The System Design, Engineering Architecture, and Preliminary Results of a Lower-Cost High-Sensitivity High-Resolution Positron Emission Mammography Camera

Abstract

A lower-cost high-sensitivity high-resolution positron emission mammography (PEM) camera is developed. It consists of two detector modules with the planar detector bank of 20 × 12 cm2. Each bank has 60 low-cost PMT-Quadrant-Sharing (PQS) LYSO blocks arranged in a 10 × 6 array with two types of geometries. One is the symmetric 19.36 × 19.36 mm2 block made of 1.5 × 1.5 × 10 mm3 crystals in a 12 × 12 array. The other is the 19.36 × 26.05 mm2 asymmetric block made of 1.5 × 1.9 × 10 mm3 crystals in 12 × 13 array. One row (10) of the elongated blocks are used along one side of the bank to reclaim the half empty PMT photocathode in the regular PQS design to reduce the dead area at the edge of the module. The bank has a high overall crystal packing fraction of 88%, which results in a very high sensitivity. Mechanical design and electronics have been developed for low-cost, compactness, and stability purposes. Each module has four Anger-HYPER decoding electronics that can handle a count-rate of 3 Mcps for single events. A simple two-module coincidence board with a hardware delay window for random coincidences has been developed with an adjustable window of 6 to 15 ns. Some of the performance parameters have been studied by preliminary tests and Monte Carlo simulations, including the crystal decoding map and the 17% energy resolution of the detectors, the point source sensitivity of 11.5% with 50 mm bank-to-bank distance, the 1.2 mm-spatial resolutions, 42 kcps peak Noise Equivalent Count Rate at 7.0-mCi total activity in human body, and the resolution phantom images. Those results show that the design goal of building a lower-cost, high-sensitivity, high-resolution PEM detector is achieved.

Reprogrammable Acquisition Architecture for Dedicated Positron Emission Tomography

“…The histogram has been obtained by separately correcting each pixel for its own conversion efficiency. The achieved energy resolution is 20% FWHM, with a minimum energy resolution per single pixel of 15% FWHM, both values comparable with the same obtained in similar PET systems [26], [27]. A long tail can be appreciated in the obtained histogram, that we ascribe as an effect of the optical absorption characteristic of the scintillating crystals used in our tests.…”

Performance evaluation of a high resolution dedicated breast PET scanner

“…The reported energy resolution, for other DbPETs, ranges from 15% to 25%. 19,27,28,47 Other works measured the uniformity of small PETs (Refs. 19 and 26), however, the results are analyzed using different methods.…”

Breast-Dedicated Radionuclide Imaging Systems

“…To maximize sensitivity for lesions at the chest wall, the dead area near the chest wall should be minimized (13). Dual-panel limited-angle tomography systems that can compress the breast can generally image the chest wall more effectively than ring-based systems, either by taking a different mammographic view of the breast or by bringing into the FOV more of the breast tissue that is near the chest wall.…”

“…Another option is to use charge multiplexing (e.g., resistive readout) of photodetector arrays. Light-sharing techniques involving specially engineered crystal reflectors enable position encoding using standard photomultiplier tubes (13).…”