Cerenkov luminescence imaging under ambient lighting conditions for intraoperative applications (Conference Presentation)

Cerenkov luminescence (CL), optical radiation induced by PET radiotracers, has shown promise as a means to visualize tumor margins during surgery. However, detecting this faint optical signal under ambient lighting conditions represents a major challenge. We have developed an ambient light CL imaging system that uses a sensitive imaging detector, custom electronic control board, and an LED illumination array. By gating both LED illumination and imaging detector, we have demonstrated that is possible to image faint Cerenkov-emitting sources in a perceptually well-lit room, without harm to the sensitive detector. System performance was characterized by imaging 18F radionuclide solution contained in 10 mm well plates, ranging in activity from >1 MBq to 30 µW/cm2. Both detector and LED illumination were gated at 30 Hz with 10 ms active duty cycles. Contrast-to-noise ratio (CNR) was computed from ROIs drawn over activity-containing wells. Though CNR decreased with increasing illumination levels, an activity of 240 kBq, was unambiguously detectable with gated illumination of 37 µW/cm2 (equivalent to typical indoor light levels) and an activity of <24 kBq was unambiguously detectable with gated illumination of 2 µW/cm2. Furthermore, we have characterized sources of noise for the imaging system, which have provided insight into strategies for optimization in anticipation of use in an intraoperative setting.