A one-shot rescaling process, namely Automated Scaling Region of Interest (AS-ROI), is combined with an inversion technique of Forward-Backward Time-Stepping (FBTS). The purpose is to alleviate the ill-posedness and nonlinearity of inverse problem by reducing the size of the unknown problem. The inversion solution is carried out to reconstruct tumour as an unknown object in coarse investigation domain of lung area which is then rescaled down corresponding to object location and size. In this paper, edge preserving methods consisting of edge preserving regularization and anisotropic diffusion are imposed alternately on the solution and reconstructed profiles to improve the current method of AS-ROI. Results on the reconstructed lungs and tumours give significant insight of the proposed work. Accuracy level for the reconstructed profiles are significantly improved in spite that spatial resolution is retained as the original setting of FBTS.