Charles Paul H, Crowe Scott, Kairn Tanya
Herston Biofabrication Institute, Brisbane, QLD, Australia.
School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, QLD, Australia.
Phys Eng Sci Med. 2021 Mar;44(1):331-335. doi: 10.1007/s13246-021-00979-3. Epub 2021 Feb 16.
Monte Carlo simulations of lung equivalent materials often involve the density being artificially lowered rather than a true lung tissue (or equivalent plastic) and air composition being simulated. This study used atomic composition analysis to test the suitability of this method. Atomic composition analysis was also used to test the suitability of 3D printing PLA or ABS with air to simulate lung tissue. It was found that there was minimal atomic composition difference when using an artificially lowered density, with a 0.8 % difference in Nitrogen the largest observed. Therefore, excluding infill pattern effects, lowering the density of the lung tissue (or plastic) in simulations should be sufficiently accurate to simulate an inhaled lung, without the need to explicitly include the air component. The average electron density of 3D printed PLA and air, and ABS and air were just 0.3 % and 1.3 % different to inhaled lung, confirming their adequacy for MV photon dosimetry. However large average atomic number differences (5.6 % and 20.4 % respectively) mean that they are unlikely to be suitable for kV photon dosimetry.
肺等效材料的蒙特卡罗模拟通常涉及人为降低密度，而非模拟真实的肺组织（或等效塑料）和空气成分。本研究采用原子组成分析来测试该方法的适用性。原子组成分析还用于测试用含空气的3D打印聚乳酸（PLA）或丙烯腈-丁二烯-苯乙烯共聚物（ABS）模拟肺组织的适用性。研究发现，使用人为降低的密度时，原子组成差异极小，观察到的最大差异是氮含量有0.8%的差异。因此，排除填充图案的影响，在模拟中降低肺组织（或塑料）的密度应该足以准确模拟吸入的肺，而无需明确包含空气成分。3D打印的PLA与空气以及ABS与空气的平均电子密度与吸入肺的平均电子密度仅相差0.3%和1.3%，证实了它们适用于兆伏级（MV）光子剂量测定。然而，较大的平均原子序数差异（分别为5.6%和20.4%）意味着它们不太可能适用于千伏级（kV）光子剂量测定。
