Qurashi A, Rainford L, Ajlan A, Khashoggi K, Ashkar L, Al-Raddadi M, Al-Ghamdi M, Al-Thobaiti M, Foley S
Radiography and Diagnostic Imaging, School of Medicine, University College Dublin, Ireland; Faculty of Applied Medical Sciences, Taibah University, Madinah, Saudi Arabia.
Radiography and Diagnostic Imaging, School of Medicine, University College Dublin, Ireland.
Radiography (Lond). 2018 Feb;24(1):e1-e12. doi: 10.1016/j.radi.2017.08.003. Epub 2017 Aug 25.
This study investigated the impact of different protocols on radiation dose and image quality for obese patients undergoing abdominal CT examinations.
Five abdominal/pelvis CT protocols employed across three scanners from a single manufacturer in a single centre used a variety of parameters (kV: 100/120, reference mAs: 150/190/218/250/300, image reconstruction: filtered back projection (FBP)/iterative (IR)). The routine protocol employed 300 reference mAs and 120 kV. Data sets resulting from obese patient examinations (n = 42) were assessed for image quality using visual grading analysis by three experienced radiologists. Objective assessment (noise, signal/contrast-noise ratios) and radiation dose was compared to determine optimal protocols for prospective testing on a further sample of patients (n = 47) for scanners using FBP and IR techniques.
Compared to the routine protocol, mean radiation dose was reduced by 60% when using 100 kV and SAFIRE technique strength 3 (p = 0.001). Reduction of up to 30% in radiation dose was noted for the FBP protocol: 120 kV and 190 reference mAs (p = 0.008). Subjective and objective image quality for both protocols were comparable to that of the routine protocol (p > 0.05). An overall improvement in image quality with increasing strength of SAFIRE was noted. Upon clinical implementation of the optimal dose protocols, local radiology consensus deemed image quality to be acceptable for the participating obese patient cohort.
Radiation dose for obese patients can be optimised whilst maintaining image quality. Where iterative reconstruction is available relatively low kV and quality reference mAs are also viable for imaging obese patients at 30-60% lower radiation doses.
本研究调查了不同扫描方案对接受腹部CT检查的肥胖患者辐射剂量和图像质量的影响。
在单一中心，使用来自单一制造商的三台扫描仪，采用了五种腹部/盆腔CT扫描方案，这些方案使用了各种参数（管电压：100/120千伏，参考毫安秒：150/190/218/250/300，图像重建：滤波反投影（FBP）/迭代重建（IR））。常规方案采用300参考毫安秒和120千伏。由三名经验丰富的放射科医生通过视觉分级分析对肥胖患者检查（n = 42）产生的数据集进行图像质量评估。比较客观评估（噪声、信号/对比噪声比）和辐射剂量，以确定使用FBP和IR技术的扫描仪对另外一组患者（n = 47）进行前瞻性测试的最佳方案。
与常规方案相比，使用100千伏和SAFIRE技术强度3时，平均辐射剂量降低了60%（p = 0.001）。FBP方案（120千伏和190参考毫安秒）的辐射剂量降低了30%（p = 0.008）。两种方案的主观和客观图像质量与常规方案相当（p > 0.05）。随着SAFIRE强度的增加，图像质量总体有所改善。在临床实施最佳剂量方案后，当地放射学界的共识认为参与研究的肥胖患者队列的图像质量是可接受的。
肥胖患者的辐射剂量可以在保持图像质量的同时得到优化。在可使用迭代重建的情况下，相对较低的管电压和合适的参考毫安秒对于以低30 - 60%的辐射剂量对肥胖患者进行成像也是可行的。
