BACKGROUND:Digital radiography (DR) is grayscale adjustable and it can be unclear whether an acquired DR image is captured with the minimum radiation dose required. It is necessary to make an image of the amount of noise when taken at a lower dose than the acquired image, without increased exposure. OBJECTIVE:To examine whether an image of unacquired dose can be created from two types of dose DR images acquired using a phantom. METHODS:To create an additive image from two images of different doses, the pixel value of one image is multiplied by a coefficient and added to the other. The normalized noise power spectra (NNPS) of the normal image and the additive image with the same signal-to-noise ratio (SNR) are compared. The image noise of the unacquired doses is estimated from the graph changes of the pixel values and standard deviations of two images. The error between the SNR of the image obtained by changing the dose and the estimated SNR is measured. We propose a multiplication coefficient calculation formula that theoretically adjusts the additive image to the target SNR. The SNR error of the image created based on this formula is measured. RESULTS:The NNPS curves of the additive and normal images show a difference on the high frequency side. According to the statistics considering the preset of mAs value, there is no significant difference at 85%. The SNR estimation error is approximately 1%. The SNR error of the additive image created based on the formula is approximately 5%. CONCLUSION:The noise of the image of unacquired dose can be estimated, and the additive image adjusted to this value can be considered equivalent to the image taken at the actual dose.

中文翻译：

---

从数字射线照相中的两种剂量图像创建未获取剂量图像的检查

背景：数字射线照相 (DR) 是灰度可调的，并且不清楚所获得的 DR 图像是否是在所需的最小辐射剂量下捕获的。当以低于所获取图像的剂量拍摄时，有必要在不增加曝光的情况下制作噪声量的图像。目的：检查是否可以从使用体模获取的两种类型的剂量 DR 图像中创建未获取剂量的图像。方法：为了从两张不同剂量的图像中创建一个相加图像，将一张图像的像素值乘以一个系数并与另一张图像相加。比较具有相同信噪比（SNR）的正常图像和加性图像的归一化噪声功率谱（NNPS）。未获取剂量的图像噪声是根据两个图像的像素值和标准偏差的图形变化来估计的。测量通过改变剂量获得的图像的 SNR 与估计的 SNR 之间的误差。我们提出了一种乘法系数计算公式，理论上将加法图像调整为目标 SNR。测量基于此公式创建的图像的 SNR 误差。结果：加性图像和正常图像的NNPS曲线在高频侧存在差异。根据 mAs 值的预设统计，在 85% 时没有显着差异。SNR 估计误差约为 1%。基于公式创建的叠加图像的 SNR 误差约为 5%。结论：未获得剂量图像的噪声可以估计，