edVirtus Reference

What Is RF Dosimetry?

How Are Internal RF Fields and Absorbed Energy Quantified?

RF dosimetry is the determination, by measurement or calculation, of the electromagnetic fields induced within the body and the power or energy absorbed by its tissues during exposure to radio-frequency fields. It connects external exposure conditions with internal physical quantities.

A field measured outside the body is altered by the body's presence. Energy may be reflected, transmitted, focused, or absorbed, and the internal distribution is generally nonuniform. The result depends on frequency, polarization, field geometry, distance, posture, body size, and the frequency-dependent electrical properties of tissues.

Dosimetric quantities include induced electric-field strength, whole-body and localized specific absorption rate, specific energy absorption, absorbed power density, and absorbed energy density. Different quantities apply over different frequency ranges, exposure durations, and spatial scales. They are not interchangeable, and no single quantity represents a universal RF dose.

Computational dosimetry uses numerical representations of the source, the environment, and simplified or anatomically detailed bodies. Methods such as finite-difference time-domain and finite element analysis solve for fields and absorbed quantities throughout the model.

Experimental dosimetry uses physical phantoms, calibrated probes, thermal measurements, or other laboratory methods. Tissue-equivalent materials reproduce relevant electrical properties so that internal fields or absorption can be measured without exposing a person during the test.

A useful dosimetric result states the source conditions, model or phantom, tissue properties, geometry, resolution, spatial and temporal averaging, uncertainty, and validation. Small changes in source position or separation can be important, especially close to an antenna.

RF dosimetry supports exposure-limit development, product compliance testing, site and task assessment, and research on RF interaction with the body. It complements external-field measurement and biological-effects assessment: it quantifies internal physical conditions but does not determine whether a biological response occurs or whether it is adverse.