Purpose. To compare the accuracies of the AAA and AcurosXB dose calculation algorithms and to predict the change in the down-stream and lateral dose deposition of high energy photons in the presence of material with densities higher that commonly found in the body. Method. Metal rods of titanium (d = 4.5 g cm⁻³), stainless steel (d=8 g cm⁻³) and tungsten (d=19.25 g cm⁻³) were positioned in a phantom. Film was position behind and laterally to the rods to measure the dose distribution for a 6 MV, 18 MV and 10 FFF photon beams. A DOSXYZnrc Monte Carlo simulation of the experimental setup was performed. The AAA and AcurosXB dose calculation algorithms were used to predict the dose distributions. The dose from film and DOSXYZnrc were compared with the dose predicted by AAA and AcurosXB. Results. AAA overestimated the dose behind the rods by 15%–25% and underestimated the dose laterally to the rods by 5%–15% depending on the range of materials and energies investigated. AcurosXB overestimated the dose behind the rods by 1%–18% and underestimated the dose laterally to the rods by up to 5% depending on the range of material and energies investigated. Conclusion. AAA cannot deliver clinically acceptable dose calculation results at a distance less than 10 mm from metals, for a single field treatment. Acuros XB is able to handle metals of low atomic numbers (Z≤26), but not tungsten (Z=74). This can be due to the restriction of the CT-density table in Eclipse^TM TPS, which has an upper HU limit of 10501.

目的。比较 AAA 和 AcurosXB 剂量计算算法的准确性，并预测在存在密度高于体内常见物质的情况下高能光子的下游和横向剂量沉积的变化。方法。钛 (d = 4.5 g cm ^-3 )、不锈钢 (d=8 g cm ^-3 ) 和钨 (d=19.25 g cm ^{-3 ) 的金属棒}) 被定位在一个幻影中。胶片位于棒的后面和侧面，以测量 6 MV、18 MV 和 10 FFF 光子束的剂量分布。对实验装置进行了 DOSXYZnrc Monte Carlo 模拟。AAA 和 AcurosXB 剂量计算算法用于预测剂量分布。将胶片和 DOSXYZnrc 的剂量与 AAA 和 AcurosXB 预测的剂量进行比较。结果。根据所研究的材料和能量的范围，AAA 高估了棒后面的剂量 15%–25%，而低估了棒侧面的剂量 5%–15%。AcurosXB 将棒后面的剂量高估了 1%–18%，而根据所研究的材料和能量的范围，将棒的侧面剂量低估了高达 5%。结论. 对于单场治疗，AAA 无法在距离金属小于 10 毫米的地方提供临床可接受的剂量计算结果。Acuros XB 能够处理低原子序数 (Z≤26) 的金属，但不能处理钨 (Z=74)。这可能是由于 Eclipse ^TM TPS 中 CT 密度表的限制，其 HU 上限为 10501。