Measurements of sensitizer fluorescence in patients by means of an ordinary fluorescence spectrometer

An ordinary fluorescence spectrometer equipped with a dichroic mirror and fiber optics can be used to measure sensitizer fluorescence in tumors and normal tissues. Our findings with such an instrument showed that after oral administration of 60 mg/kg 5-aminolevulinic acid (ALA) mucosas and rectal adenomas fluoresced stronger than normal skin. Also basal cell carcinomas (BCCs) showed a stronger porphyrin fluorescence than skin after topical application of ALA. The porphyrin fluorescence of BCCs decayed rapidly during standard laser irradiation at 630 nm. The degradation rate of porphyrins in the tumor was approximately constant down to at least 0.3 mm below the tumor surface, in agreement with an optical penetration depth of more than 1 mm.