Optimization of the Clinical Setting Using Numerical Simulations of the Electromagnetic Field in an Obese Patient Model for Deep Regional Hyperthermia of an 8 MHz Radiofrequency Capacitively Coupled Device in the Pelvis

Abstract

Background: The purpose of this study was to evaluate the effectiveness of the clinical setting for deep regional hyperthermia of an 8 MHz radiofrequency (RF) capacitively coupled device in the pelvis by using numerical simulations of the electromagnetic field. Methods: A three-dimensional patient model of cervical cancer of the uterus in an obese patient was reconstructed with computed tomography data. The specific absorption rate (SAR) and temperature distributions among the various heating settings were evaluated using numerical simulations. Results: The averaged SAR value of the deep target tumor was similar between with or without overlay boluses (OBs), and that of the subcutaneous fat (SF) at the edges of cooling boluses with OBs was lower than that of the SF without OBs. The use of OBs reduced the overheating of the SF. The 0.5% salt solution in the OB produced the least overheated areas outside the deep target tumor compared with the other concentrations. The insertion of the intergluteal cleft (IGC) bolus could improve the temperature concentration of the deep target tumor. Conclusions: The use of OBs and the salt solution concentration in the OB were important to optimize the temperature distribution. IGC bolus might contribute to temperature optimization. Further studies with individualized numerical simulations in each patient are expected.

Intensity-Modulated Radiotherapy with Regional Hyperthermia for High-Risk Localized Prostate Carcinoma

“…Recent investigations on hyperthermia treatment planning have aimed to simulate temperature patterns as well as specific absorption rate (SAR) distributions, while helping operators visualize the effects of different steering strategies in modern locoregional radiofrequency hyperthermia treatments [ 37 , 38 , 39 ]. We have previously investigated the use of electromagnetic field numerical simulations for reducing subcutaneous fat overheating, which is a major drawback of deep heating using a capacitively coupled heating system [ 40 ]. Hence, optimization of temperature distribution in the deep regional hyperthermia in the pelvis is needed [ 40 ] and we used recommended optimal settings in the numerical simulation study, such as use of overlay boluses, electrical conductivity of the circulating coolant, prone position during hyperthermia, and intergluteal cleft gauze, which resulted in improved bDFS among patients who received a good thermal dose.…”

“…We have previously investigated the use of electromagnetic field numerical simulations for reducing subcutaneous fat overheating, which is a major drawback of deep heating using a capacitively coupled heating system [ 40 ]. Hence, optimization of temperature distribution in the deep regional hyperthermia in the pelvis is needed [ 40 ] and we used recommended optimal settings in the numerical simulation study, such as use of overlay boluses, electrical conductivity of the circulating coolant, prone position during hyperthermia, and intergluteal cleft gauze, which resulted in improved bDFS among patients who received a good thermal dose. Further improvements in heating methods and selection of patients suitable for hyperthermia represent future research directions.…”

Design and Characterization of an RF Applicator for In Vitro Tests of Electromagnetic Hyperthermia

“…Some of these techniques mainly guarantee a surface power deposition, leading to a preferential heating of the external parts of the body (e.g., cold-light sources, near-infrared laser light, MW radiation), while the others can be adapted for both superficial and deep heating. For the latter, the heat control and focusing are more critical, nevertheless many hyperthermia applicators have been designed to provide an inside-out heating and successfully applied in clinical trials to treat deep-seated tumors [ 25 , 26 , 27 ].…”

Hyperthermia-Based Anti-Cancer Treatments

“…Ten original research and review papers have been included until now (status 9 March 2021). Again a range of relevant topics is covered, including technical design and innovations for improved hyperthermia treatment delivery [24][25][26][27][28], a novel small animal model for preclinical HIPEC research [29], as well as clinical application of mild hyperthermia, thermal ablation and HIPEC for bladder cancer, prostate cancer, hepatocellular carcinoma, and peritoneal surface malignancies [30][31][32][33].…”