APPARATUS AND METHOD FOR ACHIEVING THREE DIMENSIONAL SPATIAL RESOLUTION IN SILICON PHOTOMULTIPLIER BASED DETECTOR
Publication Date: 2015-Jul-29
The IP.com Prior Art Database
A technique to achieve three dimensional (3D) spatial resolution in a scintillator block detector with large area silicon photomultipliers (SiPMs) is disclosed. The 3D spatial resolution is attained by engineering transit time delay (TTD) across each SiPM device. According to an embodiment, 3D spatial resolution and higher sensitivity is acquired by reading out a top and bottom of long scintillator crystals within large area SiPMs with engineered transit time delays. According to another embodiment, 3D spatial resolution and higher sensitivity with large area SiPM is acquired by using multiple layers of short crystals with single-end SiPM readout.
The present invention relates generally to silicon photomultiplier based detectors and more particularly to a technique for achieving three dimensional (3D) spatial resolution in a silicon photomultiplier based detector.
Silicon photomultipliers are silicon single photon sensitive devices built from an avalanche photodiode (APD) array on a common Si substrate. These devices detect single photon events in sequentially connected Si APDs. A small area SiPM permits extremely compact, light and robust mechanical design of SiPM. Further, parameters of SiPMs have a significant impact on the spatial resolution performance of a medical imaging detector, which in turn provides high performance imaging.
Generally, medical imaging systems use of large number of small area silicon photomultiplier (SiPM) and readout electronics to minimize transit time delay (TTD) and achieve high spatial resolution. Achieving 3D spatial resolution with large area SiPM remains a challenge.
It would be desirable to have a technique to achieve 3D spatial resolution using large area SiPM.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 depicts a large area, typically, 6x6 mm2 SiPM device.
Figure 2 is a graph between TTD profile in a cathode ray tube (CRT) and voltage applied across the CRT.
Figure 3a depicts a top view of an engineered TTD within the large area SiPM.
Figure 3b illustrates different parts of the engineered TTD within the SiPM as depicted in Figure 3a.
Figure 4a depicts a top view of the TTD that is engineered by adding electronic delay elements to a large area hybrid SiPM.
Figure 4b illustrates different parts of the engineered TTD within the hybrid SiPM as depicted in Figure 4a.
Figure 5 depicts 3D spatial resolution of long crystals having dual ended readout by large area SiPMs with engineered TTD.
Figure 6 depicts 3D spatial resolution with two staggered or stacked crystal layers by large area SiPMs with engineered TTD.
A technique to achieve three dimensional (3D) spatial resolution in a scintillator block detector with large area silicon photomultipliers (SiPMs) is disclosed. The 3D spatial resolution is attained by engineering transit time delay (TTD) across each SiPM device. The technique is applied for high spatial resolution PET imaging for small animal or organ-specific applications, such as those for brain or breast, among other organs.
An intrinsic TTD in a typical 6x6 mm2 SiPM device ranges from ~0 ps near an anode to > 650 ps at the furthest point on the SiPM from the anode due to differences in trace network. Figure 1 depicts a large area, typically, 6x6 mm2 SiPM device.
Two short 3x3 mm2 scintillator crystals placed over the 6x6 mm2 active area of the SiPM are not distinguishable, unless coincidence resolving time of the scintillator crystals is significantly smaller, for example, <200ps than the...