The Comparative Study of Measurement of Vertebral Body Bone Density in Normal Postmenopause Women with 2000QCT and 3000QCT

Objective To explore the influence factor of QCT phantoms in measuring BMD through comparing two kinds of QCT phantoms that used to measure local normal post-menopause women's vertebra of bone mineral density (BMD). Materials and Methods The bone density of T12～L2 with QCT was measured for 116 female members in local old age university after their menopause 1～27 years using phantoms of 2000 QCT and QCT 3000 with same scanning parameter respectively. (1) The statistical difference of vertebral BMD value T value and Z value between two phantoms through pairing t test was compared, and the 95 percent confidence interval respectively as the reference of normal value was also calculated. (2) Groups of the two phantoms' vertebral BMD value T value and Z value according to age was divided, and the vertebral BMD value T value and Z value respectively through single factor variance analyzing and the inter-group difference through SNK was also compared. Results The BMD value and mean value of Z of 2000QCT's phantom was much higher than that of QCT3000, but the mean value of T was lower than that of QCT 3000 (P0.01). The inter-group statistics showed: The older of the age the BMD and T value of the two vertebral phantoms were gradually lower. It had significant statistics meaning among the three groups (P0.01). Z value among the three groups had no significant statistics meaning (P0.05). Conclusion The QCT phantom and soft ware system affect the results of the QCT measuring obviously and other factors also affect the results. When using the result to diagnose and treat osteoporosis, we should analyze the results combining the local people and the phantom's normal value.