Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States of America.
Siemens Healthineers, Erlangen, Germany.
Phys Med Biol. 2024 Jul 8;69(14). doi: 10.1088/1361-6560/ad5d4d.
The use of uniform phantoms to assess the influence of x-ray scatter and antiscatter grids on x-ray angiography and fluoroscopy image quality disregards the influence of spatially variable x-ray attenuation of patients. The purpose of this work was to measure scatter to primary ratio (SPR) and antiscatter grid SNR improvement factor () using experimental conditions which better mimic patient imaging conditions.Three adult-sized anthropomorphic phantoms were used. AP and lateral projection images of the thorax and abdomen were acquired with and without an antiscatter grid. Grids with ratio 15:1 and 29:1 (r15, r29) and x-ray fields of view 20, 25 (thorax) and 32, 42 cm (abdomen) were tested. Combined with a-priori measurements of grid scatter and primary transmission fractions, these images were used to calculate 2D SPR andmaps.Results demonstrated that measurements by uniform phantom do not describe the complex 2D SPR anddistributions associated with anthropomorphic phantoms. The regions of the images with the lowest primary x-ray intensity (greatest attenuation) had the highest SPR and the highestattributable to the grids. Considering all conditions, the 95th percentile of the SPR maps was in the range 42%-185% greater than the median values and that of themaps was 4%-20% higher than the median values. The combined influences of SID 120 vs. 107 cm and r29 vs. r15 grid resulted inin the range 1.05-1.49.Performance of anti-scatter grids using anatomically complex phantoms highlights the substantial variation of SPR andwithin 2D images. Also, this work demonstrates the benefit of the prototype r29 grid for thoracic and abdominal angiography imaging conditions is substantial, especially for large patients and radiodense image regions.
使用统一的体模来评估 X 射线散射和防散射栅格对 X 射线血管造影和透视图像质量的影响，忽略了患者空间可变的 X 射线衰减的影响。这项工作的目的是使用更好地模拟患者成像条件的实验条件来测量散射与原射线的比值（SPR）和防散射栅格 SNR 改善因子（）。
使用三个成人大小的人体模型。对胸部和腹部进行前后位和侧位投影成像，分别在使用和不使用防散射栅格的情况下进行。测试了栅格比为 15:1 和 29:1（r15、r29）以及 X 射线视野为 20、25（胸部）和 32、42cm（腹部）的栅格。结合对栅格散射和原射线透射分数的先验测量，这些图像用于计算二维 SPR 和图。
结果表明，使用统一体模的测量不能描述与人体模型相关的复杂二维 SPR 和分布。图像中具有最低原射线强度（最大衰减）的区域具有最高的 SPR 和归因于栅格的 SPR。考虑到所有条件，SPR 图的第 95 百分位数比中位数高 42%-185%，图的第 95 百分位数比中位数高 4%-20%。SID 120 与 107cm 和 r29 与 r15 栅格的综合影响导致范围为 1.05-1.49。
使用解剖结构复杂的体模的防散射栅格的性能突出了 SPR 在二维图像中的显著变化。此外，这项工作还证明了原型 r29 栅格在胸部和腹部血管造影成像条件下的性能有很大的提高，尤其是对于大患者和高对比度的图像区域。
