超低剂量CT能谱纯化技术联合高级建模迭代重建对显示肺磨玻璃结节及测量其体积的影响:体模研究

Impact of tin filtration combining advanced modeled iterative reconstruction on imaging quality of ultra-low dose CT and measuring volume of lung ground glass nodules:A phantom study

目的观察超低剂量CT能谱纯化技术联合高级建模迭代重建(ADMIRE)对显示肺磨玻璃结节(GGN)及测量其体积的影响。方法将20枚模拟GGN随机置于模拟成年男性的胸部体模肺中,以常规低剂量(A方案)及管电压Sn 100 kV能谱纯化技术(B方案)行CT扫描,并以滤波反投影法(FBP)及ADMIRE(强度1~5)进行重建;通过观察模拟GGN的CT值标准差(SD)、体积、体积相对误差(RVE)、主观图像质量评分及辐射剂量,评估B方案的价值。结果B方案各重建方式模拟肺GGN CT值SD均高于A方案(P均<0.05);相同方案不同重建方式所得CT值SD差异均有统计学意义(P均<0.05)。以相同方案不同重建方式模拟肺GGN CT图像的主观质量评分由高到低依次为ADMIRE-4、ADMIRE-3、ADMIRE-5、ADMIRE-2、ADMIRE-1及FBP;相同重建方式下,B方案所获CT图像主观质量评分均低于A方案(P均<0.05)。相同方案下,不同重建方式模拟GGN RVE差异均有统计学意义(P均<0.001),且基本随FBP及ADMIRE强度增高而呈递减趋势。以FBP、ADMIRE-1、ADMIRE-2及ADMIRE-3重建图像时,B方案模拟GGN的RVE均大于A方案(P均<0.05)。A、B方案的有效辐射剂量分别为0.51 mSv及0.12 mSv。结论采用管电压Sn 100 kV超低剂量CT能谱纯化技术结合ADMIRE-4检测体模GGN,可在降低辐射剂量的同时维持图像质量及测量其体积的精确度。

Objective To observe the impact of tin filtration combining advanced modeled iterative reconstruction(ADMIRE)on image quality of ultra-low dose CT and measuring volume of lung ground glass nodule(GGN).Methods Twenty simulated GGN were randomly placed in the lungs of a chest phantom imitating adult male.CT scanning was performed with conventional low-dose(scheme A)and tin filtration with tube voltage Sn 100 kV(scheme B),both reconstructed using filtered back projection(FBP)and ADMIRE(strength level from 1 to 5).The standard deviation(SD)of CT value,the volume,relative volume error(RVE),the subjective image quality score and radiation dose of simulated lung GGN under different scanning schemes and reconstruction modes were observed,and the value of scheme B was explored.Results SD of CT value of simulated GGN with each reconstruction mode under scheme B was higher than those of scheme A(all P<0.05).Under the same scheme,there were significant differences of SD of CT values obtained with different reconstruction modes(all P<0.05).Under the same scheme,the subjective quality scores of simulated lung GGN on CT images obtained with different reconstruction modes from high to low were ADMIRE-4,ADMIRE-3,ADMIRE-5,ADMIRE-2,ADMIRE-1 and FBP,while with the same reconstruction mode,the subjective quality scores of CT images under scheme B were lower than those under scheme A(all P<0.05).Under the same scheme,there were significant differences of simulated GGN RVE obtained with different reconstruction modes(all P<0.001),which basically decreased with FBP and ADMIRE strength increased.When reconstruction with FBP,ADMIRE-1,ADMIRE-2 and ADMIRE-3,the simulated GGN RVE of scheme B was higher than those of scheme A(all P<0.05).The effective radiation dose of scheme A and B was 0.51 mSv and 0.12 mSv,respectively.Conclusion Tin filtration with tube voltage Sn 100 kV ultra-low dose CT combined with ADMIRE-4 could effectively reduce the radiation dose and remain CT image quality as well as the accuracy of detecting measuring volume of phantom GGN.