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Biomedical subjects

A Stargardt

Publications and source records attributed to A Stargardt.

At least 55 records · Page 3Linked to original sources
PubMed1977

Evaluation of image quality in tomographic imaging.

Modulation Transfer Functions (MTF) for tomographic imaging with linear, circular, hypocycloidal and spiral motion are given. They may be determined experimentally from tomographs of slits or line pair test patterns. In some cases calculation of the MTF from the blur pattern by Fourier transformation is possible. All tomographic MTFS show the same oscillatory behaviour as MTFS of focal spots, resulting in spurious structures and contours in the tomogram. A quantity named signal/spurios signal ratio (SSR) is introduced as a figure of merit. Effective exposure angles are determined from the MTF and compared with the commmonly used 'geometric' exposure angles which result from maximum tube elongations.

Tomography, X-Ray↗
PubMed1975

[Optimal distances for direct radiographic magnification].

This paper deals with the theoretical basis for radiographic magnification. In particular, the relationship between focal size and optimal magnification for various systems is discussed. Maximal resolution was chosen as the criterion for best results. It has been shown that resolution (Lp-mm) can be improved by the reciprocal of the focal spot and for optimal magnification (see article) where f is focal spot size and AVBW is resolution of the imaging system.

Humans↗
PubMed1975

[Reduction in radiation scatter during radiographic magnification techniques (author's transl)].

The reduction in scatter during magnification techniques is compared with the effect of grids. The results of extensive measurements concerning scatter and distance in a water phantom are shown in 24 diagrams. The various factors were altered as follows: distance 0-1.5 m., phantom thickness 0-27.5 cm., area 5 cm. x 5 cm. - 30 cm. x 30 cm. and kilovoltage 50-150 kv. The amount of scatter immediately behind the phantom is compared with that through a grid by observing image quality for given amounts of scatter. This "grid-equivalent" image quality can be used to determine the circumstances under which a magnification technique can be employed without using a grid.

Radiation Dosage↗
PubMed1971

[X-ray cassettes].

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Technology, Radiologic↗