Clear-PEM system counting rates: a Monte Carlo study

Abstract

Positron Emission Mammography (PEM) with 18 F-Fluorodeoxyglucose ( 18 F-FDG) is a functional imaging technique for breast cancer detection. The development of dedicated imaging systems with high sensitivity and spatial resolution are crucial for early breast cancer diagnosis and an efficient therapy. Clear-PEM is a dual planar scanner designed for high-resolution breast cancer imaging under development by the Portuguese PET Mammography consortium within the Crystal Clear Collaboration. It brings together a favorable combination of high-density scintillator crystals coupled to compact photodetectors, arranged in a double readout scheme capable of providing depth-of-interaction information. A Monte Carlo study of the Clear-PEM system counting rates is presented in this paper. Hypothetical breast exam scenarios were simulated to estimate the single event rates, true and random coincidence rates. A realistic description of the patient and detector geometry, radiation environment, physics and instrumentation factors was adopted in this work. Special attention was given to the 18 F-FDG accumulation in the patient torso organs which, for the Clear-PEM scanner, represent significant activity outside the field-of-view (FOV) contributing to an increase of singles, randoms and scattered coincidences affecting the overall system performance. The potential benefits of patient shielding to minimize the influence of the out-of-field background was explored. The influence of LYSO:Ce crystal intrinsic natural activity due to the presence of the 176 Lu isotope on the counting rate performance of the proposed scanner, was also investigated.

Experimental characterization of the 192 channel Clear-PEM frontend ASIC coupled to a multi-pixel APD readout of LYSO:Ce crystals

“…The scanner will be subject to a flux of single photons up to 2 MHz per detector head that needs to be discarded as soon as possible in the data acquisition chain, avoiding the introduction of deadtime that could reduce the system efficiency [27]. A good time resolution is also required to minimize the presence of random events through the use of a narrow coincidence window which contribute to a contrast loss and introduction of artifacts in the reconstructed images [28].…”

Whole-body single-bed time-of-flight RPC-PET: Simulation of axial and planar sensitivities with NEMA and anthropomorphic phantoms

“…This included considering the different tissues and densities that attenuate photon emission from the human body, as well as a whole-body emission biodistribution. The different values of activity at different body organs and tissues were chosen in accordance with published data [23,24]. A grey-towhite matter uptake value of 4-to-1 was implemented at the brain [25].…”