Program Information
Initial Investigation of Various Modes in a CdTe-Based Imaging Photon Counting Detector (PCD)
A Shankar*, M Russ , J Krebs , D Bednarek , S Rudin , Toshiba Stroke and Vascualar Research Center, University at Buffalo , Buffalo, NY
Presentations
WE-AB-601-7 (Wednesday, August 2, 2017) 7:30 AM - 9:30 AM Room: 601
Purpose: To perform a preliminary comparison of linearity and sensitivity for the various operational modes of XCounter’s Actaeon imaging PCD.
Methods: In contrast to energy integration, a PCD involves counting individual photons above a fixed threshold. XCounter AB’s Actaeon imager is based on direct detection with 0.75 mm thick CdTe, 100 µm pixel pitch, and 256 x 256 pixels. The various operational modes were used to image a Stenosis/Aneurysm Artery block (Nuclear Associates model 76-705) and the total counts in an averaged frame were obtained after flat-field correction. The exposure settings were varied from 50 to 400 mA and the total counts for each mode were compared for two separate thresholds to evaluate linearity.
Results: Three of the four operational modes demonstrated linearity in response to exposure parameters. The High Sensitivity with Anti-Coincidence-On (HS-On) appears to result in overall gain of total counts compared to modes without charge sharing correction as it sums up counts below the threshold and attributes them to one pixel and one event above the threshold rather than not counting such a charge shared event where no individual pixel has a signal above the threshold as in the HS-Off mode. However, for the HS-On mode at higher photon fluence rates the linearity breaks down presumably due to delay in implementing the anti-coincidence charge sharing correction for neighboring pixels hence resulting in losses due to pulse pile up. The non-linearity occurs at both lower threshold (10 keV) and higher threshold (32 keV). The sensitivity appears to be dependent upon the energy threshold and is lowest for High Flux mode with higher thresholds and the sensitivity is in between the HS-ON and HS-OFF modes for lower thresholds.
Conclusion: Initial test of a new PCD evidenced higher sensitivity but non-linear performance when charge sharing correction was implemented.
Funding Support, Disclosures, and Conflict of Interest: This research was supported in part by Toshiba Medical Systems Corporation and NIH Grant R01EB002873
Contact Email: