| 摘要 |
A method for monitoring the presence of selected chromophores in a sample of epithelial tissue, independent of the amount of a predetermined chromophore, the method comprising: illuminating an area of tissue by projecting light fr om a light source of at least two different wavelengths .lambda.1, .lambda.2; receiving light remitted by the illuminated area of tissue at a photorecepto r; analysing the received light to identify and measure the proportion of light of each wavelength remitted from the tissue Ir (.lambda.) ; calculating the ratio of light at each wavelength returned from the tissue Rt, (.lambda.) , and then calculating Z = Formula (I); where l is chosen such that Z is independent of the amount of predetermined chromophore. Typically l is calculated such that Z = Formula (II); where j and k are such that 2 j .alpha.(.lambda.1) = 2kj .alpha.(.lambda.2 ) =1 where a(.lambda.1) and .alpha.(.lambda.2) are the absorbtion coefficients for the predetermined chromophore at each wavelength. |
