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.