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Biomedical subjects

P Schmidlin

Publications and source records attributed to P Schmidlin.

3 recordsLinked to original sources
PubMed1992

Assessment of an attenuation correction for SPET by means of PET images.

The attenuation correction for single photon emission computed tomography (SPET) data developed by Luig et al. was tested with positron emission tomography (PET) data. Since the PET attenuation correction is very precise, it may be used as a reliable measure of the functionality of the SPET correction. It was found that, in the case of homogeneous attenuation and activity distribution, the results of Luig's correction are equivalent to those obtained with the PET correction. Inhomogeneous distributions of activity are corrected satisfactorily as long as the absorption of the medium is sufficiently homogeneous. Inhomogeneous absorption, however, leads to inadequate correction. In the case of sections through the lung, Luig's method might 'correct' the data in the wrong direction.

Humans↗
PubMed1975

Development and comparison of computer methods for organ motion correction in scintigraphy.

The process of organ motion correction in scintigraphy is analysed in the frequency domain. The sequence of the chi- and gamma- coordinates registered during scintigraphic recording is converted to a frequency spectrum by a discrete Fourier transform. In the frequency domain motion correction is performed by linear filtering. Every convolution filter in the time domain corresponds to a linear filter in the frequency domain, and the filter form in the frequency domain is a good measure of the quality of the correction. With the aid of frequency analysis simple convolution filters in the time domain are developed. The usual centre of gravity method is not a convolution filter and has an unfavourable frequency behaviour. By means of phantom measurements the following correction methods are tested: the usual (non-convolutional) centre of gravity method, the convolutional centre of gravity method, a weighted convolutional centre of gravity method and the Fourier filtering method.

Computers↗