title: Method to reduce non-specific tissue heating of small animals in solenoid coils.
abstract: OBJECTIVE
  Solenoid coils that generate time-varying or alternating magnetic fields (AMFs) are used in biomedical devices for research, imaging and therapy. Interactions of AMF and tissue produce eddy currents that deposit power within tissue, thus limiting effectiveness and safety. We aim to develop methods that minimise excess heating of mice exposed to AMFs for cancer therapy experiments.
  
  
  METHODS
  Numerical and experimental data were obtained to characterise thermal management properties of water using a continuous, custom water jacket in a four-turn simple solenoid. Theoretical data were obtained with method-of-moments (MoM) numerical field calculations and finite element method (FEM) thermal simulations. Experimental data were obtained from gel phantoms and mice exposed to AMFs having amplitude >50 kA/m and frequency of 160 kHz.
  
  
  RESULTS
  Water has a high specific heat and thermal conductivity, is diamagnetic, polar, and nearly transparent to magnetic fields. We report at least a two-fold reduction of temperature increase from gel phantom and animal models when a continuous layer of circulating water was placed between the sample and solenoid, compared with no water. Thermal simulations indicate the superior efficiency in thermal management by the developed continuous single chamber cooling system over a double chamber non-continuous system. Further reductions of heating were obtained by regulating water temperature and flow for active cooling.
  
  
  CONCLUSIONS
  These results demonstrate the potential value of a contiguous layer of circulating water to permit sustained exposure to high intensity alternating magnetic fields at this frequency for research using small animal models exposed to AMFs.
authors: Lambda Z Technologies, Baltimore, MD, USA.
authors: Ananda
authors: A
authors: Kumar
authors: Anilchandra
authors: A
authors: Attaluri
authors: Rajiv
authors: R
authors: Mallipudi
authors: Christine
authors: C
authors: Cornejo
authors: David
authors: D
authors: Bordelon
authors: Michael
authors: M
authors: Armour
authors: Katherine
authors: K
authors: Morua
authors: Theodore L
authors: TL
authors: Deweese
authors: Robert
authors: R
authors: Ivkov
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation; D003080:Cold Temperature; D003198:Computer Simulation; D004867:Equipment Design; D006361:Heating / Q000009:adverse effects; D006979:Hyperthermia, Induced / Q000295:instrumentation; D060526:Magnetic Fields; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D019047:Phantoms, Imaging; D013814:Thermal Conductivity; D014867:Water
chemical_list: D014867:Water
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