Fletcher Joel G, Grant Katharine L R, Fidler Jeff L, Shiung Maria, Yu Lifeng, Wang Jia, Schmidt Bernhard, Allmendinger Thomas, McCollough Cynthia H
Department of Radiology, Mayo Clinic, Rochester, MN, USA.
J Comput Assist Tomogr. 2012 Sep-Oct;36(5):560-9. doi: 10.1097/RCT.0b013e318263cc1b.
To evaluate a method for obtaining half-dose CT images for observer studies evaluating lower-dose CT.
Phantoms of varying sizes were scanned at multiple tube potentials using dose-matched dual-source (DS) and single-source (SS) protocols. Images from single-tube reconstruction of DS data were compared with SS images acquired at half-original CTDIvol. Thirty patients underwent supine SS and dose-matched prone DS CT colonography (CTC). Half-dose prone images were reconstructed with sinogram-affirmed iterative reconstruction (SAFIRE). Two radiologists scored image quality on 2-dimensional (2D) and 3D images.
Image noise was similar between half-dose SS images and DS images reconstructed from one tube only with tube potential of 120 kV or more for phantoms 40 cm or smaller (P < 0.05). For both readers, the patients' CTC image quality scores were more than 84% concordant between SS or DS CTC images, and half-dose-prone CTC images with SAFIRE had 84% or more concordance with routine-dose CTC except for 3D image noise.
In appropriately sized patients, DS acquisition with single-tube reconstruction can create half-dose images, permitting comparison to full-dose images. For CTC, there is comparable image quality for colonic evaluation between full-dose and half-dose images reconstructed with SAFIRE.
评估一种获取半剂量CT图像的方法，用于观察者研究以评估低剂量CT。
使用剂量匹配的双源（DS）和单源（SS）协议，在多个管电压下扫描不同尺寸的体模。将DS数据单管重建的图像与在原始CTDIvol一半剂量下采集的SS图像进行比较。30例患者接受了仰卧位SS和剂量匹配的俯卧位DS结肠CT成像（CTC）。使用正弦图确认迭代重建（SAFIRE）重建半剂量俯卧位图像。两名放射科医生对二维（2D）和三维（3D）图像的图像质量进行评分。
对于40 cm或更小的体模，在管电压为120 kV或更高时，半剂量SS图像与仅从一个管重建的DS图像之间的图像噪声相似（P<0.05）。对于两位阅片者，SS或DS CTC图像之间患者的CTC图像质量评分一致性超过84%，除了3D图像噪声外，使用SAFIRE的半剂量俯卧位CTC图像与常规剂量CTC图像的一致性达到84%或更高。
在体型合适的患者中，采用单管重建的DS采集可以创建半剂量图像，以便与全剂量图像进行比较。对于CTC，使用SAFIRE重建的全剂量和半剂量图像在结肠评估方面具有可比的图像质量。
