Christel Sundberg1,2, Mats Danielsson1,3, Mats Persson1,3. 1. KTH Royal Institute of Technology, Physics of Medical Imaging, Stockholm, Sweden. 2. Prismatic Sensors, part of GE Healthcare, AlbaNova University Center, Stockholm, Sweden. 3. MedTechLabs, BioClinicum, Karolinska University Hospital, Solna, Sweden.
Abstract
Purpose: Compton interactions amount to a significant fraction of the registered counts in a silicon detector. In a Compton interaction, only a part of the photon energy is deposited and a single incident photon can result in multiple counts unless tungsten shielding is used. Deep silicon has proved to be a competitive material for photon-counting CT detectors, but to improve the performance further, one possibility is to use coincidence techniques to identify Compton-scattered photons and reconstruct their incident energies. Approach: In a detector with no tungsten shielding, incident photons can interact through a series of interactions. Based on the position and energy of each interaction, probability-based methods can be used to estimate the incident photon energy. Here, we present a maximum likelihood estimation framework along with an alternative method to estimate the incident photon energy and position in a silicon detector. Results: Assuming one incident photon per time frame, we show that the incident photon energy can be estimated with a mean error of - 0.07 ± 0.03 keV and an RMS error of 3.36 ± 0.02 keV for a realistic case in which we assume a detector with limited energy and spatial resolution. The interaction position was estimated with a mean error of - 2 ± 11 μ m in x direction and 7 ± 11 μ m in y direction. Corresponding RMS errors of 1.09 ± 0.01 and 1.10 ± 0.01 mm were achieved in x and y , respectively. Conclusions: The presented results show the potential of using probability-based methods to improve the performance of silicon detectors for CT.
Purpose: Compton interactions amount to a significant fraction of the registered counts in a silicon detector. In a Compton interaction, only a part of the photon energy is deposited and a single incident photon can result in multiple counts unless tungsten shielding is used. Deep silicon has proved to be a competitive material for photon-counting CT detectors, but to improve the performance further, one possibility is to use coincidence techniques to identify Compton-scattered photons and reconstruct their incident energies. Approach: In a detector with no tungsten shielding, incident photons can interact through a series of interactions. Based on the position and energy of each interaction, probability-based methods can be used to estimate the incident photon energy. Here, we present a maximum likelihood estimation framework along with an alternative method to estimate the incident photon energy and position in a silicon detector. Results: Assuming one incident photon per time frame, we show that the incident photon energy can be estimated with a mean error of - 0.07 ± 0.03 keV and an RMS error of 3.36 ± 0.02 keV for a realistic case in which we assume a detector with limited energy and spatial resolution. The interaction position was estimated with a mean error of - 2 ± 11 μ m in x direction and 7 ± 11 μ m in y direction. Corresponding RMS errors of 1.09 ± 0.01 and 1.10 ± 0.01 mm were achieved in x and y , respectively. Conclusions: The presented results show the potential of using probability-based methods to improve the performance of silicon detectors for CT.
Authors: S Jan; G Santin; D Strul; S Staelens; K Assié; D Autret; S Avner; R Barbier; M Bardiès; P M Bloomfield; D Brasse; V Breton; P Bruyndonckx; I Buvat; A F Chatziioannou; Y Choi; Y H Chung; C Comtat; D Donnarieix; L Ferrer; S J Glick; C J Groiselle; D Guez; P F Honore; S Kerhoas-Cavata; A S Kirov; V Kohli; M Koole; M Krieguer; D J van der Laan; F Lamare; G Largeron; C Lartizien; D Lazaro; M C Maas; L Maigne; F Mayet; F Melot; C Merheb; E Pennacchio; J Perez; U Pietrzyk; F R Rannou; M Rey; D R Schaart; C R Schmidtlein; L Simon; T Y Song; J M Vieira; D Visvikis; R Van de Walle; E Wieërs; C Morel Journal: Phys Med Biol Date: 2004-10-07 Impact factor: 3.609
Authors: Mats Persson; Robert Bujila; Patrik Nowik; Henrik Andersson; Love Kull; Jonas Andersson; Hans Bornefalk; Mats Danielsson Journal: Med Phys Date: 2016-07 Impact factor: 4.071