Lok Edwin, Liang Olivia, Malik Talbia, Wong Eric T
Brain Tumor Center & Neuro-Oncology Unit, Beth Israel Deaconess Medical Center, Boston, Massachusetts.
Division of Hematology/Oncology, Department of Medicine, Rhode Island Hospital, Providence, Rhode Island.
Adv Radiat Oncol. 2023 Feb 26;8(4):101203. doi: 10.1016/j.adro.2023.101203. eCollection 2023 Jul-Aug.
Tumor Treating Fields (TTFields) are alternating electric fields at 150 to 200 kHz that exert their anticancer effect by destroying tumor cells when they undergo mitosis. TTFields are currently being tested in patients with non-small cell lung cancer with advanced disease (NCT02973789) and those with brain metastasis (NCT02831959). However, the distribution of these fields within the thoracic compartment remains poorly understood.
Using positron emission tomography-computed tomography image data sets obtained from a series of 4 patients with poorly differentiated adenocarcinoma, the positron emission tomography-positive gross tumor volume (GTV), clinical target volume (CTV), and structures from the chest surface to the intrathoracic compartment were manually segmented, followed by 3-dimensional physics simulation and computational modeling using finite element analysis. Electric field-volume histograms, specific absorption rate-volume histograms, and current density-volume histograms were generated to produce plan quality metrics (95%, 50%, and 5% volumes) for quantitative comparisons between models.
Unlike other organs in the body, the lungs have a large volume of air, which has a very low electric conductivity value. Our comprehensive and individualized models demonstrated heterogeneity in electric field penetration to the GTVs with differences upwards of 200% and yielded a diverse range of TTFields distributions. Target contact with the conductive pleura intensified TTFields at the GTV and CTV. Furthermore, in a sensitivity analysis, varying electric conductivity and mass density of the CTV altered TTFields coverage to both the CTV and GTV.
Personalized modeling is important to accurately estimate target coverage at the tumor volumes and surrounding normal tissue structures in the thorax.
肿瘤治疗电场（TTFields）是频率在150至200千赫兹的交变电场，当肿瘤细胞进行有丝分裂时，通过破坏肿瘤细胞发挥抗癌作用。目前正在对晚期非小细胞肺癌患者（NCT02973789）和脑转移患者（NCT02831959）进行TTFields测试。然而，这些电场在胸腔内的分布仍知之甚少。
使用从4例低分化腺癌患者系列中获得的正电子发射断层扫描 - 计算机断层扫描图像数据集，手动分割正电子发射断层扫描阳性的大体肿瘤体积（GTV）、临床靶体积（CTV）以及从胸壁表面到胸腔内的结构，然后使用有限元分析进行三维物理模拟和计算建模。生成电场 - 体积直方图、比吸收率 - 体积直方图和电流密度 - 体积直方图，以产生计划质量指标（95%、50%和5%体积），用于模型之间的定量比较。
与身体其他器官不同，肺含有大量空气，其电导率值非常低。我们的综合个体化模型显示，电场穿透GTV存在异质性，差异超过200%，并且产生了多种TTFields分布。靶区与导电胸膜的接触增强了GTV和CTV处的TTFields。此外，在敏感性分析中，改变CTV的电导率和质量密度会改变TTFields对CTV和GTV的覆盖范围。
个性化建模对于准确估计胸部肿瘤体积和周围正常组织结构的靶区覆盖情况很重要。
