Numerical Analysis of Solenoidal and Helmholtz Coils for Magnetic Hyperthermia with Intratumoral Nanofluid Injection

Abstract Magnetic fluid hyperthermia (MFH) is an emerging, minimally invasive cancer therapy that induces localized tumor heating using magnetic nanoparticles exposed to an alternating magnetic field. The present study explores the performance of two magnetic-coil arrangements, the Helmholtz coil and a solenoidal coil, through numerical analysis to evaluate their effectiveness in inducing therapeutic hyperthermia in a liver tumor infused with a nanofluid. The computational model incorporates intratumoral injection and diffusion of MNP-based nanofluid, where the transport of diluted species governs nanoparticle distribution. Temperature increase due to nanoparticle power dissipation is modelled using the Pennes bioheat equation. Results show that the Helmholtz coil offers better magnetic field uniformity, leading to more consistent tumor heating even at off-centre positions. In contrast, the solenoidal coil exhibits reduced effectiveness near the tumor edges due to field non-uniformity. The study also underscores the limitation of single-point nanoparticle injection, where limited diffusion results in poor edge heating. These findings suggest that both coil design and nanoparticle delivery strategy play critical roles in enhancing MFH efficacy.