminance (cd/m 2 ) 0 40 80 120 S N R / C R T - P i x e l P45 Phosphor P 104 Phosphor.

5. Display Function 0.00100.00200.00300.00 Command Level (ADU) 0.00 40.00 80.00 120.00 160.00 200.00 L u m i n a n c e (cd/m 2 ) P45 P104

6. Veiling Glare 02004006008001000 Disk Diameter in # of Pixels 0 0.004 0.008 0.012 0.016 0.020 P45 P104 Veiling glare ratio

7. Pixel Emitted intensity 0246810 # Pixels in Pixel String 0.2 0.4 0.6 0.8 1.0 1.2 P i x e l E m i t t e d I n t e n s i t y P104 P45

8. MTF M TF 0.00.51.01.52.02.5 0.00.51.01.52.02.5 Frequency (lp/mm) 0.0 0.4 0.8 1.2 Vertical MTF Horizontal MTF 113 ADU 200 ADU 113 ADU 200 ADU 0.0 0.4 0.8 1.2 - 113 ADU 200 ADU 113 ADU 200 ADU Vertical MTF Horizontal MTF P45P104

9. Luminance Uniformity

10. JND Performance F = 28.55 df = 23 p < 0.0001

11. Methods & Materials b 20 chest images 5 lesion free5 lesion free 15 solitary pulmonary nodule15 solitary pulmonary nodule b Image Systems P45 & P104 monitors 1600 x 1200 resolution1600 x 1200 resolution Pixel size = 0.245 mmPixel size = 0.245 mm b 6 radiologists as observers

12. Images - Conventional radiographs 150 mA 125 kVp - CT confirmation - Digitized with VIDAR VXR - 2100 x 2552 x 16-bits

13. Viewing Conditions b Eye-position recorded ASL 4000 SU with head-trackerASL 4000 SU with head-tracker < 1 deg accuracy< 1 deg accuracy b Ambient lights off b No time restrictions b ~ 2 weeks between sessions

14. ROC Az Results b MeanAz : P45 = 0.9235 P104 = 0.8851 P104 = 0.8851 b ANOVA Treatment : F = 0.4516, p = 0.5097Treatment : F = 0.4516, p = 0.5097 Cases : F = 0.4038, p = 0.9864Cases : F = 0.4038, p = 0.9864 Readers : F = 0.1548, p = 0.9781Readers : F = 0.1548, p = 0.9781 No significant interaction effectsNo significant interaction effects

15. Eye-Position Results

16. Eye-Position Results* b Mean Viewing Times Overall - P45 = 22.36 seconds - P104 = 27.41 seconds * ~ 75% of the data. Future will split out lesion vs lesion-free images & residents vs radiologists * ~ 75% of the data. Future will split out lesion vs lesion-free images & residents vs radiologists

17. Eye-Position Results b Median Dwell Times x Decision (msec) P45P104 TP =2043<2237 FN = 1528>1411 FP = 1986<1958 TN = 470<513

18. Eye-Position Results b Mean Time to First “Hit” nodules (msec) P45P104 TP = 312<369 FN = 563<602

19. Conclusions b Phosphor may not affect diagnostic accuracy b May affect search parameters b Might influence purchase & clinical use choices

20. Caveats b Detection not classification b Pulmonary nodules only b No image processing (window / level) allowed b Task & stimuli may influence results b Further studies should be done