Size-specific dose estimation (SSDE) is suggested for accurate measurement of CT dose. Various methods have been developed for SSDE calculation by both manual and automated methods. However, truncation artefact may affect the specific size determination and SSDE calculation. In this article, we evaluate how truncation affects measurements of SSDE and compare the manual SSDE measurement based on individual sizes (effective diameter, D and water equivalent diameter, D) with the automated calculation using IndoseCT software on truncated CT images. A phantom study was conducted using Siemens SOMATOM Definition AS + CT scanner with two CTDI phantoms of different sizes, 22 cm and 32 cm. Phantom images were acquired by varying the phantom positioning to simulate truncation percentages (TP) of 5%, 10%, 15%, and 20%. The SSDE values were manually calculated based on the D and D methods (AAPM, 2014). SSDE was also calculated automatically using IndoseCT software (Version 20 b) and compared with manual calculation. The percentage error due to different TP was calculated in comparison to the non-truncated image (TP 0%). The errors due to truncation on SSDE calculation was also compared between both manual and automated methods. Statistical analysis was carried out to determine the statistical differences and correlation. The findings show that D for non-truncated image yields better results with lower percentage errors (mean PE = 0.75% and mean PE = 0.14%) as compared to D (mean PE = 6.11% and mean PE = 5.81%). There is a positive strong correlation between percentage error and truncation percentage. There are strong positive correlations between TP and percentage error, PE (r = 0.96 and r = 0.94) in determination of SSDE and SSDE, respectively. D approach resulted higher percentage error as compared to D. Truncation is strongly correlated with SSDE calculation, and therefore correction for truncation artefact is crucial to minimise error in SSDE measurement. The automated calculation of SSDE can be confidently replaced the manual method in both D and D approaches to ensure rapid and accurate SSDE measurement.

中文翻译：

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截断 CT 图像上基于 Deff 和 Dw 方法的手动计算 SSDE 与 IndoseCT 计算 SSDE 的比较

建议使用特定尺寸剂量估计 (SSDE) 来准确测量 CT 剂量。 SSDE 计算已经开发出多种手动和自动方法。然而，截断伪影可能会影响具体大小的确定和SSDE计算。在本文中，我们评估截断如何影响 SSDE 的测量，并将基于个体尺寸（有效直径 D 和水当量直径 D）的手动 SSDE 测量与使用 IndoseCT 软件在截断 CT 图像上自动计算进行比较。使用西门子 SOMATOM Definition AS + CT 扫描仪和两个不同尺寸（22 厘米和 32 厘米）的 CTDI 模型进行模型研究。通过改变模型定位以模拟 5%、10%、15% 和 20% 的截断百分比 (TP) 来获取模型图像。 SSDE值是根据D和D方法手动计算的（AAPM，2014）。 SSDE 还使用 IndoseCT 软件（版本 20 b）自动计算，并与手动计算进行比较。与未截断图像 (TP 0%) 相比，计算了由于不同 TP 导致的百分比误差。还比较了手动方法和自动方法之间因 SSDE 计算截断而产生的误差。进行统计分析以确定统计差异和相关性。研究结果表明，与 D（平均 PE = 6.11% 和平均 PE = 5.81%）相比，非截断图像的 D 产生更好的结果，且百分比误差更低（平均 PE = 0.75% 和平均 PE = 0.14%）。百分比误差和截断百分比之间存在正相关性。在确定 SSDE 和 SSDE 时，TP 和百分比误差 PE（r = 0.96 和 r = 0.94）之间存在很强的正相关性。与 D 相比，D 方法产生更高的百分比误差。截断与 SSDE 计算密切相关，因此截断伪影的校正对于最小化 SSDE 测量中的误差至关重要。 SSDE的自动计算可以放心地取代D和D方法中的手动方法，以确保快速准确的SSDE测量。