Biomedical subjects

C E Metz

Publications and source records attributed to C E Metz.

At least 91 records · Page 5Linked to original sources

PubMed1976

The effect of x-ray spectra from molybdenum and tungsten target tubes on image quality in mammography.

The measured x-ray spectra from a molybdenum anode Senographe mammography unit and a tungsten anode unit were used to calculate the x-ray energy spectra transmitted through various thicknesses of fat and water (breast-equivalent materials). The dependence of subject contrast and patient exposure on (a) x-ray spectra, (b) attenuation properties of two breast-equivalent materials, and (c) thickness of breast-equivalent material was predicted. Radiographs of resected breast tissue confirmed these predictions and demonstrated the general relative effects of x-ray beam quality on image contrast in mammography.

Adipose Tissue↗

PubMed1976

Observer performance in detecting multiple radiographic signals. Prediction and analysis using a generalized ROC approach.

The theories of decision processes and signal detection provide a framework for evaluation of observer performance. Some radiological procedures involve a search for multiple similar lesions, e.g., plain radiographic examinations for gallstones or pneumoconiosis. Presuming knowledge of the conventional ROC curve for detection of a single radiographic signal, a model is presented which is used to predict observer performance in an experiment requiring detection of more than one such signal. An experiment tests the validity of this model for detecting radiographically the presence of zero, one, or two low-contrast, 2-mm diameter, Lucite beads. Results confirm the validity of the model and suggest that observer performance in relatively complex detection tasks can be predicted from simpler experiments.

Decision Making↗

PubMed1975

A mathematical model for the determination of cardiac regurgitant and ejection fractions from radioisotope angiocardiograms.

A mathematical model taking into account the pulsatile pumping action of the heart has been developed which describes, in terms of a set of four recursive equations, the activity in the atrium and in the ventricle of the left or right heart at successive end-systoles and end-diastoles after bolus injection. The resulting closed form solutions permit calculations of chamber forward ejection fractions and valvular regurgitant fractions from computerized radioisotope angiocardiogram data. The method has been applied to a series of over thirty clinical studies with encouraging results.

Angiocardiography↗

PubMed1975

Visual detection and localization of radiographic images.

In conventional receiver-operating-characteristic (ROC) curve analysis of visual detection performance, the observer is credited with a true-positive response if a visual signal is present somewhere in a radiograph called "positive" by the observer; however, the measured true-positive rate can be different for a given false-positive rate if the observer is required to identify the correct location of the visual signal in order to receive credit for a true-positive response. The authors describe and have confirmed experimentally a model which can be used to predict observer performance in an experiment requiring both detection and localization on the basis of the conventional ROC curve determined in a detection experiment. Implications for the use of signal detection theory in the assessment of radiographic image quality are discussed.

Humans↗

PubMed1974