Sandborg M, Dance D R, Carlsson G A, Persliden J
Department of Radiation Physics, Faculty of Health Sciences, Linköping University, Sweden.
Br J Radiol. 1993 Dec;66(792):1151-63. doi: 10.1259/0007-1285-66-792-1151.
A Monte Carlo computer program has been developed for the study of anti-scatter grids used in diagnostic radiology. The program estimates the scatter from soft tissue phantoms representative of either adult or paediatric examinations and uses dose increase, signal-to-noise ratio improvement and contrast improvement factors to study grid performance. It has been used to quantify the advantage of replacing grids with aluminium covers and interspaces by grids using materials of low atomic number for these components. Two approaches are used. First, the aluminium and low atomic number alternatives are compared for five grid ratios at fixed strip density and width and for tube potentials of 50, 70, 100 and 150 kV. Second, 44 commercially available grids are compared for three different imaging situations (lumbar spine, chest and paediatric). The results demonstrate that grids made with carbon fibre cover and cotton fibre interspace result in greater improvements in contrast and signal-to-noise ratio, and lower dose increase factors, than do grids made with aluminium. The dose reduction varies with irradiation conditions and is generally larger at lower tube potentials, higher grid ratios and lower strip densities. A typical reduction in mean absorbed dose in the patient is 30% in an adult lumbar spine (AP view) at 70 kV with a grid with 36 strips per centimetre and ratio 12.
已开发出一个蒙特卡罗计算机程序，用于研究诊断放射学中使用的反散射格栅。该程序估计来自代表成人或儿科检查的软组织体模的散射，并使用剂量增加、信噪比改善和对比度改善因子来研究格栅性能。它已被用于量化用低原子序数材料制成的格栅部件取代带有铝盖和间隔的格栅的优势。使用了两种方法。首先，在固定的条带密度和宽度以及50、70、100和150 kV的管电压下，比较铝和低原子序数替代品在五种格栅比值下的情况。其次，比较44种市售格栅在三种不同成像情况（腰椎、胸部和儿科）下的情况。结果表明，与铝制格栅相比，用碳纤维覆盖层和棉纤维间隔制成的格栅在对比度和信噪比方面有更大的改善，并且剂量增加因子更低。剂量减少随照射条件而变化，通常在较低管电压、较高格栅比值和较低条带密度下更大。在70 kV下，对于每厘米有36条带且比值为12的格栅，成人腰椎（前后位视图）患者的平均吸收剂量典型降低为30%。
