Biomedical subjects

G Revesz

Publications and source records attributed to G Revesz.

6 recordsLinked to original sources

PubMed1977

Psychophysical studies of detection errors in chest radiology.

In 62 of 124 cases analyzed, there occurred a failure to detect a pulmonary nodule which was retrospectively noted only after detection at a subsequent examination. The characteristics of the lesions and their surrounds were measured, and a computer analysis used, to identify that combination of parameters (the conspicuity, K) which was best capable of separating the group into populations of missed and detected lesions.

Diagnostic Errors↗

PubMed1976

Lesion conspicuity, structured noise, and film reader error.

The concept of conspicuity is introduced in an attempt to objectively quantitate radiographic observational error. Defined as a ratio between lesion contrast and surround complexity, the measure correlates well with the probability of detecting faint nodular lesions in chest radiographs. The concept helps in understanding why abnormalities are missed by radiologists. It is also used to explain why image-processing techniques advocated in the past did not yield improvements in diagnostic accuracy and to outline directions for the future. Preliminary results are presented which show that photographic subtraction can increase the conspicuity of simulated early lung lesions and improve their detection.

Absorptiometry, Photon↗

PubMed1975

Breast thermography as a screening technique. An evaluation of performance data.

The concepts of relative operating characteristics (ROC-curves) and detectability index (d') are introduced for the purpose of evaluating performance in breast thermography. In assessing published information on the subject we have found that much of it is anecdotal and lacks sufficient data to determine performance. We have also found that for those published findings which had sufficient data it was possible to reconcile conflicting conclusions as to the efficacy of thermography, and that performance could be quantitated with the use of the detectability index. Conclusions for optimizing available clinical thermographic techniques are given together with ways for future improvement.

Breast Neoplasms↗

PubMedDate not supplied

The influence of film density on the radiologic detection of lung lesions.

Experiments were conducted on a series of chest radiographs to evaluate the effects of mean film density on reader performance. It was found that the false negative is not measurably affected, in agreement with earlier published data. It was also found, however, that the false positive rate increases with increasing film density. The causes and implications of these results are discussed.

False Negative Reactions↗

PubMedDate not supplied

Contrast gradient and the detection of lung nodules.

The effects of edge gradient and blur on the detection pulmonary nodules were studied, using a test series of 175 artificial nodules on 30 chest films. The nodules were of homogeneous texture, about 1 cm in diameter and had a mean contrast of .12. Six observers viewed the film set, scoring both location and confidence. The sensitivity or the probability of a true-positive response was linearly related to the blur and a modified ROC analysis resulted in a family of ROC curves with the index of detectability monotonically decreasing with increased blur.

Evaluation Studies as Topic↗

PubMedDate not supplied

A laser scanner for the densitometric analysis of radiographs.

An instrument is described which can scan radiographs and collect densitometric readings for subsequent computer analysis. A laser beam is focused onto the film. Raster scan of the beam is provided by two orthogonal mirror galvanometers. The light, attenuated by the radiograph, is gathered by a lens in such a way that it is directed into a small detector regardless of the scan position. Beam position signals and density readings are stored and analyzed in a minicomputer.

Absorptiometry, Photon↗