Computational aspects of a new matrix equation‐based thermal‐wave subsurface diffraction tomographic method for object field reconstructions of transverse slices (planes) perpendicular to a material surface are presented. The method can be implemented on conventional workstations and mainframe computers. It uses the photothermally measured backpropagation (front detection) or transmission (back‐surface detection) scanned thermal‐wave field data in the solution of the Helmholtz thermal pseudowave equation, by solving the equivalent integral equation. The numerical computations of the inverse problem used in the slice image reconstruction were satisfactorily carried out via the Born approximation. Simulated thermal‐wave tomographic data/case studies were used to evaluate the imaging characteristics of large‐scale computational thermal‐wave diffraction tomography as a quantitative measurement and nondestructive evaluation imaging discipline.