| We have developed a high sensitivity beta camera with good spatial resolution for use in 18FDG guided surgery. The camera is based on novel photodetectors called silicon photomultipliers (SiPMs). These detectors can be employed in the place of photomultiplier tubes (PMTs), the current standard for nuclear medicine instrumentation. The SiPM is extremely compact, high gain, insensitive to magnetic fields, and operates at low bias voltage, all of which features are advantageous for an instrument designed for surgical oncology. We have tested various models of SiPMs to evaluate their suitability for this application.;We have built a series of beta imagers, the performance of which has improved along with the manufacturing technology. The first two dimensional imaging array was built for proof of principle only; the extremely low form factor of 2.5% led to distortion in the linearity of the spatial response and poor spatial resolution of 15 mm for a 1 mm source. The second design was a linear 1 x 4 array; and two versions were constructed with SiPMs from two different manufacturers. The performance was greatly improved for these arrays, with spatial resolution of about 2 mm for both arrays and sensitivities of 0.28 cps/Bq and 0.15 cps/Bq.;The final design discussed in this work was a 17 mm x 17 mm two dimensional array, based on the most recent and best performing SiPMs, with the front-end electronics designed to fit into the handle of a surgical probe. The spatial response was linear for all but the outer 3 mm of the camera and the spatial resolution near the center was 2.0 mm. Sensitivity was determined to be 0.36 cps/Bq. The array performance was evaluated in terms of image contrast with background sources of radiation. The results show that this beta camera should continue to be developed into a clinically implementable instrument. |
