====== Thermobrachytherapy ======

[[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. 

A study of Stauffer et al. 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.

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.

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.

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 [[trial]]s, this new capability is expected to improve both [[survival]] and [[quality of life]] in patients with [[glioblastoma]] multiforme
((Stauffer PR, Rodrigues DB, Goldstein R, Nguyen T, Yu Y, Wan S, Woodward R, Gibbs M, Vasilchenko IL, Osintsev AM, Bar-Ad V, Leeper DB, Shi W, Judy KD, Hurwitz MD. Feasibility of removable balloon implant for simultaneous magnetic nanoparticle heating and HDR brachytherapy of brain tumor resection cavities. Int J Hyperthermia. 2020;37(1):1189-1201. doi: 10.1080/02656736.2020.1829103. PMID: 33047639.)).