A feasibility study of the use of fluorescence bronchoscopy for localization of small lung tumours

The possible use of fluorescence bronchoscopy for localization of bronchogenic tumours at the carcinoma in situ stage has been investigated. The target lesion is 80 micrometer thick with a mass of 250 microgram, containing 250 pg of haematoporphyrin derivative. The injected haematoporphyrin-derivative is preferentially taken up or retained by a malignant tumour, and can be detected in small amounts by its red flourescence under illumination by violet light. Previous clincial trials were successful in detecting tumours, but the instrumentation was only marginally adequate, the fluorescent compound was not standardized and no measurements or calculation of sensitivity were made. In this work, a fibreoptic bronchoscope system with a 200 W mercury vapour lamp, special violet-transmitting light conductor, sharp cut-off blue and red filters and three-stage image intensifier tube was designed and assembled. Measurements in vitro indicate the design objectives were met, and test on tumours are in progress.