Some novel reconstruction algorithms have recently been proposed to solve the problem of reconstruction from transverse truncated projections of fan-beam scans. This paper introduced and reformulated the exact backprojection-filtration (BPF)-type reconstruction algorithm for fan-beam scans based on Zou and Pan’s work. Subsequently, a legible and implementary BPF algorithm for region-of-interest (ROI) reconstruction is presented using projection data truncated not only in angle-scanning but also in the transverse direction. The algorithm can be widely used for fan-beam full-scans, short-scans, or super-short-scans. The algorithm uses less projection data than the preceding super-short-scan. The algorithm is implemented using the Shepp-Logan phantom and some primary results are presented. Some new discoveries and implications of ROI reconstruction from truncated data are discussed, which suggests that the BPF algorithm can be used in the ROI reconstruction from truncated projections.