Siemens Aktiengesellschaft

Klaus Killig

Dietrich Hassler

Rudolf Schittenhelm

Karl-Hans Reiss

Wolfhart Lichtenberg

A method for generating an ultrasound image of a plane of a section of an examination subject having a non-uniform speed of sound distribution near the surface of the subject includes the steps of scanning the section plane line-by-line with a transducer array in an adaption phase and calculating values from the received, focussed echo signals which deviate from anticipated values which would arise given a uniform speed of sound distribution, the calculation being undertaken by a cross-correlation function of neighboring elementary transducers. Correction values are formed from the deviating values depending on the angle of incidence of the echo signals on the elementary transducers. In an imaging phase following the adaption phase, the delay values for focussing are modified dependent on the incident angle of the echo signals and dependent on the correction values for this incident angle. Image disturbances due to the non-uniform speed of sound distribution can thus be compensated even in the presence of thick, transducer-proximate disturbing layers in the examination subject.

Method for ultrasound imaging

In the exemplary embodiments, a radiation measuring arrangement which includes radiation source is rotated for irradiating the radiography subject from different directions. A measured value converter calculates a layer image from the output signals of the detectors of the radiation receiver. For shielding against stray radiation, two hollow cylinders of equal diameter and with a common axis and comprised of a radiation-absorbing material lie between the radiation source and the radiation receiver, a gap for the passage of the x-ray beam being left therebetween. The radiography subject is introduced into the hollow cylinders.

Tomographic apparatus for producing transverse layer images

In the illustrated embodiments radiant energy at a plurality of distinct energy levels (each above 150 keV) is directed along one or more primary beam paths, and a series of detectors are arranged to receive scatter radiation from the same or successive points irradiated by the primary beam energy, with the detectors either collecting scatter energy over identical solid angles and at identical mean scattering angles or having their respective outputs equalized to a common scattering sample for each respective scatter energy spectrum. By relatively shifting a group of detectors a linear or layer region can be scanned, and the respective outputs from each detector can be individually recorded for subsequent processing to eliminate the effects of multiple scattering and unequal mean scattering angles. With detectors stationary, a time series of respective output signals from each detector can be recorded to facilitate the study of local ventilation of defined zones in the lungs, for example. By suitable processing, the output signals can be converted to numerical density readings and/or an accurate graphical display of density variations in a region of medical interest.

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Hoechstadt/Aisch, Germany

Klaus Killig