The method of laser scattering tomography (LST) was adapted to investigate scatterers in semi-insulating GaAs grown by the vapour pressure controlled Czochralski (VCz) technique. The LST method was extended to evaluate quantitatively the scattering for macroscopic fields. The LST images of as-grown VCz GaAs crystals showed a reduced number of scattering particles in comparison with conventional LEC crystals. The dependency of the total scattered intensities along a wafer radius and intensity histograms are discussed.