TY - GEN
T1 - Improvement of dead time and decoding resolution for position-sensitive detectors using a fully dynamic approach of light collection
AU - Li, Hongdi
AU - Wang, Chao
AU - An, Shaohui
AU - Baghaei, Hossain
AU - Zhang, Yuxuan
AU - Liu, Shitao
AU - Ramirez, Rocio
AU - Wong, Wai Hoi
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2010
Y1 - 2010
N2 - Photo-sensor sharing (multiple blocks or crystals) can achieve high-resolution position-sensitive detectors but it also increases the dead time and pileups for scintillation event detection. Several methods such as pulse-clipping and HYPER (high-yield-pileup-event-recovery) have been introduced to minimize the dead time and pileups with a trade-off of less scintillation light collection. However, collecting smaller number photoelectrons would increase the statistical error, which in a turn will decrease the decoding resolution. In this study, instead of applying the HYPER method to 3 Anger-signal (X, Y and E) simultaneously, we use an individual dynamic approach for each photo-sensor to maximize the scintillation light collection while it still has a capability of rejecting pileups. The photo-electron collection for one photo-sensor involving a current event decoding will not be disturbed until a new event is detected that also requires this photo-sensor for position-decoding. If a new event comes from an adjacent detector block only sharing one photo-sensor currently involving the previous event decoding, it may only disturb the light collection of this sharing photo-senor; hence only one photo-sensor creates a poor statistical error and the rest photo-sensors can still collect a large number of photo electrons with good statistics for the previous event to achieve a good decoding resolution. This paper compares the decoding results using pulse clipping and this new proposed fully dynamic approach at various count-rates for a regular position-sensitive block detector and a PMT-quadrant-sharing (PQS) block detector. To study the decoding resolution at various high count-rates, a pulse waveform library was built by recording a large number of pulses by a digital oscilloscope from a detector test-bench at a low count-rate first and then boost to different high count-rates by software generated Poisson event time sequence. The result shows this fully dynamic approach reduces the dead space of PQS detectors by x2.25 without increasing the statistical noise.
AB - Photo-sensor sharing (multiple blocks or crystals) can achieve high-resolution position-sensitive detectors but it also increases the dead time and pileups for scintillation event detection. Several methods such as pulse-clipping and HYPER (high-yield-pileup-event-recovery) have been introduced to minimize the dead time and pileups with a trade-off of less scintillation light collection. However, collecting smaller number photoelectrons would increase the statistical error, which in a turn will decrease the decoding resolution. In this study, instead of applying the HYPER method to 3 Anger-signal (X, Y and E) simultaneously, we use an individual dynamic approach for each photo-sensor to maximize the scintillation light collection while it still has a capability of rejecting pileups. The photo-electron collection for one photo-sensor involving a current event decoding will not be disturbed until a new event is detected that also requires this photo-sensor for position-decoding. If a new event comes from an adjacent detector block only sharing one photo-sensor currently involving the previous event decoding, it may only disturb the light collection of this sharing photo-senor; hence only one photo-sensor creates a poor statistical error and the rest photo-sensors can still collect a large number of photo electrons with good statistics for the previous event to achieve a good decoding resolution. This paper compares the decoding results using pulse clipping and this new proposed fully dynamic approach at various count-rates for a regular position-sensitive block detector and a PMT-quadrant-sharing (PQS) block detector. To study the decoding resolution at various high count-rates, a pulse waveform library was built by recording a large number of pulses by a digital oscilloscope from a detector test-bench at a low count-rate first and then boost to different high count-rates by software generated Poisson event time sequence. The result shows this fully dynamic approach reduces the dead space of PQS detectors by x2.25 without increasing the statistical noise.
UR - http://www.scopus.com/inward/record.url?scp=79960324471&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79960324471&partnerID=8YFLogxK
U2 - 10.1109/NSSMIC.2010.5874378
DO - 10.1109/NSSMIC.2010.5874378
M3 - Conference contribution
AN - SCOPUS:79960324471
SN - 9781424491063
T3 - IEEE Nuclear Science Symposium Conference Record
SP - 3133
EP - 3136
BT - IEEE Nuclear Science Symposuim and Medical Imaging Conference, NSS/MIC 2010
T2 - 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010
Y2 - 30 October 2010 through 6 November 2010
ER -