Real-time monitoring of photodynamic therapy over an extended time

Abstract

Progress of photodynamic therapy (PDT) administered over an extended period of time is monitored using an ultrasonic probe, which produces ultrasound images of an internal treatment site in real time. The ultrasound images indicate the extent and volume of an infarction zone within a tumor or other diseased tissue at the internal treatment site within a patient's body. Light is administered to the internal treatment site from either an internal or external light source that produces light in a waveband corresponding to the characteristic absorption waveband a photoreactive agent that is administered to a patient. Prior to or shortly after initiating administration of the light therapy, a baseline ultrasound image is produced for comparison to subsequent ultrasound images made after the effects of the PDT on the diseased tissue have occurred. By evaluating changes in the internal treatment site shown in the ultrasound images during the progress of the PDT, the intensity and/or duration of intervals of light being administered to the patient can be varied, and/or terminated at an appropriate time, thereby minimizing risk of harm to normal tissue surrounding the internal treatment site. Light is delivered from an external laser source through an optical fiber, or through an implanted light probe that includes one or more light emitting sources, or by an external array of light emitting diodes that emit light of sufficiently long wavelength to penetrate a dermal layer into the internal treatment site.