Investigations to monitor laser-induced thermotherapy (LITT) of breast tumors with photon density waves (PDW)

摘要

Abstract: An experimental setup will be presented which provides the detection of photon density waves (PDW) in transmission through tissue samples of up to 4 cm thickness. A laser diode (825 nm) which was modulated at frequencies between 40 - 1000 MHz served as light source. Amplitude and phase of the PDW were measured at various positions on tissue phantoms as well as during interstitial laser coagulation of tissue samples (porcine liver) by scanning source and detector. A Nd:YAG laser was used in combination with a scattering applicator to produce thermal lesions. Due to a change of the optical properties the actual size of the coagulated volume could be monitored during the therapy. Several phantom and in vitro experiments have been performed to show that this monitoring technique is capable of visualizing the coagulated region with a clinically relevant precision. !4