<title>Real-time system for fluorescence lifetime imaging</title>

Abstract

In this paper we report on the experimental setup and the performances of a fluorescence lifetime imaging system designed by the authors for cancer detection. The experimental apparatus relies on a CCD video camera coupled to a light intensifier and on a pulsed laser. Two or more fluorescence images are acquired within suitable time windows at different delays, with respect to the excitation pulses. The images are processed using matrix algorithms implemented in the fast processor of an advanced frame grabber; then, the resulting lifetime map is displayed in pseudocolor or gray shade images. The instrumentation is fully computer controlled and the whole process takes about 1 second per lifetime image. Using a faster processor this time could be easily reduced to some milliseconds for true real time measurements. The system has been successfully applied to detect experimental tumors in mice sensitized with hematoporphyrin derivative, which is a clinically approved photosensitizing drug.