&lt;title&gt;An Empirical Investigation Of Variability In Contrast-Detail Diagram Measurements&lt;/title&gt;

Loo, L. N. D.; Doi, Kunio; Ishida, M.; Metz, Charles E.; Chan, Heang Ping; Higashida, Yoshiharu; Kodera, Yoshie

doi:10.1117/12.936007

Cited by 27 publications

(15 citation statements)

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“…Human detection efficiency is seen to improve with an increasing display contrast, in accordance with earlier experience with static images. 8,25,26 ͑It is noted that these studies, and the present one, correspond to an uniform background; the results of Seltzer et al 27 suggest that contrast enhancement may not be as effective when a background with anatomic variability is considered.͒ The efficiency, averaged over different imaging conditions, is 30%-40% when the display contrast is high, 15%-25% for the normal-contrast display, and below 15% for the reduced-contrast display. The efficiency for high- contrast static frames is of the same order as found in earlier studies.…”

Section: Resultsmentioning

confidence: 75%

“…1 Compared to the 2AFC experiments the observers seem to operate at a high confidence level. This effect of observers being overly conservative in visual threshold determination tests is common, 16,25,28 and seems here to be especially pronounced in the coarse test object data. The relative standard deviation of the threshold determination test by the coarse test object was somewhat higher than found in the image intensifiertelevision studies of Launders et al 29 and Marshall et al, 30 which may be explained by the experience of their observers in such measurements.…”

Section: Resultsmentioning

confidence: 88%

“…Following the conclusion of Loo et al 25 concerning static radiographs, we note that in fluoroscopy, if there is only one observer who may not be the same in each test, the method can reliably reveal only large differences in imaging performance; the threshold contrasts from such measurements can easily be different by a factor of 2 without any real change in the imaging system. The precision is probably better if the observations are made by the same person, but this has only been demonstrated for observations that are made within a few days 29 or weeks.…”

Section: Discussionmentioning

confidence: 94%

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Efficiency of low‐contrast detail detectability in fluoroscopic imaging

Tapiovaara

1997

Medical Physics

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The detectability of a static low-contrast detail in the dynamic fluoroscopic image of a homogeneous phantom was assessed by physical measurement of the signal-to-noise ratio (SNR) and by psychophysical measurement of the human observer detectability index d'. The two-alternative forced-choice method was used for human observer tests. The image data consisted of digitally recorded fluoroscopic image sequences which were displayed in a continuous loop of varying length (1-50 frames) at a rate of 25 frames/s. Human detection performance was seen to improve with the SNR in all cases studied: when the signal was made stronger, the image noise lower, or when the SNR in the image sequence was made higher by increasing the length of the image sequence. The results imply that the statistical efficiency of humans decreases slowly when the number of frames in the displayed loop is increased. This decrease of efficiency with loop length was not seen in all test series, however, and it is possible that the phenomenon is partly related to the high d' values found at the greatest loop lengths studied. When the display contrast was high, the statistical efficiency of the human observer was 30%-40% for both static and dynamic images. The efficiency was somewhat lower, 15%-25%, for images that were displayed with a display contrast gain setting more typical of fluoroscopy. The accumulation rate of SNR2 is a suitable quantity for the measurement of fluoroscopic image quality as related to a given static signal detection task. In contrast to this, visibility measurement by determination of the threshold contrast was seen to be unacceptably imprecise if the test is based on only one observer's opinion, as is often the case in practical quality assurance testing. The precision of the threshold contrast measurement could, however, be improved by using several observers and test objects with a smaller step between details than is usual.

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Section: Resultsmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 94%

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Efficiency of low‐contrast detail detectability in fluoroscopic imaging

Tapiovaara

1997

Medical Physics

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“…35), it is necessary to compute the coefficients, k (j (Eqs. [27][28][29][30] and the SNR for low-and highenergy images, SNR S (Eq. 22).…”

Section: Methodsmentioning

confidence: 99%

“…[25][26][27][28][29][30][31][32][33][34][35] Contrast-detail curves of different digital chest systems have been independently studied without being compared to each other. Due to inter-reader variations are differences in study conditions (x-ray techniques, reading and scoring, etc.…”

Section: Mammographymentioning

confidence: 99%