In order to improve efficiency and resolution of inversion and computation in concrete tomography, we propose a probability weighted conjugate gradient algorithm, in which weight is added on imaging unit instead of equation. IART algorithm is adopt to determine weight factor and initial value. Simulation examples and a real physical experiment show that the algorithm is of fast convergence, feasibility and validity.

A weighting approach for ray matrix in ART algorithm for ultrasonic computerized tomogrnphy of concrete is developed. Firstly。a low-resolution image is generated by BPT algorithm and which is used asinitial value of iteration.Then,information of lowresolution image is used as weighting coefficients for ray matrix of ART algorithm.Image information and numerical information are used fully.High speed and low speed abnormal units can be weighted.As data error is less than 0.5%.examples show that the accuracy and iteration speed of improved method are better than that of traditional ART algorithm.