Abstract: Accurate diagnosis of osteoporosis (OP) relies on precise measurement of bone mineral density (BMD). The current gold standard, dual-energy X-ray absorptiometry (DXA), reveals areal bone mineral density information that is influenced by bone size, vertebral degeneration, and vascular calcification. This technique also cannot distinguish between trabecular and cortical bone. These limitations underlie demand for new technologies capable of providing true volumetric bone density and multidimensional information on bone quality. Quantitative computed tomography (QCT) has emerged as a key technology to meet these demands. Based on clinical CT, QCT utilizes thin-slice scanning and three-dimensional reconstruction to accurately measure volumetric bone mineral density and independently analyze trabecular and cortical bone. Its advantages extend beyond density measurement to include acquisition of three-dimensional geometric parameters of bone structure and noninvasive estimation of bone strength through finite element analysis. This review systematically outlines technical principles underlying QCT and its methodological evolution, summarizes its multidimensional parameter system and clinical applications in the spine, hip, and peripheral skeleton, and discusses ongoing challenges facing its standardization.