Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan; Department of Radiography & Radiotherapy, Faculty of Allied Health Sciences, General Sir John Kotelawala Defence University, Werahera, Sri Lanka.
Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan; Department of Radiology, Juntendo University Shizuoka Hospital, Japan.
Radiography (Lond). 2022 May;28(2):340-347. doi: 10.1016/j.radi.2021.11.004. Epub 2021 Nov 24.
The aim of this study was to evaluate mean glandular dose (MGD) and image quality in low energy imaging from contrast-enhanced spectral mammography (CESM) when using double-layer filtration.
A dedicated phantom was used to quantitatively estimate the MGD and image quality. The target slab of the phantom consisted of three iodine coins having a concentration of 1.0 mgI/cm, 2.0 mgI/cm, 4.0 mgI/cm, a 100% adipose equivalent coin and a 100% glandular equivalent coin. The phantom was exposed using a semiautomated function at 28 k, 30 kV and 32 kV. MGD. Contrast to noise ratio (CNR) and figure of merit (FOM) were estimated for Mo/Rh, Mo/Rh + Cu, Mo/Rh + Al and Mo/Rh + Cd combinations using three breast equivalent compositions.
MGD was reduced up to a maximum of 1.03 mGy from 1.17 mGy for 100% adipose tissue. 1.18 mGy from 1.34 mGy for 50% glandular tissue and 1.39 mGy from 1.72 mGy for the 100% glandular phantom when using double-layer filtration. All of the above-mentioned results were obtained for the 50 mm phantom using 32 kV. CNR and FOM values were not significantly reduced with a double-layer filter when compared to a single-layer filter.
The present study concluded that Mo/Rh + Cu is the best combination to reduce the MGD significantly when compared to Mo/Rh + Al or Mo/Rh + Cd. Mo/Rh + Cu also achieved optimal image quality when compared to the Mo/Rh single filter combination.
The use of a double-layer filter in low energy imaging of CESM results in a significant reduction in MGD without degrading the quality of the image.
本研究旨在评估对比增强能谱乳腺摄影（CESM）中使用双层滤过时低能成像的平均腺体剂量（MGD）和图像质量。
使用专用模体定量估计 MGD 和图像质量。模体的靶板由三个碘币组成，浓度分别为 1.0 mgI/cm、2.0 mgI/cm、4.0 mgI/cm、100%脂肪等效币和 100%腺体等效币。模体在 28 k、30 kV 和 32 kV 下使用半自动功能进行曝光。使用三种乳腺等效组成物，对 Mo/Rh、Mo/Rh+Cu、Mo/Rh+Al 和 Mo/Rh+Cd 组合分别估计 MGD、对比噪声比（CNR）和品质因数（FOM）。
当使用双层滤过时，对于 100%脂肪组织，MGD 从 1.17 mGy 降低到 1.03 mGy，最大降低 1.03 mGy；对于 50%腺体组织，MGD 从 1.34 mGy 降低到 1.18 mGy，最大降低 0.16 mGy；对于 100%腺体模体，MGD 从 1.72 mGy 降低到 1.39 mGy，最大降低 0.33 mGy。所有上述结果均使用 32 kV 和 50mm 模体获得。与单层滤过相比，使用双层滤过时 CNR 和 FOM 值没有明显降低。
本研究得出结论，与 Mo/Rh+Al 或 Mo/Rh+Cd 相比，Mo/Rh+Cu 是降低 MGD 的最佳组合。与 Mo/Rh 单滤过组合相比，Mo/Rh+Cu 还实现了最佳的图像质量。
在 CESM 的低能成像中使用双层滤过可显著降低 MGD，而不会降低图像质量。
