Background

We investigated the influence of dose, spectral separation, pitch, rotation time, and reconstruction kernel on accuracy and image noise of virtual non-calcium images using a bone marrow phantom.

Methods

The phantom was developed at our institution and scanned using a third-generation dual-source dual-energy CT scanner at five different spectral separations by varying the tube-voltage combinations (70 kV/Sn150 kV, 80 kV/Sn150 kV, 90 kV/Sn150 kV, and 100 kV/Sn150 kV, all with 0.6-mm tin filter [Sn]; 80 kV/140 kV without tin filter) at six different doses (volume computed tomography dose index from 1 to 80 mGy). In separate experiments, rotation times, pitch, and reconstruction kernels were varied at a constant dose and tube voltage. Accuracy was determined by measuring the mean error between virtual non-calcium values in the fluid within and outside of the bone. Image noise was defined as the standard deviation of virtual non-calcium values.

Results

Spectral separation, dose, rotation time, or pitch did not significantly correlate (p > 0.083) with mean error. Increased spectral separation (r_s-0.96, p < 0.001) and increased dose (r_s-0.98, p < 0.001) correlated significantly with decreased image noise. Increasing sharpness of the reconstruction kernel correlated with mean error (r_s 0.83, p = 0.015) and image noise (r_s 1.0, p < 0.001).

Conclusions

Increased dose and increased spectral separation significantly lowered image noise in virtual non-calcium images but did not affect the accuracy. Virtual non-calcium reconstructions with similar accuracy and image noise could be achieved at a lower tube-voltage difference by increasing the dose.

中文翻译：

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优化双能CT扫描参数以实现虚拟的虚拟非钙成像骨髓：一项幻像研究。

背景

我们研究了剂量，光谱分离，间距，旋转时间和重建内核对使用骨髓体模的虚拟非钙图像的准确性和图像噪声的影响。

方法

幻像是在我们的机构开发的，并使用第三代双源双能CT扫描仪通过改变管电压组合（70 kV / Sn150 kV，80 kV / Sn150 kV，90 kV / Sn150 kV和100 kV / Sn150 kV，均具有0.6毫米的锡过滤器[Sn]；无锡过滤器的80 kV / 140 kV，均具有六种不同的剂量（体积计算机断层摄影剂量指数从1到80 mGy）。在单独的实验中，旋转时间，螺距和重建内核在恒定剂量和管电压下发生变化。通过测量骨骼内外流体中虚拟非钙值之间的平均误差来确定准确性。图像噪声定义为虚拟非钙值的标准偏差。

结果

光谱分离，剂量，旋转时间或螺距 与平均误差没有显着相关性（p > 0.083）。增加的频谱分离（ř_小号-0.96，p  <0.001）和增加的剂量（ř_小号-0.98，p  <0.001）具有降低的图像噪声显著相关。重建内核清晰度的提高与平均误差（r _s 0.83，p  = 0.015）和图像噪声（r _s 1.0，p  <0.001）相关。

结论

增加剂量和增加光谱分离可显着降低虚拟非钙图像中的图像噪声，但不会影响准确性。通过增加剂量，可以在较低的管电压差下实现具有相似精度和图像噪声的虚拟非钙重建。