Department of Radiation Oncology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
Department of Paediatric Oncology/Haematology, Otto-Heubner Centre for Paediatric and Adolescent Medicine (OHC), Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
Int J Hyperthermia. 2021;38(1):663-678. doi: 10.1080/02656736.2021.1909757.
To create an improved planning method for pediatric regional hyperthermia (RHT) using the SIGMA-30 applicator (SIGMA-30).
An electromagnetic model of SIGMA-30 was generated for use with the finite-difference time-domain (FDTD) method. Applying special MATLAB-based algorithms, voxel models of a pediatric patient with pelvic rhabdomyosarcoma were created from Computed-Tomography (CT) contours for use with the FDTD method and the finite-difference (FD) method capable of using either temperature-independent or temperature-dependent perfusion models for solving the Bioheat Transfer Equation (BHTE). Patient models were parametrized regarding, first, the positioning in the applicator, second, the absorbed power range and, third, different perfusion models, resulting in the so-called (PTMs). A novel dedicated optimization procedure was developed based on quantitative comparison of numerical calculations against temperature and power measurements from two RHT therapies.
Using measured data, a realistic absorbed power range in the patient model was estimated. Within this range, several FDTD and BHTE runs were performed and, applying the aforementioned optimization scheme, the best PTMs and perfusion models were identified for each therapy via a retrospective comparison with measurements in 14 temperature sensor positions: 5 in the tumor, 8 in rectum and one in bladder.
A novel dedicated optimization procedure for identification of suitable patient-specific electromagnetic and thermal models, which can be used for improved patient planning, was developed and evaluated by comparison with treatment-derived measurements using SIGMA-30. The optimization procedure can be extended to other hyperthermia applicators and to other patient types, including adults.
利用 SIGMA-30 施源器创建一种改进的儿科区域热疗（RHT）计划方法。
生成了 SIGMA-30 的电磁场模型，用于有限差分时域（FDTD）方法。应用特殊的基于 MATLAB 的算法，从盆腔横纹肌肉瘤患儿的 CT 轮廓创建了用于 FDTD 方法和 FD 方法的体素模型，FD 方法能够使用温度无关或温度依赖的灌注模型来求解生物传热方程（BHTE）。针对患者模型进行了参数化，首先是在施源器中的定位，其次是吸收功率范围，第三是不同的灌注模型，从而产生了所谓的（PTM）。基于对两种 RHT 治疗的数值计算与温度和功率测量的定量比较，开发了一种新颖的专用优化程序。
使用实测数据，估算了患者模型中的实际吸收功率范围。在此范围内，进行了多次 FDTD 和 BHTE 运行，并通过上述优化方案，针对每个治疗方案，通过与 14 个温度传感器位置（肿瘤内 5 个、直肠内 8 个和膀胱内 1 个）的测量值进行回顾性比较，确定了最佳的 PTM 和灌注模型。
开发了一种用于识别适合特定患者的电磁和热模型的专用优化程序，该程序可用于改进患者计划，并通过使用 SIGMA-30 与治疗衍生的测量值进行比较进行了评估。该优化程序可以扩展到其他热疗施源器和其他患者类型，包括成人。
