[Image properties of computer tomography. III. Measurements on homogenous materials. Relationship of attenuation and scatter to various parameters (author's transl)]. / Abbildungseigenschaften der Computertomographie. III. Messungen an homogenen Materialien. Abhängigkeit der Dichtewerte und der Dichtewertstreuung von verschiedenen Parametern.

ABSTRACT

The present paper investigates the variations due to various parameters on the image of homogeneous materials as obtained with the Somatom CT scanner. Sugar solutions were used with concentrations equivalent to the absorption values of soft tissues. Because of quantum noise, attentuation at various points is not uniform, but is distributed in a Gaussian manner round a mean value. Using the Evaluskop it was possible to determine the degree of scatter. It was shown that, with increasing density of the material, the scatter increased and that this can be reduced by subjecting the tomogram to a smoothing process. It was further shown how the scatter depends on various parameters, such as thickness and dose. The amount of scatter in a tomogram is important in determining the density gradation which can be a achieved.