Molecular Imaging Instrumentation Laboratory  

Peer-reviewed Papers

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    Author Title Year Jour./Proc./Book
    Arbab-Zadeh; Russo, R.J.; Bhargava, V.; Levin, C.S.; Jani, S.K.; Lucisano, J. & Teirstein, P.S. Centered Versus Non-Centered Source For Intracoronary Artery Radiation Therapy: A Model Based on the Scripps Trial 2002 American Heart Journal
    Vol. 143-2, pp. 342-8  
    BibTeX:
    @article{Arbab-Zadeh2002,
      author = {Arbab-Zadeh and R. J. Russo and V. Bhargava and C. S. Levin and S. K. Jani and J. Lucisano and P. S. Teirstein},
      title = {Centered Versus Non-Centered Source For Intracoronary Artery Radiation Therapy: A Model Based on the Scripps Trial},
      journal = {American Heart Journal},
      year = {2002},
      volume = {143-2},
      pages = {342-8}
    }
    					
    Cherry, S.R.; Tornai, M.P.; Levin, C.S.; Siegel, S. & Hoffman, E.J. A Comparison of PET Detector Modules Employing Rectangular and Round Photomultiplier Tubes 1995 IEEE Transactions on Nuclear Science
    Vol. 42-4, pp. 1064-1068  
    BibTeX:
    @article{Cherry1995,
      author = {S. R. Cherry and M. P. Tornai and C. S. Levin and S. Siegel and E. J. Hoffman},
      title = {A Comparison of PET Detector Modules Employing Rectangular and Round Photomultiplier Tubes},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1995},
      volume = {42-4},
      pages = {1064-1068}
    }
    					
    Chinn, G. & Levin, C.S. A Maximum NEC Criterion for Compton Collimation to Accurately Identify True Coincidences in PET 2011 Medical Imaging, IEEE Transactions on
    Vol. 30, pp. 1341-1352  
    BibTeX:
    @article{Chinn2011,
      author = {G. Chinn and C. S. Levin},
      title = {A Maximum NEC Criterion for Compton Collimation to Accurately Identify True Coincidences in PET},
      journal = {Medical Imaging, IEEE Transactions on},
      year = {2011},
      volume = {30},
      number = {7},
      pages = {1341--1352},
      doi = {http://dx.doi.org/10.1109/TMI.2011.2113379}
    }
    					
    Cui, J.; Pratx, G.; Prevrhal, S. & Levin, C.S. Fully 3D List-Mode Time-of-Flight PET Image Reconstruction on GPUs Using CUDA 2011 Medical Physics
    Vol. 38, pp. 6775-6786  
    BibTeX:
    @article{Cui2011CUDA,
      author = {J. Cui and G. Pratx and S. Prevrhal and C. S. Levin},
      title = {Fully 3D List-Mode Time-of-Flight PET Image Reconstruction on GPUs Using CUDA},
      journal = {Medical Physics},
      year = {2011},
      volume = {38},
      number = {12},
      pages = {6775-6786}
    }
    					
    Dhanasopon, A.P.; Levin, C.S.; Foudray, A.M.K.; Olcott, P.D. & Habte, F. Scintillation Crystal Design Features for a Miniature Gamma-Ray Camera 2005 IEEE Transactions on Nuclear Science
    Vol. 52, pp. 1439-1446  
    BibTeX:
    @article{Dhanasopon2005,
      author = {A. P. Dhanasopon and C. S. Levin and A. M. K. Foudray and P. D. Olcott and F. Habte},
      title = {Scintillation Crystal Design Features for a Miniature Gamma-Ray Camera},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2005},
      volume = {52},
      number = {5},
      pages = {1439-1446}
    }
    					
    Foudray, A.M.K.; Habte, F.; Chinn, G.; Zhang, J. & Levin, C.S. Count Rate Studies of a Box-Shaped PET Breast Imaging System Comprised of Position Sensitive Avalanche Photodiodes Utilizing Monte Carlo Simulation 2006 Physica Medica
    Vol. 21, pp. 64-67  
    BibTeX:
    @article{Foudray2006a,
      author = {A. M. K. Foudray and F. Habte and G. Chinn and J. Zhang and C. S. Levin},
      title = {Count Rate Studies of a Box-Shaped PET Breast Imaging System Comprised of Position Sensitive Avalanche Photodiodes Utilizing Monte Carlo Simulation},
      journal = {Physica Medica},
      year = {2006},
      volume = {21},
      pages = {64-67}
    }
    					
    Foudray, A.M.K.; Habte, F.; Levin, C.S. & Olcott, P.D. Positioning Annihilation Photon Interactions in a Thin LSO Crystal Sheet with a Position-Sensitive Avalanche Photodiodes 2006 IEEE Transactions on Nuclear Science
    Vol. 53, pp. 2549-2556  
    BibTeX:
    @article{Foudray2006,
      author = {A. M. K. Foudray and F. Habte and C. S. Levin and P. D. Olcott},
      title = {Positioning Annihilation Photon Interactions in a Thin LSO Crystal Sheet with a Position-Sensitive Avalanche Photodiodes},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2006},
      volume = {53},
      number = {5},
      pages = {2549-2556}
    }
    					
    Foudray, A.M.K. & Levin, C.S. Bayesian Estimator for Angle Recovery: Event Classification and Reconstruction in Positron Emission Tomography 2007 Journal of Bayesian Inference and Maximum Entropy Methods in Science and Engineering, American Institutes of Physics
    Vol. 954, pp. 362-371  
    BibTeX:
    @article{Foudray2007,
      author = {A. M. K. Foudray and C. S. Levin},
      title = {Bayesian Estimator for Angle Recovery: Event Classification and Reconstruction in Positron Emission Tomography},
      journal = {Journal of Bayesian Inference and Maximum Entropy Methods in Science and Engineering, American Institutes of Physics},
      year = {2007},
      volume = {954},
      pages = {362-371}
    }
    					
    Gu, Y.; Matteson, J.L.; Skelton, R.T.; Deal, A.C.; Stephan, E.A.; Duttweiler, F.; Gasaway, T.M. & Levin, C.S. Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET 2011 Physics in Medicine and Biology
    Vol. 56, pp. 1563-1584  
    Abstract: This paper investigates the performance of 1 mm resolution cadmium zinc telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm ? 40 mm ? 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06 ? 0.39% at 511 keV throughout most of the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44 ? 0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78 ? 0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes??as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.
    BibTeX:
    @article{Gu2011,
      author = {Y. Gu and J. L. Matteson and R. T. Skelton and A. C. Deal and E. A. Stephan and F. Duttweiler and T. M. Gasaway and C. S. Levin},
      title = {Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET},
      journal = {Physics in Medicine and Biology},
      year = {2011},
      volume = {56},
      number = {6},
      pages = {1563-1584}
    }
    					
    Gu, Y.; Pratx, G.; Lau, F.W.Y. & Levin, C.S. Effects of multiple-interaction photon events in a high-resolution PET system that uses 3-D positioning detectors 2010 MEDICAL PHYSICS
    Vol. 37, pp. 5494-5508  
    Abstract: Purpose: The authors' laboratory is developing a dual-panel, breast-dedicated PET system. The detector panels are built from dual-LSO-position-sensitive avalanche photodiode (PSAPD) modules-units holding two 8 X 8 arrays of 1 mm(3) LSO crystals, where each array is coupled to a PSAPD. When stacked to form an imaging volume, these modules are capable of recording the 3-D coordinates of individual interactions of a multiple-interaction photon event (MIPE). The small size of the scintillation crystal elements used increases the likelihood of photon scattering between crystal arrays. In this article, the authors investigate how MIPEs impact the system photon sensitivity, the data acquisition scheme, and the quality and quantitative accuracy of reconstructed PET images. Methods: A Monte Carlo simulated PET scan using the dual-panel system was performed on a uniformly radioactive phantom for the photon sensitivity study. To establish the impact of MIPEs on a proposed PSAPD multiplexing scheme, experimental data were collected from a dual-LSO-PSAPD module edge-irradiated with a Na-22 point source, the data were compared against simulation data based on an identical setup. To assess the impact of MIPEs on the dual-panel PET images, a simulated PET of a phantom comprising a matrix of hot spherical radiation sources of varying diameters immersed in a warm background was performed. The list-mode output data were used for image reconstruction, where various methods were used for estimating the location of the first photon interaction in MIPEs for more accurate line of response positioning. The contrast recovery coefficient (CRC), contrast to noise ratio (CNR), and the full width at half maximum spatial resolution of the spheres in the reconstructed images were used as figures of merit to facilitate comparison. Results: Compared to image reconstruction employing only events with interactions confined to one LSO array, a potential single photon sensitivity gain of >46.9% (>115.7% for coincidence) was noted for a uniform phantom when MIPEs with summed-energy falling within a +/- 12% window around the photopeak were also included. Both experimental and simulation data demonstrate that <0.4% of the events whose summed-energy deposition falling within that energy window interacted with both crystal arrays within the same dual-LSO-PSAPD module. This result establishes the feasibility of a proposed multiplexed readout of analog output signals of the two PSAPDs within each module. Using MIPEs with summed-energy deposition within the 511 keV +/- 12% photopeak window and a new method for estimating the location of the first photon interaction in MIPEs, the corresponding reconstructed image exhibited a peak CNR of 7.23 for the 8 mm diameter phantom spheres versus a CNR of 6.69 from images based solely on single LSO array interaction events. The improved system photon sensitivity could be exploited to reduce the scan time by up to approximately 10 while still maintaining image quality comparable to that achieved if MIPEs were excluded. Conclusions: MIPE distribution in the detectors allows the proposed photodetector multiplexing arrangement without significant information loss. Furthermore, acquiring MIPEs can enhance system photon sensitivity and improve PET image CNR and CRC. The system under development can therefore competently acquire and analyze MIPEs and produce high-resolution PET images. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3483262]
    BibTeX:
    @article{Gu2010,
      author = {Y. Gu and G. Pratx and F. W. Y. Lau and C. S. Levin},
      title = {Effects of multiple-interaction photon events in a high-resolution PET system that uses 3-D positioning detectors},
      journal = {MEDICAL PHYSICS},
      year = {2010},
      volume = {37},
      number = {10},
      pages = {5494-5508},
      doi = {http://dx.doi.org/10.1118/1.3483262}
    }
    					
    Habte, F.; Foudray, A.M.K.; Olcott, P.D. & Levin, C.S. Effects of System Geometry and Other Physical Factors on Photon Sensitivity of High Resolution Positron Emission Tomography 2007 Physics in Medicine and. Biology
    Vol. 52, pp. 3753-3772  
    BibTeX:
    @article{Habte2007a,
      author = {F. Habte and A. M. K. Foudray and P. D. Olcott and C. S. Levin},
      title = {Effects of System Geometry and Other Physical Factors on Photon Sensitivity of High Resolution Positron Emission Tomography},
      journal = {Physics in Medicine and. Biology},
      year = {2007},
      volume = {52},
      pages = {3753-3772}
    }
    					
    Habte, F. & Levin, C.S. Study of Low Noise Multi-Channel Readout Electronics for High Sensitivity PET Systems Based on Avalanche Photodiode Arrays 2004 IEEE Transactions on Nuclear Science
    Vol. 51-3, pp. 764-769  
    BibTeX:
    @article{Habte2004,
      author = {F. Habte and C. S. Levin},
      title = {Study of Low Noise Multi-Channel Readout Electronics for High Sensitivity PET Systems Based on Avalanche Photodiode Arrays},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2004},
      volume = {51-3},
      number = {2},
      pages = {764-769}
    }
    					
    Habte, F.; Olcott, P.D.; Foudray, A.M.K.; Levin, C.S.; Zhang, J. & Chinn, G. Simulation and Measurement of Gamma-Ray and Annihilation Photon Imaging Detectors 2008 IEEE Transactions on Nuclear Science  
    BibTeX:
    @article{Habte2008,
      author = {F. Habte and P. D. Olcott and A. M. K. Foudray and C. S. Levin and J. Zhang and G. Chinn},
      title = {Simulation and Measurement of Gamma-Ray and Annihilation Photon Imaging Detectors},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2008},
      note = {Submitted}
    }
    					
    Habte, F.; Olcott, P.D. & Levin, C.S. High Resolution, Light Multiplexed 3D Positioning Scintillation Detector for High Resolution PET 2009 IEEE Transactions on Nuclear Science  
    BibTeX:
    @article{Habte2009,
      author = {F. Habte and P. D. Olcott and C. S. Levin},
      title = {High Resolution, Light Multiplexed 3D Positioning Scintillation Detector for High Resolution PET},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2009},
      note = {Submitted}
    }
    					
    Habte, F.; Olcott, P.D.; Levin, C.S. & Foudray, A.M.K. Prototype Parallel Readout System for Position Sensitive PMT based Gamma-Ray Imaging Systems 2007 IEEE Transactions on Nuclear Science
    Vol. 54, pp. 60-65  
    BibTeX:
    @article{Habte2007,
      author = {F. Habte and P. D. Olcott and C. S. Levin and A. M. K. Foudray},
      title = {Prototype Parallel Readout System for Position Sensitive PMT based Gamma-Ray Imaging Systems},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2007},
      volume = {54},
      number = {1},
      pages = {60-65}
    }
    					
    Habte, F.; Pratx, G.; Olcott, P.D. & Levin, C.S. New Geometry for a Whole Body PET System 2009 IEEE Transactions on Nuclear Science  
    BibTeX:
    @article{Habte2009a,
      author = {F. Habte and G. Pratx and P. D. Olcott and C. S. Levin},
      title = {New Geometry for a Whole Body PET System},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2009},
      note = {Submitted}
    }
    					
    Hoffman, E.J.; Tornai, M.P.; Levin, C.S.; MacDonald, L.R. & Holdsworth, C.H. A Dual Detector Beta-Ray Imaging Probe with Gamma-Ray Background Suppression for Use in Intra-Operative Detection of Radiolabeled Tumors 1998 Nuclear Instruments and Methods in Physics Research A
    Vol. 409, pp. 511-516  
    BibTeX:
    @article{Hoffman1998,
      author = {E. J. Hoffman and M. P. Tornai and C. S. Levin and L. R. MacDonald and C. H. Holdsworth},
      title = {A Dual Detector Beta-Ray Imaging Probe with Gamma-Ray Background Suppression for Use in Intra-Operative Detection of Radiolabeled Tumors},
      journal = {Nuclear Instruments and Methods in Physics Research A},
      year = {1998},
      volume = {409},
      pages = {511-516}
    }
    					
    Hoffman, E.J.; Tornai, M.P.; Levin, C.S.; MacDonald, L.R. & Siegel, S. Design and Performance of Gamma and Beta Intra-Operative Imaging Probes 1997 Physica Medica
    Vol. 13, pp. S243-247  
    BibTeX:
    @article{Hoffman1997,
      author = {E. J. Hoffman and M. P. Tornai and C. S. Levin and L. R. MacDonald and S. Siegel},
      title = {Design and Performance of Gamma and Beta Intra-Operative Imaging Probes},
      journal = {Physica Medica},
      year = {1997},
      volume = {13},
      pages = {S243-247}
    }
    					
    Hoffman, E.J.; Tornai, M.P.; Levin, C.S.; MacDonald, L.R. & Siegel, S. Gamma and Beta Intra-Operative Imaging Probes 1997 Nuclear Instruments and Methods in Physics Research A
    Vol. 392, pp. 324-329  
    BibTeX:
    @article{Hoffman1997a,
      author = {E. J. Hoffman and M. P. Tornai and C. S. Levin and L. R. MacDonald and S. Siegel},
      title = {Gamma and Beta Intra-Operative Imaging Probes},
      journal = {Nuclear Instruments and Methods in Physics Research A},
      year = {1997},
      volume = {392},
      pages = {324-329}
    }
    					
    Holdsworth, C.; Levin, C.S.; Dahlbom, M.; Farquhar, T. & Hoffman, E.J. Investigation of Accelerated Monte Carlo Techniques for PET Simulation and 3-D PET Scatter Correction 2001 IEEE Transactions on Nuclear Science
    Vol. 48-1, pp. 74-81  
    BibTeX:
    @article{Holdsworth2001,
      author = {C. Holdsworth and C. S. Levin and M. Dahlbom and T. Farquhar and E. J. Hoffman},
      title = {Investigation of Accelerated Monte Carlo Techniques for PET Simulation and 3-D PET Scatter Correction},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2001},
      volume = {48-1},
      number = {1},
      pages = {74-81}
    }
    					
    Holdsworth, C.H.; Levin, C.S.; Janecek, M.; Dahlbom, M. & Hoffman, E.J. Performance Analysis of an Improved 3-D PET Monte Carlo Simulation and Scatter Correction 2002 IEEE Transactions on Nuclear Science
    Vol. 49-1, pp. 83-89  
    BibTeX:
    @article{Holdsworth2002,
      author = {C. H. Holdsworth and C. S. Levin and M. Janecek and M. Dahlbom and E. J. Hoffman},
      title = {Performance Analysis of an Improved 3-D PET Monte Carlo Simulation and Scatter Correction},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2002},
      volume = {49-1},
      number = {1},
      pages = {83-89}
    }
    					
    Keren, S.; Gheysens, O.; Levin, C.S. & Gambhir, S.S. Characterization of a Small Animal Time-Domain Fluorescence Tomography Imaging System 2008 IEEE Transactions on Medical Imaging
    Vol. 27, pp. 58-63  
    BibTeX:
    @article{Keren2008,
      author = {S. Keren and O. Gheysens and C. S. Levin and S. S. Gambhir},
      title = {Characterization of a Small Animal Time-Domain Fluorescence Tomography Imaging System},
      journal = {IEEE Transactions on Medical Imaging},
      year = {2008},
      volume = {27},
      number = {1},
      pages = {58-63}
    }
    					
    Lau, F.W.Y.; Vandenbroucke, A.; Reynolds, P.D.; Ho, H.; Innes, D. & Levin, C.S. Signal Conditioning Technique for Position Sensitive Photodetectors to Manipulate Pixelated Crystal Identification Capabilities 2012 Nuclear Science, IEEE Transactions on
    Vol. 59, pp. 1815 -1822  
    BibTeX:
    @article{Lau2012,
      author = {F. W. Y. Lau and A. Vandenbroucke and P. D. Reynolds and H. Ho and D. Innes and C. S. Levin},
      title = {Signal Conditioning Technique for Position Sensitive Photodetectors to Manipulate Pixelated Crystal Identification Capabilities},
      journal = {Nuclear Science, IEEE Transactions on},
      year = {2012},
      volume = {59},
      number = {5},
      pages = {1815 -1822}
    }
    					
    Lau, F.W.Y.; Vandenbroucke, A.; Reynolds, P.D.; Olcott, P.D.; Horowitz, M.A. & Levin, C.S. Analog Signal Multiplexing for PSAPD-Based PET Detectors: Simulation and Experimental Validation 2010 Physics in Medicine and Biology
    Vol. 55, pp. 7149-7174  
    BibTeX:
    @article{Lau2009,
      author = {F. W. Y. Lau and A. Vandenbroucke and P. D. Reynolds and P. D. Olcott and M. A. Horowitz and C. S. Levin},
      title = {Analog Signal Multiplexing for PSAPD-Based PET Detectors: Simulation and Experimental Validation},
      journal = {Physics in Medicine and Biology},
      year = {2010},
      volume = {55},
      number = {23},
      pages = {7149-7174}
    }
    					
    Levin, C.S. Promising New Photon Detection Concepts for High-Resolution Clinical and Preclinical PET 2012 #JNM#
    Vol. 53, pp. 167-170  
    BibTeX:
    @article{Craig2012,
      author = {C. S. Levin},
      title = {Promising New Photon Detection Concepts for High-Resolution Clinical and Preclinical PET},
      journal = {#JNM#},
      year = {2012},
      volume = {53},
      number = {2},
      pages = {167--170}
    }
    					
    Levin, C.S. New Imaging Technologies to Enhance the Molecular Sensitivity of Positron Emission Tomography 2008 Proceedings of the IEEE, pp. 439-467  
    BibTeX:
    @article{Levin2008,
      author = {C. S. Levin},
      title = {New Imaging Technologies to Enhance the Molecular Sensitivity of Positron Emission Tomography},
      booktitle = {Proceedings of the IEEE},
      year = {2008},
      pages = {439-467}
    }
    					
    Levin, C.S. Primer on Molecular Imaging Technology 2005 European Journal of Nuclear Medicine and Molecular Imaging
    Vol. 32, pp. S325-345  
    BibTeX:
    @article{Levin2005,
      author = {C. S. Levin},
      title = {Primer on Molecular Imaging Technology},
      journal = {European Journal of Nuclear Medicine and Molecular Imaging},
      year = {2005},
      volume = {32},
      number = {2},
      pages = {S325-345}
    }
    					
    Levin, C.S. Detector Design Issues for Compact Nuclear Emission Cameras Dedicated to Functional Breast Imaging 2003 Nuclear Instruments and Methods in Physics Research A
    Vol. 497-1, pp. 60-74  
    BibTeX:
    @article{Levin2003,
      author = {C. S. Levin},
      title = {Detector Design Issues for Compact Nuclear Emission Cameras Dedicated to Functional Breast Imaging},
      journal = {Nuclear Instruments and Methods in Physics Research A},
      year = {2003},
      volume = {497-1},
      pages = {60-74}
    }
    					
    Levin, C.S. Design of a High-Resolution and High-Sensitivity Scintillation Crystal Array for PET with Nearly Complete Light Collection 2002 IEEE Transactions on Nuclear Science
    Vol. 49-5, pp. 2236-2243  
    BibTeX:
    @article{Levin2002,
      author = {C. S. Levin},
      title = {Design of a High-Resolution and High-Sensitivity Scintillation Crystal Array for PET with Nearly Complete Light Collection},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2002},
      volume = {49-5},
      number = {1},
      pages = {2236-2243}
    }
    					
    Levin, C.S.; Dahlbom, M. & Hoffman, E.J. A Monte Carlo Correction for the Effect of Compton Scattering in 3-D PET Brain Imaging 1995 IEEE Transactions on Nuclear Science
    Vol. 42-4, pp. 1181-1185  
    BibTeX:
    @article{Levin1995,
      author = {C. S. Levin and M. Dahlbom and E. J. Hoffman},
      title = {A Monte Carlo Correction for the Effect of Compton Scattering in 3-D PET Brain Imaging},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1995},
      volume = {42-4},
      pages = {1181-1185}
    }
    					
    Levin, C.S.; Foudray, A.M.K. & Habte, F. Impact of High Energy Resolution Detectors on the Performance of a PET System Dedicated to Breast Cancer Imaging, (Selected Top 10 Most Cited Papers in Physica Medica (European Journal of Medical Physics) 2006 Physica Medica
    Vol. 21, pp. 28-34  
    BibTeX:
    @article{Levin2006a,
      author = {C. S. Levin and A. M. K. Foudray and F. Habte},
      title = {Impact of High Energy Resolution Detectors on the Performance of a PET System Dedicated to Breast Cancer Imaging, (Selected Top 10 Most Cited Papers in Physica Medica (European Journal of Medical Physics)},
      journal = {Physica Medica},
      year = {2006},
      volume = {21},
      pages = {28-34}
    }
    					
    Levin, C.S.; Foudray, A.M.K.; Olcott, P.D. & Habte, F. Investigation of Position Sensitive Avalanche Photodiodes for a New High Resolution PET Detector Design 2004 IEEE Transactions on Nuclear Science
    Vol. 51-3, pp. 805-810  
    BibTeX:
    @article{Levin2004a,
      author = {C. S. Levin and A. M. K. Foudray and P. D. Olcott and F. Habte},
      title = {Investigation of Position Sensitive Avalanche Photodiodes for a New High Resolution PET Detector Design},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2004},
      volume = {51-3},
      number = {2},
      pages = {805-810}
    }
    					
    Levin, C.S.; Habte, F. & Foudray, A.M.K. Methods to Extract More Light from Minute Scintillation Crystals Used in an Ultra-High Resolution Positron Emission Tomography Detector 2004 Nuclear Instruments and Methods in Physics Research A
    Vol. 527 (1-2), pp. 35-40  
    BibTeX:
    @article{Levin2004,
      author = {C. S. Levin and F. Habte and A. M. K. Foudray},
      title = {Methods to Extract More Light from Minute Scintillation Crystals Used in an Ultra-High Resolution Positron Emission Tomography Detector},
      journal = {Nuclear Instruments and Methods in Physics Research A},
      year = {2004},
      volume = {527 (1-2)},
      pages = {35-40}
    }
    					
    Levin, C.S. & Hoffman, E.J. Calculation of positron range and its effect on the fundamental limit of positron emission tomography system spatial resolution 2000 Physics in Medicine and Biology
    Vol. 45, pp. 559-559  
    BibTeX:
    @article{Levin2000,
      author = {C. S. Levin and E. J. Hoffman},
      title = {Calculation of positron range and its effect on the fundamental limit of positron emission tomography system spatial resolution},
      journal = {Physics in Medicine and Biology},
      year = {2000},
      volume = {45},
      number = {2},
      pages = {559-559}
    }
    					
    Levin, C.S. & Hoffman, E.J. Calculation of Positron Range and its Effect on Positron Emission Tomography System Spatial Resolution 1999 Physics in Medicine and Biology
    Vol. 44, pp. 781-799  
    BibTeX:
    @article{Levin1999,
      author = {C. S. Levin and E. J. Hoffman},
      title = {Calculation of Positron Range and its Effect on Positron Emission Tomography System Spatial Resolution},
      journal = {Physics in Medicine and Biology},
      year = {1999},
      volume = {44},
      pages = {781-799}
    }
    					
    Levin, C.S. & Hoffman, E.J. Investigation of a New Readout Scheme for High Resolution Scintillation Crystal Arrays Using Photodiodes 1997 IEEE Transactions on Nuclear Science
    Vol. 44-3, pp. 1208-1213  
    BibTeX:
    @article{Levin1997c,
      author = {C. S. Levin and E. J. Hoffman},
      title = {Investigation of a New Readout Scheme for High Resolution Scintillation Crystal Arrays Using Photodiodes},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1997},
      volume = {44-3},
      number = {2},
      pages = {1208-1213}
    }
    					
    Levin, C.S.; Hoffman, E.J.; Tornai, M.P. & MacDonald, L.R. PSPMT and Photodiode Designs of a Small Scintillation Camera for Imaging Malignant Breast Tumors 1997 IEEE Transactions on Nuclear Science
    Vol. 44-4, pp. 1513-1520  
    BibTeX:
    @article{Levin1997b,
      author = {C. S. Levin and E. J. Hoffman and M. P. Tornai and L. R. MacDonald},
      title = {PSPMT and Photodiode Designs of a Small Scintillation Camera for Imaging Malignant Breast Tumors},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1997},
      volume = {44-4},
      number = {1},
      pages = {1513-1520}
    }
    					
    Levin, C.S.; MacDonald, L.R.; Tornai, M.P.; Hoffman, E.J. & Park, J. Optimizing Light Collection from Thin Scintillators Used in a Beta-Ray Camera for Surgical Use 1996 IEEE Transactions on Nuclear Science
    Vol. 43-3, pp. 2053-2060  
    BibTeX:
    @article{Levin1996,
      author = {C. S. Levin and L. R. MacDonald and M. P. Tornai and E. J. Hoffman and J. Park},
      title = {Optimizing Light Collection from Thin Scintillators Used in a Beta-Ray Camera for Surgical Use},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1996},
      volume = {43-3},
      number = {2},
      pages = {2053-2060}
    }
    					
    Levin, C.S.; Tornai, M.P.; Cherry, S.R.; MacDonald, L.R. & Hoffman, E.J. Compton Scatter and X-Ray Crosstalk and the Use of Very Thin Intercrystal Septa in High Resolution PET Detectors 1997 IEEE Transactions on Nuclear Science
    Vol. 44-2, pp. 18-24  
    BibTeX:
    @article{Levin1997,
      author = {C. S. Levin and M. P. Tornai and S. R. Cherry and L. R. MacDonald and E. J. Hoffman},
      title = {Compton Scatter and X-Ray Crosstalk and the Use of Very Thin Intercrystal Septa in High Resolution PET Detectors},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1997},
      volume = {44-2},
      pages = {18-24}
    }
    					
    Levin, C.S.; Tornai, M.P.; MacDonald, L.R. & Hoffman, E.J. Annihilation Gamma-Ray Background Characterization and Rejection for a Small Beta Camera Used for Tumor Localization During Surgery 1997 IEEE Transactions on Nuclear Science
    Vol. 44-4, pp. 1120-1126  
    BibTeX:
    @article{Levin1997a,
      author = {C. S. Levin and M. P. Tornai and L. R. MacDonald and E. J. Hoffman},
      title = {Annihilation Gamma-Ray Background Characterization and Rejection for a Small Beta Camera Used for Tumor Localization During Surgery},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1997},
      volume = {44-4},
      pages = {1120-1126}
    }
    					
    Levin, C.S.; Tornai, M.P.; Pani, R.; Garibaldi, F. & Mankoff, D.M. Preface 2006 Physica Medica
    Vol. 21, pp. 1-1  
    BibTeX:
    @article{Levin2006,
      author = {C. S. Levin and M. P. Tornai and R. Pani and F. Garibaldi and D. M. Mankoff},
      title = {Preface},
      journal = {Physica Medica},
      year = {2006},
      volume = {21},
      pages = {1-1}
    }
    					
    Levin, C.S. & Zaidi, H. Current Trends in Pre-Clinical Positron Emission Tomography System Design 2007 PET Clinics
    Vol. 2, pp. 125-160  
    BibTeX:
    @article{Levin2007,
      author = {C. S. Levin and H. Zaidi},
      title = {Current Trends in Pre-Clinical Positron Emission Tomography System Design},
      journal = {PET Clinics},
      year = {2007},
      volume = {2},
      number = {2},
      pages = {125-160}
    }
    					
    MacDonald, L.R.; Tornai, M.P.; Levin, C.S.; Park, J.; Atac, M.; Cline, D.B. & Hoffman, E.J. Investigation of the Physical Aspects of Beta Imaging Probes Using Scintillating Fibers and Visible Light Photon Counters 1995 IEEE Transactions on Nuclear Science
    Vol. 42-4, pp. 1351-1357  
    BibTeX:
    @article{MacDonald1995,
      author = {L. R. MacDonald and M. P. Tornai and C. S. Levin and J. Park and M. Atac and D. B. Cline and E. J. Hoffman},
      title = {Investigation of the Physical Aspects of Beta Imaging Probes Using Scintillating Fibers and Visible Light Photon Counters},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1995},
      volume = {42-4},
      pages = {1351-1357}
    }
    					
    McElroy, D.P.; Hoffman, E.J.; MacDonald, L.; Patt, B.E.; Iwanczyk, J.S.; Yamaguchi, Y. & Levin, C.S. Evaluation of Breast Tumor Detectability with Two Dedicated, Compact Scintillation Cameras 2002 IEEE Transactions on Nuclear Science
    Vol. 49-3, pp. 794-802  
    BibTeX:
    @article{McElroy2002,
      author = {D. P. McElroy and E. J. Hoffman and L. MacDonald and B. E. Patt and J. S. Iwanczyk and Y. Yamaguchi and C. S. Levin},
      title = {Evaluation of Breast Tumor Detectability with Two Dedicated, Compact Scintillation Cameras},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2002},
      volume = {49-3},
      number = {1},
      pages = {794-802}
    }
    					
    Olcott, P.D.; Habte, F.; Levin, C.S. & Foudray, A.M.K. Performance Characterization of a Miniature, High Sensitivity Gamma-Ray Camera 2007 IEEE Transactions on Nuclear Science
    Vol. 54, pp. 1492-1497  
    BibTeX:
    @article{Olcott2007,
      author = {P. D. Olcott and F. Habte and C. S. Levin and A. M. K. Foudray},
      title = {Performance Characterization of a Miniature, High Sensitivity Gamma-Ray Camera},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2007},
      volume = {54},
      number = {5},
      pages = {1492-1497}
    }
    					
    Olcott, P.D. & Levin, C.S. Image Processing Algorithms to Facilitate and Enhance Sentinel Node Detection using a Hand-Held Gamma-Ray Camera in Surgical Breast Cancer Staging 2006 Physica Medica
    Vol. 21, pp. 99-101  
    BibTeX:
    @article{Olcott2006,
      author = {P. D. Olcott and C. S. Levin},
      title = {Image Processing Algorithms to Facilitate and Enhance Sentinel Node Detection using a Hand-Held Gamma-Ray Camera in Surgical Breast Cancer Staging},
      journal = {Physica Medica},
      year = {2006},
      volume = {21},
      pages = {99-101}
    }
    					
    Olcott, P.D.; Peng, H. & Levin, C.S. Novel Electro-Optical Coupling Technique for Magnetic Resonance-Compatible Positron Emission Tomography Detectors 2009 MOLECULAR IMAGING
    Vol. 8, pp. 74-86  
    Abstract: A new magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL) diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs.
    BibTeX:
    @article{Olcott2009,
      author = {P. D. Olcott and H. Peng and C. S. Levin},
      title = {Novel Electro-Optical Coupling Technique for Magnetic Resonance-Compatible Positron Emission Tomography Detectors},
      journal = {MOLECULAR IMAGING},
      year = {2009},
      volume = {8},
      number = {2},
      pages = {74-86},
      doi = {http://dx.doi.org/10.2310/7290.2009.00012}
    }
    					
    Olcott, P.D.; Pratx, G. & Levin, C.S. Novel Hand Held Intraoperative Radionuclide Imaging 2010 ANNALS OF SURGICAL ONCOLOGY
    Vol. 17, pp. S106-S107  
    BibTeX:
    @article{Olcott2010,
      author = {P. D. Olcott and G. Pratx and C. S. Levin},
      title = {Novel Hand Held Intraoperative Radionuclide Imaging},
      journal = {ANNALS OF SURGICAL ONCOLOGY},
      year = {2010},
      volume = {17},
      number = {Suppl. 1},
      pages = {S106-S107}
    }
    					
    Olcott, P.D.; Talcott, J.A.; Levin, C.S.; Habte, F. & Foudray, A.M.K. Compact Readout Electronics for Position Sensitive Photomultiplier Tubes 2005 IEEE Transactions on Nuclear Science
    Vol. 52, pp. 21-27  
    BibTeX:
    @article{Olcott2005,
      author = {P. D. Olcott and J. A. Talcott and C. S. Levin and F. Habte and A. M. K. Foudray},
      title = {Compact Readout Electronics for Position Sensitive Photomultiplier Tubes},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2005},
      volume = {52},
      number = {1},
      pages = {21-27}
    }
    					
    Patt, B.E.; Iwanczyk, J.S.; Tornai, M.P.; Levin, C.S. & Hoffman, E.J. Development of a Mercuric Iodide Detector Array for Medical Imaging Applications 1995 Nuclear Instruments and Methods in Physics Research A
    Vol. 366, pp. 173-182  
    BibTeX:
    @article{Patt1995,
      author = {B. E. Patt and J. S. Iwanczyk and M. P. Tornai and C. S. Levin and E. J. Hoffman},
      title = {Development of a Mercuric Iodide Detector Array for Medical Imaging Applications},
      journal = {Nuclear Instruments and Methods in Physics Research A},
      year = {1995},
      volume = {366},
      pages = {173-182}
    }
    					
    Patt, B.E.; Iwanczyk, J.S.; Tornai, M.P.; Levin, C.S. & Hoffman, E.J. Development of a Mercuric Iodide Detector Array for in-vivo X-Ray Imaging 1995 Advances in X-Ray Analysis
    Vol. 38, pp. 615-624  
    BibTeX:
    @article{Patt1995a,
      author = {B. E. Patt and J. S. Iwanczyk and M. P. Tornai and C. S. Levin and E. J. Hoffman},
      title = {Development of a Mercuric Iodide Detector Array for in-vivo X-Ray Imaging},
      journal = {Advances in X-Ray Analysis},
      year = {1995},
      volume = {38},
      pages = {615-624}
    }
    					
    Patt, B.E.; Iwanczyk, J.S.; Wang, Y.J.; Tornai, M.P.; Levin, C.S. & Hoffman, E.J. Mercuric Iodide Photodetector Arrays for Gamma-Ray Imaging 1996 Nuclear Instruments and Methods in Physics Research A
    Vol. 380, pp. 295-300  
    BibTeX:
    @article{Patt1996,
      author = {B. E. Patt and J. S. Iwanczyk and Y. J. Wang and M. P. Tornai and C. S. Levin and E. J. Hoffman},
      title = {Mercuric Iodide Photodetector Arrays for Gamma-Ray Imaging},
      journal = {Nuclear Instruments and Methods in Physics Research A},
      year = {1996},
      volume = {380},
      pages = {295-300}
    }
    					
    Patt, B.E.; Tornai, M.P.; Iwanczyk, J.S.; Levin, C.S. & Hoffman, E.J. Development of an Intraoperative Gamma Camera Based on a 256-Pixel Mercuric Iodide Detector Array 1997 IEEE Transactions on Nuclear Science
    Vol. 44-3, pp. 1242-1248  
    BibTeX:
    @article{Patt1997,
      author = {B. E. Patt and M. P. Tornai and J. S. Iwanczyk and C. S. Levin and E. J. Hoffman},
      title = {Development of an Intraoperative Gamma Camera Based on a 256-Pixel Mercuric Iodide Detector Array},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1997},
      volume = {44-3},
      number = {2},
      pages = {1242-1248}
    }
    					
    Peng, H. & Levin, C.S. Study of PET intrinsic spatial resolution and contrast recovery improvement for PET/MRI systems 2012 Physics in Medicine and Biology
    Vol. 57, pp. N101  
    BibTeX:
    @article{Peng2012,
      author = {H. Peng and C. S. Levin},
      title = {Study of PET intrinsic spatial resolution and contrast recovery improvement for PET/MRI systems},
      journal = {Physics in Medicine and Biology},
      year = {2012},
      volume = {57},
      number = {9},
      pages = {N101}
    }
    					
    Peng, H. & Levin, C.S. Design study of a high-resolution breast-dedicated PET system built from cadmium zinc telluride detectors 2010 PHYSICS IN MEDICINE AND BIOLOGY
    Vol. 55, pp. 2761-2788  
    Abstract: We studied the performance of a dual-panel positron emission tomography ( PET) camera dedicated to breast cancer imaging using Monte Carlo simulation. The proposed system consists of two 4 cm thick 12 x 15 cm(2) area cadmium zinc telluride (CZT) panels with adjustable separation, which can be put in close proximity to the breast and/or axillary nodes. Unique characteristics distinguishing the proposed system from previous efforts in breast-dedicated PET instrumentation are the deployment of CZT detectors with superior spatial and energy resolution, using a cross-strip electrode readout scheme to enable 3D positioning of individual photon interaction coordinates in the CZT, which includes directly measured photon depth-of-interaction (DOI), and arranging the detector slabs edge-on with respect to incoming 511 keV photons for high photon sensitivity. The simulation results show that the proposed CZT dual-panel PET system is able to achieve superior performance in terms of photon sensitivity, noise equivalent count rate, spatial resolution and lesion visualization. The proposed system is expected to achieve similar to 32% photon sensitivity for a point source at the center and a 4 cm panel separation. For a simplified breast phantom adjacent to heart and torso compartments, the peak noise equivalent count (NEC) rate is predicted to be similar to 94.2 kcts s(-1) (breast volume: 720 cm(3) and activity concentration: 3.7 kBq cm(-3)) for a similar to 10% energy window around 511 keV and similar to 8 ns coincidence time window. The system achieves 1 mm intrinsic spatial resolution anywhere between the two panels with a 4 cm panel separation if the detectors have DOI resolution less than 2 mm. For a 3 mm DOI resolution, the system exhibits excellent sphere resolution uniformity (sigma(rms)/mean) <= 10 across a 4 cm width FOV. Simulation results indicate that the system exhibits superior hot sphere visualization and is expected to visualize 2 mm diameter spheres with a 5:1 activity concentration ratio within roughly 7 min imaging time. Furthermore, we observe that the degree of spatial resolution degradation along the direction orthogonal to the two panels that is typical of a limited angle tomography configuration is mitigated by having high-resolution DOI capabilities that enable more accurate positioning of oblique response lines.
    BibTeX:
    @article{Peng2010,
      author = {H. Peng and C. S. Levin},
      title = {Design study of a high-resolution breast-dedicated PET system built from cadmium zinc telluride detectors},
      journal = {PHYSICS IN MEDICINE AND BIOLOGY},
      year = {2010},
      volume = {55},
      number = {9},
      pages = {2761-2788},
      doi = {http://dx.doi.org/10.1088/0031-9155/55/9/022}
    }
    					
    Peng, H. & Levin, C.S. Recent Developments in PET Instrumentation 2010 CURRENT PHARMACEUTICAL BIOTECHNOLOGY
    Vol. 11, pp. 555-571  
    Abstract: Positron emission tomography (PET) is used in the clinic and in vivo small animal research to study molecular processes associated with diseases such as cancer, heart disease, and neurological disorders, and to guide the discovery and development of new treatments. This paper reviews current challenges of advancing PET technology and some of newly developed PET detectors and systems. The paper focuses on four aspects of PET instrumentation: high photon detection sensitivity; improved spatial resolution; depth-of-interaction (DOI) resolution and time-of-flight (TOF). Improved system geometry, novel non-scintillator based detectors, and tapered scintillation crystal arrays are able to enhance the photon detection sensitivity of a PET system. Several challenges for achieving high resolution with standard scintillator-based PET detectors are discussed. Novel detectors with 3-D positioning capability have great potential to be deployed in PET for achieving spatial resolution better than 1 mm, such as cadmium-zinc-telluride (CZT) and position-sensitive avalanche photodiodes (PSAPDs). DOI capability enables a PET system to mitigate parallax error and achieve uniform spatial resolution across the field-of-view (FOV). Six common DOI designs, as well as advantages and limitations of each design, are discussed. The availability of fast scintillation crystals such as LaBr3, and the silicon photomultiplier (SiPM) greatly advances TOF-PET development. Recent instrumentation and initial results of clinical trials are briefly presented. If successful, these technology advances, together with new probe molecules, will substantially enhance the molecular sensitivity of PET and thus increase its role in preclinical and clinical research as well as evaluating and managing disease in the clinic.
    BibTeX:
    @article{Peng2010a,
      author = {H. Peng and C. S. Levin},
      title = {Recent Developments in PET Instrumentation},
      journal = {CURRENT PHARMACEUTICAL BIOTECHNOLOGY},
      year = {2010},
      volume = {11},
      number = {6},
      pages = {555-571}
    }
    					
    Peng, H.; Levin, C.S. & Chronik, B.A. Simulation study of PET spatial resolution and contrast recovery improvement for PET/MRI dual modality systems 2009 Medical Physics  
    BibTeX:
    @article{Peng2009a,
      author = {H. Peng and C. S. Levin and B. A. Chronik},
      title = {Simulation study of PET spatial resolution and contrast recovery improvement for PET/MRI dual modality systems},
      journal = {Medical Physics},
      year = {2009},
      note = {Submitted}
    }
    					
    Peng, H.; Olcott, P.D.; Spanoudaki, V. & Levin, C.S. Investigation of a clinical PET detector module design that employs large-area avalanche photodetectors 2011 Physics in Medicine and Biology
    Vol. 56, pp. 3603-3627  
    BibTeX:
    @article{Peng2011,
      author = {H. Peng and P. D. Olcott and V. Spanoudaki and C. S. Levin},
      title = {Investigation of a clinical PET detector module design that employs large-area avalanche photodetectors},
      journal = {Physics in Medicine and Biology},
      year = {2011},
      volume = {56},
      number = {12},
      pages = {3603-3627},
      url = {http://stacks.iop.org/0031-9155/56/i=12/a=010}
    }
    					
    Peng, H.; Olcott, P.D.; Spanoudaki, V.C. & Levin, C.S. Can large-area avalanche photodiodes be used for a PET detector insert for an MRI system? 2009 Medical Physics  
    BibTeX:
    @article{Peng2009b,
      author = {H. Peng and P. D. Olcott and V. C. Spanoudaki and C. S. Levin},
      title = {Can large-area avalanche photodiodes be used for a PET detector insert for an MRI system?},
      journal = {Medical Physics},
      year = {2009},
      note = {Submitted}
    }
    					
    Pratx, G. & Levin, C.S. Online detector response calculations for high-resolution PET image reconstruction 2011 Physics in Medicine and Biology
    Vol. 56, pp. 4023-4040  
    BibTeX:
    @article{Pratx2011d,
      author = {G. Pratx and C. S. Levin},
      title = {Online detector response calculations for high-resolution PET image reconstruction},
      journal = {Physics in Medicine and Biology},
      year = {2011},
      volume = {56},
      number = {13},
      pages = {4023-4040}
    }
    					
    Pratx, G. & Levin, C.S. Bayesian reconstruction of photon interaction sequences for high-resolution PET detectors, (Selected as Feature Article of the Month, American Institute of Physics, August 2009) 2009 Physics in Medicine and Biology
    Vol. 54, pp. 5073-5094  
    BibTeX:
    @article{Pratx2009a,
      author = {G. Pratx and C. S. Levin},
      title = {Bayesian reconstruction of photon interaction sequences for high-resolution PET detectors, (Selected as Feature Article of the Month, American Institute of Physics, August 2009)},
      journal = {Physics in Medicine and Biology},
      year = {2009},
      volume = {54},
      number = {17},
      pages = {5073-5094}
    }
    					
    Pratx, G. & Levin, C.S. Online calculation of the detector response for high-resolution PET iterative image reconstruction 2009 IEEE Transactions on Medical Imaging  
    BibTeX:
    @article{Pratx2009b,
      author = {G. Pratx and C. S. Levin},
      title = {Online calculation of the detector response for high-resolution PET iterative image reconstruction},
      journal = {IEEE Transactions on Medical Imaging},
      year = {2009},
      note = {Submitted}
    }
    					
    Pratx, G.; Olcott, P.D.; Chinn, G. & Levin, C.S. Fast, Accurate and Shift-Varying Line Projections for Iterative Reconstruction Using the GPU 2009 IEEE Transactions in Medical Imaging
    Vol. 28, pp. 435-445  
    BibTeX:
    @article{Pratx2009,
      author = {G. Pratx and P. D. Olcott and G. Chinn and C. S. Levin},
      title = {Fast, Accurate and Shift-Varying Line Projections for Iterative Reconstruction Using the GPU},
      journal = {IEEE Transactions in Medical Imaging},
      year = {2009},
      volume = {28},
      number = {3},
      pages = {435-445}
    }
    					
    Pratx, G.; Surti, S. & Levin, C.S. Fast List-Mode Reconstruction for Time-of-Flight PET Using Graphics Hardware 2011 Nuclear Science, IEEE Transactions on
    Vol. 58, pp. 105 -109  
    BibTeX:
    @article{Pratx2011,
      author = {G. Pratx and S. Surti and C. S. Levin},
      title = {Fast List-Mode Reconstruction for Time-of-Flight PET Using Graphics Hardware},
      journal = {Nuclear Science, IEEE Transactions on},
      year = {2011},
      volume = {58},
      number = {1},
      pages = {105 -109},
      doi = {http://dx.doi.org/10.1109/TNS.2010.2081376}
    }
    					
    Reynolds, P.D.; Olcott, P.D.; Pratx, G.; Lau, F.W.Y. & Levin, C.S. Convex Optimization of Coincidence Time Resolution for a High-Resolution PET System 2011 Medical Imaging, IEEE Transactions on
    Vol. 30, pp. 391 -400  
    BibTeX:
    @article{Reynolds2011,
      author = {P. D. Reynolds and P. D. Olcott and G. Pratx and F. W. Y. Lau and C. S. Levin},
      title = {Convex Optimization of Coincidence Time Resolution for a High-Resolution PET System},
      journal = {Medical Imaging, IEEE Transactions on},
      year = {2011},
      volume = {30},
      number = {2},
      pages = {391 -400},
      doi = {http://dx.doi.org/10.1109/TMI.2010.2080282}
    }
    					
    Sigg, D.M.; Levin, C.S. & Quon, A. Sampling Error in CT-based Partial Volume Correction of Lesions Imaged by PET 2009 Journal of Nuclear Medicine  
    BibTeX:
    @article{Sigg2009,
      author = {D. M. Sigg and C. S. Levin and A. Quon},
      title = {Sampling Error in CT-based Partial Volume Correction of Lesions Imaged by PET},
      journal = {Journal of Nuclear Medicine},
      year = {2009},
      note = {Submitted}
    }
    					
    Spanoudaki, V.C.; Lau, F.W.Y.; Vandenbroucke, A. & Levin, C.S. Physical effects of mechanical design parameters on photon sensitivity and spatial resolution performance of a breast-dedicated PET system 2010 MEDICAL PHYSICS
    Vol. 37, pp. 5838-5849  
    Abstract: Purpose: This study aims to address design considerations of a high resolution, high sensitivity positron emission tomography scanner dedicated to breast imaging. Methods: The methodology uses a detailed Monte Carlo model of the system structures to obtain a quantitative evaluation of several performance parameters. Special focus was given to the effect of dense mechanical structures designed to provide mechanical robustness and thermal regulation to the minuscule and temperature sensitive detectors. Results: For the energies of interest around the photopeak (450-700 keV energy window), the simulation results predict a 6.5% reduction in the single photon detection efficiency and a 12.5% reduction in the coincidence photon detection efficiency in the case that the mechanical structures are interspersed between the detectors. However for lower energies, a substantial increase in the number of detected events (approximately 14% and 7% for singles at a 100-200 keV energy window and coincidences at a lower energy threshold of 100 keV, respectively) was observed with the presence of these structures due to backscatter. The number of photon events that involve multiple interactions in various crystal elements is also affected by the presence of the structures. For photon events involving multiple interactions among various crystal elements, the coincidence photon sensitivity is reduced by as much as 20% for a point source at the center of the field of view. There is no observable effect on the intrinsic and the reconstructed spatial resolution and spatial resolution uniformity. Conclusions: Mechanical structures can have a considerable effect on system sensitivity, especially for systems processing multi-interaction photon events. This effect, however, does not impact the spatial resolution. Various mechanical structure designs are currently under evaluation in order to achieve optimum trade-off between temperature stability, accurate detector positioning, and minimum influence on system performance. (C) 2010 American Association of Physicists in Medicine. [DOI: 10.1118/1.3484059]
    BibTeX:
    @article{Spanoudaki2010b,
      author = {V. C. Spanoudaki and F. W. Y. Lau and A. Vandenbroucke and C. S. Levin},
      title = {Physical effects of mechanical design parameters on photon sensitivity and spatial resolution performance of a breast-dedicated PET system},
      journal = {MEDICAL PHYSICS},
      year = {2010},
      volume = {37},
      number = {11},
      pages = {5838-5849},
      doi = {http://dx.doi.org/10.1118/1.3484059}
    }
    					
    Spanoudaki, V.C.; Lau, F.W.Y.; Vandenbroucke, A. & Levin, C.S. Monte Carlo assessment of a dense mechanical design for a 1 mm3 resolution breast-dedicated PET system: effects on photon sensitivity, spatial resolution and multi-interaction photon events 2009 Medical Physics  
    BibTeX:
    @article{Spanoudaki2009,
      author = {V. C. Spanoudaki and F. W. Y. Lau and A. Vandenbroucke and C. S. Levin},
      title = {Monte Carlo assessment of a dense mechanical design for a 1 mm3 resolution breast-dedicated PET system: effects on photon sensitivity, spatial resolution and multi-interaction photon events},
      journal = {Medical Physics},
      year = {2009},
      note = {Submitted}
    }
    					
    Spanoudaki, V.C. & Levin, C.S. Investigating the temporal resolution limits of scintillation detection from pixellated elements: comparison between experiment and simulation 2011 Physics in Medicine and Biology
    Vol. 56, pp. 735-756  
    Abstract: This study investigates the physical limitations involved in the extraction of accurate timing information from pixellated scintillation detectors for positron emission tomography (PET). Accurate physical modeling of the scintillation detection process, from scintillation light generation through detection, is devised and performed for varying detector attributes, such as the crystal element length, light yield, decay time and surface treatment. The dependence of light output and time resolution on these attributes, as well as on the photon interaction depth (DoI) of the annihilation quanta within the crystal volume, is studied and compared with experimental results. A theoretical background which highlights the importance of different time blurring factors for instantaneous ('ideal') and exponential ('realistic') scintillation decay is developed and compared with simulated data. For the case of a realistic scintillator, our experimental and simulation findings suggest that dependence of detector performance on DoI is more evident for crystal elements with rough ('as cut') compared to polished surfaces (maximum observed difference of 64% (25%) and 22% (19%) in simulation (measurement) for light output and time resolution, respectively). Furthermore we observe distinct trends of the detector performance dependence on detector element length and surface treatment. For short crystals (3 ? 3 ? 5 mm 3 ) an improvement in light output and time resolution for 'as cut' compared to polished crystals is observed (3% (7%) and 9% (9%) for simulation (measurement), respectively). The trend is reversed for longer crystals (3 ? 3 ? 20 mm 3 ) and an improvement in light output and time uncertainty for polished compared to 'as cut' crystals is observed (36% (6%) and 40% (20%) for simulation (measurement), respectively). The results of this study are used to guide the design of PET detectors with combined time of flight (ToF) and DoI features.
    BibTeX:
    @article{Spanoudaki2011,
      author = {V. C. Spanoudaki and C. S. Levin},
      title = {Investigating the temporal resolution limits of scintillation detection from pixellated elements: comparison between experiment and simulation},
      journal = {Physics in Medicine and Biology},
      year = {2011},
      volume = {56},
      number = {3},
      pages = {735-756}
    }
    					
    Spanoudaki, V.C. & Levin, C.S. Scintillation induced response in passively-quenched Si-based single photon counting avalanche diode arrays 2011 Opt. Express
    Vol. 19, pp. 1665-1679  
    Abstract: An optical electrical model which studies the response of Si-based single photon counting arrays, specifically silicon photomultipliers (SiPMs), to scintillation light has been developed and validated with analytically derived and experimental data. The scintillator-photodetector response in terms of relative pulse height, 1090% rise/decay times to light stimuli of different rise times (ranging from 0.1 to 5 ns) and decay times (ranging from 1 to 50 ns), as well as for different decay times of the photodetector are compared in theory and simulation. A measured detector response is used as a reference to further validate the model and the results show a mean deviation of simulated over measured values of 1
    BibTeX:
    @article{Spanoudaki2011a,
      author = {V. C. Spanoudaki and C. S. Levin},
      title = {Scintillation induced response in passively-quenched Si-based single photon counting avalanche diode arrays},
      journal = {Opt. Express},
      publisher = {OSA},
      year = {2011},
      volume = {19},
      number = {2},
      pages = {1665--1679},
      doi = {http://dx.doi.org/10.1364/OE.19.001665}
    }
    					
    Spanoudaki, V.C. & Levin, C.S. Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET) 2010 SENSORS
    Vol. 10, pp. 10484-10505  
    Abstract: We present the most recent advances in photo-detector design employed in time of flight positron emission tomography (ToF-PET). PET is a molecular imaging modality that collects pairs of coincident (temporally correlated) annihilation photons emitted from the patient body. The annihilation photon detector typically comprises a scintillation crystal coupled to a fast photo-detector. ToF information provides better localization of the annihilation event along the line formed by each detector pair, resulting in an overall improvement in signal to noise ratio (SNR) of the reconstructed image. Apart from the demand for high luminosity and fast decay time of the scintillation crystal, proper design and selection of the photo-detector and methods for arrival time pick-off are a prerequisite for achieving excellent time resolution required for ToF-PET. We review the two types of photo-detectors used in ToF-PET: photomultiplier tubes (PMTs) and silicon photo-multipliers (SiPMs) with a special focus on SiPMs.
    BibTeX:
    @article{Spanoudaki2010a,
      author = {V. C. Spanoudaki and C. S. Levin},
      title = {Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET)},
      journal = {SENSORS},
      year = {2010},
      volume = {10},
      number = {11},
      pages = {10484-10505},
      doi = {http://dx.doi.org/10.3390/s101110484}
    }
    					
    Tornai, M.P.; Archer, C.; Wiesenberger, A.G.; Wojcik, R.; Popov, V.; Keppel, C.E.; Levin, C.S.; Majewski, S.; Tipnis, S.V. & Nagarkar, V.V. Investigation of Microcolumnar Scintillators on an Optical Fiber Coupled Compact Imaging System 2001 IEEE Transactions on Nuclear Science
    Vol. 48-3, pp. 637-644  
    BibTeX:
    @article{Tornai2001,
      author = {M. P. Tornai and C. Archer and A. G. Wiesenberger and R. Wojcik and V. Popov and C. E. Keppel and C. S. Levin and S. Majewski and S. V. Tipnis and V. V. Nagarkar},
      title = {Investigation of Microcolumnar Scintillators on an Optical Fiber Coupled Compact Imaging System},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2001},
      volume = {48-3},
      number = {2},
      pages = {637-644}
    }
    					
    Tornai, M.P.; Hoffman, E.J.; Levin, C.S. & MacDonald, L.R. Characterization of Fluor Concentration and Geometry in Organic Scintillators for in situ Beta Imaging 1996 IEEE Transactions on Nuclear Science
    Vol. 43-6, pp. 3342-3347  
    BibTeX:
    @article{Tornai1996a,
      author = {M. P. Tornai and E. J. Hoffman and C. S. Levin and L. R. MacDonald},
      title = {Characterization of Fluor Concentration and Geometry in Organic Scintillators for in situ Beta Imaging},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1996},
      volume = {43-6},
      pages = {3342-3347}
    }
    					
    Tornai, M.P.; Levin, C.S.; MacDonald, L.R.; Hoffman, E.J. & Park, J. Investigation of Crystal Geometries for Fiber Coupled Gamma Imaging Intra-Operative Probes 1997 IEEE Transactions on Nuclear Science
    Vol. 44-3, pp. 1254-1261  
    BibTeX:
    @article{Tornai1997,
      author = {M. P. Tornai and C. S. Levin and L. R. MacDonald and E. J. Hoffman and J. Park},
      title = {Investigation of Crystal Geometries for Fiber Coupled Gamma Imaging Intra-Operative Probes},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1997},
      volume = {44-3},
      number = {2},
      pages = {1254-1261}
    }
    					
    Tornai, M.P.; Levin, C.S.; MacDonald, L.R.; Holdsworth, C.H. & Hoffman, E.J. A Miniature Phoswich Detector for Gamma-Ray Localization and Beta Imaging 1998 IEEE Transactions on Nuclear Science
    Vol. 45-3, pp. 1166-1173  
    BibTeX:
    @article{Tornai1998,
      author = {M. P. Tornai and C. S. Levin and L. R. MacDonald and C. H. Holdsworth and E. J. Hoffman},
      title = {A Miniature Phoswich Detector for Gamma-Ray Localization and Beta Imaging},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1998},
      volume = {45-3},
      number = {2},
      pages = {1166-1173}
    }
    					
    Tornai, M.P.; MacDonald, L.R.; Levin, C.S.; Siegel, S. & Hoffman, E.J. Design Considerations and Initial Performance of a 1.2 cm^2 Beta Imaging Intra-Operative Probe 1996 IEEE Transactions on Nuclear Science
    Vol. 43-4, pp. 2326-2335  
    BibTeX:
    @article{Tornai1996,
      author = {M. P. Tornai and L. R. MacDonald and C. S. Levin and S. Siegel and E. J. Hoffman},
      title = {Design Considerations and Initial Performance of a 1.2 cm^2 Beta Imaging Intra-Operative Probe},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1996},
      volume = {43-4},
      number = {1},
      pages = {2326-2335}
    }
    					
    Tornai, M.P.; Patt, B.E.; Iwanczyk, J.S.; Levin, C.S. & Hoffman, E.J. Discrete Scintillator Coupled Mercuric Iodide Photodetector Arrays for Breast Imaging 1997 IEEE Transactions on Nuclear Science
    Vol. 44-3, pp. 1127-1133  
    BibTeX:
    @article{Tornai1997a,
      author = {M. P. Tornai and B. E. Patt and J. S. Iwanczyk and C. S. Levin and E. J. Hoffman},
      title = {Discrete Scintillator Coupled Mercuric Iodide Photodetector Arrays for Breast Imaging},
      journal = {IEEE Transactions on Nuclear Science},
      year = {1997},
      volume = {44-3},
      number = {2},
      pages = {1127-1133}
    }
    					
    Vandenbroucke, A.; Foudray, A.M.K.; Olcott, P.D. & Levin, C.S. Performance characterization of a new high resolution PET scintillation detector 2010 PHYSICS IN MEDICINE AND BIOLOGY
    Vol. 55, pp. 5895-5911  
    Abstract: Performance of a new high resolution PET detection concept is presented. In this new concept, annihilation radiation enters the scintillator detectors edge-on. Each detector module comprises two 8 x 8 LYSO scintillator arrays of 0.91 x 0.91 x 1 mm(3) crystals coupled to two position-sensitive avalanche photodiodes (PSAPDs) mounted on a flex circuit. Appropriate crystal segmentation allows the recording of all three spatial coordinates of the interaction(s) simultaneously with submillimeter resolution. We report an average energy resolution of 14.6 +/- 1.7% for 511 keV photons at FWHM. Coincident time resolution was determined to be 2.98 +/- 0.13 ns FWHM on average. The coincidence point spread function (PSF) has an average FWHM of 0.837 +/- 0.049 mm (using a 500 mu m spherical source) and is uniform across the arrays. Both PSF and coincident time resolution degrade when Compton interactions are included in the data. Different blurring factors were evaluated theoretically, resulting in a calculated PSF of 0.793 mm, in good agreement with the measured value.
    BibTeX:
    @article{Vandenbroucke2010,
      author = {A. Vandenbroucke and A. M. K. Foudray and P. D. Olcott and C. S. Levin},
      title = {Performance characterization of a new high resolution PET scintillation detector},
      journal = {PHYSICS IN MEDICINE AND BIOLOGY},
      year = {2010},
      volume = {55},
      number = {19},
      pages = {5895-5911},
      doi = {http://dx.doi.org/10.1088/0031-9155/55/19/018}
    }
    					
    Vandenbroucke, A.; McLaughlin, T.J. & Levin, C.S. Influence of temperature and bias voltage on the performance of a high resolution PET detector built with position sensitive avalanche photodiodes 2012 Journal of Instrumentation
    Vol. 7, pp. P08001  
    BibTeX:
    @article{Vandenbroucke2012,
      author = {A. Vandenbroucke and T. J. McLaughlin and C. S. Levin},
      title = {Influence of temperature and bias voltage on the performance of a high resolution PET detector built with position sensitive avalanche photodiodes},
      journal = {Journal of Instrumentation},
      year = {2012},
      volume = {7},
      number = {08},
      pages = {P08001}
    }
    					
    Yeom, J.Y.; Vinke, R. & Levin, C.S. Optimizing timing performance of silicon photomultiplier-based scintil lation detectors 2013 Physics in Medicine and Biology
    Vol. 58, pp. 1207  
    BibTeX:
    @article{Yeom2013,
      author = {J. Y. Yeom and R. Vinke and C. S. Levin},
      title = {Optimizing timing performance of silicon photomultiplier-based scintil lation detectors},
      journal = {Physics in Medicine and Biology},
      year = {2013},
      volume = {58},
      number = {4},
      pages = {1207}
    }
    					
    Zhang, J.; Chinn, G.; Foudray, A.M.K.; Habte, F.; Olcott, P.D. & Levin, C.S. Evaluation of a Dual-Head PET Camera Design Dedicated to Breast Cancer Imaging 2006 Physica Medica
    Vol. 21, pp. 94-98  
    BibTeX:
    @article{Zhang2006,
      author = {J. Zhang and G. Chinn and A. M. K. Foudray and F. Habte and P. D. Olcott and C. S. Levin},
      title = {Evaluation of a Dual-Head PET Camera Design Dedicated to Breast Cancer Imaging},
      journal = {Physica Medica},
      year = {2006},
      volume = {21},
      pages = {94-98}
    }
    					
    Zhang, J.; Foudray, A.M.K.; Olcott, P.D. & Levin, C.S. Performance Characterization of a Novel Thin Position-Sensitive Avalanche Photodiode for High Resolution Positron Emission Tomography 2007 IEEE Transactions on Nuclear Science
    Vol. 54, pp. 415-421  
    BibTeX:
    @article{Zhang2007b,
      author = {J. Zhang and A. M. K. Foudray and P. D. Olcott and C. S. Levin},
      title = {Performance Characterization of a Novel Thin Position-Sensitive Avalanche Photodiode for High Resolution Positron Emission Tomography},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2007},
      volume = {54},
      number = {3},
      pages = {415-421}
    }
    					
    Zhang, J.; Olcott, P.D.; Chinn, G.; Foudray, A.M.K. & Levin, C.S. Study of the Performance of a Novel 1 mm Resolution Dual-Panel PET Camera Design Dedicated to Breast Cancer Imaging Using Monte Carlo Simulation 2007 Medical Physics
    Vol. 34, pp. 689-702  
    BibTeX:
    @article{Zhang2007,
      author = {J. Zhang and P. D. Olcott and G. Chinn and A. M. K. Foudray and C. S. Levin},
      title = {Study of the Performance of a Novel 1 mm Resolution Dual-Panel PET Camera Design Dedicated to Breast Cancer Imaging Using Monte Carlo Simulation},
      journal = {Medical Physics},
      year = {2007},
      volume = {34},
      number = {2},
      pages = {689-702}
    }
    					
    Zhang, J.; Olcott, P.D. & Levin, C.S. A New Positioning Algorithm for Position-Sensitive Avalanche Photodiodes 2007 IEEE Transactions on Nuclear Science
    Vol. 54, pp. 433-437  
    BibTeX:
    @article{Zhang2007a,
      author = {J. Zhang and P. D. Olcott and C. S. Levin},
      title = {A New Positioning Algorithm for Position-Sensitive Avalanche Photodiodes},
      journal = {IEEE Transactions on Nuclear Science},
      year = {2007},
      volume = {54},
      number = {3},
      pages = {433-437}
    }
    					

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