Objective To investigate the influence of low dose multi-detector helical CT scan on the accuracy of lumbar spine bone mineral density ( BMD ) measurement by QCT. Materials and Methods Thirty adult inpatients ( 10 males and 20 females ) underwent routine lumbar CT scan with 250 mA and QCT with 50 mA as standard pre-operation protocol for spine surgery in our institution. The CT scans were performed with the Mindways QCT calibration phantom placed beneath the patient. The CT volume data were then transferred to the QCT workstation to measure the BMD of vertebral body of L2, L3 and L4. Paired t test was performed to determine the difference between two groups with SPSS 15. 0. Results It was no statistically significant in differences of BMD measured in 250 mA and 50 mA in lumbar spine L2-L4 ( P > 0. 05 ). Radiation dose was 229. 06 ± 12. 35 mGy · cm for 250 mA and 45. 78 ± 2. 48 mGy · cm for 50 mA. Conclusion Low-dose CT scan with 50mA for lumbar spine QCT BMD measurement ensures the accuracy of BMD measurement, and decreases the radiation dose greatly.%目的 通过临床验证多排螺旋定量CT腰椎低剂量扫描参数,制定最佳的低剂量多排螺旋QCT腰椎扫描协议.资料与方法 选取住院拟进行腰椎手术,术前行常规多排螺旋CT平扫和腰椎QCT检查的30位患者.其中男:10例,女20例;年龄48～79岁,平均年龄63.97±8.66岁.分两次采集常规250 mA和50 mA两组腰椎加校准体模QCT容积数据,将两组L2-L4容积数据传至骨密度工作站进行骨密度(Bone Mineral Density)测量.应用统计软件SPSS 15.0进行统计分析.结果 250 mA组与50 mA组L2、L3、L4平均BMD值无差异(P>0.05);两组三椎体总平均BMD值无差异(p>0.05);250 mA组辐射剂量DLP值为229.06±12.35 mGy· cm.50 mA组DLP值为45.78±2.48 mGy· cm.结论 多排螺旋定量QCT腰椎低剂量扫描技术能够保证BMD测量准确性,同时使患者的受辐射剂量比常规多排螺旋CT腰椎扫描大幅度降低.
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