Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-city, Osaka 565-0871, Japan.
Radiology. 2010 Jun;255(3):944-54. doi: 10.1148/radiol.10091010.
To evaluate the image quality of both standard- and reduced-dose computed tomography (CT) by comparing multidetector CT with garnet-based detectors with multidetector CT with conventional detectors.
The study was approved by the internal ethics review board. Informed consent was obtained. Eleven cadaveric lungs inflated and fixed by using the Heitzman method were scanned by using both CT with garnet-based detectors and CT with conventional detectors. Tube current was 400 mA for standard-dose and 10 mA for reduced-dose CT, and voltage was 120 kVp. Either normal scan mode with 984 views (conventional and garnet-based detectors) or high-resolution mode with 2496 views was used. Image quality at conventional-detector CT and garnet-based-detector CT in all modes was graded by two independent observers with a five-point scale. The evaluation items included normal lung structures, subjective visual noise, and abnormal CT findings. Quantitative image noise measurements were calculated by measuring the standard deviations in a circular region of interest on each selected image.
At standard-dose CT, image quality at CT with garnet-based detectors (high-resolution mode) was significantly improved (P < .001, Tukey-Kramer). However, there was no significant difference between quantitative image noise measurements (P > or = .24). At reduced-dose CT, only noise differed significantly, with both subjective visual noise and quantitative image noise measurements significantly greater at CT with garnet-based detectors (high-resolution mode) (P < or = .01). There was no significant difference in image quality except for noise between conventional-detector CT and garnet-based-detector CT (P > or = .06).
The image quality of standard-dose garnet-based-detector CT (high-resolution) was significantly improved. Although highly reduced-dose garnet-based-detector CT (high-resolution mode) provided more image noise, overall image quality was not different between conventional-detector CT and garnet-based-detector CT.
通过比较基于石榴石的探测器多层 CT 与传统探测器多层 CT，评估标准剂量和低剂量 CT 的图像质量。
本研究经内部伦理审查委员会批准，并获得了知情同意。使用 Heitzman 方法充气和固定的 11 具尸体肺采用基于石榴石的探测器和传统探测器的 CT 进行扫描。标准剂量时管电流为 400mA，低剂量时为 10mA，管电压为 120kVp。使用常规扫描模式（984 个视野）或高分辨率模式（2496 个视野）。两位独立观察者使用五分制对所有模式下的传统探测器 CT 和基于石榴石的探测器 CT 的图像质量进行分级。评估项目包括正常肺结构、主观视觉噪声和异常 CT 发现。通过在每个选定图像的圆形感兴趣区域内测量标准偏差来计算定量图像噪声测量值。
在标准剂量 CT 中，基于石榴石的探测器（高分辨率模式）的 CT 图像质量显著提高（P <.001，Tukey-Kramer）。然而，定量图像噪声测量值之间没有显著差异（P > or =.24）。在低剂量 CT 中，只有噪声有显著差异，基于石榴石的探测器（高分辨率模式）的主观视觉噪声和定量图像噪声测量值均显著更高（P < or =.01）。除噪声外，传统探测器 CT 和基于石榴石的探测器 CT 的图像质量没有显著差异（P > or =.06）。
标准剂量基于石榴石的探测器（高分辨率）的图像质量显著提高。虽然高度降低剂量基于石榴石的探测器（高分辨率模式）提供了更多的图像噪声，但在传统探测器 CT 和基于石榴石的探测器 CT 之间，整体图像质量没有差异。
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