A method of using photodynamic therapy to perform selective targeted therapy of biological tissue. The method includes intravenously injecting a porphyrin-based photosensitizing drug followed by irradiating the tissue with light while the drug is being injected. The duration of the irradiation and other parameters are controlled so that the selected biological tissue is treated and non-selected tissue is not damaged. By controlling the flow rate of the injection and other parameters, so that irradiation of the effected tissue overlaps with injection of drug, the target tissue is effectively treated without damage to non-target tissue.
