[Abstraet] Purpose To explore the application of noise reduction settings among modelbased iterative reconstruction (MBIRn) on decreasing radiation dose in CTA through experimental study.Materials and Methods Spectral CT was used to scan vessel model which could accommodate 8 tubes under static condition under 120 kVp fixed tube voltage at 10 mA,50 mA,150 mA and 600 mA.The tubes were filled with purified water,1,2,5,10,20 and 30 mgI/ml solutions and 30 mgCa/ml solution.Algorithms of FBP (standard),ASIR40 (combined by 40％ ASIR and FBP),MBIRc and MBIRn with optimized spatial resolution setting as MBIRRP20,MBIRstnd (standard setting),and MBIRNR40 (noise reduction setting) were adopted for original scanning data to reconstruct images of 0.625 mm slice thickness for contrastive analysis.Three fixed layers were chosen and regions of interest were placed on central tube and surrounding ester matrix,and CT value and standard variation (SD) were measured to represent noise.Noise reduction setting MBIRNR40 and solution noise of other reconstruction algorithm images were calculated and compared and average value of contrast noise ratio (CNR) was compared.Results Compared to FBP under different tube currents,ASIR40,MBIRc,MBIRRP20,MBIRstnd and MBIRNR40 reduce noise and increase CNR at different levels.Average noise of MBIRNR40 was the lowest (reduced by 78.33％) and CNR the highest (increased by 241.74％),making it superior to other reconstruction algorithm images (P＜0.05).Meanwhile,the lower the radiation dose was,the more obvious its advantage was.Reconstruction image noise of MBIRNR40 at 10 mA was close to that of FBP and ASIR40 at 600 mA.CNR was obvious greater than that of FBP and ASIR40 at other tube voltage.Conclusion Reconstruction algorithms of MBIRc,MBIRn and ASIR can help enhance CTA image quality and reduce radiation dose.Noise reduction setting MBIRNR40 from MBIRn has the lowest noise and greatest CNR.The lower the radiation dose is,the more obvious its advantage is.%目的 通过模型实验探讨基于模型的迭代重建(MBIRn)中降噪设置在降低CT血管造影(CTA)辐射剂量中的应用价值.资料与方法 使用能谱CT在固定管电压120 kVp,10、50、150、600 mA不同管电流条件下,扫描静止状态容纳8支试管的血管模型.试管内分别填满纯净水、1、2、5、10、20、30 mgI/ml溶液和30 mgCa/ml溶液.原始扫描数据分别使用标准算法FBP、ASIR40 (40％ASIR与FBP混合)、MBIRc和MBIRn中优化空间分辨率设置MBIRRP20、标准设置MBIRstnd、降噪设置MBIRNR406种算法重建层厚0.625 mm的图像后进行对比分析.选取3个固定层面在试管中心及周围酯性基质放置感兴趣区,并测量CT值与标准差(SD),以代表噪声.计算并比较降噪设置MBIRNR40与其他重建算法图像各溶液噪声和对比噪声比(CNR)的平均值.结果 在不同管电流条件下,与FBP相比,ASIR40、MBIRc、MBIRRP20、MBIRstnd和MBIRNR40均不同程度减少噪声和提高CNR;MBIRNR40平均噪声最低(降低78.33％),CNR最大(升高241.74％),优于其他重建算法图像(P＜0.05);且辐射剂量越低,其优势越明显.10 mA条件下MBIRNR40重建图像噪声与600 mA条件下FBP和ASIR40相近,其余管电压条件下CNR明显大于FBP和ASIR40.结论 MBIRc、MBIRn和ASIR重建算法有助于提高CTA图像质量,降低辐射剂量.MBIRn降噪设置MBIRNR40噪声最低,CNR最大,且辐射剂量越小,其优势越明显.
展开▼
