TPS Medical Technology

In the following, we give a concise overview of the theory underpinning the novel TPS Medical application.

For the TPS method as described in the international standard ISO 22007-2,  a “probing depth” has been defined accordingly:

Here  is the thermal diffusivity of the given material and is the part of the transient recording, which has been selected for evaluating the thermal transport properties of the material in question.

A transient recording from a measurement on a selected material which is not homogeneous (e.g. human skin), should in principle contain information on how the thermal transport properties would vary with the (probing) depth measured from the thermal probe into the relevant living tissue or inert material.

If the transient recording is divided into a number of consecutive time intervals from  to  , and if evaluations are performed from  to  , this will yield information on the thermal transport properties (mean values) for the tissue or other material located under the thermal probe to a depth of  .

One way to track the variation of the thermal transport properties as a function of depth would be to successively increase the range of the time window from  to  . However, for each such calculation one would include information from all previous windows. As expected, this becomes a rather insensitive method of pin-pointing the variation of the thermal transport properties.

A different and more sensitive method of acquiring information on the said variation would entail the calculation of the thermal transport properties from each time window, starting with  and ending with  . The number of such windows is obviously  , and this analysis has proven very sensitive to structural variations in the tissue or other material located immediately under the thermal probe.

A perceived difficulty with this latter method of evaluating the transport properties is the impossibility of directly referring a transport coefficient to a certain depth. However, detailed information on the inhomogeneity of the tissue/material can nevertheless be garnered by comparing the experimental results with numerical simulations performed on a number of assumed structural distributions. Evaluations of this kind have proven to furnish good results.