A study of repeatability and reproducibility for tongue diagnosis instrument in TCM

We design a solid phantom with painted tongue body as a simulation of human tongue and analyze the average color distance of the phantom images to evaluate the repeatability and reproducibility of this instrument. The color difference is applied as a tolerance of Precision-to-Tolerance ratio (P/T) in QS9000. The P/T ratio of total measurement is used to indicate whether the instrument is correctly built or in good condition for continuous use. We may find some confounding factors of these instruments through this examination. The result shows the unsteady condition for image capture by the instrument or operator factors such as light, vibration, operators training and so on could be adjusted or modified. The study of repeatability and reproducibility needs to be performed when a new tongue diagnosis instrument is being introduced, and could help TCM doctors to establish a standard tongue diagnosis environment.