Homolka Peter, Leithner Robert, Billinger Jochen, Gruber Michael
Zentrum für Medizinische Physik und Biomedizinische Technik, Medizinische Universität Wien, Währinger Gürtel 18-20, A-1090 Wien, Österreich.
Zentrum für Medizinische Physik und Biomedizinische Technik, Medizinische Universität Wien, Währinger Gürtel 18-20, A-1090 Wien, Österreich.
Z Med Phys. 2014 Sep;24(3):224-30. doi: 10.1016/j.zemedi.2013.12.005. Epub 2014 Jan 17.
To determine typical doses from common CT examinations of standard sized adult patients and their variability between CT operators for common CT indications.
In a nationwide Austrian CT dose survey doses from approx. 10,000 common CT examinations of adults during 2009 and 2010 were collected and "typical" radiation doses to the "average patient", which turned out to have 75.6kg body mass, calculated. Conversion coefficients from DLP to effective dose were determined and effective doses calculated according to ICRP 103. Variations of typically applied doses to the "average patient" were expressed as ratios between 90(th) and 10(th) percentile (inter-percentile width, IPW90/10), 1(st) and 3(rd) quartile (IPW75/25), and Maximum/Minimum.
Median effective doses to the average patients for standard head and neck scans were 1.8 mSv (cervical spine), 1.9 mSv (brain: trauma/bleeding, stroke) to 2.2 mSv (brain: masses) with typical variation between facilities of a factor 2.5 (IPW90/10) and 1.7 (IPW75/25). In the thorax region doses were 6.4 to 6.8 mSv (pulmonary embolism, pneumonia and inflammation, oncologic scans), the variation between facilities was by a factor of 2.1 (IPW90/10) and 1.5 (IPW75/25), respectively. In the abdominal region median effective doses from 6.5 mSv (kidney stone search) to 22 mSv (liver lesions) were found (acute abdomen, staging/metastases, lumbar spine: 9-12 mSv; oncologic abdomen plus chest 16 mSv; renal tumor 20 mSv). Variation factors between facilities were on average for abdominal scans 2.7 (IPW90/10) and 1.8 (IPW75/25).
Variations between CT operators are generally moderate for most operators, but in some indications the ratio between the minimum and the maximum of average dose to the typical standard patients exceeds a factor of 4 or even 5. Therefore, comparing average doses to Diagnostic Reference Levels (DRLs) and optimizing protocols need to be encouraged.
确定标准体型成年患者常见CT检查的典型剂量及其在不同CT操作人员之间对于常见CT适应症的变异性。
在奥地利全国范围内的CT剂量调查中，收集了2009年至2010年期间约10,000例成人常见CT检查的剂量，并计算了对“平均患者”（其体重为75.6kg）的“典型”辐射剂量。确定了从剂量长度乘积（DLP）到有效剂量的转换系数，并根据国际辐射防护委员会（ICRP）第103号出版物计算有效剂量。对“平均患者”通常应用剂量的变化表示为第90百分位数与第10百分位数之间的比值（百分位数间距，IPW90/10）、第1四分位数与第3四分位数之间的比值（IPW75/25）以及最大值/最小值。
标准头部和颈部扫描对平均患者的中位有效剂量为：颈椎1.8 mSv，脑部（创伤/出血、中风）1.9 mSv至脑部（肿块）2.2 mSv，不同设备之间的典型变异性为2.5倍（IPW90/10）和1.7倍（IPW75/25）。在胸部区域，剂量为6.4至6.8 mSv（肺栓塞、肺炎和炎症、肿瘤扫描），不同设备之间的变异性分别为2.1倍（IPW90/10）和1.5倍（IPW75/25）。在腹部区域，发现中位有效剂量从6.5 mSv（肾结石检查）到22 mSv（肝脏病变）不等（急腹症、分期/转移、腰椎：9 - 12 mSv；腹部加胸部肿瘤扫描16 mSv；肾肿瘤20 mSv）。腹部扫描不同设备之间的变异系数平均为2.7（IPW90/10）和1.8（IPW75/25）。
对于大多数操作人员来说，CT操作人员之间的变异性通常较为适中，但在某些适应症中，对典型标准患者的平均剂量最小值与最大值之比超过4倍甚至5倍。因此，应鼓励将平均剂量与诊断参考水平（DRL）进行比较并优化检查方案。
