Dose Is Not Always What It Seems: Where Very Misleading Values Can Result From Volume CT Dose Index and Dose Length Product
Dose Is Not Always What It Seems: Where Very Misleading Values Can Result From Volume CT Dose Index and Dose Length Product
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DOI：
10.1016/j.jacr.2013.10.010
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发表时间：
2014-03-01
影响因子：
4.5
通讯作者：
Lamba, Ramit
中科院分区：
文献类型：
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作者：
Seibert, J. Anthony;Boone, John M.;Lamba, Ramit
目的：体积CT剂量指数（CTDIvol）和剂量长度产品，通常报告在临床CT扫描仪上进行的检查，不应作为患者剂量的替代品。这是因为当患者的实际体型与直径16厘米或32厘米的CTDIvol幻象不匹配时，可能会出现对这些实际值的严重低估或高估。由于一些制造商使用大直径假体而另一些制造商使用小直径假体作为CTDIvol参考假体，因此在儿童身体检查中这种不匹配可能会加剧。方法：描述了一个儿科患者的临床例子，尽管患者实际吸收的剂量大致相同，但术前CT检查与术后CT检查的CTDIvol相差4倍。使用美国医学物理学家协会发表的方法，我们计算了尺寸特异性剂量估计值（SSDE），并将SSDE估计值与CTDIvol进行了比较。结果：使用SSDE显著降低了临床研究中CTDIvol辐射剂量估计的差异，使扫描仪之间的剂量估计比较更有意义。结论：当使用SSDE度量代替CTDIvol度量来报告和比较患者剂量指数时，辐射剂量估计更准确。
Purpose: The volume CT dose index (CTDIvol) and the dose-length product, commonly reported for examinations performed on clinical CT scanners, should not be used as surrogates for patient dose. This is because significant under or overestimates of these actual values can occur when there is a mismatch between the actual body size of the patient and the 16 cm or 32 cm diameter CTDIvol phantoms. This mismatch can be exacerbated in pediatric body examinations because of the fact that some manufacturers use the large diameter phantom while other manufacturers use the small diameter phantom as the CTDIvol reference phantom.Method: A clinical example is described for a pediatric patient with a 4-fold difference in CTDIvol between a presurgical CT examination and a postsurgical CT examination, even though the actual dose absorbed by the patient was about the same. Using methods published by the American Association of Physicists in Medicine, we calculated the size-specific dose estimate (SSDE), and compared the estimated measurement of dose using the SSDE with the CTDIvol.Results: Using SSDE significantly reduced the discrepancy in radiation dose estimates of CTDIvol in the clinical study, and allowed dose estimate comparisons between scanners to be more meaningful.Conclusions: Radiation dose estimates are more accurate when using the SSDE metric in lieu of the CTDIvol metric for reporting and comparing patient dose indices.