Nosratieh Anita, Hernandez Andrew, Shen Sam Z, Yaffe Martin J, Seibert J Anthony, Boone John M
Department of Radiology, Biomedical Engineering Graduate Group, University of California Davis, CA 95616, USA.
Phys Med Biol. 2015 Sep 21;60(18):7179-90. doi: 10.1088/0031-9155/60/18/7179. Epub 2015 Sep 8.
To develop tables of normalized glandular dose coefficients D(g)N for a range of anode-filter combinations and tube voltages used in contemporary breast imaging systems. Previously published mono-energetic D(g)N values were used with various spectra to mathematically compute D(g)N coefficients. The tungsten anode spectra from TASMICS were used; molybdenum and rhodium anode-spectra were generated using MCNPX Monte Carlo code. The spectra were filtered with various thicknesses of Al, Rh, Mo or Cu. An initial half value layer (HVL) calculation was made using the anode and filter material. A range of the HVL values was produced with the addition of small thicknesses of polymethyl methacrylate (PMMA) as a surrogate for the breast compression paddle, to produce a range of HVL values at each tube voltage. Using a spectral weighting method, D(g)N coefficients for the generated spectra were calculated for breast glandular densities of 0%, 12.5%, 25%, 37.5%, 50% and 100% for a range of compressed breast thicknesses from 3 to 8 cm. Eleven tables of normalized glandular dose (D(g)N) coefficients were produced for the following anode/filter combinations: W + 50 μm Ag, W + 500 μm Al, W + 700 μm Al, W + 200 μm Cu, W + 300 μm Cu, W + 50 μm Rh, Mo + 400 μm Cu, Mo + 30 μm Mo, Mo + 25 μm Rh, Rh + 400 μm Cu and Rh + 25 μm Rh. Where possible, these results were compared to previously published D(g)N values and were found to be on average less than 2% different than previously reported values.Over 200 pages of D(g)N coefficients were computed for modeled x-ray system spectra that are used in a number of new breast imaging applications. The reported values were found to be in excellent agreement when compared to published values.
为一系列当代乳腺成像系统中使用的阳极-滤过组合和管电压制定归一化腺体剂量系数D(g)N表。以前公布的单能D(g)N值与各种能谱一起用于通过数学计算得出D(g)N系数。使用了TASMICS中的钨阳极能谱；钼和铑阳极能谱使用MCNPX蒙特卡罗代码生成。能谱用不同厚度的铝、铑、钼或铜进行滤过。使用阳极和滤过材料进行初始半价层（HVL）计算。通过添加小厚度的聚甲基丙烯酸甲酯（PMMA）作为乳房压迫板的替代物来产生一系列HVL值，以便在每个管电压下产生一系列HVL值。使用光谱加权方法，针对3至8厘米范围内一系列压缩乳房厚度，计算了0%、12.5%、25%、37.5%、50%和100%乳房腺体密度下生成能谱的D(g)N系数。针对以下阳极/滤过组合生成了11张归一化腺体剂量（D(g)N）系数表：W + 50μm银、W + 500μm铝、W + 700μm铝、W + 200μm铜、W + 300μm铜、W + 50μm铑、Mo + 400μm铜、Mo + 30μm钼、Mo + 25μm铑、Rh + 400μm铜和Rh + 25μm铑。在可能的情况下，将这些结果与以前公布的D(g)N值进行比较，发现平均与以前报告的值相差不到2%。针对许多新的乳腺成像应用中使用的建模X射线系统能谱，计算了超过200页的D(g)N系数。与已发表的值相比，报告的值显示出极佳的一致性。
