A method of determining the specific absorption rate around an energy applicator, comprising the steps of: providing an energy applicator including a radiating section; providing a thermally-sensitive medium including a cut-out portion defining a void in the thermally-sensitive medium, the cut-out portion configured to receive at least a portion of the radiating section therein; providing a housing having an interior area configured to contain a hydrogel, the housing including a port opening into the interior area configured to receive the energy applicator therethrough; positioning the thermally-sensitive medium in the interior area to substantially align a longitudinal axis of the cut-out portion with a central longitudinal axis of the port; positioning the at least a portion of the radiating section within the cut-out portion, wherein the energy applicator is centrally aligned with the longitudinal axis of the cut-out portion; causing the radiating section to emit electromagnetic energy; capturing a series of sequential images of at least a portion of the thermally-sensitive medium; and analyzing the series of sequential images to determine a specific absorption rate around the energy applicator, characterised in that analyzing the series of sequential images to determine a specific absorption rate around the energy applicator includes the steps of: selecting a color band of the series of sequential images; determining a change in temperature as a function of positional transition of an inner boundary or an outer boundary of the selected color band in each of the sequential images; and calculating a specific absorption rate around the energy applicator as a function of the determined change in temperature. providing an energy applicator including a radiating section; providing a thermally-sensitive medium including a cut-out portion defining a void in the thermally-sensitive medium, the cut-out portion configured to receive at least a portion of the radiating section therein; providing a housing having an interior area configured to contain a hydrogel, the housing including a port opening into the interior area configured to receive the energy applicator therethrough; positioning the thermally-sensitive medium in the interior area to substantially align a longitudinal axis of the cut-out portion with a central longitudinal axis of the port; positioning the at least a portion of the radiating section within the cut-out portion, wherein the energy applicator is centrally aligned with the longitudinal axis of the cut-out portion; causing the radiating section to emit electromagnetic energy; capturing a series of sequential images of at least a portion of the thermally-sensitive medium; and analyzing the series of sequential images to determine a specific absorption rate around the energy applicator, selecting a color band of the series of sequential images; determining a change in temperature as a function of positional transition of an inner boundary or an outer boundary of the selected color band in each of the sequential images; and calculating a specific absorption rate around the energy applicator as a function of the determined change in temperature.