Improving spatial resolution in skin-contact thermography: Comparison between a spline based and linear interpolation

Abstract 

A wearable device for skin-contact thermography [Giansanti D, Maccioni G. Development and testing of a wearable integrated thermometer sensor for skin contact thermography. Med Eng Phys 2006 [ahead of print]] using a 2-D array of 4×4 integrated silicon sensors has been designed and constructed. The thermal resolution was equal to 0.03°C and the spatial resolution equal to 1.6×10⁻⁵m² in the range 25–41°C. The improvement of spatial resolution is strongly needed in several medical correlated applications of skin-contact thermography such as the breast cancer monitoring and the feature recognition. A cubic-spline interpolation procedure has been designed to improve the spatial resolution. The performances have been investigated in a significant medical application. Results were compared to those ones obtained by means of an infrared digital video camera and a linear based interpolation procedure. The comparison showed that: (1) the spline based interpolation procedure permitted to improve the spatial resolution of the device to 1.5×10⁻⁸m² with an interpolating number of pixels equal to 128×. (2) The accuracy of the thermal reconstruction obtained by means of the spline interpolation in each one of the pixels was better than the one obtained by a pure linear interpolation; in particular the maximal error was equal to, 81×10⁻³°C.

Keywords: Wearable devices, Contact thermography, Skin thermography