ABSTRACT
Fluorescence lifetime-resolved imaging records fluorescence lifetimes in an image and the spectroscopic information related to the lifetime of the fluorescence decay is displayed at every pixel of the image. Fluorescence lifetimes are typically measured in the time domain or the frequency domain. The time domain is a direct measurement of the time decay process; data points are acquired at specific times following the excitation of the sample, usually with a very short pulse of light. The frequency domain carries out the measurement by repetitively modulating the light continuously at a very high frequency, and detecting the frequency dispersion of the signal. The chapter provides a short discussion of data acquisition and data analysis for the time and frequency domain lifetime measurements. Data analysis in the frequency domain is usually carried out by Fourier analysis or direct nonlinear regression. Photodynamic therapy is a non-invasive way of removing tumor cells using reactive oxygen species generated by excited intracellular photosensitizers.
