Transcutaneous bilirubinometry during phototherapy

Transcutaneous bilirubinometry based on reflectance spectroscopy technique requires the modelling of bilirubin photochemistry and metabolism in skin, and the solution of inverse problems to derive pigment concentrations from spectral measurements. The influence of bilirubin photochemistry occurring during the initial stage of phototherapy on the reflectance spectrum of an icteric tissue is analyzed using a 5-layer skin model, and an algorithm is presented to evaluate bilirubin concentration during phototherapy. An in vivo reflectance spectrum during phototherapy is presented where the configurational, reversible photoisomerization of bilirubin is observed for the first time.