Quality control of fan beam scanning data processing with in vitro material

In vivo assessment of human body composition quantities from imaging/scanning systems in clinical research and public health has led to proliferation of indirect methods and techniques that deliver approximating values. The systems are based on morphological or biochemical models and assumptions. Since the development of dual-energy X-ray absorptiometry (DXA) for the bone density, mineral content and the detection of osteoporosis, it assesses lean tissue and fat also. This study conducts a quality control of DXA variables using direct dissection of 14 porcine hind legs as the criterion method. Results show good to excellent correlations between DXA and dissection data (r² =0.75 to 0.99), but absolute indirect DXA and direct dissection values were significantly different (P<0.05). In addition DXA provides erroneous values for bone density and the data dimensions are morphological, not chemical values as claimed by the manufacturer. Validation and accuracy studies with intact whole bodies are advised.