Mackenzie Alistair, Boita Joana, Dance David R, Young Kenneth C
Royal Surrey NHS Foundation Trust, National Coordinating Centre for the Physics of Mammography, Guildford, United Kingdom.
Radboud University Medical Centre, Department of Medical Imaging, Nijmegen, The Netherlands.
J Med Imaging (Bellingham). 2022 May;9(3):033504. doi: 10.1117/1.JMI.9.3.033504. Epub 2022 Jun 8.
We set out a fully developed algorithm for adapting mammography images to appear as if acquired using different technique factors by changing the signal and noise within the images. The algorithm accounts for difference between the absorption by the object being imaged and the imaging system. Images were acquired using a Hologic Selenia Dimensions x-ray unit for the validation, of three thicknesses of polymethyl methacrylate (PMMA) blocks with or without different thicknesses of PMMA contrast objects acquired for a range of technique factors. One set of images was then adapted to appear the same as a target image acquired with a higher or lower tube voltage and/or a different anode/filter combination. The average linearized pixel value, normalized noise power spectra (NNPS), and standard deviation of the flat field images and the contrast-to-noise ratio (CNR) of the contrast object images were calculated for the simulated and target images. A simulation study tested the algorithm on images created using a voxel breast phantom at different technique factors and the images compared using local signal level, variance, and power spectra. The average pixel value, NNPS, and standard deviation for the simulated and target images were found to be within 9%. The CNRs of the simulated and target images were found to be within 5% of each other. The differences between the target and simulated images of the voxel phantom were similar to those of the natural variability. We demonstrated that images can be successfully adapted to appear as if acquired using different technique factors. Using this conversion algorithm, it may be possible to examine the effect of tube voltage and anode/filter combination on cancer detection using clinical images.
我们开发了一种完善的算法，通过改变乳腺钼靶图像中的信号和噪声，使其看起来像是使用不同技术参数采集的。该算法考虑了被成像物体与成像系统吸收之间的差异。使用Hologic Selenia Dimensions X射线设备采集图像进行验证，针对三种厚度的聚甲基丙烯酸甲酯（PMMA）块，在一系列技术参数下采集有无不同厚度PMMA对比物体的图像。然后将一组图像调整为与使用更高或更低管电压和/或不同阳极/滤过组合采集的目标图像相同。计算模拟图像和目标图像的平均线性化像素值、归一化噪声功率谱（NNPS）、平场图像的标准差以及对比物体图像的对比噪声比（CNR）。一项模拟研究在不同技术参数下使用体素乳房模型创建的图像上测试了该算法，并使用局部信号水平、方差和功率谱对图像进行比较。发现模拟图像和目标图像的平均像素值、NNPS和标准差在9%以内。发现模拟图像和目标图像的CNR彼此相差在5%以内。体素模型的目标图像和模拟图像之间的差异与自然变异性的差异相似。我们证明了图像可以成功调整，使其看起来像是使用不同技术参数采集的。使用这种转换算法，有可能利用临床图像研究管电压和阳极/滤过组合对癌症检测的影响。
