COMPARATIVE STUDY OF 2450 MHz AND 915 MHz DIATHERMY APPLICATORS WITH PHANTOMS
Authors not listed
The 2450 MHz diathermy applicators required less power and produced lower leakage radiation than 915 MHz applicators, especially when not in direct contact with the phantom.
Plain English Summary
Researchers evaluated three BRH applicators and four microwave hyperthermia applicators by thermographically analyzing them using planar phantoms, measuring leakage radiation, net power required to deliver 235 W/kg SAR, and heating patterns. The BRH 2450 MHz applicator had less than 5 mW/cm² leakage for both direct contact and 1 cm spacing, while the 915 MHz applicators exceeded that level when spaced 1 cm from the phantom. The depth of penetration into muscle tissue was nearly identical for both frequencies, at about 2 cm beneath the fat-muscle interface.
Why This Matters
The proposed microwave diathermy standard required leakage of not more than 10 mW/cm² at 5 cm from the phantom-applicator boundary, measured while delivering a SAR of 235 W/kg to simulated muscle tissue beneath a 1 cm or 2 cm fat layer. All three BRH applicators met the requirements of the proposed standard, though the smaller 915 MHz applicator required a thin sheet of absorbing material around the exterior choke surface to do so. It was found to be much easier to control leakage at 2450 MHz than at 915 MHz. For the BRH 2450 MHz applicator in direct contact, delivering 235 W/kg required 19 watts for the 1 cm fat layer and 57 watts for the 2 cm fat layer; at 1 cm spacing those values rose to 31 watts and 64 watts. At 1 cm spacing, the small 915 MHz BRH applicator required about 350 watts with a leakage of about 130 mW/cm² for the 2 cm layer. The hyperthermia applicators from cancer therapy groups had no special design features to control leakage radiation.
Exposure Details
- SAR
- 235 W/kg
- Power Density
- 10 mW/cm²
Exposure Context
This study used 10 mW/cm² for radio frequency:
- 1,000Mx above the Building Biology guideline of 0.1 μW/m²
- 16.7Mx above the BioInitiative Report recommendation of 0.0006 μW/cm²
This study used 235 W/kg for SAR (device absorption):
- 587.5x above the Building Biology guideline of 0.4 W/kg
Building Biology guidelines are practitioner-based limits from real-world assessments. BioInitiative Report recommendations are based on peer-reviewed science. Check Your Exposure to compare your own measurements.
Where This Falls on the Concern Scale
Study Details
To evaluate the relative effectiveness and safety of 2450 MHz and 915 MHz diathermy applicators with phantoms, focusing on leakage radiation and power requirements.
Three recently developed BRH applicators with chokes, one for 2450 MHz and two for 915 MHz use, were...
The BRH 2450 MHz applicator has less than 5 mW/cm² leakage for both direct contact and 1 cm spacing ...
915 MHz applicators require much more net power than 2450 MHz applicators to deliver the same SAR to muscle tissue, when not in direct contact. For even a small spacing between aperture and phantom (1 cm), excessive leakage results. In addition, since depth of penetration is about the same, 2450 MHz applicators seem to be considerably more effective and safe.
Show BibTeX
@article{comparative_study_of_2450_mhz_and_915_mhz_diathermy_applicators_with_phantoms_g5398,
author = {Unknown},
title = {COMPARATIVE STUDY OF 2450 MHz AND 915 MHz DIATHERMY APPLICATORS WITH PHANTOMS},
year = {n.d.},
}