Abstract

Aim

Hyperthermia (HT) has been shown to improve clinical response to radiation therapy (RT) for cancer. Synergism is dramatically enhanced if HT and RT are combined simultaneously, but appropriate technology to apply treatments together does not exist. This study investigates the feasibility of delivering HT with RT to a 5-10mm annular rim of at-risk tissue around a tumor resection cavity using a temporary thermobrachytherapy (TBT) balloon implant.

Methods

A balloon catheter was designed to deliver radiation from High Dose Rate (HDR) brachytherapy concurrent with HT delivered by filling the balloon with magnetic nanoparticles (MNP) and immersing it in a radiofrequency magnetic field. Temperature distributions in brain around the TBT balloon were simulated with temperature dependent brain blood perfusion using numerical modeling. A magnetic induction system was constructed and used to produce rapid heating (>0.2°C/s) of MNP-filled balloons in brain tissue-equivalent phantoms by absorbing 0.5 W/ml from a 5.7 kA/m field at 133 kHz.

Results

Simulated treatment plans demonstrate the ability to heat at-risk tissue around a brain tumor resection cavity between 40-48°C for 2-5cm diameter balloons. Experimental thermal dosimetry verifies the expected rapid and spherically symmetric heating of brain phantom around the MNP-filled balloon at a magnetic field strength that has proven safe in previous clinical studies.

Conclusions

These preclinical results demonstrate the feasibility of using a TBT balloon to deliver heat simultaneously with HDR brachytherapy to tumor bed around a brain tumor resection cavity, with significantly improved uniformity of heating over previous multi-catheter interstitial approaches. Considered along with results of previous clinical thermobrachytherapy trials, this new capability is expected to improve both survival and quality of life in patients with glioblastoma multiforme.

中文翻译：

---

可拆卸球囊植入物用于脑肿瘤切除腔同时磁性纳米颗粒加热和 HDR 近距离放射治疗的可行性

 抽象的

 目的

热疗 (HT) 已被证明可以改善癌症放射治疗 (RT) 的临床反应。如果同时结合 HT 和 RT，协同作用会显着增强，但同时应用治疗的适当技术尚不存在。本研究探讨了使用临时热近距离放射治疗 (TBT) 球囊植入物将 HT 与 RT 输送到肿瘤切除腔周围的 5-10mm 危险组织环形边缘的可行性。

 方法

球囊导管旨在输送高剂量率 (HDR) 近距离放射治疗的辐射，同时通过在球囊中填充磁性纳米粒子 (MNP) 并将其浸入射频磁场来输送 HT。使用数值模型通过温度依赖性脑血液灌注来模拟 TBT 球囊周围大脑的温度分布。构建了磁感应系统，通过从 133 kHz 的 5.7 kA/m 场吸收 0.5 W/ml 的功率，对脑组织等效模型中的 MNP 填充气球产生快速加热 (>0.2°C/s)。

 结果

模拟治疗计划证明，直径为 2-5 厘米的球囊能够将脑肿瘤切除腔周围的危险组织加热到 40-48°C。实验热剂量测定验证了 MNP 填充气球周围大脑模型在磁场强度下的预期快速和球对称加热，该磁场强度已在之前的临床研究中证明是安全的。

 结论

这些临床前结果证明了使用 TBT 球囊与 HDR 近距离放射治疗同时向脑肿瘤切除腔周围的肿瘤床输送热量的可行性，与以前的多导管间质方法相比，加热的均匀性显着提高。与之前的临床近距离热放射治疗试验的结果一起考虑，这一新功能有望提高多形性胶质母细胞瘤患者的生存率和生活质量。