Radiol Technol. 2020 Jul;91(6):516-524.
To investigate the viability of the 10 kVp rule as a substitute for the 15% rule in obtaining extremity radiographs of high diagnostic quality while lowering patient radiation dose. The intention of this substitution is to allow technologists a simpler and quicker calculation for use in clinical settings to benefit patients without disrupting workflow.
Three anteroposterior or posteroanterior exposures were made on 3 anthropomorphic phantom extremities: hand, knee, and shoulder. Thermoluminescent dosimeters (TLDs) were placed at the center of each phantom; a new TLD was used for each exposure. Exposures were made on a Defininium 8000 digital radiography system (General Electric) using the unaltered, system-preset techniques used by the authors' imaging department, techniques adapted from the 10 kVp rule, and techniques adapted from the 15% rule. The detector exposure indicator from each image was used to compare image quality among the 3 exposures in each group. Entrance skin dose measured from the TLDs also were compared among the 3 exposures for each extremity. One TLD was used as a control to determine the amount of background radiation to which the TLDs were exposed.
The detector exposure indicator remained in optimal range for every exposure with both applied rules as well as the system-preset techniques. Entrance skin dose was lower for both rules in the shoulder and hand trials, with the possibility of error during exposure and reading of the system-preset technique used on the knee phantom. Entrance skin dose also was lower for the shoulder and hand exposures when using the 10 kVp techniques compared with the 15% rule techniques.
Aside from unknown entrance skin dose errors during knee imaging, no failures of the tested rules were found. Using manual technique selection rather than automatic exposure control allowed for consistent manipulation of technical factors. TLDs allowed for relatively reliable and quick readings from each exposure, although they could have been the cause of an error in the exposure reading of the preset technique of the knee. Environment and equipment were unchanged to maintain consistency.
Results demonstrated that both the 15% rule and the 10 kVp rule successfully maintained or slightly improved image quality according to the detector exposure indicators. The results also demonstrated lowered patient dose according to the entrance skin doses. Based on these results, the 10 kVp rule might be a reasonable substitute for the 15% rule. Further research should be conducted with more repetitions that include digital radiography equipment for a wider range of examinations.
探讨 10kVp 规则替代 15%规则在获得高质量诊断性四肢 X 射线照片的同时降低患者辐射剂量的可行性。这种替代的目的是为技术人员提供一种更简单、更快捷的计算方法，以便在临床环境中为患者带来益处，同时不影响工作流程。
在 3 个模拟人体四肢（手、膝和肩）上进行 3 次前后位或后前位曝光。在每个模拟人体的中心放置一个热释光剂量计（TLD）；每次曝光使用一个新的 TLD。使用作者所在影像科使用的未经修改的、系统预设的技术，以及从 10kVp 规则和 15%规则改编的技术，在 Defininium 8000 数字放射摄影系统（通用电气）上进行曝光。从每个图像的探测器曝光指示器比较每组 3 次曝光的图像质量。还比较了每个肢体 3 次曝光的 TLD 测量的入射皮肤剂量。使用一个 TLD 作为对照，以确定 TLD 所暴露的背景辐射量。
应用这两种规则以及系统预设技术，每个探测器的曝光指示器都保持在最佳范围内。在肩部和手部试验中，两种规则的入射皮肤剂量均较低，而在对膝关节模拟体进行系统预设技术曝光和读数时，可能存在误差。与 15%规则技术相比，使用 10kVp 技术时，肩部和手部的入射皮肤剂量也较低。
除了在膝关节成像时未知的入射皮肤剂量误差外，没有发现测试规则的失败。使用手动技术选择而不是自动曝光控制允许对技术因素进行一致的操作。TLD 允许相对可靠和快速地读取每个曝光，但它们可能是膝关节预设技术曝光读数错误的原因。为了保持一致性，环境和设备保持不变。
结果表明，根据探测器曝光指示器，15%规则和 10kVp 规则都成功地维持或略微提高了图像质量。根据入射皮肤剂量，结果还表明降低了患者剂量。基于这些结果，10kVp 规则可能是 15%规则的合理替代方案。应进行更多重复的进一步研究，包括数字放射摄影设备，以涵盖更广泛的检查范围。
