Estimation of mean glandular dose for contrast enhanced digital mammography: factors for use with the UK, European and IAEA breast dosimetry protocols
Estimation of mean glandular dose for contrast enhanced digital mammography: factors for use with the UK, European and IAEA breast dosimetry protocols
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DOI：
10.1088/0031-9155/59/9/2127
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发表时间：
2014-05-07
影响因子：
3.5
通讯作者：
Young, K. C.
中科院分区：
文献类型：
--
作者：
Dance, D. R.;Young, K. C.
英国、欧洲和国际原子能机构关于乳房X线摄影中乳房剂量测定的协议使用转换因子表，将入射空气比释动能的测量值与乳房的平均腺体剂量联系起来。为了补充现有的表格，已经使用蒙特卡罗计算机程序来计算用于对比度增强数字乳腺X射线摄影的高能光谱的转换因子。计算了钨靶（管电压范围40-50 kV）经0.28、0.30和0.32 mm铜过滤的X射线光谱，以及钼和铑靶（管电压范围40-49 kV）经0.30 mm铜过滤的X射线光谱。将所有这些光谱的g因子绘制为每个乳房厚度的半值层（HVL）的函数，并发现其位于0.3%以内的平滑曲线上。这反映了钼和铑光谱中存在的特征X射线被严重过滤的事实，所有光谱基本上都是韧致辐射。因此，之前在剂量测定方案中用于调整不同目标/过滤器组合的s因子可以被视为所有考虑的光谱的统一。提供了乳房厚度在20 - 110 mm范围内和铝HVL在2.4-3.6 mm范围内的g系数和c系数表。对于参加英国国家乳腺筛查计划的40-49岁和50-64岁年龄段的女性，给出了0.1%-100%范围内乳腺腺体和典型腺体的c因子表。
The UK, European and IAEA protocols for breast dosimetry in mammography use tabulations of conversion factors, which relate measurements of incident air kerma to the mean glandular dose to the breast. To supplement the existing tabulations, a Monte Carlo computer program has been used to calculate conversion factors for the high-energy spectra used for contrast enhanced digital mammography. The calculations were made for the x-ray spectra from a tungsten target (tube voltage range 40-50 kV) filtered by 0.28, 0.30 and 0.32 mm of copper, and from molybdenum and rhodium targets (tube voltage range 40-49 kV), each filtered by 0.30 mm of copper. The g-factors for all of these spectra were plotted for each breast thickness as a function of half value layer (HVL) and were found to lie on smooth curves within 0.3%. These reflect the fact that the characteristic x-rays present in the spectra from molybdenum and rhodium are heavily filtered and all the spectra are essentially Bremsstrahlung. As a consequence, the s-factor previously used in the dosimetry protocols to adjust for different target/filter combinations can be taken as unity for all of the spectra considered. Tables of g-factors and c-factors are provided for breast thicknesses in the range 20110 mm and HVLs in the range 2.4-3.6 mm of aluminium. The tables of c-factors are given for breast glandularities in the range 0.1%-100% and for typical glandularities for women in the age bands 40-49 and 50-64 attending the UK national breast screening programme.