Comparison of second directional derivative boundary detection methods for SPECT

The authors investigate three methods of calculating the derivative of an image for the second directional derivative (SDD) operator, which has been shown by M.A. Gennert et al. (1991) to provide improved accuracy of volume quantitation. The three methods are Zucker-Hummel finite-impulse-response (ZH-FIR) filtering, Monga-Deriche finite-impulse-response (MD-IIR) filtering, and the Gaussian-derivative Fourier transform (GD-FT) method. The three methods resulted in very similar volumes when applied to the simulated images of a set of spherical sources. It is also found that, by using an interpolative background subtraction technique, the quantitation accuracy of the low-contrast spheres can be significantly improved