Radiation Biophysics Group, Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden.
Int J Radiat Biol. 2012 Jan;88(1-2):189-94. doi: 10.3109/09553002.2011.624572.
To compare dose distributions on the central- and off-axis for (12)C and (7)Li ion beams simulated by the codes SHIELD-HIT (Heavy Ion Transport) and FLUKA (FLUKtuierende KAskade), and compare with experimental data for 300 MeV/u (12)C and 185 MeV/u (7)Li ion beams.
The general purpose Monte Carlo codes, SHIELD-HIT10 and FLUKA 2008.3d.1 were used for the ion dose distribution calculations. SHIELD-HIT transports hadrons and atomic nuclei of arbitrary charge and mass number in an energy range from 1 keV/u up to 1 GeV/u. Similarly, FLUKA transports charged hadrons in an energy range from 100 keV up to 20 TeV. Neutrons are transported down to thermal energies in both codes. Inelastic nuclear interactions are modelled in SHIELD-HIT by the Many Stage Dynamical Model (MSDM), whereas in FLUKA the Pre-Equilibrium Approach to Nuclear Thermalisation (PEANUT) package which includes a Generalized Intra-Nuclear Cascade model was used.
The dose distributions in water irradiated with 300 MeV/u (12)C and 185 MeV/u (7)Li ion beams were simulated with the two codes. Studies were performed of the energy deposition both on the central axis and at lateral distances up to 10 cm off-axis. The dose distributions calculated by SHIELD-HIT and FLUKA were compared with published experimental data. The dose mean lineal energy [Formula: see text], frequency mean lineal energy [Formula: see text], dose mean specific energy [Formula: see text], and frequency mean specific energy [Formula: see text] were calculated with the ion track-structure code PITS99 (Positive Ion Track Structure 99), coupled with the electron code KURBUC for the primary and secondary ions average energies at 1 mm before the Bragg peak.
The Monte Carlo codes show good agreement with experimental results for off-axis dose distributions. The disagreements in the Bragg peak region for the central-axis dose distributions imply that further improvements especially in the nuclear interaction models are required to increase the accuracy of the codes.
比较由 SHIELD-HIT（重离子传输）和 FLUKA（FLUKtuierende KAskade）代码模拟的（12）C 和（7）Li 离子束在中心轴和离轴上的剂量分布，并与 300 MeV/u（12）C 和 185 MeV/u（7）Li 离子束的实验数据进行比较。
通用蒙特卡罗代码 SHIELD-HIT10 和 FLUKA 2008.3d.1 用于离子剂量分布计算。SHIELD-HIT 传输任意荷质比和质量数的强子和原子核，能量范围从 1 keV/u 到 1 GeV/u。同样，FLUKA 传输能量范围从 100 keV 到 20 TeV 的带电强子。在这两个代码中，中子都被传输到热能。在 SHIELD-HIT 中，非弹性核相互作用由多阶段动力学模型（MSDM）建模，而在 FLUKA 中，使用了包括广义核内级联模型的核热化前平衡方法（PEANUT）包。
用这两个代码模拟了 300 MeV/u（12）C 和 185 MeV/u（7）Li 离子束辐照水中的剂量分布。研究了在中心轴和侧向距离达 10 cm 离轴处的能量沉积。用 SHIELD-HIT 和 FLUKA 计算的剂量分布与已发表的实验数据进行了比较。用离子轨迹结构代码 PITS99（正离子轨迹结构 99）计算了剂量平均线性能量[公式：见正文]、频率平均线性能量[公式：见正文]、剂量平均比能[公式：见正文]和频率平均比能[公式：见正文]，并结合电子代码 KURBUC 计算了初级和次级离子在布拉格峰前 1 毫米处的平均能量。
蒙特卡罗代码与离轴剂量分布的实验结果吻合良好。在中心轴剂量分布的布拉格峰区域的差异表明，需要进一步改进核相互作用模型，以提高代码的准确性。
