Institute for Clinical Radiology, Hospital of the Ludwig Maximilian University of Munich, Campus Grosshadern, Marchioninistraße 15, 81377 Munich, Germany.
AJR Am J Roentgenol. 2013 Jun;200(6):W628-34. doi: 10.2214/AJR.12.9635.
The purpose of this study was to determine the effectiveness of a radiation dose reduction strategy for CT angiography by the combination of higher iodine delivery rate and automated tube potential selection with adjusted reference values for tube current-exposure time product, as well as to measure the impact of this approach on image quality.
One hundred consecutive patients underwent high-pitch CT angiography of the thorax and abdomen using either 90 mL of iomeprol 300 (n = 44, protocol A) or 90 mL of iomeprol 400 (n = 56, protocol B) at the same flow rate. Automated tube potential selection was used with reference tube current-time products of 330 mAs and 250 mAs for protocols A and B, respectively. Twenty vascular segments were analyzed for attenuation and image noise by two readers. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for all segments. The dose-length product (DLP) was documented to calculate effective dose and was compared between protocols both globally and for body mass index (BMI) subgroups.
There were no differences in sex, height, weight, or BMI between both groups. Images from patients scanned with protocol B showed higher levels of image noise but also higher signal in all vascular segments. As a result, there were no differences in SNR between both groups. Conversely, CNR was significantly higher for almost all vascular segments in the group scanned using protocol B. Furthermore, DLP was significantly lower when protocol B was used, particularly in patients with a BMI of less than 30.
In CT angiography, a combination of higher iodine delivery rate and automated tube potential selection with adjusted reference values for the tube current-time product allows reductions in radiation dose by approximately 30% without compromising image quality.
本研究旨在确定通过提高碘输送率和自动管电压选择相结合，并调整管电流-曝光时间乘积的参考值，以及测量这种方法对图像质量的影响，来实现 CT 血管造影的辐射剂量降低策略的有效性。
100 例连续患者接受了胸部和腹部高分辨率 CT 血管造影检查，分别使用 90ml 的碘普罗胺 300（n = 44，方案 A）或碘普罗胺 400（n = 56，方案 B），流速相同。使用自动管电压选择，并分别为方案 A 和 B 设置 330mAs 和 250mAs 的参考管电流-时间乘积。两位读者分析了 20 个血管段的衰减和图像噪声。计算了所有节段的信噪比（SNR）和对比噪声比（CNR）。记录剂量长度乘积（DLP）以计算有效剂量，并在全局和体重指数（BMI）亚组之间比较两种方案。
两组患者的性别、身高、体重或 BMI 均无差异。使用方案 B 扫描的患者的图像显示出更高的图像噪声水平，但所有血管段的信号也更高。因此，两组的 SNR 没有差异。相反，使用方案 B 扫描的组中，几乎所有血管段的 CNR 都显著更高。此外，当使用方案 B 时，DLP 显著降低，特别是在 BMI 小于 30 的患者中。
在 CT 血管造影中，高碘输送率和自动管电压选择相结合，并调整管电流-曝光时间乘积的参考值，可以在不影响图像质量的情况下将辐射剂量降低约 30%。
