Non-Destructive Evaluation (NDE) of plate structures is frequently carried out in industrial and laboratory environments. In this paper the wave scattering from horizontally oriented internal cavities or cracks in a plate are studied using DPSM (Distributed Point Source Method). DPSM has gained popularity in last few years in the field of ultrasonic field modelling. DPSM is a semi-analytical technique that can be used to calculate the ultrasonic field (pressure, velocity and displacement fields in a fluid, or stress and displacement fields in a solid) generated by ultrasonic transducers. So far the technique has been used to model ultrasonic field near a fluid-solid interface when a solid half-space is immersed in a fluid. This method has also been used to model the ultrasonic field generated in a homogeneous isotropic solid plate immersed in a fluid. The objective of this study is to present the theoretical modelling of the diffraction and scattering pattern of guided waves in the solid plate when the transducers of finite dimension are placed on both side of the defective plate.