Fluorescence tomography applied to prostate cancer diagnosis using white pulsed laser

摘要

Prostate cancer diagnosis is based on PSA rate measurement and ultrasound guided biopsy. Recently criticized for its lack of specificity, new approaches are currently investigated: MRI, elastography, TEP, NIRS and Time Resolved (TR) fluorescence tomography. The advantage of TR fluorescence tomography relies on its good complementarity with the standard ultrasound protocol and on the possible localization of prostate tumors marked by specific probes. After a first TR system based on a bulky titanium-sapphire laser, we designed a new one taking advantage of a more compact white pulsed laser (supercontinuum). The improved compactness is now fully compatible with clinical environment. The light, filtered by two linear variable filters to select a 770±20 nm window, is driven to the transrectal probe which also collects the fluorescence light emitted by the marker. The signal is detected by photomultipliers connected to TCSPC boards. A reconstruction algorithm based on intensities and time of flight allows a fast localization of the fluorophore. We compared the performances of the new white laser system to the previous titanium-sapphire on prostate mimicking phantoms. The laser power delivered on the phantom by the new laser appeared to be suitable to fluorescence measurements, just below cutaneous maximum permitted exposure. The new system allowed us to localize fluorescent inclusions of a fluorescent nanoemulsion at fixed positions inside a prostate mimicking phantom.