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

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 × 10−5 m2 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 × 10−8 m2 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.