Revolution CT能谱成像测量腰椎体模骨密度的准确性及可重复性

目的观察Revolution CT能谱成像测量腰椎体模骨密度(BMD)的准确性及可重复性。方法采用2台同型号Revolution CT,分别以不同管电流及不同球管转速组合共计20组扫描条件对欧洲腰椎体模(ESP)重复进行10次扫描;利用能谱物质分离功能分别测量体模L1、L2、L3椎体羟基磷灰石(HAP)值,比较HAP测值与真实值之间的差异,评价其准确性;记录各扫描条件下CT容积剂量指数(CTDI_(vol))。对比不同CT设备之间测量结果的可重复性。结果 20组条件下,L1、L2、L3椎体HAP测值差异均有统计学意义(P均0.001)。取管电流230 mA、球管转速0.8 s/rot及管电流315 mA、球管转速1.0 s/rot,L1、L2、L3椎体HAP测值与体模实际值差异均无统计学意义(P均0.05),CTDI_(vol)分别为9.09 mGy和15.46 mGy,且2台CT所测L1、L2、L3椎体HAP值差异无统计学意义(P均0.05)。结论 Revolution CT扫描测量ESP BMD准确性高,尤以球管转速0.8 s/rot配合管电流230 mA条件准确性更高,且辐射剂量低;同型号不同CT设备间可重复性好。

Accuracy and repeatability of Revolution CT energy spectrum imaging in measurement of bone mineral density of spine phantom

Objective To observe the accuracy and repeatability of Revolution CT energy spectrum imaging for measuring bone mineral density (BMD) of lumbar vertebra phantom. Methods Revolution CT was used with different tube current and different tube rotation speed combinations, a total of 20 sets of scanning conditions, and the European spine phantom (ESP) were scanned repeatedly for 10 times. The Hydroxyapatite (HAP) value of L1, L2, and L3 vertebral bodies were measured by energy spectral material decomposition technique, and the measured HAP values were compared with actual values. At the same time, the volume CT dose index (CTDI_vol) of each scanning condition were recorded and compared. Then the repeatability of measurements with CT machines was observed. Results Under 20 groups of conditions, the measured HAP values of L1, L2 and L3 intervertebral bodies were statistically significant (all P<0.001). With tube current 230 mA and tube rotating speed 0.8 s/rot or tube current 315 mA and tube rotating speed 1.0 s/rot, no significant difference was found between measured HAP values and the actual values of L1, L2 and L3 vertebral body, nor between measured HAP values obtained with 2 CT machines (all P>0.05), and CTDI_vol was 9.09 mG and 15.46 mGy, respectively. Conclusion Revolution CT scan is accurate in measuring BMD of ESP, especially with tube rotation speed 0.8 s/rot and tube current 230 mA, and the radiation dose is low. The repeatability between different CT machines of same model is good.