Leakage in the Proximity of Microwave Diathermy Applicators Used on Humans or Phantom Models
Howard I. Bassen, Gideon Kantor, Paul S. Ruggera, Donald M. Witters, Jr. · 1978
Government testing revealed that medical microwave diathermy machines leak radiation, creating potential exposure risks for patients and staff.
Plain English Summary
This 1978 government report examined microwave radiation leakage from diathermy machines used in medical treatments. Researchers measured how much microwave energy escaped from these therapeutic devices when used on both human patients and phantom test models. The study was part of federal efforts to assess potential exposure risks from medical microwave equipment.
Why This Matters
This government investigation into medical microwave leakage represents an important early recognition that therapeutic EMF devices could pose unintended exposure risks. Microwave diathermy machines generate intense electromagnetic fields to heat deep tissues for pain relief and healing, but any leakage exposes patients and medical staff to potentially harmful radiation. The reality is that medical devices have long been a significant but overlooked source of EMF exposure. What makes this study particularly relevant today is how it demonstrates that even beneficial uses of microwave technology require careful monitoring for unintended radiation exposure. The science shows that proximity matters enormously with microwave sources, and medical settings often involve extended close contact between devices and people.
Finding
From typical 2450 MHz microwave diathermy treatments using a BRH-developed Transco applicator and performed on humans or phantoms at low levels, the leakage at 5 cm from the surface of the applicator/tissue interface was extrapolated to effective treatment conditions (235 W/kg delivered to the phantom muscle material). The leakage levels for the human back, thigh, and elbow treatments were computed to be less than 5 mW/cm2
In their words
“From typical 2450 MHz microwave diathermy treatments using a BRH-developed Transco applicator and performed on humans or phantoms at low levels, the leakage at 5 cm from the surface of the applicator/tissue interface was extrapolated to effective treatment conditions (235 W/kg delivered to the phantom muscle material). The leakage levels for the human back, thigh, and elbow treatments were computed to be less than 5 mW/cm2”
Figures from the Original Paper
Diagrams extracted from the original research document.
Exposure Information
Specific exposure levels were not quantified in this study. Duration: less than 1-minute duration
Study Details
To evaluate the practicality of using phantoms to predict leakage that would occur during actual clinical treatment procedures
Leakage radiation measurements were made in the immediate vicinity of a Transco 2450 MHz circularly ...
The leakage levels for the human back, thigh, and elbow treatments were computed to be less than 5 m...
The Transco contact applicator is generally appropriate for low-leakage back and thigh treatments. There is good agreement (within a factor of 2) between virtually all actual leakage data (human) and simulated (phantom) treatments, provided that appropriate phantoms are used. These results can be applied to the proposed BRH microwave diathermy standard (which purposely omits the use of human subjects for diathermy equipment performance testing). Leakage testing with appropriate phantoms is a reasonable means for minimizing unnecessary microwave leakage in clinical conditions. Phantom data on leakage and energy deposition for conventional, non-contact applicators (types B and E) revealed that high leakage (35.5 and 44.0 mW/cm2) would have occurred under identical 'effective' treatment conditions.
Show BibTeX
@article{leakage_in_the_proximity_of_microwave_diathermy_applicators_used_on_humans_or_ph_g6059,
author = {Howard I. Bassen and Gideon Kantor and Paul S. Ruggera and Donald M. Witters and Jr.},
title = {Leakage in the Proximity of Microwave Diathermy Applicators Used on Humans or Phantom Models},
year = {1978},
}