使用基于图像空间的迭代重建技术，非增强胸部 CT 的辐射剂量可降低 40%。
Radiation dose of non-enhanced chest CT can be reduced 40% by using iterative reconstruction in image space.
机构信息
Second Affiliated Hospital of Zhejiang University College of Medicine, Hangzhou, Zhejiang Province, China.
出版信息
Clin Radiol. 2011 Nov;66(11):1023-9. doi: 10.1016/j.crad.2011.04.008. Epub 2011 Sep 8.
AIM
To evaluate the image quality and dose reduction capability of non-enhanced chest computed tomography (CT) examinations using iterative reconstruction in image space (IRIS).
MATERIALS AND METHODS
A CT water phantom was scanned at 120 kV/150 mAs and 100 kV/270 mAs as the reference, and the tube current was decreased in 10% intervals down to 40% of the reference value. Image noise was evaluated and compared between filtered back-projection (FBP) and IRIS reconstructed data. In the patient study, 90 patients underwent non-enhanced chest CT examinations; the patients were randomly assigned into three groups: group A (n=30) standard dose protocol, 120 kV/110 mAs; group B (n=30) low dose, 100 kV/110 mAs; group C (n=30) low dose, 120 kV/67 mAs. All images were reconstructed by FBP and IRIS algorithm using matched kernels of B30 and I30. The objective image noise (OIN), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the aorta and latissimus dorsi were measured. The subjective image quality and noise were scored using a three-point scale by two experienced radiologists. The results of the subjective and objective image assessment were compared between groups B and C (low dose) IRIS and group A (standard dose) FBP.
RESULTS
The phantom study showed comparable image noise between the scans using 60% dose with IRIS and 100% dose with FBP for both 120 and 100 kV. In the patient study, groups A, B, and C had effective dose of 3.81 ± 0.43, 2.40 ± 0.19, and 2.41 ± 0.15 mSv. IRIS significantly improved the OIN, SNR, and CNR compared with FBP for the same patient. The OIN, SNR, and CNR using IRIS in group B and C were improved or comparable to those in group A using FBP. No significant difference was found in subjective image quality and noise between groups B and C using IRIS and group A using FBP.
CONCLUSION
Compared with FBP, IRIS can maintain or improve image quality on unenhanced chest CT image reconstruction while saving 40% radiation dose.
目的
评估使用迭代重建在图像空间（IRIS）中的非增强胸部 CT 检查的图像质量和剂量降低能力。
材料与方法
使用 120kV/150mAs 和 100kV/270mAs 作为参考对 CT 水模体进行扫描，并以 10%的间隔降低管电流，直至降至参考值的 40%。评估并比较滤波反投影（FBP）和 IRIS 重建数据之间的图像噪声。在患者研究中，90 名患者接受了非增强胸部 CT 检查；患者被随机分为三组：A 组（n=30）标准剂量方案，120kV/110mAs；B 组（n=30）低剂量，100kV/110mAs；C 组（n=30）低剂量，120kV/67mAs。所有图像均由 FBP 和使用 B30 和 I30 匹配内核的 IRIS 算法重建。测量主动脉和背阔肌的客观图像噪声（OIN）、信噪比（SNR）和对比噪声比（CNR）。两位经验丰富的放射科医生使用三分制对主观图像质量和噪声进行评分。比较组 B 和 C（低剂量）IRIS 与组 A（标准剂量）FBP 之间的主观和客观图像评估结果。
结果
体模研究表明，对于 120kV 和 100kV，使用 60%剂量的 IRIS 与使用 100%剂量的 FBP 的扫描之间的图像噪声相当。在患者研究中，A、B 和 C 组的有效剂量分别为 3.81±0.43、2.40±0.19 和 2.41±0.15mSv。与 FBP 相比，IRIS 显著提高了相同患者的 OIN、SNR 和 CNR。B 组和 C 组使用 IRIS 的 OIN、SNR 和 CNR 得到改善或与 A 组使用 FBP 的结果相当。使用 IRIS 的 B 组和 C 组与使用 FBP 的 A 组之间的主观图像质量和噪声没有显著差异。
结论
与 FBP 相比，IRIS 可以在不增强胸部 CT 图像重建中保持或提高图像质量，同时降低 40%的辐射剂量。
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