In AAPM Report 291, “Principles and applications of multienergy CT: Report of AAPM Task Group 291,”¹ scientists from Canon Medical Systems Corporation, GE Healthcare Technologies, Philips Healthcare, and Siemens Healthcare GmbH participated as authors and contributed sections to describe, in general, the technology used in their company’s dual- or multi-energy CT systems. Specific scanner models were sometimes mentioned to provide examples of the overall approach. The general statements made about the approach may not, however, apply to the specific scanner model used as an example. The intermingling of the general and specific statements is regrettable, as it is ready source of potential confusion.

Readers should view each section as a description of an overall dual- or multi-energy CT approach, even if a specific scanner model is mentioned as an example. Readers should refer to manufacturer specifications and the published literature to assess the specifications and performance of a specific CT system.

A numerical error exists on page e895 in the second paragraph of the limitations section for kV switching. The statement “… so the system software currently prevents the use of gantry rotation times of less than approximately 500 ms, which may limit the quality of cardiac examinations,” implies that a minimum 500 ms rotation time applies to the scanner used as an example in the kV switching setting (GE Discovery CT750 HD). However, this value (500 msec) does not reflect the minimum rotation time on the GE Discovery CT750 HD. Rather, from the earliest publications on the use of this specific CT scanner model for dual-energy cardiac imaging, the minimum rotation time of 350 ms was used.^{2, 3}

The second and third paragraphs in this same section on the limitations of kV switching reiterate the physics principles discussed on page e894, at the top of the second. Namely, as first demonstrated in 1979 by Kelcz et al., decreased spectral separation causes increased noise in decomposed material-specific images.⁴ In 2009, Primak et al. demonstrated that tube-specific filtration can increase spectral separation and decrease image noise in material decomposed images using a commercial dual-source CT system.⁵ While spectral separation is indeed an important determinant of the underlying noise properties of the acquired data, noise reduction methods can be applied such that the material decomposition calculations performed using kV switching (or other non-dual-source approaches) can also yield accurate quantification of iodine concentration.⁶

在AAPM报告291“多能CT的原理和应用：AAPM任务组291的报告”中，来自佳能医疗系统公司，GE Healthcare Technologies，Philips Healthcare和Siemens Healthcare GmbH的^1位科学家作为作者参加了会议，并提供了部分内容来描述：通常，在他们公司的双能或多能CT系统中使用的技术。有时会提到特定的扫描仪型号，以提供整体方法的示例。但是，有关此方法的一般性声明可能不适用于作为示例的特定扫描仪模型。一般陈述和具体陈述的混杂令人遗憾，因为这很容易引起潜在的混乱。

读者应将每个部分视为对整体双能量或多能量CT方法的描述，即使以特定的扫描仪型号为例。读者应参考制造商的规格和出版的文献，以评估特定CT系统的规格和性能。

kV切换的限制部分第二部分的e895页上存在数字错误。语句“……因此，系统软件当前阻止使用小于500毫秒的龙门架旋转时间，这可能会限制心脏检查的质量”，这意味着至少有500毫秒的旋转时间适用于扫描仪，例如kV开关设置（GE Discovery CT750 HD）。但是，此值（500毫秒）不反映GE Discovery CT750 HD的最短旋转时间。确切地说，从最早使用此特定CT扫描仪模型进行双能心脏成像的出版物中，可以使用最少350 ms的旋转时间。^{2 3}

同一部分中有关kV开关限制的第二段和第三段重申了第二段顶部第e894页讨论的物理原理。即，如Kelcz等人在1979年首次证明的那样，减少的光谱分离会导致分解的特定于材料的图像中的噪声增加。⁴ 2009年，Primak等人。证明了使用商业化双源CT系统进行管子特有的过滤可以增加材料分离图像中的光谱分离并降低图像噪声。⁵虽然频谱分离确实是获取数据的基本噪声特性的重要决定因素，但可以应用降噪方法，以便使用kV开关（或其他非双源方法）进行的材料分解计算也可以对噪声进行准确的量化。碘浓度。⁶