Department of Epidemiology and Biostatistics, University of California San Francisco, 550 16Th Street, San Francisco, CA, 94158, USA.
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, CA, USA.
Eur Radiol. 2024 Apr;34(4):2394-2404. doi: 10.1007/s00330-023-10076-6. Epub 2023 Sep 21.
To characterize the use and impact of radiation dose reduction techniques in actual practice for routine abdomen CT.
We retrospectively analyzed consecutive routine abdomen CT scans in adults from a large dose registry, contributed by 95 hospitals and imaging facilities. Grouping exams into deciles by, first, patient size, and second, size-adjusted dose length product (DLP), we summarized dose and technical parameters and estimated which parameters contributed most to between-protocols dose variation. Lastly, we modeled the total population dose if all protocols with mean size-adjusted DLP above 433 or 645 mGy-cm were reduced to these thresholds.
A total of 748,846 CTs were performed using 1033 unique protocols. When sorted by patient size, patients with larger abdominal diameters had increased dose and effective mAs (milliampere seconds), even after adjusting for patient size. When sorted by size-adjusted dose, patients in the highest versus the lowest decile in size-adjusted DLP received 6.4 times the average dose (1680 vs 265 mGy-cm) even though diameter was no different (312 vs 309 mm). Effective mAs was 2.1-fold higher, unadjusted CTDI 2.9-fold, and phase 2.5-fold for patients in the highest versus lowest size-adjusted DLP decile. There was virtually no change in kV (kilovolt). Automatic exposure control was widely used to modulate mAs, whereas kV modulation was rare. Phase was the strongest driver of between-protocols variation. Broad adoption of optimized protocols could result in total population dose reductions of 18.6-40%.
There are large variations in radiation doses for routine abdomen CT unrelated to patient size. Modification of kV and single-phase scanning could result in substantial dose reduction.
Radiation dose-optimization techniques for routine abdomen CT are routinely under-utilized leading to higher doses than needed. Greater modification of technical parameters and number of phases could result in substantial reduction in radiation exposure to patients.
• Based on an analysis of 748,846 routine abdomen CT scans in adults, radiation doses varied tremendously across patients of the same size and optimization techniques were routinely under-utilized. • The difference in observed dose was due to variation in technical parameters and phase count. Automatic exposure control was commonly used to modify effective mAs, whereas kV was rarely adjusted for patient size. Routine abdomen CT should be performed using a single phase, yet multi-phase was common. • kV modulation by patient size and restriction to a single phase for routine abdomen indications could result in substantial reduction in radiation doses using well-established dose optimization approaches.
描述实际常规腹部 CT 中使用和影响辐射剂量降低技术的情况。
我们回顾性分析了一个大型剂量登记处来自 95 家医院和影像设施的连续成人常规腹部 CT 扫描。我们首先根据患者体型，其次根据体型调整后的剂量长度乘积（DLP），将检查分为 10 个十进制组，总结剂量和技术参数，并估计哪些参数对协议间剂量变化的影响最大。最后，如果所有平均体型调整后的 DLP 高于 433 或 645 mGy-cm 的协议都降低到这些阈值，我们将对总人群剂量进行建模。
共使用 1033 个独特协议进行了 748846 次 CT 检查。当按患者体型排序时，即使在按体型调整后，腹部直径较大的患者剂量和有效毫安秒（milliampere seconds）也会增加。当按体型调整后的剂量排序时，体型调整后的 DLP 最高与最低十分位数的患者接受的平均剂量相差 6.4 倍（1680 与 265 mGy-cm），尽管直径没有差异（312 与 309 mm）。有效毫安秒高 2.1 倍，未调整的 CTDI 高 2.9 倍，体型调整后的 DLP 最高与最低十分位数的患者相位高 2.5 倍。千伏（kV）几乎没有变化。自动曝光控制被广泛用于调节毫安秒，而千伏调节则很少。相位是协议间变化的最强驱动因素。广泛采用优化的协议可以使总人群剂量减少 18.6-40%。
常规腹部 CT 的辐射剂量存在与患者体型无关的较大差异。kV 和单相扫描的修改可导致剂量大幅降低。
常规腹部 CT 的辐射剂量优化技术通常未得到充分利用，导致剂量高于所需剂量。更多地修改技术参数和相位数可使患者的辐射暴露量大幅减少。
根据对 748846 例成人常规腹部 CT 扫描的分析，相同体型的患者之间的辐射剂量差异巨大，而且优化技术的应用通常不足。
观察到的剂量差异是由于技术参数和相位数的变化。自动曝光控制常用于调整有效毫安秒，而千伏则很少根据患者体型进行调整。
对患者进行体型调节 kV 和限制常规腹部 CT 为单相扫描，同时采用已建立的剂量优化方法，可使辐射剂量大幅降低。
