Evaluation of the effect of chest wall thickness, tissue composition, and photon energy on the quantity muscle-equivalent chest-wall-thickness by Monte Carlo simulation
Evaluation of the effect of chest wall thickness, tissue composition, and photon energy on the quantity muscle-equivalent chest-wall-thickness by Monte Carlo simulation
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DOI：
10.1093/oxfordjournals.rpd.a032612
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发表时间：
1999-01-01
影响因子：
1
通讯作者：
Burns, LC
中科院分区：
文献类型：
--
作者：
Kramer, GH;Burns, LC
蒙特卡罗模拟已被用来推导计数效率和胸壁厚度和脂肪质量分数之间的关系，作为光子能量的函数。脂肪质量分数可以通过使用导出的量肌肉等效胸壁厚度来消除，从而简化关系。因此，任何脂肪质量分数的计数效率都可以从计数效率对肌肉等效胸壁厚度的单个指数图中预测;因此，没有必要为不同的脂肪质量分数值绘制一系列曲线。由于受试者脂肪质量分数的测量以及受试者胸部（肋骨、软骨）与体模之间的差异导致的不均匀性无法通过使用肌肉等效胸壁厚度来消除。脂肪的质量分数的测量是重要的，只有17千电子伏的光子，可以忽略光子能量大于40千电子伏。
Monte Carlo simulations have been used to derive the relationship between the counting efficiency and both the chest wall thickness and adipose mass fraction as a function of photon energy. Adipose mass fraction can be eliminated by the use of the derived quantity muscle-equivalent chest wall thickness and thus simplify the relationship. As a result, the counting efficiency at any adipose mass fraction can be predicted from a single exponential plot of counting efficiency against muscle-equivalent chest wall thickness; therefore, it is unnecessary to have a family of curves for different adipose mass fraction values. Uncertainties due to the measurement of the subject's adipose mass fraction and the difference between the subject's chest (ribs, cartilage) compared to the phantom cannot be eliminated by the use of muscle-equivalent chest wall thickness. Adipose mass fraction measurements are only important for 17 keV photons and can be neglected at photon energies greater than 40 keV.