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Materials for Selective Tissue Heating in a Radiofrequency Electromagnetic Field for the Combined Chemothermal Treatment of Brain Tumors

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R. A. MOIDEL, S. K. WOLFSON, JR., R. G. SELKER, S. B. WEINER · 1976

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Radiofrequency fields can create intense localized heating in metallic materials implanted in tissue, demonstrating RF energy's thermal effects in biological systems.

Plain English Summary

Summary written for general audiences

Researchers in 1976 studied implanting metallic materials like carbon steel rods into brain tissue, then exposing the head to radiofrequency electromagnetic fields to create localized heating. They found that carbon steel rods and Hysterloy heated most effectively (about 1000 and 655 cal/g-min, respectively), with rods oriented parallel to the RF field producing the most heat. The goal was to combine targeted brain heating with chemotherapy to concentrate cancer drugs in tumors while keeping healthy tissue cool.

Why This Matters

This early research reveals how radiofrequency fields can create significant heating effects when metallic objects are present in tissue. While this was intended for medical treatment, it demonstrates eddy-current heating of metals in an RF field. The study shows that at 37 kHz the field itself produced a negligible amount of direct tissue heating, while carbon steel rods oriented parallel to the field reached about 1000 cal/g-min. Water alone in the field did not change in temperature over 5 minutes, and preliminary experiments produced localized heating in a live squirrel monkey brain, warming the right frontal lobe to 37-39°C while the other lobes were held at 29-31°C.

Figures from the Original Paper

Diagram extracted from the original research document.

diagramPage 4 - Fig. 1. Experimental arrangement of test metal and RFEM coil for calorimetry.
p. 4 of the original PDF
Cite This Study
R. A. MOIDEL, S. K. WOLFSON, JR., R. G. SELKER, S. B. WEINER (1976). Materials for Selective Tissue Heating in a Radiofrequency Electromagnetic Field for the Combined Chemothermal Treatment of Brain Tumors.
Show BibTeX
@article{materials_for_selective_tissue_heating_in_a_radiofrequency_electromagnetic_field_g5174,
  author = {R. A. MOIDEL and S. K. WOLFSON and JR. and R. G. SELKER and S. B. WEINER},
  title = {Materials for Selective Tissue Heating in a Radiofrequency Electromagnetic Field for the Combined Chemothermal Treatment of Brain Tumors},
  year = {1976},
  
  
}
No DOI on file for this study.

Quick Questions About This Study

Yes, this study found that metallic materials like carbon steel rods implanted in brain tissue heated significantly when exposed to RF fields, reaching rates of about 1000 calories per gram per minute for carbon steel rods and 655 for Hysterloy under optimal conditions.
Carbon steel rods and Hysterlo material were the most effective, with Hysterlo achieving heating rates of 655 cal/g-min. The heating occurred primarily through eddy currents induced by the RF field.
Yes, metal rods oriented parallel to the RF field produced the most heat. Shape and orientation significantly affected heating rates because the heating mechanism relies on eddy currents flowing through the material.
Evidence suggested warmer cells have greater uptake of chemotherapeutic drugs. The goal was concentrating cancer drugs in heated brain tumors while keeping healthy tissue cool to prevent toxicity.
RF electromagnetic fields induce circular electrical currents (eddy currents) within conductive metals. These currents encounter resistance in the material, converting electromagnetic energy into heat through electrical losses.