Gabriel Cañizares;Santiago Jiménez-Serrano;Alejandro Lucero;Constantino Morera-Ballester;Enrique Muñoz;José M. Benlloch;Antonio J. González
{"title":"Simulation Study of Clinical PET Scanners With Different Geometries, Including TOF and DOI Capabilities","authors":"Gabriel Cañizares;Santiago Jiménez-Serrano;Alejandro Lucero;Constantino Morera-Ballester;Enrique Muñoz;José M. Benlloch;Antonio J. González","doi":"10.1109/TRPMS.2024.3365911","DOIUrl":null,"url":null,"abstract":"Total body positron emission tomography (TB-PET) scanners provide high-quality images due to the large sensitivity. Our motivation is to design a TB-PET system with up to 70 cm axial coverage that mitigates the parallax error degradation by using a detector concept based on semi-monolithic LYSO crystals. Furthermore, this detector approach allows to simultaneously reach an accurate coincidence time resolution (CTR) to enhance the image quality by means of time-of-flight (TOF) reconstruction algorithms. We have simulated and compared two positron emission tomography (PET) prototypes with about 70 cm but a different number of detector rings (7 versus 5). The NEMA NU 2 2018 protocol has been implemented. By correcting the parallax error with the depth-of-interaction (DOI) information, the spatial resolution remains homogeneous and below 3 mm in the entire field of view (FOV), differently from designs based on pixelated crystals. The sensitivity reaches values of 58 and 115 cps/kBq, for the 5 and 7 rings configurations, respectively. The noise equivalent count rate (NECR) was found at 563 kcps/mL. This value is lower than other systems, most likely due to the requirement to process a larger number of channels to characterize the DOI. Percent contrasts obtained for two different phantoms are in general beyond 80% for the largest spheres, nearly 100% for the 7 rings configuration once TOF is applied during the reconstruction process. In conclusion, although the sensitivity and NECR results for the 5-rings configuration are lower compared to the 7-rings approach, its overall performance is enhanced by the addition of TOF and parallax error correction, improving that of conventional Whole Body PET scanners (axial length: 20–30 cm) in terms of image quality.","PeriodicalId":46807,"journal":{"name":"IEEE Transactions on Radiation and Plasma Medical Sciences","volume":"8 6","pages":"690-699"},"PeriodicalIF":4.6000,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10436427","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"IEEE Transactions on Radiation and Plasma Medical Sciences","FirstCategoryId":"1085","ListUrlMain":"https://ieeexplore.ieee.org/document/10436427/","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING","Score":null,"Total":0}
引用次数: 0
Abstract
Total body positron emission tomography (TB-PET) scanners provide high-quality images due to the large sensitivity. Our motivation is to design a TB-PET system with up to 70 cm axial coverage that mitigates the parallax error degradation by using a detector concept based on semi-monolithic LYSO crystals. Furthermore, this detector approach allows to simultaneously reach an accurate coincidence time resolution (CTR) to enhance the image quality by means of time-of-flight (TOF) reconstruction algorithms. We have simulated and compared two positron emission tomography (PET) prototypes with about 70 cm but a different number of detector rings (7 versus 5). The NEMA NU 2 2018 protocol has been implemented. By correcting the parallax error with the depth-of-interaction (DOI) information, the spatial resolution remains homogeneous and below 3 mm in the entire field of view (FOV), differently from designs based on pixelated crystals. The sensitivity reaches values of 58 and 115 cps/kBq, for the 5 and 7 rings configurations, respectively. The noise equivalent count rate (NECR) was found at 563 kcps/mL. This value is lower than other systems, most likely due to the requirement to process a larger number of channels to characterize the DOI. Percent contrasts obtained for two different phantoms are in general beyond 80% for the largest spheres, nearly 100% for the 7 rings configuration once TOF is applied during the reconstruction process. In conclusion, although the sensitivity and NECR results for the 5-rings configuration are lower compared to the 7-rings approach, its overall performance is enhanced by the addition of TOF and parallax error correction, improving that of conventional Whole Body PET scanners (axial length: 20–30 cm) in terms of image quality.