The novel phantom-less quantitative computed tomography for different CT machine systems: Bone mineral density quality assurance evaluation

Background/Purpose

Quality assurance (QA) study is a significant research for bone mineral densitometry (BMD). Especially for quantitative computed tomography (QCT), such study was clinical practical as QCT bone density measurements were generally executed on different CT machines. This QA study aimed to evaluate quality parameters includes accuracy and precision of vBMD measurements by a novel phantom-less QCT (PL-QCT) on different CT machines. European spine phantom (ESP) was used as measurement reference in this study.

Methods

10 CT machines and 100 patients were enrolled. For each CT machine, the ESP was scanned independently 10 times with repositioning under 120kV. CT data of 10 patients scanned on the same CT machine in the same day under 120kV were randomly selected for PL-QCT BMD calibration. An automatic algorithm was used for calibration region of interest (ROI) placement on soft tissues (muscle and fat) in PL-QCT software. ESP reference values by manufacturer were used as standard for BMD measurements evaluation.

Results

For all CT machines, the average of ten repeated ESP L1-3 vBMD measurements did not exceed ±5mg/cm3 in comparison with ESP reference value. Only one CT machine failed to satisfy the ±5mg/cm3 threshold for L3 segment. The linear regression of the three vBMD measurements for each CT scanner yielded a median SEE of 1.44 mg/cm3, with a range from 1.37 to 2.28 mg/cm3. The mean and range of the coefficients of variation measured by all CT scanners was approximately 0.12% (0.11-0.14%).

Conclusions

The deviations of BMD results on different CT machines are within the acceptable range. This novel PL-QCT was a reliable and applicable osteoporosis evaluation device, combining its benefits on retrospective screening, it could be a QCT technique worth promoting.