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| T-RPMS Home | Editorial Board | T-RPMS in IEEE Xplore | Manuscript Submission | ||
| FEATURED STORIES - SEPTEMBER 2017 | ||
"Subsurface Laser Engraving Techniques for Scintillator Crystals: Methods, Applications, and Advantages"by G. Konstantinou, R. Chil, M. Desco, and J. J. Vaquero Pixelated scintillators are commonly used for gamma radiation detection in PET scanners. Dimensions, surface treatment, and reflector thickness affect the resolution and sensitivity of the detector and increase the signal to noise ratio. Pixel arrays fabrication is laborious and expensive, while by including nonscintillating material the active area of the detector is reduced. This process can be simplified and improved by the application of subsurface laser engraving techniques, where a grid of laser-induced microcracks form semitransparent walls inside the scintillator. Conceptual development of such patterns including simulations and photometric measurements is presented as a proof that pixelation without the application of external reflectors is possible, liberating pixel size and shape and allowing detector-specific patterns to be created. To demonstrate this, a case study of a hexagonal grid of pixels of 1.4 mm 2 size on LYSO monolithic scintillators is proposed and results presented. Depth of interaction is also implemented on same size pixels, through different approaches. Advantages, concerning sensitivity, packing fraction, and cost effectiveness are discussed, supporting the viability of the process as an alternative to conventional pixelated array fabrication techniques which combines advantageous characteristics of both monolithic and pixelated scintillators.more... |
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"The Effect of Time-of-Flight and Point Spread Function Modeling on Quantitative Cardiac PET of Large Patients: Phantom Studies"by Paul K. R. Dasari, Judson P. Jones, Michael E. Casey and Mark F. Smith The purpose of this paper was to evaluate the effects of time-of-flight (TOF) and point spread function (PSF) modeling on quantitation accuracy in cardiac positron emission tomography (PET) of large patients. Medium and large anthropomorphic cardiac torso phantoms with three anatomical configurations were used in simulating medium and large patients with: 1) arms inside the field of view (FOV); 2) breast for female anatomy; and 3) arms outside the FOV. The effects of TOF and PSF modeling were assessed under two experimental conditions, with and without mismatch in CT attenuation-correction (CTAC) maps. The PET data were reconstructed using analytical and iterative algorithms which included TOF and PSF in combination with six incremental post-reconstruction smoothing filter widths. Polar maps were created by sampling the left ventricle cardiac insert and used for further analyses. The quantitation accuracy of global and regional activity estimates were quantified with contrast recovery coefficient and coefficient of variation. Relative activity bias in the polar maps was compared between the mismatched CTAC reconstructions and their reference matched CTAC reconstructions. more... |
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"A Time-Walk Correction Method for PET Detectors Based on Leading Edge Discriminators"by Junwei Du, Jeffrey P. Schmall, Martin S. Judenhofer, Kun Di, Yongfeng Yang, and Simon R. Cherry The leading edge timing pick-off technique is the simplest timing extraction method for PET detectors. Due to the inherent time-walk of the leading edge technique, corrections should be made to improve timing resolution, especially for time-of-flight PET. Time-walk correction can be done by utilizing the relationship between the threshold crossing time and the event energy on an event-by-event basis. In this paper, a time-walk correction method is proposed and evaluated using timing information from two identical detectors both using leading edge discriminators. This differs from other techniques that use an external dedicated reference detector, such as a fast PMT-based detector using constant fraction techniques to pick-off timing information. In our proposed method, one detector was used as reference detector to correct the time-walk of the other detector. Time-walk in the reference detector was minimized by using events within a small energy window (508.5-513.5 keV). To validate this method, a coincidence detector pair was assembled using two SensL MicroFB SiPMs and two 2.5 mm ×2.5 mm ×20 mm polished lutetium-yttrium oxyorthosilicate crystals. more... |
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"GATE Monte-Carlo Simulation of an MV-CBCT Flat Panel for Synergistic Imaging and Dosimetric Applications in Radiotherapy"by Saadia Benhalouche, Julien Bert, Nicolas Boussion, Awen Autret, Olivier Pradier, and Dimitris Visvikis The purpose of this paper was to evaluate the effects of time-of-flight (TOF) and point spread function (PSF) modeling on quantitation accuracy in cardiac positron emission tomography (PET) of large patients. Medium and large anthropomorphic cardiac torso phantoms with three anatomical configurations were used in simulating medium and large patients with: 1) arms inside the field of view (FOV); 2) breast for female anatomy; and 3) arms outside the FOV. The effects of TOF and PSF modeling were assessed under two experimental conditions, with and without mismatch in CT attenuation-correction (CTAC) maps. The PET data were reconstructed using analytical and iterative algorithms which included TOF and PSF in combination with six incremental post-reconstruction smoothing filter widths. Polar maps were created by sampling the left ventricle cardiac insert and used for further analyses. The quantitation accuracy of global and regional activity estimates were quantified with contrast recovery coefficient and coefficient of variation. Relative activity bias in the polar maps was compared between the mismatched CTAC reconstructions and their reference matched CTAC reconstructions. more... |
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A PUBLICATION OF THE IEEE NUCLEAR AND PLASMA SCIENCES SOCIETY |
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| SEPTEMBER 2017 | VOLUME 1 | NUMBER 5 | ITRPFI | (SSN 2469-7311) | ||
SCINTILLATORS AND DETECTORS Subsurface Laser Engraving Techniques for Scintillator Crystals: Methods, Applications, and Advantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. Konstantinou, R. Chil, M. Desco, and J. J. Vaquero A Time-Walk Correction Method for PET Detectors Based on Leading Edge Discriminators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. Du, J. P. Schmall, M. S. Judenhofer, K. Di, Y. Yang, and S. R. Cherry Toward Implementing Multichannels, Ring-Oscillator-Based, Vernier Time-to-Digital Converter in FPGAs: Key Design Points and Construction Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K. Cui, X. Li, Z. Liu, and R. Zhu CAMERA DESIGN AND IMAGING PERFORMANCE Effective Radiofrequency Attenuation Methods to Reduce the Interference Between PET and MRI Systems . . . . . . . . S. Yamamoto Molecular Breast Imaging Using Synthetic Projections From High-Purity Germanium Detectors: A Simulation Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D. Campbell and T. Petersona IMAGE RECONSTRUCTION AND DATA PROCESSING The Effect of Time-of-Flight and Point Spread Function Modeling on Quantitative Cardiac PET of Large Patients: Phantom Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. K. R. Dasari, J. P. Jones, M. E. Casey, and M. F. Smith Numerical Algorithms for Scatter-to-Attenuation Reconstruction in PET: Empirical Comparison of Convergence, Acceleration, and the Effect of Subsets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Y. Berker, J. S. Karp, and V. Schulz Optimization of an Adaptive SPECT System With the Scanning Linear Estimator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. Ghanbari, E. Clarkson, M. Kupinski, and X. Li RADIATION THERAPY GATE Monte-Carlo Simulation of an MV-CBCT Flat Panel for Synergistic Imaging and Dosimetric Applications in Radiotherapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. Benhalouche, J. Bert, N. Boussion, A. Autret, O. Pradier, and D. Visvikis Monitoring Tumor Lung Irradiation With Megavoltage Patient-Scattered Radiation: A Full System Simulation Study . . . . . . . . . . . . . . . . . . . . H. Simões, A. L. Lopes, C. Travassos, P. Crespo, M. A. Barros, J. Lencart, P. J. B. M. Rachinhas, and J. A. M. Santos PLASMA MEDICINE A Novel DC-Driven Atmospheric-Pressure Cold Microplasma Source for Biomedical Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. Liu, P. Yi, W. Lu, X. Zeng, L. Xu, X. Wang, Q. Zhu, and Q. Xiong Applying on Bacillus cereus of Low-Pressure and Low-Temperature Plasma Jet in a Postdischarge Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. Ilik, P. Aytar Çelik, Y. Toptas ̧, A. Çabuk, and T. Akan |
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