Evidence of Radiosensitization with Concurrent Coil-Generated Electric/Magnetic Fields In Glioblastoma Cells.
Abstract
Purpose
Low-intensity, nonthermal electric and magnetic field–based therapies have emerged as effective clinical treatments for glioblastoma (Optune and Oncomagnetic devices). Here, we investigate the feasibility of concurrent radiotherapy (RT) with low-intensity field-based therapy (LIFT) delivery and explore exposure parameter optimization in-vitro using clonogenic survival assays.
Methods
A saddle coil (ID 6.3cm, length 10.5cm) was 3D-printed and implemented using lumped-element matching circuitry. The coil was driven by a function-generator and RF power amplifier (+38 dB gain), producing a 13MHz carrier waveform with 10Hz amplitude modulation. COMSOL simulations were used to predict spatial distributions of electric (E) and magnetic (B) fields and to guide sample placement. The coil was integrated into an Xstrahl cabinet x-ray irradiator via a coaxial feedthrough, enabling simultaneous field exposure and photon irradiation. Rat glioblastoma cells (B104) cultured in T25 flasks were positioned within the integrated coil–irradiator system based on simulation-guided geometry. Clonogenic colony formation assays were used to assess treatment response. Initial feasibility experiments evaluated concurrent LIFT and RT at a fixed coil current of 100mA, with LIFT exposure matching x-ray beam-on time. Subsequent optimization studies varied LIFT strength, spatial position, and exposure duration across radiation doses of 2–8Gy.
Results
Simulations predicted a largely homogeneous magnetic field within the target region, while the electric field exhibited spatial heterogeneity, with lower magnitudes near the geometric center and higher magnitudes off-center. In clonogenic assays, concurrent LIFT and radiotherapy reduced surviving fraction by approximately 40% compared with RT alone. Survival was similar across tested LIFT amplitudes, suggesting a non-monotonic response within the explored parameter range. Spatial-position and exposure-duration optimization studies are ongoing.
Conclusion
Concurrent treatment enhanced RT response in glioblastoma cells. Simulation-guided characterization supports the feasibility of non-invasive LIFT delivery and its potential for clinical translation as a compatible adjunct to standard RT workflows.