Department of Radiation Oncology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
Med Phys. 2013 Oct;40(10):103303. doi: 10.1118/1.4821544.
Accurate thermal simulations in hyperthermia treatment planning require discrete modeling of large blood vessels. The very long computation time of the finite difference based DIscrete VAsculature model (DIVA) developed for this purpose is impractical for clinical applications. In this work, a fast steady-state thermal solver was developed for simulations with realistic 3D vessel networks. Additionally, an efficient temperature-based optimization method including the thermal effect of discrete vasculature was developed.
The steady-state energy balance for vasculature and tissue was described by a linear system, which was solved with an iterative method on the graphical processing unit. Temperature calculations during optimization were performed by superposition of several precomputed temperature distributions, calculated with the developed thermal solver. The thermal solver and optimization were applied to a human anatomy, with the prostate being the target region, heated with the eight waveguide 70 MHz AMC-8 system. Realistic 3D pelvic vasculature was obtained from angiography. Both the arterial and venous vessel networks consisted of 174 segments and 93 endpoints with a diameter of 1.2 mm.
Calculation of the steady-state temperature distribution lasted about 3.3 h with the original DIVA model, while the newly developed method took only ≈ 1-1.5 min. Temperature-based optimization with and without taking the vasculature into account showed differences in optimized waveguide power of more than a factor 2 and optimized tumor T90 differed up to ≈ 0.5°C. This shows the necessity to take discrete vasculature into account during optimization.
A very fast method was developed for thermal simulations with realistic 3D vessel networks. The short simulation time allows online calculations and makes temperature optimization with realistic vasculature feasible, which is an important step forward in hyperthermia treatment planning.
在热疗计划中进行准确的热模拟需要对大血管进行离散建模。为此目的开发的基于有限差分的离散血管模型（DIVA）计算时间非常长，不适合临床应用。在这项工作中，开发了一种快速的稳态热求解器，用于具有逼真 3D 血管网络的模拟。此外，还开发了一种基于温度的高效优化方法，包括离散血管的热效应。
血管和组织的稳态能量平衡由一个线性系统描述，该系统在图形处理单元上通过迭代方法求解。优化过程中的温度计算是通过叠加几个预先计算的温度分布来完成的，这些温度分布是用开发的热求解器计算的。热求解器和优化应用于人体解剖结构，目标区域是前列腺，用 8 个波导 70 MHz AMC-8 系统加热。从血管造影中获得真实的 3D 骨盆血管。动脉和静脉血管网络分别由 174 个节段和 93 个端点组成，直径为 1.2 毫米。
使用原始的 DIVA 模型计算稳态温度分布大约需要 3.3 小时，而新开发的方法只需要 ≈ 1-1.5 分钟。考虑和不考虑血管的基于温度的优化显示优化波导功率的差异超过 2 倍，优化肿瘤 T90 的差异高达 ≈ 0.5°C。这表明在优化过程中考虑离散血管是必要的。
开发了一种用于具有真实 3D 血管网络的热模拟的非常快速的方法。短的模拟时间允许在线计算，并使具有真实血管的温度优化成为可能，这是热疗计划中的一个重要进展。
