Effect of ¹⁷⁶Lu intrinsic radioactivity on dual head PET system imaging and data acquisition, simulation, and experimental measurements

Abstract

It has been proven that the lack of the (176)Lu intrinsic radioactivity has an impact on the design of the simulation model's dead time. Even if there is an alignment with experimental results still the noise properties, for a wide range of activities, are overestimated. In addition, for low activities, better image quality, is presented, mainly due to the lack of the (176)Lu photons which blur the images. Furthermore, it was shown that the use of a high hardware threshold allows the application of a wide energy window, which improves the statistics without a significant compromise on the quality of the detected photons, mainly, due to the early rejection of the low energy photons and the low scatter factor.

¹⁷⁶Lu effect on the minimum detectable activity limits for a dual head, LSO: Ce based, PET system

“…The small animal PET prototype camera, which was used as reference, has been extensively presented previously [3], [6], [7]. In brief, it consists of two LSO:Ce based heads, the crystal arrays have 20×20 pixels and H8500 Hamamatsu PSPMTs.…”

“…The coincidence window of the system was 6ns and the hardware threshold was set at 160keV. All coincidence images were reconstructed using the focal plane tomography method (FPT) [3], [8]. The LSO intrinsic radioactivity was simulated using an ion source of 176 Lu, which was placed at the same global coordinates as the crystals, but not confined to them [2], [3].…”

“…All coincidence images were reconstructed using the focal plane tomography method (FPT) [3], [8]. The LSO intrinsic radioactivity was simulated using an ion source of 176 Lu, which was placed at the same global coordinates as the crystals, but not confined to them [2], [3]. The activity of the 176 Lu source was set to 277 Bq cm 3 as described in literature [9].…”

“…The concept of the minimum detectable activity (MDA) has been extensively investigated for cylindrical geometries [1], [2]. Dual head PET cameras are proven valuable tools for preclinical, imaging mainly due to their low cost, the ability to adjust their field of view (FOV), according to the specific needs and fast creation of planar images which are suitable for radiopharmaceuticals with fast kinetics [3], [4]. The importance of the minimul detactable activity (MDA) rises when referring to 176 Lu based scanners which have a non-negligible background count rate, due to 176 Lu intrinsic radioactivity.…”

Fully Digital FPGA-Based Data Acquisition System for Dual Head PET Detectors

“…Coincidence data were grouped to projections using the non-iterative Focal Plane Tomography (FPT) algorithm [47]. An energy window of 250-650 keV was applied to all reconstructed images [34].…”