Mangat J, Morgan J, Benson E, Båth M, Lewis M, Reilly A
Cardiac CT Department, Barts Heart Centre, Bartshealth NHS Trust, London, UK
Radiography Department, School of Health Sciences, City University, London, UK.
Radiat Prot Dosimetry. 2016 Jun;169(1-4):92-9. doi: 10.1093/rpd/ncw084. Epub 2016 Apr 21.
The recent reintroduction of iterative reconstruction in computed tomography has facilitated the realisation of major dose saving. The aim of this article was to investigate the possibility of achieving further savings at a site with well-established Adaptive Statistical iterative Reconstruction (ASiR™) (GE Healthcare) brain protocols. An adult patient study was conducted with observers making visual grading assessments using image quality criteria, which were compared with the frequency domain metrics, noise power spectrum and modulation transfer function. Subjective image quality equivalency was found in the 40-70% ASiR™ range, leading to the proposal of ranges for the objective metrics defining acceptable image quality. Based on the findings of both the patient-based and objective studies of the ASiR™/tube-current combinations tested, 60%/305 mA was found to fall within all, but one, of these ranges. Therefore, it is recommended that an ASiR™ level of 60%, with a noise index of 12.20, is a viable alternative to the currently used protocol featuring a 40% ASiR™ level and a noise index of 11.20, potentially representing a 16% dose saving.
近期计算机断层扫描中迭代重建技术的重新引入有助于实现大幅剂量节省。本文的目的是研究在一个已建立成熟的自适应统计迭代重建（ASiR™）（通用电气医疗集团）脑部扫描方案的场所进一步节省剂量的可能性。进行了一项成年患者研究，由观察者使用图像质量标准进行视觉分级评估，并将其与频域指标、噪声功率谱和调制传递函数进行比较。在40 - 70% ASiR™范围内发现主观图像质量相当，从而提出了定义可接受图像质量的客观指标范围。基于对所测试的ASiR™/管电流组合的患者研究和客观研究结果，发现60%/305 mA除了一个范围外，均落在所有这些范围内。因此，建议采用ASiR™水平为60%、噪声指数为12.20的方案，作为当前使用的ASiR™水平为40%、噪声指数为11.20方案的可行替代方案，这可能意味着剂量节省16%。
