Near infrared diffuse optical tomography (DOT) is a significant potential means of detecting breast cancer. Compared with other system structures, the parallel-plate scanning mode has such advantages like adapting to different breast size, as well as increasing the transmission of light by compressing. Traditional parallel-plate DOT systems utilized the fibers for photon transmission and photomultiplier tube (PMT) or CCD for photon detection, which resulted in the high complexity and cost. In this study, we propose a fiber-free parallel-plate continuous-wave DOT system for breast cancer detection based on Silicon photomultiplier (SiPM) and multi-wavelength light emitting diode (LED). 50 three-wavelength (660 nm, 750nm and 840nm) LEDs are arranged in a printed circuit board (PCB) array as the source plate. Parallel to this plate, the other plate with 56 silicon photomultipliers (SiPM) arranged is designed as the detection plate. The control of the light source excitation and the detection of the SiPMs output are implemented by a module based on a data acquisition card. The structure of proposed system is very simple, and the acquisition time is no more than 5 minutes. The feasibility of the system was verified by polyoxymethylene and agar phantom experiments, which indicated that the parallel-plate system can accurately reconstruct optical parameters.
Cerenkov fluorescence imaging (CLI) has set a bridge between optical and nuclear imaging technologies by using an optical method to detect the distribution of radiotracers. Combining the emerged CLI technique with a clinical endoscope, the Cerenkov luminescence endoscope (CLE) was developed to avoid the problem of the poor penetration depth of the Cerenkov light. However, due to low energy of the Cerenkov light and the transportation loss during endoscopic imaging, the acquisition time of CLE signal is long and the imaging results are poor, which has limited the clinical applications of CLE. There are two ways to improve the availability of the current CLE system. First is to enhance the emitted signals of the Cerenkov light at the source end by developing new kinds of imaging probes or selecting high yield radionuclides. However, this will introduce the in vivo unfriendly problem in clinical translations. The second method is to improve the detection sensitivity of CLE system by optimizing the structure of the system. Here, we customized four endoscopes with different field of view (FOV) angles of endoscope probe and different monofilament diameters of imaging fiber bundles. By comparing the results obtained by different CLE systems, we optimized the parameters of system. The CLE imaging of 18F-FDG showed that when the distance between the probe and radionuclide source was fixed, smaller angle of FOV and lager monofilament diameter will provide higher collection efficiency.