Measurement Of Modulation Transfer Functions In Applied Potential Tomography

The accuracy in measuring the point spread function (PSF) and the errors involved in computing its Fourier transform must be considered in detail, when the modulation transfer function (MTF) is used to evaluate any imaging system. Through the use of various theoretical PSF and simulated transfer functions, as well as actual PSF (rods) measured in a tank of saline water, criteria are analyzed for making accurate PSF measurements and MTF computations for the case of an impedance imaging system. By varying parameters such as rod size and positioning, point of PSF truncation. signal-to-noise ratio and sampling distance, conclusions were drawn as to their actual and theoretical effects upon the computed MTF. Experimental results from the groups in Sheffield, Barcelona and Toulouse are discussed.