A Clinical Prototype Transrectal Diffuse Optical Tomography (TRDOT) System for In vivo Monitoring of Photothermal Therapy (PTT) of Focal Prostate Cancer.

We describe the rationale, design, fabrication and performance of a clinical transrectal diffuse optical tomography (TRDOT) system for in vivo monitoring of photothermal therapy (PTT) of localized prostate cancer. The system comprises a 32-channel fiberoptic-based, MRI-compatible transrectal probe connected to a computer-controlled instrument that includes laser diode sources, an optical fiber switch and photomultiplier tube detectors. Performance tests were performed in tissue-simulating phantoms and in ex vivo muscle tissue during PTT treatment. The safety and technical feasibility of in vivo transrectal use were tested in a canine prostate model and in a first-in-human study in a patient before PTT treatment. Limitations of the system are discussed, as well as further developments to translate it into planned clinical trials for monitoring the photocoagulation boundary in the prostate during PTT.