Computational investigation of the tumor position and ambient conditions on magnetic nanoparticle thermo-therapy

Abstract

• Estimation of effects of tumor position beneath the skin on magnetic nanoparticle hyperthermia (MNPH). • Estimation of effects of therapeutic environmental conditions on MNPH. • Quantification of thermal damage in tumor as well healthy tissues in diverse therapeutic environmental conditions. • Estimation of the critical depth of the tumor up to which the variations in the therapeutic effects of MNPH are significant. The present study elucidate the effects of tumor position and clinical environmental conditions on the therapeutic effects of magnetic nanoparticle hyperthermia (MNH) in superficial like breast tumor tissue. Effects of these two factors are investigated through a three-dimensional (3D) tumor model. The position of the tumor tissue (of size 1.5 cm) within the 3D model as well as the heat transfer rate through the skin is altered to evaluate their effects on MNH. Six different positions of tumor ranging from zero-depth to the tumor depth of 1.5 times the tumor size from the skin are considered. Similarly, three different heat transfer coefficients ( h c = 2.5, 5.5, 7.5 W / m 2 K ) on the skin during thermotherapy are considered to simulate a wide range of clinical environmental conditions. MNH is induced for 1 hour using two different heating powers (with amplitudes of 10 k A / m and 12.5 k A / m at 130 k H z ) to evaluate the thermal damage (Arrhenius ( Ω =4.6) and cumulative equivalent minutes C E M 43 60 in the tissue. Results show that there exists a critical depth, which is nearly half of the tumor size, up to which the MNH is influenced by the position of the tumor. Similarly, the effects of the ambient conditions during this thermotherapy on thermal dosimetry, also cease beyond this critical depth. The estimation of the critical depth of the tumor will help in predicting the therapeutic effects of magnetic hyperthermia applicators for specifically positioned tumors in actual environmental conditions.