Cherenkov luminescence measurements with digital silicon photomultipliers: a feasibility study

Abstract

BackgroundA feasibility study was done to assess the capability of digital silicon photomultipliers to measure the Cherenkov luminescence emitted by a β source. Cherenkov luminescence imaging (CLI) is possible with a charge coupled device (CCD) based technology, but a stand-alone technique for quantitative activity measurements based on Cherenkov luminescence has not yet been developed. Silicon photomultipliers (SiPMs) are photon counting devices with a fast impulse response and can potentially be used to quantify β-emitting radiotracer distributions by CLI.MethodsIn this study, a Philips digital photon counting (PDPC) silicon photomultiplier detector was evaluated for measuring Cherenkov luminescence. The PDPC detector is a matrix of avalanche photodiodes, which were read one at a time in a dark count map (DCM) measurement mode (much like a CCD). This reduces the device active area but allows the information from a single avalanche photodiode to be preserved, which is not possible with analog SiPMs. An algorithm to reject the noisiest photodiodes and to correct the measured count rate for the dark current was developed.ResultsThe results show that, in DCM mode and at (10–13) °C, the PDPC has a dynamic response to different levels of Cherenkov luminescence emitted by a β source and transmitted through an opaque medium. This suggests the potential for this approach to provide quantitative activity measurements. Interestingly, the potential use of the PDPC in DCM mode for direct imaging of Cherenkov luminescence, as a opposed to a scalar measurement device, was also apparent.ConclusionsWe showed that a PDPC tile in DCM mode is able to detect and image a β source through its Cherenkov radiation emission. The detector’s dynamic response to different levels of radiation suggests its potential quantitative capabilities, and the DCM mode allows imaging with a better spatial resolution than the conventional event-triggered mode. Finally, the same acquisition procedure and data processing could be employed also for other low light levels applications, such as bioluminescence.Electronic supplementary materialThe online version of this article (doi:10.1186/s40658-015-0134-z) contains supplementary material, which is available to authorized users.

Cerenkov luminescence imaging: physics principles and potential applications in biomedical sciences

“…Abbreviations: Brems = Bremsstrahlung, photoel = photoelectron, δ = δ ray, C̆ = Cerenkov radiation. Adapted from [69] …”

“…One group has used a photomultiplier tube coupled to fiber optics for proton-therapy dosimetry [26], while in [69] digital silicon photomultipliers (SiPM) have been proposed as an alternative technology to CCDs. SiPMs are single photon sensitive devices, in the sense that they produce an output signal that allows to discriminate each detected photon.…”

“…Bottom left : Decay in time of the count rate due to 18 F measured by the PDPC, before and after data correction [27]. Bottom right : Linearity of the Cerenkov count rate in the PDPC with the 18 F activity level, adapted from [69] …”

“…One study has investigated the quantitative capabilities of digital silicon photomultipliers (dSiPMs) for CLI [69]. In fact, dSiPMs provide directly the number of detected photons and might therefore allow an easier quantitative reconstruction of the activity with respect to CCDs (which instead require some sort of calibration to recover the number of detected photons).…”

“…In particular, the 18 F half life could be obtained from the experimental data with very high precision. Figure 11 (bottom left) shows the effect of the data correction algorithm on the 18 F decay curve in time (from [27]), Figure 11 (bottom right) shows the linearity of the Cerenkov count rate in the PDPC with the 18 F activity level, after data correction (adapted from [69]).…”