Company F Z, Allen B J, Mino C
School of Engineering and Industrial Design, University of Western Sydney, NSW, Australia.
Australas Phys Eng Sci Med. 2000 Sep;23(3):88-93.
In radiography the scattered radiation from the off-target region decreases the contrast of the target image. We propose that a bundle of collimated, closely spaced, microplanar beams can reduce the scattered radiation and eliminate the effect of secondary electron dose, thus increasing the image dose contrast in the detector. The lateral and depth dose distributions of 20-200 keV microplanar beams are investigated using the EGS4 Monte Carlo code to calculate the depth doses and dose profiles in a 6 cm x 6 cm x 6 cm tissue phantom. The maximum dose on the primary beam axis (peak) and the minimum inter-beam scattered dose (valley) are compared at different photon energies and the optimum energy range for microbeam radiography is found. Results show that a bundle of closely spaced microplanar beams can give superior contrast imaging to a single macrobeam of the same overall area.
在放射成像中，来自非靶区的散射辐射会降低靶区图像的对比度。我们提出，一束准直的、间距紧密的微平面束可以减少散射辐射并消除二次电子剂量的影响，从而提高探测器中的图像剂量对比度。使用EGS4蒙特卡罗代码研究了20 - 200 keV微平面束的横向和深度剂量分布，以计算6 cm×6 cm×6 cm组织模体中的深度剂量和剂量分布。在不同光子能量下比较了主束轴上的最大剂量（峰值）和束间最小散射剂量（谷值），并找到了微束放射成像的最佳能量范围。结果表明，一束间距紧密的微平面束能比相同总面积的单个宏束提供更好的对比度成像。
