Department of Medical Imaging, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan.
Department of Medical Imaging and Radiological Sciences, Tzu Chi University of Science and Technology, Hualien, Taiwan.
PLoS One. 2021 Nov 12;16(11):e0259772. doi: 10.1371/journal.pone.0259772. eCollection 2021.
Exposure to ionizing radiation can cause cancer, especially in children. In computed tomography (CT), a trade-off exists between the radiation dose and image quality. Few studies have investigated the effect of dose reduction on image quality in pediatric neck CT. We aimed to assess the effect of peak kilovoltage on the radiation dose and image quality in pediatric neck multidetector-row CT. Measurements were made using three phantoms representative of children aged 1, 5, and 10 years, with tube voltages of 80, 100, and 120 kilovoltage peak (kVp); tube current of 10, 40, 80, 120, 150, 200, and 250 mA; and exposure time = 0.5 s (pitch, 0.984:1). Radiation dose estimates were derived from the dose-length product with a 64-multidetector-row CT scanner. Images obtained from the control protocol (120 kVp) were compared with the 80- and 100-kVp protocols. The effective dose (ED) was determined for each protocol and compared with the 120-kVp protocol. Quantitative analysis entailed noise measurements by recording the standard deviation of attenuation for a circular 1-cm2 region of interest placed on homogeneous soft tissue structures in the phantom. The mean noise of the various kVp protocols was compared using the unpaired Student t-test. Reduction of ED was 37.58% and 68.58% for neck CT with 100 kVp and 80 kVp, respectively. The image noise level increased with the decrease in peak kilovoltage. Noise values were higher at 80 kVp at all neck levels, but did not increase at 100 kVp, compared to 120 kVp in the three phantoms. The measured noise difference was the greatest at 80 kVp (absolute increases<2.5 HU). The subjective image quality did not differ among the protocols. Thus, reducing voltage from 120 to 80 kVp for neck CT may achieve ED reduction of 68.58%, without compromising image quality.
电离辐射会导致癌症，尤其是在儿童中。在计算机断层扫描（CT）中，辐射剂量和图像质量之间存在权衡。很少有研究调查降低剂量对儿科颈部 CT 图像质量的影响。我们旨在评估峰值千伏对儿科颈部多排 CT 辐射剂量和图像质量的影响。使用三个代表 1 岁、5 岁和 10 岁儿童的体模进行测量，管电压分别为 80、100 和 120 千伏峰值（kVp）；管电流分别为 10、40、80、120、150、200 和 250 mA；曝光时间=0.5 s（螺距，0.984：1）。使用 64 排多层 CT 扫描仪从剂量长度乘积中得出辐射剂量估计值。比较了从对照方案（120 kVp）获得的图像与 80 和 100 kVp 方案。确定了每个方案的有效剂量（ED），并与 120 kVp 方案进行了比较。通过记录圆形 1 cm2 感兴趣区域在体模中的均匀软组织结构上的衰减标准差来进行定量分析。使用未配对学生 t 检验比较了各种 kVp 方案的平均噪声。100 kVp 和 80 kVp 颈部 CT 的 ED 分别降低了 37.58%和 68.58%。随着峰值千伏的降低，图像噪声水平增加。在所有颈部水平，80 kVp 处的噪声值较高，但在三个体模中，100 kVp 处的噪声值与 120 kVp 相比并未增加。在 80 kVp 处测量的噪声差异最大（绝对值增加<2.5 HU）。在所有协议中，图像质量没有差异。因此，颈部 CT 从 120 kVp 降低到 80 kVp 可能会使 ED 降低 68.58%，而不会影响图像质量。
