Bio

Bio


Professor Levin's research interests involve the development of novel instrumentation and software algorithms for in vivo imaging of molecular signatures of disease in humans and small laboratory animals. These new cameras efficiently image radiation emissions in the form of positrons, annihilation photons, gamma rays, and light from molecular probes developed to target molecular signals from deep within tissue of live subjects.
The goals of the instrumentation projects are to advance the sensitivity and spatial, spectral, and/or temporal resolutions. The algorithm goals are to understand the physical system comprising the subject tissues, radiation transport, and imaging system, and to provide the best available image quality and quantitative accuracy.
The work involves computer modeling, position sensitive sensors, readout electronics, data acquisition, image formation, image processing, and data/image analysis algorithms, and incorporating these innovations into practical imaging devices
The ultimate goal is to introduce these new imaging tools into studies of molecular mechanisms and new treatments of disease within living subjects.

Academic Appointments


Administrative Appointments


  • Chair of Faculty Search Committee, Department of Radiology (2009 - 2010)
  • Chair of Faculty Search Committee, Department of Radiology (2008 - 2009)
  • Chair of Faculty Search Committee, Department of Radiology (2007 - 2008)
  • Chair of Faculty Search Committee, Department of Radiology (2006 - 2007)
  • Co-Director, Stanford Center for Innovation in In Vivo Imaging (2004 - Present)

Honors & Awards


  • Pilot Research Award, Society of Nuclear Medicine (1996)
  • National Research Service Award, National Institutes of Health (1993-5)
  • Bates Graduate Fellowship, Jonathan Edwards College, Yale University (1987-91)
  • Full Tuition and Research Fellowship, Yale University (1985-93)
  • Sigma Pi Sigma National Honors in Physics, University of California at Los Angeles (1985)
  • B.S. Summa Cum Laude, University of California at Los Angeles (1985)
  • Sherwood Prize in Mathematics, University of California at Los Angeles (1985)
  • E. Lee Kinsey Award in Physics, University of Calfornia at Los Angeles (1985)
  • Marilyn F. Lohr Award in Physics, University of California at Los Angeles (1984)
  • Phi Beta Kappa National Honors, University of California at Los Angeles (1984)
  • Stanford Linear Accelerator Center Undergraduate Fellowship, University of California at Los Angeles (1983)
  • Physics, Mathematics, and College Honors Programs, University of Calfornia at Los Angeles (1981-5)
  • Phi Eta Sigma National Honors, University of California at Los Angeles (1981)

Professional Education


  • Ph.D., Yale University, Physics (1993)
  • M.Phil., Yale University, Physics (1987)
  • M.S., Yale University, Physics (1987)
  • B.S., UCLA, Physics and Mathematics (1985)

Research & Scholarship

Current Research and Scholarly Interests


Molecular Imaging Instrumentation Laboratory

Our research interests involve the development of novel instrumentation and software algorithms for in vivo imaging of cellular and molecular signatures of disease in humans and small laboratory animal subjects. These new cameras efficiently image radiation emissions in the form of positrons, annihilation photons, gamma rays, and light from molecular probes developed to target molecular signals from deep within tissue of live subjects. The goals of the instrumentation projects are to push the sensitivity and spatial, spectral, and/or temporal resolutions as far as physically possible. The algorithm goals are to understand the physical system comprising the subject tissues, radiation transport, and imaging system, and to provide the best available image quality and quantitative accuracy. The work involves computer modeling, position sensitive sensors, readout electronics, data acquisition, image formation, image processing, and data/image analysis algorithms, and incorporating these innovations into practical imaging devices. The ultimate goal is to introduce these new imaging tools into studies of molecular mechanisms and treatments of disease within living subjects.

Clinical Trials


  • Efficacy of Gamma Camera Used Intraoperatively for ID of Sentinel Lymph Nodes w/ Lymphoscintigraphy Not Recruiting

    Lymphoscintigraphy is an accepted and commonly performed procedure used for staging of certain cancers, especially melanoma and breast cancer. It involves injecting a small amount of radioactivity under the skin in order to identify lymph nodes which should be biopsied (i.e., the "sentinel node") to determine if cancer has spread. Our objective is to evaluate the potential benefit of a new, camera-based technology which allows actual images to be obtained intraoperatively in the identification of sentinel nodes.

    Stanford is currently not accepting patients for this trial. For more information, please contact Mike YaO, (312) 543 - 5207.

    View full details

Teaching

2013-14 Courses


Graduate and Fellowship Programs


Publications

Journal Articles


  • Readout strategy of an electro-optical coupled PET detector for time-of-flight PET/MRI PHYSICS IN MEDICINE AND BIOLOGY Bieniosek, M. F., Olcott, P. D., Levin, C. S. 2013; 58 (20): 7227-7238

    Abstract

    Combining PET with MRI in a single system provides clinicians with complementary molecular and anatomical information. However, existing integrated PET/MRI systems do not have time-of-flight (ToF) PET capabilities. This work describes an MRI-compatible front-end electronic system with ToF capabilities. The approach employs a fast arrival-time pickoff comparator to digitize the timing information, and a laser diode to drive a 10 m fiber-optic cable to optically transmit asynchronous timing information to a photodiode receiver readout system. The FWHM jitter of the comparator and this electo-optical link is 11.5 ps in response to a fast digital pulse. When configured with LYSO scintillation crystals and Hamamatsu MPPC silicon photo-multipliers the comparator and electro-optical link achieved a 511 keV coincidence time resolution of 254.7 ps +/- 8.0 ps FWHM with 3 × 3 × 20 mm(3) crystals and 166.5 +/- 2.5 ps FWHM with 3 × 3 × 5 mm(3) crystals.

    View details for DOI 10.1088/0031-9155/58/20/7227

    View details for Web of Science ID 000325172500013

    View details for PubMedID 24061218

  • Readout strategy of an electro-optical coupled PET detector for time-of-flight PET/MRI PHYSICS IN MEDICINE AND BIOLOGY Bieniosek, M. F., Olcott, P. D., Levin, C. S. 2013; 58 (20): 7227-7238

    Abstract

    Combining PET with MRI in a single system provides clinicians with complementary molecular and anatomical information. However, existing integrated PET/MRI systems do not have time-of-flight (ToF) PET capabilities. This work describes an MRI-compatible front-end electronic system with ToF capabilities. The approach employs a fast arrival-time pickoff comparator to digitize the timing information, and a laser diode to drive a 10 m fiber-optic cable to optically transmit asynchronous timing information to a photodiode receiver readout system. The FWHM jitter of the comparator and this electo-optical link is 11.5 ps in response to a fast digital pulse. When configured with LYSO scintillation crystals and Hamamatsu MPPC silicon photo-multipliers the comparator and electro-optical link achieved a 511 keV coincidence time resolution of 254.7 ps +/- 8.0 ps FWHM with 3 × 3 × 20 mm(3) crystals and 166.5 +/- 2.5 ps FWHM with 3 × 3 × 5 mm(3) crystals.

    View details for DOI 10.1088/0031-9155/58/20/7227

    View details for Web of Science ID 000325172500013

    View details for PubMedID 24061218

  • Readout Electronics and Data Acquisition of a Positron Emission Tomography Time-of-Flight Detector Module With Waveform Digitizer IEEE TRANSACTIONS ON NUCLEAR SCIENCE Yeom, J. Y., Vinke, R., Spanoudaki, V. C., Hong, K. J., Levin, C. S. 2013; 60 (5): 3735-3741
  • Compact pulse width modulation circuitry for silicon photomultiplier readout PHYSICS IN MEDICINE AND BIOLOGY Bieniosek, M. F., Olcott, P. D., Levin, C. S. 2013; 58 (15)

    Abstract

    The adoption of solid-state photodetectors for positron emission tomography (PET) system design and the interest in 3D interaction information from PET detectors has lead to an increasing number of readout channels in PET systems. To handle these additional readout channels, PET readout electronics should be simplified to reduce the power consumption, cost, and size of the electronics for a single channel. Pulse-width modulation (PWM), where detector pulses are converted to digital pulses with width proportional to the detected photon energy, promises to simplify PET readout by converting the signals to digital form at the beginning of the processing chain, and allowing a single time-to-digital converter to perform the data acquisition for many channels rather than routing many analogue channels and digitizing in the back end. Integrator based PWM systems, also known as charge-to-time converters (QTCs), are especially compact, reducing the front-end electronics to an op-amp integrator with a resistor discharge, and a comparator. QTCs, however, have a long dead-time during which dark count noise is integrated, reducing the output signal-to-noise ratio. This work presents a QTC based PWM circuit with a gated integrator that shows performance improvements over existing QTC based PWM. By opening and closing an analogue switch on the input of the integrator, the circuit can be controlled to integrate only the portions of the signal with a high signal-to-noise ratio. It also allows for multiplexing different detectors into the same PWM circuit while avoiding uncorrelated noise propagation between photodetector channels. Four gated integrator PWM circuits were built to readout the spatial channels of two position sensitive solid-state photomultiplier (PS-SSPM). Results show a 4 × 4 array 0.9 mm × 0.9 mm × 15 mm of LYSO crystals being identified on the 5 mm × 5 mm PS-SSPM at room temperature with no degradation for twofold multiplexing. In principle, much larger multiplexing ratios are possible, limited only by count rate issues.

    View details for DOI 10.1088/0031-9155/58/15/5049

    View details for Web of Science ID 000322028000006

    View details for PubMedID 23831601

  • Sparse Signal Recovery Methods for Multiplexing PET Detector Readout IEEE TRANSACTIONS ON MEDICAL IMAGING Chinn, G., Olcott, P. D., Levin, C. S. 2013; 32 (5): 932-942

    Abstract

    Nuclear medicine imaging detectors are commonly multiplexed to reduce the number of readout channels. Because the underlying detector signals have a sparse representation, sparse recovery methods such as compressed sensing may be used to develop new multiplexing schemes. Random methods may be used to create sensing matrices that satisfy the restricted isometry property. However, the restricted isometry property provides little guidance for developing multiplexing networks with good signal-to-noise recovery capability. In this work, we describe compressed sensing using a maximum likelihood framework and develop a new method for constructing multiplexing (sensing) matrices that can recover signals more accurately in a mean square error sense compared to sensing matrices constructed by random construction methods. Signals can then be recovered by maximum likelihood estimation constrained to the support recovered by either greedy l? iterative algorithms or l?-norm minimization techniques. We show that this new method for constructing and decoding sensing matrices recovers signals with 4%-110% higher SNR than random Gaussian sensing matrices, up to 100% higher SNR than partial DCT sensing matrices 50%-2400% higher SNR than cross-strip multiplexing, and 22%-210% higher SNR than Anger multiplexing for photoelectric events.

    View details for DOI 10.1109/TMI.2013.2246182

    View details for Web of Science ID 000318643500009

    View details for PubMedID 23475349

  • Distributed MLEM: An Iterative Tomographic Image Reconstruction Algorithm for Distributed Memory Architectures IEEE TRANSACTIONS ON MEDICAL IMAGING Cui, J., Pratx, G., Meng, B., Levin, C. S. 2013; 32 (5): 957-967

    Abstract

    The processing speed for positron emission tomography (PET) image reconstruction has been greatly improved in recent years by simply dividing the workload to multiple processors of a graphics processing unit (GPU). However, if this strategy is generalized to a multi-GPU cluster, the processing speed does not improve linearly with the number of GPUs. This is because large data transfer is required between the GPUs after each iteration, effectively reducing the parallelism. This paper proposes a novel approach to reformulate the maximum likelihood expectation maximization (MLEM) algorithm so that it can scale up to many GPU nodes with less frequent inter-node communication. While being mathematically different, the new algorithm maximizes the same convex likelihood function as MLEM, thus converges to the same solution. Experiments on a multi-GPU cluster demonstrate the effectiveness of the proposed approach.

    View details for DOI 10.1109/TMI.2013.2252913

    View details for Web of Science ID 000318643500011

    View details for PubMedID 23529079

  • First Performance Results of Ce:GAGG Scintillation Crystals With Silicon Photomultipliers IEEE TRANSACTIONS ON NUCLEAR SCIENCE Yeom, J. Y., Yamamoto, S., Derenzo, S. E., Spanoudaki, V. C., Kamada, K., Endo, T., Levin, C. S. 2013; 60 (2): 988-992
  • Optimizing timing performance of silicon photomultiplier-based scintillation detectors PHYSICS IN MEDICINE AND BIOLOGY Yeom, J. Y., Vinke, R., Levin, C. S. 2013; 58 (4): 1207-1220

    Abstract

    Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362-33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm(3) and with 3 × 3 × 20 mm(3) LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm(3) LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15° C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals.

    View details for DOI 10.1088/0031-9155/58/4/1207

    View details for Web of Science ID 000314396800029

    View details for PubMedID 23369872

  • In situ study of the impact of inter- and intra-reader variability on region of interest (ROI) analysis in preclinical molecular imaging. American journal of nuclear medicine and molecular imaging Habte, F., Budhiraja, S., Keren, S., Doyle, T. C., Levin, C. S., Paik, D. S. 2013; 3 (2): 175-181

    Abstract

    We estimated reader-dependent variability of region of interest (ROI) analysis and evaluated its impact on preclinical quantitative molecular imaging. To estimate reader variability, we used five independent image datasets acquired each using microPET and multispectral fluorescence imaging (MSFI). We also selected ten experienced researchers who utilize molecular imaging in the same environment that they typically perform their own studies. Nine investigators blinded to the data type completed the ROI analysis by drawing ROIs manually that delineate the tumor regions to the best of their knowledge and repeated the measurements three times, non-consecutively. Extracted mean intensities of voxels within each ROI are used to compute the coefficient of variation (CV) and characterize the inter- and intra-reader variability. The impact of variability was assessed through random samples iterated from normal distributions for control and experimental groups on hypothesis testing and computing statistical power by varying subject size, measured difference between groups and CV. The results indicate that inter-reader variability was 22.5% for microPET and 72.2% for MSFI. Additionally, mean intra-reader variability was 10.1% for microPET and 26.4% for MSFI. Repeated statistical testing showed that a total variability of CV < 50% may be needed to detect differences < 50% between experimental and control groups when six subjects (n = 6) or more are used and statistical power is adequate (80%). Surprisingly high variability has been observed mainly due to differences in the ROI placement and geometry drawn between readers, which may adversely affect statistical power and erroneously lead to negative study outcomes.

    View details for PubMedID 23526701

  • Signal Conditioning Technique for Position Sensitive Photodetectors to Manipulate Pixelated Crystal Identification Capabilities IEEE TRANSACTIONS ON NUCLEAR SCIENCE Lau, F. W., Vandenbroucke, A., Reynolds, P., Ho, H., Innes, D., Levin, C. S. 2012; 59 (5): 1815-1822
  • Influence of temperature and bias voltage on the performance of a high resolution PET detector built with position sensitive avalanche photodiodes JOURNAL OF INSTRUMENTATION Vandenbroucke, A., McLaughlin, T. J., Levin, C. S. 2012; 7
  • Study of PET intrinsic spatial resolution and contrast recovery improvement for PET/MRI systems PHYSICS IN MEDICINE AND BIOLOGY Peng, H., Levin, C. S. 2012; 57 (9)

    Abstract

    This paper studied PET intrinsic spatial resolution and contrast recovery improvement for PET/MRI dual modality systems. A Monte Carlo simulation tool was developed to study positron diffusion in tissues with and without a magnetic field for six commonly used isotopes ((18)F, (11)C, (13)N, (15)O, (68)Ga and (82)Rb). A convolution process was implemented to investigate PET intrinsic spatial resolution, taking into account three factors: positron diffusion range, collinear photon annihilation and finite detector element width. The resolution improvement was studied quantitatively as a function of magnetic field strength for three PET system configurations (whole-body, brain-dedicated and small-animal PET). When the magnetic field strength increases up to 10 T, the system spatial resolution in directions orthogonal to the field for (15)O, (68)Ga and (82)Rb is comparable to that of (18)F without the magnetic field. Beyond 10 T, no significant improvement of spatial resolution was observed. In addition, the modulation transfer function was studied to predict the intrinsic contrast recovery improvement for several existing and promising PET/MRI configurations.

    View details for DOI 10.1088/0031-9155/57/9/N101

    View details for Web of Science ID 000303046200001

    View details for PubMedID 22481596

  • Promising New Photon Detection Concepts for High-Resolution Clinical and Preclinical PET JOURNAL OF NUCLEAR MEDICINE Levin, C. S. 2012; 53 (2): 167-170

    Abstract

    The ability of PET to visualize and quantify regions of low concentration of PET tracer representing subtle cellular and molecular signatures of disease depends on relatively complex biochemical, biologic, and physiologic factors that are challenging to control, as well as on instrumentation performance parameters that are, in principle, still possible to improve on. Thus, advances to the latter can somewhat offset barriers of the former. PET system performance parameters such as spatial resolution, contrast resolution, and photon sensitivity contribute significantly to PET's ability to visualize and quantify lower concentrations of signal in the presence of background. In this report we present some technology innovations under investigation toward improving these PET system performance parameters. We focus particularly on a promising advance known as 3-dimensional position-sensitive detectors, which are detectors capable of distinguishing and measuring the position, energy, and arrival time of individual interactions of multi-interaction photon events in 3 dimensions. If successful, these new strategies enable enhancements such as the detection of fewer diseased cells in tissue or the ability to characterize lower-abundance molecular targets within cells. Translating these advanced capabilities to the clinic might allow expansion of PET's roles in disease management, perhaps to earlier stages of disease. In preclinical research, such enhancements enable more sensitive and accurate studies of disease biology in living subjects.

    View details for DOI 10.2967/jnumed.110.084343

    View details for Web of Science ID 000300032800006

    View details for PubMedID 22302960

  • The Trend of Data Path Structures for Data Acquisition Systems in Positron Emission Tomography 2012 18TH IEEE-NPSS REAL TIME CONFERENCE (RT) Kim, E., Hong, K. J., Yeom, J. Y., Olcott, P. D., Levin, C. S. 2012
  • Strategies to Achieve More Compact Pulse Width Modulation Circuitry for Silicon Photomultiplier Readout 2012 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE RECORD (NSS/MIC) Bieniosek, M. F., Olcott, P. D., Levin, C. S. 2012: 3812-3814
  • Readout Electronics and Data Acquisition of a Time of Flight Detector for Positron Emission Tomography 2012 18TH IEEE-NPSS REAL TIME CONFERENCE (RT) Yeom, J. Y., Vinke, R., Spanoudaki, V., Hong, K. J., Levin, C. S. 2012
  • Fully 3D list-mode time-of-flight PET image reconstruction on GPUs using CUDA MEDICAL PHYSICS Cui, J., Pratx, G., Prevrhal, S., Levin, C. S. 2011; 38 (12): 6775-6786

    Abstract

    List-mode processing is an efficient way of dealing with the sparse nature of positron emission tomography (PET) data sets and is the processing method of choice for time-of-flight (ToF) PET image reconstruction. However, the massive amount of computation involved in forward projection and backprojection limits the application of list-mode reconstruction in practice, and makes it challenging to incorporate accurate system modeling.The authors present a novel formulation for computing line projection operations on graphics processing units (GPUs) using the compute unified device architecture (CUDA) framework, and apply the formulation to list-mode ordered-subsets expectation maximization (OSEM) image reconstruction. Our method overcomes well-known GPU challenges such as divergence of compute threads, limited bandwidth of global memory, and limited size of shared memory, while exploiting GPU capabilities such as fast access to shared memory and efficient linear interpolation of texture memory. Execution time comparison and image quality analysis of the GPU-CUDA method and the central processing unit (CPU) method are performed on several data sets acquired on a preclinical scanner and a clinical ToF scanner.When applied to line projection operations for non-ToF list-mode PET, this new GPU-CUDA method is >200 times faster than a single-threaded reference CPU implementation. For ToF reconstruction, we exploit a ToF-specific optimization to improve the efficiency of our parallel processing method, resulting in GPU reconstruction >300 times faster than the CPU counterpart. For a typical whole-body scan with 75?×?75?×?26 image matrix, 40.7 million LORs, 33 subsets, and 3 iterations, the overall processing time is 7.7 s for GPU and 42 min for a single-threaded CPU. Image quality and accuracy are preserved for multiple imaging configurations and reconstruction parameters, with normalized root mean squared (RMS) deviation less than 1% between CPU and GPU-generated images for all cases.A list-mode ToF OSEM library was developed on the GPU-CUDA platform. Our studies show that the GPU reformulation is considerably faster than a single-threaded reference CPU method especially for ToF processing, while producing virtually identical images. This new method can be easily adapted to enable more advanced algorithms for high resolution PET reconstruction based on additional information such as depth of interaction (DoI), photon energy, and point spread functions (PSFs).

    View details for DOI 10.1118/1.3661998

    View details for Web of Science ID 000298250100045

    View details for PubMedID 22149859

  • Online detector response calculations for high-resolution PET image reconstruction PHYSICS IN MEDICINE AND BIOLOGY Pratx, G., Levin, C. 2011; 56 (13): 4023-4040

    Abstract

    Positron emission tomography systems are best described by a linear shift-varying model. However, image reconstruction often assumes simplified shift-invariant models to the detriment of image quality and quantitative accuracy. We investigated a shift-varying model of the geometrical system response based on an analytical formulation. The model was incorporated within a list-mode, fully 3D iterative reconstruction process in which the system response coefficients are calculated online on a graphics processing unit (GPU). The implementation requires less than 512 Mb of GPU memory and can process two million events per minute (forward and backprojection). For small detector volume elements, the analytical model compared well to reference calculations. Images reconstructed with the shift-varying model achieved higher quality and quantitative accuracy than those that used a simpler shift-invariant model. For an 8 mm sphere in a warm background, the contrast recovery was 95.8% for the shift-varying model versus 85.9% for the shift-invariant model. In addition, the spatial resolution was more uniform across the field-of-view: for an array of 1.75 mm hot spheres in air, the variation in reconstructed sphere size was 0.5 mm RMS for the shift-invariant model, compared to 0.07 mm RMS for the shift-varying model.

    View details for DOI 10.1088/0031-9155/56/13/018

    View details for Web of Science ID 000291866800020

    View details for PubMedID 21677367

  • A Maximum NEC Criterion for Compton Collimation to Accurately Identify True Coincidences in PET IEEE TRANSACTIONS ON MEDICAL IMAGING Chinn, G., Levin, C. S. 2011; 30 (7): 1341-1352

    Abstract

    In this work, we propose a new method to increase the accuracy of identifying true coincidence events for positron emission tomography (PET). This approach requires 3-D detectors with the ability to position each photon interaction in multi-interaction photon events. When multiple interactions occur in the detector, the incident direction of the photon can be estimated using the Compton scatter kinematics (Compton Collimation). If the difference between the estimated incident direction of the photon relative to a second, coincident photon lies within a certain angular range around colinearity, the line of response between the two photons is identified as a true coincidence and used for image reconstruction. We present an algorithm for choosing the incident photon direction window threshold that maximizes the noise equivalent counts of the PET system. For simulated data, the direction window removed 56%-67% of random coincidences while retaining > 94% of true coincidences from image reconstruction as well as accurately extracted 70% of true coincidences from multiple coincidences.

    View details for DOI 10.1109/TMI.2011.2113379

    View details for Web of Science ID 000292164900004

    View details for PubMedID 21317079

  • Investigation of a clinical PET detector module design that employs large-area avalanche photodetectors PHYSICS IN MEDICINE AND BIOLOGY Peng, H., Olcott, P. D., Spanoudaki, V., Levin, C. S. 2011; 56 (12): 3603-3627

    Abstract

    We investigated the feasibility of designing an Anger-logic PET detector module using large-area high-gain avalanche photodiodes (APDs) for a brain-dedicated PET/MRI system. Using Monte Carlo simulations, we systematically optimized the detector design with regard to the scintillation crystal, optical diffuser, surface treatment, layout of large-area APDs, and signal-to-noise ratio (SNR, defined as the 511 keV photopeak position divided by the standard deviation of noise floor in an energy spectrum) of the APD devices. A detector prototype was built comprising an 8 × 8 array of 2.75 × 3.00 × 20.0 mm3 LYSO (lutetium-yttrium-oxyorthosilicate) crystals and a 22.0 × 24.0 × 9.0 mm3 optical diffuser. From the four designs of the optical diffuser tested, two designs employing a slotted diffuser are able to resolve all 64 crystals within the block with good uniformity and peak-to-valley ratio. Good agreement was found between the simulation and experimental results. For the detector employing a slotted optical diffuser, the energy resolution of the global energy spectrum after normalization is 13.4 ± 0.4%. The energy resolution of individual crystals varies between 11.3 ± 0.3% and 17.3 ± 0.4%. The time resolution varies between 4.85 ± 0.04 (center crystal), 5.17 ± 0.06 (edge crystal), and 5.18 ± 0.07 ns (corner crystal). The generalized framework proposed in this work helps to guide the design of detector modules for selected PET system configurations, including scaling the design down to a preclinical PET system, scaling up to a whole-body clinical scanner, as well as replacing APDs with other novel photodetectors that have higher gain or SNR such as silicon photomultipliers.

    View details for DOI 10.1088/0031-9155/56/12/010

    View details for Web of Science ID 000291095700011

    View details for PubMedID 21610292

  • Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET PHYSICS IN MEDICINE AND BIOLOGY Gu, Y., Matteson, J. L., Skelton, R. T., Deal, A. C., Stephan, E. A., Duttweiler, F., Gasaway, T. M., Levin, C. S. 2011; 56 (6): 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.

    View details for DOI 10.1088/0031-9155/56/6/004

    View details for Web of Science ID 000287848600004

    View details for PubMedID 21335649

  • Investigating the temporal resolution limits of scintillation detection from pixellated elements: comparison between experiment and simulation PHYSICS IN MEDICINE AND BIOLOGY Spanoudaki, V. C., Levin, C. S. 2011; 56 (3): 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.

    View details for DOI 10.1088/0031-9155/56/3/013

    View details for Web of Science ID 000286223100013

    View details for PubMedID 21239845

  • Convex Optimization of Coincidence Time Resolution for a High-Resolution PET System IEEE TRANSACTIONS ON MEDICAL IMAGING Reynolds, P. D., Olcott, P. D., Pratx, G., Lau, F. W., Levin, C. S. 2011; 30 (2): 391-400

    Abstract

    We are developing a dual panel breast-dedicated positron emission tomography (PET) system using LSO scintillators coupled to position sensitive avalanche photodiodes (PSAPD). The charge output is amplified and read using NOVA RENA-3 ASICs. This paper shows that the coincidence timing resolution of the RENA-3 ASIC can be improved using certain list-mode calibrations. We treat the calibration problem as a convex optimization problem and use the RENA-3's analog-based timing system to correct the measured data for time dispersion effects from correlated noise, PSAPD signal delays and varying signal amplitudes. The direct solution to the optimization problem involves a matrix inversion that grows order (n(3)) with the number of parameters. An iterative method using single-coordinate descent to approximate the inversion grows order (n). The inversion does not need to run to convergence, since any gains at high iteration number will be low compared to noise amplification. The system calibration method is demonstrated with measured pulser data as well as with two LSO-PSAPD detectors in electronic coincidence. After applying the algorithm, the 511 keV photopeak paired coincidence time resolution from the LSO-PSAPD detectors under study improved by 57%, from the raw value of 16.3 ±0.07 ns full-width at half-maximum (FWHM) to 6.92 ±0.02 ns FWHM ( 11.52 ±0.05 ns to 4.89 ±0.02 ns for unpaired photons).

    View details for Web of Science ID 000286931000019

    View details for PubMedID 20876008

  • Fast List-Mode Reconstruction for Time-of-Flight PET Using Graphics Hardware IEEE TRANSACTIONS ON NUCLEAR SCIENCE Pratx, G., Surti, S., Levin, C. 2011; 58 (1): 105-109
  • Scintillation induced response in passively-quenched Si-based single photon counting avalanche diode arrays OPTICS EXPRESS Spanoudaki, V. C., Levin, C. S. 2011; 19 (2): 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, 10%-90% 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%.

    View details for Web of Science ID 000286314600127

    View details for PubMedID 21263706

  • Algorithms that exploit multi-interaction photon events in sub-millimeter resolution CZT detectors for PET 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Chinn, G., Levin, C. S. 2011: 3669-3671
  • Time Resolution Performance of an Electro-Optical-Coupled PET Detector for Time-of-Flight PET/MRI 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Bieniosek, M. F., Olcott, P. D., Levin, C. S. 2011: 2531-2533
  • Compressed Sensing for the multiplexing of PET detectors 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Olcott, P. D., Chinn, G., Levin, C. S. 2011: 3224-3226
  • All-optical encoding of PET detector signals 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Grant, A. M., Olcott, P. D., Levin, C. S. 2011: 2258-2260
  • A New Data Path Design for a PET Data Acquisition System: A Packet Based Approach 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Kim, E., Olcott, P., Levin, C. 2011: 3871-3873
  • Functionality Test of a Readout Circuit for a 1mm(3) Resolution Clinical PET System 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Zhai, J., Vandenbroucke, A., Reynolds, P. D., Levin, C. S. 2011: 3945-3949
  • Measuring 511 ke V photon interaction locations in three dimensions using 3-D position sensitive scintillation detectors 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Vandenbroucke, A., Lau, F. W., Reynolds, P. O., Levin, C. S. 2011: 3635-3638
  • Study of Readout for Groups of Position Sensitive Avalanche Photodiodes Used in a 1 mm(3) Resolution Clinical PET System 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Reynolds, P. D., Lau, F. W., Vandenbroucke, A., Levin, C. S. 2011: 3253-3255
  • Signal Conditioning Technique for Position Sensitive Photo detectors to Manipulate Pixelated Crystal Identification Capabilities 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Lau, F. W., Vandenbroucke, A., Reynolds, P., Ho, H., Innes, D., Levin, C. S. 2011: 1647-1653
  • Measurement-Based Spatially-Varying Point Spread Function for List-Mode PET Reconstruction on GPU 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Cui, J., Pratx, G., Prevrhal, S., Zhang, B., Shao, L., Levin, C. S. 2011: 2593-2596
  • Point Spread Function for PET Detectors Based on the Probability Density Function of the Line Segment 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Gonzalez, E., Cui, J., Pratx, G., Bieniosek, M., Olcott, P. D., Levin, C. S. 2011: 4386-4389
  • Methods for Increasing the Sensitivity of Simultaneous Multi-Isotope Positron Emission Tomography 2011 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC) Gonzalez, E., Olcott, P. D., Bieniosek, M., Levin, C. S. 2011: 3597-3601
  • Analog signal multiplexing for PSAPD-based PET detectors: simulation and experimental validation PHYSICS IN MEDICINE AND BIOLOGY Lau, F. W., Vandenbroucke, A., Reynolds, P. D., Olcott, P. D., Horowitz, M. A., Levin, C. S. 2010; 55 (23): 7149-7174

    Abstract

    A 1 mm(3) resolution clinical positron emission tomography (PET) system employing 4608 position-sensitive avalanche photodiodes (PSAPDs) is under development. This paper describes a detector multiplexing technique that simplifies the readout electronics and reduces the density of the circuit board design. The multiplexing scheme was validated using a simulation framework that models the PSAPDs and front-end multiplexing circuits to predict the signal-to-noise ratio and flood histogram performance. Two independent experimental setups measured the energy resolution, time resolution, crystal identification ability and count rate both with and without multiplexing. With multiplexing, there was no significant degradation in energy resolution, time resolution and count rate. There was a relative 6.9 ± 1.0% and 9.4 ± 1.0% degradation in the figure of merit that characterizes the crystal identification ability observed in the measured and simulated ceramic-mounted PSAPD module flood histograms, respectively.

    View details for DOI 10.1088/0031-9155/55/23/001

    View details for Web of Science ID 000284261000015

    View details for PubMedID 21081831

  • Physical effects of mechanical design parameters on photon sensitivity and spatial resolution performance of a breast-dedicated PET system MEDICAL PHYSICS Spanoudaki, V. C., Lau, F. W., Vandenbroucke, A., Levin, C. S. 2010; 37 (11): 5838-5849

    Abstract

    This study aims to address design considerations of a high resolution, high sensitivity positron emission tomography scanner dedicated to breast imaging.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.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.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.

    View details for DOI 10.1118/1.3484059

    View details for Web of Science ID 000283747600030

    View details for PubMedID 21158296

  • Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET) SENSORS Spanoudaki, V. C., Levin, C. S. 2010; 10 (11): 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.

    View details for DOI 10.3390/s101110484

    View details for Web of Science ID 000284578200058

    View details for PubMedID 22163482

  • Performance characterization of a new high resolution PET scintillation detector PHYSICS IN MEDICINE AND BIOLOGY Vandenbroucke, A., Foudray, A. M., Olcott, P. D., Levin, C. S. 2010; 55 (19): 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 × 8 LYSO scintillator arrays of 0.91 × 0.91 × 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 ?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.

    View details for DOI 10.1088/0031-9155/55/19/018

    View details for Web of Science ID 000282061800018

    View details for PubMedID 20844332

  • Effects of multiple-interaction photon events in a high-resolution PET system that uses 3-D positioning detectors MEDICAL PHYSICS Gu, Y., Pratx, G., Lau, F. W., Levin, C. S. 2010; 37 (10): 5494-5508

    Abstract

    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 mm3 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.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 22Na 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.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.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.

    View details for DOI 10.1118/1.3483262

    View details for Web of Science ID 000283483700038

    View details for PubMedID 21089785

  • Recent Developments in PET Instrumentation CURRENT PHARMACEUTICAL BIOTECHNOLOGY Peng, H., Levin, C. S. 2010; 11 (6): 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 LaBr(3), 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.

    View details for Web of Science ID 000281435100003

    View details for PubMedID 20497121

  • Design study of a high-resolution breast-dedicated PET system built from cadmium zinc telluride detectors PHYSICS IN MEDICINE AND BIOLOGY Peng, H., Levin, C. S. 2010; 55 (9): 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 approximately 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 approximately 94.2 kcts s(-1) (breast volume: 720 cm(3) and activity concentration: 3.7 kBq cm(-3)) for a approximately 10% energy window around 511 keV and approximately 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) < or = 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.

    View details for DOI 10.1088/0031-9155/55/9/022

    View details for Web of Science ID 000276816400022

    View details for PubMedID 20400807

  • Acceleration of PET Monte Carlo simulation using the graphics hardware ray-tracing engine 2010 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD (NSS/MIC) Wang, Z., Olcott, P. D., Levin, C. S. 2010: 1848-1855
  • Effects of External Shielding on the Performance of a 1 mm(3) Resolution Breast PET Camera 2010 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD (NSS/MIC) Vandenbroucke, A., Innes, D., Levin, C. S. 2010: 3644-3648
  • Optical Network-based PET DAQ System: One Fiber Optical Connection 2010 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD (NSS/MIC) Kim, E., Olcott, P., Levin, C. 2010: 2020-2025
  • Fully 3-D List-mode Positron Emission Tomography Image Reconstruction on GPU using CUDA 2010 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD (NSS/MIC) Cui, J., Pratx, G., Prevrhal, S., Shao, L., Levin, C. S. 2010: 2635-2637
  • Readout Design and Validation for a 1 mm(3) Resolution Clinical PET System 2010 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD (NSS/MIC) Reynolds, P. D., Lau, F. W., Vandenbroucke, A., Levin, C. S. 2010: 3097-3099
  • Improving SNR with a Maximum Likelihood Compressed Sensing Decoder for Multiplexed PET Detectors 2010 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD (NSS/MIC) Chinn, G., Olcott, P. D., Levin, C. S. 2010: 3353-3356
  • Mixture Model for Fast Estimation of Positron Range 2010 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD (NSS/MIC) Olcott, P. D., Gonzalez, E., Vandenbroucke, A., Levin, C. S. 2010: 3058-3060
  • Novel Electro-Optical Coupling Technique for Magnetic Resonance-Compatible Positron Emission Tomography Detectors MOLECULAR IMAGING Olcott, P. D., Peng, H., Levin, C. S. 2009; 8 (2): 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.

    View details for DOI 10.2310/7290.2009.00012

    View details for Web of Science ID 000265948200004

    View details for PubMedID 19397853

  • Bayesian reconstruction of photon interaction sequences for high-resolution PET detectors. Physics in Medicine and Biology. Selected as Feature Article of the Month, American Institute of Physics, August Pratx, G., Levin, CS. 2009; Vol. 54 (Issue 17,): pp. 5073-5094,
  • Charge Collection Studies of a High Resolution CZT-Based Detector for PET 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Matteson, J. L., Gu, Y., Skelton, R. T., Deal, A. C., Stephan, E. A., Duttweiler, F., Huszar, G. L., Gasaway, T. M., Levin, C. S. 2009: 5310-5317
  • Optimization of Coincidence Time Resolution for a High Resolution PET System. Submitted to IEEE Transactions on Medical Imaging P.D. Reynolds,, P.D. Olcott, G. Pratx, F.W.Y. Lau, C.S. Levin. 2009
  • Design study of a high-resolution breast-dedicated PET system built from cadmium zinc telluride detectors. Submitted to Physics in Medicine Biology H. Peng,, P.D. Olcott, C.S. Levin. 2009
  • New Geometry for a Whole Body PET System. Submitted to IEEE Transactions on Nuclear Science, F. Habte,, G. Pratx, P.D. Olcott, C.S. Levin. 2009
  • 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. Submitted to Medical Physics V.C. Spanoudaki,, F.W.Y. Lau, A. Vandenbroucke, C.S. Levin. 2009
  • Study of a High Resolution, 3-D Positioning Cross-Strip Cadmium Zinc Telluride Detector for PET. Submitted to Medical Physics Y. Gu,, J. L. Matteson, R.T. Skelton, A.C. Deal, E.A. Stephan, F. Duttweiler, T. M. Gasaway, C.S. Levin. 2009
  • Sampling Error in CT-based Partial Volume Correction of Lesions Imaged by PET. Submitted to Journal of Nuclear Medicine D. M. Sigg,, C.S. Levin, A. Quon. 2009
  • High Resolution, Light Multiplexed 3D Positioning Scintillation Detector for High Resolution PET. Submitted to IEEE Transactions on Nuclear Science F. Habte,, P.D. Olcott, C.S. Levin. 2009
  • Can large-area avalanche photodiodes be used for a PET detector insert for an MRI system? Submitted to Medical Physics H. Peng,, P.D. Olcott, V. Spanoudaki, C.S. Levin. 2009
  • A Method to Reject Random Coincidences and Extract True from Multiple Coincidences in PET using 3-D Detectors 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Chinn, G., Levin, C. S. 2009: 4515-4520
  • Temperature and Bias Voltage Studies of a Large Area Position Sensitive Avalanche Photodiode 2009 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5 Vandenbroucke, A., Lee, J., Spanoudaki, V., Lau, F. W., Reynolds, P. D., Levin, C. S. 2009: 3664-3669
  • Faster Maximum-Likelihood Reconstruction via Explicit Conjugation of Search Directions 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Pratx, G., Reader, A. J., Levin, C. S. 2009: 4336-4341
  • Study of Scintillation Crystal Array Parameters for an Advanced PET Scanner Dedicated to Breast Cancer Imaging 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Vandenbroucke, A., Levin, C. S. 2009: 4180-4185
  • Performance characterization of a new high resolution PET scintillation detector. Submitted to Physics in Medicine and Biology A. Vandenbrouke,, A.M.K. Foudray, P.D. Olcott, C.S. Levin. 2009
  • Fast, Accurate and Shift-Varying Line Projections for Iterative Reconstruction Using the GPU. IEEE Transactions in Medical Imaging, March G. Pratx,, P.D. Olcott, G. Chinn, C.S. Levin. 2009; Vol. 28, (No. 3,): 435-445
  • Online calculation of the detector response for high-resolution PET iterative image reconstruction. Submitted to IEEE Transactions on Medical Imaging G. Pratx,, C.S. Levin. 2009
  • Multiplexing circuits for PSAPD-Based PET Detectors: Simulation and Experimental Validation. Submitted to IEEE Transactions on Nuclear Science F.W.Y. Lau,, A. Vandenbrouke, P.D. Reynolds, P.D. Olcott, M.A. Horowitz, C.S. Levin. 2009
  • Simulation study of PET spatial resolution and contrast recovery improvement for PET/MRI dual modality systems. Submitted to Medical Physics H. Peng, C.S Levin, B.A Chronik. 2009
  • Maximum NEC Incident Photon Direction Window Using Compton Kinematics for 3-D Positioning PET Detectors. Submitted to IEEE Transactions on Medical Imaging G. Chinn,, C.S. Levin. 2009
  • Novel Electro-Optical Coupling Technique for Magnetic Resonance-Compatible Positron Emission Tomography Detectors. Molecular Imaging, MAR-APR P.D. Olcott,, H. Peng, C.S. Levin. 2009; Volume 8, (Issue 2,): 74-86,
  • 1 mm(3) Resolution Breast-Dedicated PET System 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Lau, F. W., Fang, C., Reynolds, P. D., Olcott, P. D., Vandenbroucke, A., Spanoudaki, V. C., Olutade, F., Horowitz, M. A., Levin, C. S. 2009: 5378-5381
  • Front-End Electronics for a 1 mm(3) Resolution Avalanche Photodiode-Based PET System with Analog Signal Multiplexing 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Lau, F. W., Vandenbroucke, A., Reynolds, P. D., Olcott, P. D., Horowitz, M. A., Levin, C. S. 2009: 3146-3149
  • Study of a High Resolution, 3-D Positioning Cross-Strip Cadmium Zinc Telluride Detector for PET 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Gu, Y., Matteson, J. L., Skelton, R. T., Deal, A. C., Stephan, E. A., Duttweiler, F., Gasaway, T. M., Levin, C. S. 2009: 2871-2878
  • Effects of Multiple Photon Interactions in a High Resolution PET System that Uses 3-D Positioning Detectors 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Gu, Y., Pratx, G., Lau, F. W., Levin, C. S. 2009: 3089-3094
  • Effects of Thermal Regulation Structures on the Photon Sensitivity and Spatial Resolution of a 1 mm(3) Resolution Breast-Dedicated PET System 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Spanoudaki, V. C., Vandenbroucke, A., Lau, F. W., Fang, C., Levin, C. S. 2009: 5416-5420
  • Performance characterization of a new high resolution PET scintillation detector 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Vandenbroucke, A., Foudray, A. M., Lau, F. W., Olcott, P. D., Reynolds, P. D., Levin, C. S. 2009: 2879-2883
  • Can large-area avalanche photodiodes be used for a clinical PET/MRI block detector? 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Peng, H., Olcott, P. D., Spanoudaki, V., Levin, C. S. 2009: 3948-3953
  • Convex Optimization of Coincidence Time Resolution for High Resolution PET Systems 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Reynolds, P. D., Olcott, P. D., Pratx, G., Lau, F. W., Levin, C. S. 2009: 3343-3348
  • Pulse Width Modulation: a Novel Readout Scheme for High Energy Photon Detection 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Olcott, P. D., Levin, C. S. 2009: 3804-3809
  • Novel Electro-Optically Coupled MR-Compatible PET Detectors 2008 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (2008 NSS/MIC), VOLS 1-9 Olcott, P. D., Peng, H., Levin, C. S. 2009: 3913-3918
  • New geometry for a whole body PET system. Submitted to IEEE Transactions on Nuclear Science F. Habte,, G. Pratx, P. Olcott, C.S Levin. 2009
  • New imaging technologies to enhance the molecular sensitivity of positron emission tomography PROCEEDINGS OF THE IEEE Levin, C. S. 2008; 96 (3): 439-467
  • Characterization of a Small Animal Time-Domain Fluorescence Tomography Imaging System., IEEE Transactions on Medical Imaging. Jan. S. Keren, O. Gheysens, C.S. Levin, S.S. Gambhir. 2008; Volume 27 (Issue 1,): Page(s):58 - 63.
  • New Imaging Technologies to Enhance the Molecular Sensitivity of Positron Emission Tomography. Proceedings of the IEEE, March C.S. Levin. 2008; Vol.96, (No.3,): pp. 439-67.
  • Simulation and Measurement of Gamma-Ray and Annihilation Photon Imaging Detectors. IEEE Transactions on Nuclear Science. F. Habte,, P.D. Olcott, A.M.K. Foudray, C.S. Levin, J. Zhang, G. Chinn. 2008: Undergoing review,
  • Performance characterization of a miniature, high sensitivity gamma ray camera IEEE TRANSACTIONS ON NUCLEAR SCIENCE Olcott, P. D., Habte, F., Foudray, A. M., Levin, C. S. 2007; 54 (5): 1492-1497
  • Effects of system geometry and other physical factors on photon sensitivity of high-resolution positron emission tomography PHYSICS IN MEDICINE AND BIOLOGY Habte, F., Foudray, A. M., Olcott, P. D., Levin, C. S. 2007; 52 (13): 3753-3772

    Abstract

    We are studying two new detector technologies that directly measure the three-dimensional coordinates of 511 keV photon interactions for high-resolution positron emission tomography (PET) systems designed for small animal and breast imaging. These detectors are based on (1) lutetium oxyorthosilicate (LSO) scintillation crystal arrays coupled to position-sensitive avalanche photodiodes (PSAPD) and (2) cadmium zinc telluride (CZT). The detectors have excellent measured 511 keV photon energy resolutions (8% photon sensitivity for the LSO-PSAPD box configuration and >15% for CZT box geometry, using a 350-650 keV energy window setting. These simulation results compare well with analytical estimations. The trend is different for a clinical whole-body PET system that uses conventional LSO-PMT block detectors with larger crystal elements. Simulations predict roughly the same sensitivity for both box and cylindrical detector configurations. This results from the fact that a large system diameter (>80 cm) results in relatively small inter-module gaps in clinical whole-body PET. In addition, the relatively large block detectors (typically >5 x 5 cm(2) cross-sectional area) and large crystals (>4 x 4 x 20 mm(3)) enable a higher fraction of detector scatter photons to be absorbed compared to a small animal system. However, if the four detector sides (panels) of a box-shaped system geometry are configured to move with respect to each other, to better fit the transaxial FOV to the actual size of the object to be imaged, a significant increase in photon sensitivity is possible. Simulation results predict a 60-100% relative increase of photon sensitivity for the proposed small animal PET box configurations and >60% increase for a clinical whole-body system geometry. Thus, simulation results indicate that for a PET system built from rectangular-shaped detector modules, arranging them into a box-shaped system geometry may help us to significantly boost photon sensitivity for both small animal and clinical PET systems.

    View details for DOI 10.1088/0031-9155/52/13/007

    View details for Web of Science ID 000247048300007

    View details for PubMedID 17664575

  • A new positioning algorithm for position-sensitive avalanche photodiodes IEEE TRANSACTIONS ON NUCLEAR SCIENCE Zhang, J., Olcott, P. D., Levin, C. S. 2007; 54 (3): 433-437
  • Performance characterization of a novel thin position-sensitive avalanche photodiode for 1 mm resolution positron emission tomography IEEE TRANSACTIONS ON NUCLEAR SCIENCE Zhang, J., Foudray, A. M., Cott, P. D., Farrell, R., Shah, K., Levin, C. S. 2007; 54 (3): 415-421
  • Study of the performance of a novel 1 mm resolution dual-panel PET camera design dedicated to breast cancer imaging using Monte Carlo simulation MEDICAL PHYSICS Zhang, J., Olcott, P. D., Chinn, G., Foudray, A. M., Levin, C. S. 2007; 34 (2): 689-702

    Abstract

    We studied the performance of a dual-panel positron emission tomography (PET) camera dedicated to breast cancer imaging using Monte Carlo simulation. The PET camera under development has two 10x 15 cm(2) plates that are constructed from arrays of I X 1 X 3 mm(3) LSO crystals coupled to novel ultra-thin (<200 Am) silicon position-sensitive avalanche photodiodes (PSAPD). In this design the photodetectors are configured "edge-on" with respect to incoming photons which encounter a minimum of 2 cm thick of LSO with directly measured photon interaction depth. Simulations predict that this camera will have 10-15% photon sensitivity, for an 8-4 cm panel separation. Detector measurements show approximately 1 mm(3) intrinsic spatial resolution, <12% energy resolution, and approximately 2 ns coincidence time resolution. By performing simulated dual-panel PET studies using a phantom comprising active breast, heart, and torso tissue, count performance was studied as a function of coincident time and energy windows. We also studied visualization of hot spheres of 2.5-4.0 mm diameter and various locations within the simulated breast tissue for 1 X 1 X 3 mm(3), 2 x 2 x 10 mm(3), 3 x 3 x 30 mm(3), and 4 X 4 X 20 mm(3) LSO crystal resolutions and different panel separations. Images were reconstructed by focal plane tomography with attenuation and normalization corrections applied. Simulation results indicate that with an activity concentration ratio of tumor:breast:heart:torso of 10:1:10:1 and 30 s of acquisition time, only the dual-plate PET camera comprising 1 X 1 X 3 mm(3) crystals could resolve 2.5 mm diameter spheres with an average peak-to-valley ratio of 1.3.

    View details for DOI 10.1118/1.2409480

    View details for Web of Science ID 000244424200035

    View details for PubMedID 17388187

  • Prototype parallel readout system for position sensitive PMT based gamma ray imaging systems IEEE TRANSACTIONS ON NUCLEAR SCIENCE Habte, F., Olcott, P. D., Levin, C. S., Foudray, A. M. 2007; 54 (1): 60-65
  • Evaluation of free-running ADCs for high resolution PET data acquisition 2007 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-11 Peng, H., Olcott, P. D., Foudray, A. M., Levin, C. S. 2007: 3328-3331
  • Accurately positioning events in a high-resolution PET system that uses 3D CZT detectors 2007 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-11 Pratx, G., Levin, C. S. 2007: 2660-2664
  • PET image reconstruction with a Bayesian projector for multi-electronic collimation schemes 2007 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-11 Chinn, G., Levin, C. S. 2007: 2799-2802
  • Bayesian estimator for angle recovery: Event classification and reconstruction in positron emission tomography BAYESIAN INFERENCE AND MAXIMUM ENTROPY METHODS IN SCIENCE AND ENGINEERING Foudray, A. M., Levin, C. S. 2007; 954: 362-371
  • Bayesian Estimator for Angle Recovery: Event Classification and Reconstruction in Positron Emission Tomography, Journal of Bayesian Inference and Maximum Entropy Methods in Science and Engineering, American Institutes of Physics, A.M.K. Foudray, and C.S. Levin. 2007; Volume 954: pp. 362-371,
  • Prototype Parallel Readout System for Position Sensitive PMT based Gamma-Ray Imaging Systems. IEEE Transactions on Nuclear Science. F. Habte,, P.D. Olcott, C. S. Levin, A.M. Foudray. 2007; 54-1(1),: 60-65
  • Study of the Performance of a Novel 1 mm Resolution Dual-Panel PET Camera Design Dedicated to Breast Cancer Imaging Using Monte Carlo Simulation. Medical Physics Zhang J, Olcott PD, Chinn G, Foudray AMK, Levin CS. 2007; 34(2),: 689-702
  • Performance Characterization of a Novel Thin Position-Sensitive Avalanche Photodiode for High Resolution Positron Emission Tomography. IEEE Transactions on Nuclear Science. Part 1 June J. Zhang,, A.M.K Foudray, P.D. Olcott, C.S. Levin. 2007; Volume 54 (3): Page(s):415 - 421
  • Effects of System Geometry and Other Physical Factors on Photon Sensitivity of High Resolution Positron Emission Tomography. Physics in Medicine and. Biology. F. Habte,, A.M.K. Foudray, P.D. Olcott, C.S. Levin. 2007; 52: 3753-3772.
  • A New Positioning Algorithm for Position-Sensitive Avalanche Photodiodes. IEEE Transactions on Nuclear Science. J. Zhang,, P.D. Olcott, C.S. Levin. 2007; Volume 54 (3, Part 1): Page(s):433 ? 437.
  • Performance Characterization of a Miniature, High Sensitivity Gamma-Ray Camera. IEEE Transactions on Nuclear Science. Part 1 OCT P.D. Olcott,, F. Habte, C.S. Levin, A.M.K. Foudray. 2007; 54(5): 1492-1497
  • Current Trends in Pre-Clinical Positron Emission Tomography System Design. PET Clinics, C.S. Levin,, H. Zaidi. 2007; Vol. 2 (No. 2): pp 125-160
  • Noise analysis of LSO-PSAPD PET detector front-end multiplexing circuits 2007 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-11 Lau, F. W., Olcott, P. D., Horowitz, M. A., Peng, H., Levin, C. S. 2007: 3212-3219
  • Data acquisition system design for a 1 mm(3) resolution PSAPD-based PET system 2007 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-11 Olcott, P. D., Lau, F. W., Levin, C. S. 2007: 3206-3211
  • Design study of a high-resolution breast-dedicated PET system built from cadmium zinc telluride detectors 2007 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-11 Peng, H., Olcott, P. D., Pratx, G., Foudray, A. M., Chinn, G., Levin, C. S. 2007: 3700-3704
  • Positioning annihilation photon interactions in a thin LSO crystal sheet with a position-sensitive avalanche photodiode IEEE TRANSACTIONS ON NUCLEAR SCIENCE Foudray, A. M., Habte, F., Levin, C. S., Olcott, P. D. 2006; 53 (5): 2549-2556
  • Incident Photon Direction Calculation Using Bayesian Estimation for High Energy Photon Detector Systems with 3D Positioning Capability 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 Foudray, A. M., Chinn, G., Levin, C. S. 2006: 2008-2010
  • Impact of High Energy Resolution Detectors on the Performance of a PET System Dedicated to Breast Cancer Imaging. . Physica Medica. Selected Top 10 Most Cited Papers in Physica Medica (European Journal of Medical Physics). C.S. Levin,, F. Habte, A.M.K. Foudray, J. Chang, G. Chinn. 2006; Vol. XXI (Suppl. 1): pp. 28-34
  • A Method to Include Single Photon Events in Image Reconstruction for a 1 mm Resolution PET System Built with Advanced 3-D Positioning Detectors 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 Chinn, G., Foudray, A. M., Levin, C. S. 2006: 1740-1745
  • Accurately Positioning and Incorporating Tissue-Scattered Photons into PET Image Reconstruction 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 Chinn, G., Foudray, A. M., Levin, C. S. 2006: 1746-1751
  • Positioning Annihilation Photon Interactions in a Thin LSO Crystal Sheet with a Position-Sensitive Avalanche Photodiodes. IEEE Transactions on Nuclear Science. A.M.K. Foudray,, F. Habte, C.S. Levin, P.D. Olcott. 2006; 53-5(1), (Part 1 Oct): 2549-2556,
  • Image Processing Algorithms to Facilitate and Enhance Sentinel Node Detection using a Hand-Held Gamma-Ray Camera in Surgical Breast Cancer Staging. Physica Medica. P.D. Olcott,, C.S. Levin. 2006; Vol. XXI (Suppl. 1): pp.99-101
  • Evaluation of a Dual-Head PET Camera Design Dedicated to Breast Cancer Imaging. Physica Medica. J. Zhang,, G. Chinn, A.M.K. Foudray, F. Habte, P.D. Olcott, C.S. Levin. 2006; Vol. XXI (Suppl.1): pp. 94-98
  • 2004 Workshop on the Nuclear Radiology of Breast Cancer - Rome (Italy) October 22-23, 2004 - Preface PHYSICA MEDICA Levin, C. S., Tornai, M. P., Pani, R., Garibaldi, F., Mankoff, D. A. 2006; 21: 1-1
  • Count Rate Studies of a Box-Shaped PET Breast Imaging System Comprised of Position Sensitive Avalanche Photodiodes Utilizing Monte Carlo Simulation. Physica Medica. Angela M. K. Foudray,, F. Habte, G. Chinn, J. Zhang, Craig S. Levin. 2006; Vol. XXI (Suppl. 1): pp. 64-67
  • GRAY: High Energy Photon Ray Tracer for PET Applications 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 Olcott, P. D., Buss, S. R., Levin, C. S., Pratx, G., Sramek, C. K. 2006: 2011-2015
  • Fully 3-D List-Mode OSEM Accelerated by Graphics Processing Units 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 Pratx, G., Chinn, G., Habte, F., Olcott, P., Levin, C. 2006: 2196-2202
  • Characterization of Two Thin Postion-Sensitive Avalanche Photodiodes on a Single Flex Circuit for Use in 3-D Positioning PET Detectors 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 Foudray, A. M., Farrell, R., Olcott, P. D., Shah, K. S., Levin, C. S. 2006: 2469-2472
  • A high speed fully digital data acquisition system for Positron Emission Tomography 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 Olcott, P. D., Fallu-Labruyere, A., Habte, F., Levin, C. S., Warburton, W. K. 2006: 1909-1911
  • 2004 Workshop on the Nuclear Radiology of Breast Cancer - Rome (Italy) October 22-23, 2004 ? Preface, Physica Medica, Levin, C., Tornai, MP; Pani, R, Garibaldi, F;, Mankoff, DM. 2006; Volume: 21 (Suppl. 1): Pages: 1-1
  • Scintillation crystal design features for a miniature gamma ray camera IEEE TRANSACTIONS ON NUCLEAR SCIENCE Dhanasopon, A. P., Levin, C. S., Foudray, A. M., Olcott, P. D., Habte, F. 2005; 52 (5): 1439-1446
  • Compact readout electronics for position sensitive photomultiplier tubes IEEE TRANSACTIONS ON NUCLEAR SCIENCE Olcott, P. D., Talcott, J. A., Levin, C. S., Habte, F., Foudray, A. M. 2005; 52 (1): 21-27
  • Investigation of scintillation light multiplexing for PET detectors based on position sensitive avalanche photodiodes 2005 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5 Habte, F., Olcott, P. D., Levin, C. S., Foudray, A. M. 2005: 2027-2030
  • Comparing geometries for a PET system with 3-D photon positioning capability 2005 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5 Chinn, G., Foudray, A. M., Levin, C. S. 2005: 1709-1712
  • Component based normalization for PET systems with depth of interaction measurement capability 2005 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5 Foudray, A. M., Chinn, G., Levin, C. S. 2005: 2108-2111
  • Compact Readout Electronics for Position Sensitive Photomultiplier Tubes. IEEE Transactions on Nuclear Science, P.D. Olcott,, .A. Talcott, C.S. Levin, F. Habte, A.M.K. Foudray. 2005; 52-1(1),: 21-27,
  • Primer on Molecular Imaging Technology. European Journal of Nuclear Medicine and Molecular Imaging, C.S. Levin. 2005; , 32-2,: S325-45,
  • Scintillation Crystal Design Features for a Miniature Gamma-Ray Camera. IEEE Transactions on Nuclear Science, A.P. Dhanasopon,, C.S. Levin, A. M. K. Foudray, P. D. Olcott, F. Habte. 2005; 52-5(1),: 1439-1446,
  • Monte Carlo simulation study of a dual-plate PET camera dedicated to breast cancer Imaging 2005 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5 Zhang, J., Olcott, P. D., Foudray, A. M., Chinn, G., Levin, C. S. 2005: 1667-1671
  • Finite element model based spatial linearity correction for scintillation detectors that use position sensitive avalanche photodiodes 2005 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5 Olcott, P. D., Zhang, J., Levin, C. S., Habte, F., Foudray, A. M. 2005: 2459-2462
  • Performance characterization of a novel thin position-sensitive avalanche photodiode-based detector for high resolution PET 2005 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5 Zhang, J., Foudray, A. M., Olcott, P. D., Levin, C. S. 2005: 2478-2482
  • Charge multiplexing readout for position sensitive avalanche photodiodes 2005 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5 Olcott, P. D., Habte, F., Zhang, J., Levin, C. S. 2005: 2935-2937
  • Study of low noise multichannel readout electronics for high sensitivity PET systems based on avalanche photodiode arrays IEEE TRANSACTIONS ON NUCLEAR SCIENCE Habte, F., Levin, C. S. 2004; 51 (3): 764-769
  • Investigation of position sensitive avalanche photodiodes for a new high-resolution PET detector design IEEE TRANSACTIONS ON NUCLEAR SCIENCE Levin, C. S., Foudray, A. M., Olcott, P. D., Habte, F. 2004; 51 (3): 805-810
  • Scintillation crystal design features for a miniature gamma ray camera 2003 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-5 Dhanasopon, A. P., Levin, C. S., Foudray, A. M., Olcott, P. D., Talcott, J. A., Habte, F. 2004: 1967-1971
  • Investigation of position sensitive avalanche photodiodes for a new high resolution PET detector design 2003 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-5 Levin, C. S., Foudray, A. M., Olcott, P. D., Habte, F. 2004: 2262-2266
  • Prototype parallel readout system for position sensitive PMT based gamma ray imaging systems 2003 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-5 Habte, F., Olcott, P. D., Levin, C. S., Foudray, A. M., Talcott, J. A. 2004: 1891-1894
  • Compact readout electronics for position sensitive photomultiplier tubes 2003 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-5 Olcott, P. D., Talcott, J. A., Levin, C. S., Habte, F., Foudray, A. M. 2004: 1962-1966
  • Study of Low Noise Multi-Channel Readout Electronics for High Sensitivity PET Systems Based on Avalanche Photodiode Arrays. IEEE Transactions on Nuclear Science, F. Habte, and C.S. Levin. 2004; 51-3(2),: 764-9,
  • Investigation of Position Sensitive Avalanche Photodiodes for a New High Resolution PET Detector Design. IEEE Transactions on Nuclear Science, C.S. Levin,, A.M.K. Foudray, P.D. Olcott, F. Habte. 2004; 51-3(2),: 805-810,
  • Methods to Extract More Light from Minute Scintillation Crystals Used in an Ultra-High Resolution Positron Emission Tomography Detector. Nuclear Instruments and Methods in Physics Research A, C.S. Levin,, F. Habte, A.M. Foudray. 2004; 527(1-2):: 35-40.
  • Positioning annihilation photon interactions in a thin LSO crystal sheet with a position-sensitive avalanche photodiode 2004 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-7 Foudray, A. M., Habte, F., Levin, C. S., Olcott, P. D. 2004: 2985-2989
  • Characterization of performance of a miniature, high sensitivity gamma ray camera 2004 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-7 Olcott, P. D., Habte, F., Levin, C. S., Foudray, A. M. 2004: 3997-4000
  • Simulation and measurement of gamma ray and annihilation photon imaging detectors 2004 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-7 Habte, F., Olcott, P. D., Foudray, A. M., Levin, C. S., Zhang, J., Chinn, G. 2004: 4019-4022
  • Detector Design Issues for Compact Nuclear Emission Cameras Dedicated to Functional Breast Imaging. Nuclear Instruments and Methods in Physics Research A, C.S. Levin. 2003; 497-1,: 60-74,
  • Investigation of low noise, low cost readout electronics for high sensitivity PET systems based on avalanche photodiode arrays 2002 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-3 Habte, F., Levin, C. S. 2003: 661-665
  • Initial studies of a new detector design for ultra-high resolution Positron Emission Tomography 2002 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-3 Levin, C. S., Habte, F. 2003: 1751-1755
  • Centered Versus Non-Centered Source For Intracoronary Artery Radiation Therapy: A Model Based on the Scripps Trial. American Heart Journal, Arbab-Zadeh, RJ Russo, V Bhargava, C.S. Levin, SK Jani, J Lucisano, PS Teirstein. 2002; 143-2: 342-8
  • Design of a High-Resolution and High-Sensitivity Scintillation Crystal Array for PET with Nearly Complete Light Collection. IEEE Transactions on Nuclear Science, C.S. Levin. 2002; 49-5(1),: 2236-43
  • Evaluation of Breast Tumor Detectability with Two Dedicated, Compact Scintillation Cameras. IEEE Transactions on Nuclear Science, D.P. McElroy,, E.J. Hoffman, L. MacDonald, B.E. Patt, J.S. Iwanczyk, Y. Yamaguchi, C.S. Levin. 2002; 49-3(1),: 794-802,
  • Performance Analysis of an Improved 3-D PET Monte Carlo Simulation and Scatter Correction. IEEE Transactions on Nuclear Science, C.H. Holdsworth,, C.S. Levin, M. Janecek, M. Dahlbom, E.J. Hoffman. 2002; 49-1(1),: 83-89,
  • Investigation of Accelerated Monte Carlo Techniques for PET Simulation and 3-D PET Scatter Correction. IEEE Transactions on Nuclear Science, C. Holdsworth, C.S. Levin, M. Dahlbom, T. Farquhar, E.J. Hoffman. 2001; 48-1(1),: 74-81
  • Investigation of Microcolumnar Scintillators on an Optical Fiber Coupled Compact Imaging System. IEEE Transactions on Nuclear Science, MP Tornai, C Archer, AG Wiesenberger, R. Wojcik, V Popov, CE Keppel, CS Levin, S Majewski, SV Tipnis, VV Nagarkar. 2001; 48-3(2),: 637-44,
  • Corrigendum: Calculation of Positron Range and its Effect on Positron Emission Tomography System Spatial Resolution. Physics in Medicine and Biology C.S. Levin, and E. J. Hoffman. 2000; 45-2: 559
  • Calculation of Positron Range and its Effect on Positron Emission Tomography System Spatial Resolution. Physics in Medicine and Biology C.S. Levin, and E.J. Hoffman. 1999; 44,: 781-799,
  • A Miniature Phoswich Detector for Gamma-Ray Localization and Beta Imaging. IEEE Transactions on Nuclear Science, M.P. Tornai,, C.S. Levin, L.R. MacDonald, C.H. Holdsworth, E.J. Hoffman. 1998; 45-3(2),: 1166-73,
  • A Dual Detector Beta-Ray Imaging Probe with Gamma-Ray Background Suppression for Use in Intra-Operative Detection of Radiolabeled Tumors. Nuclear Instruments and Methods in Physics Research A E.J. Hoffman,, M.P. Tornai, C.S. Levin, L.R. MacDonald, C.H. Holdsworth. 1998; 409: 511-16,
  • Gamma and Beta Intra-Operative Imaging Probes. Nuclear Instruments and Methods in Physics Research A, E.J. Hoffman, M.P. Tornai, C.S. Levin, L.R. MacDonald, S. Siegel. 1997; 392: 324-29
  • Investigation of a New Readout Scheme for High Resolution Scintillation Crystal Arrays Using Photodiodes. IEEE Transactions on Nuclear Science C.S. Levin, and E.J. Hoffman. 1997; 44-3(2),: 1208-13
  • Development of an Intraoperative Gamma Camera Based on a 256-Pixel Mercuric Iodide Detector Array. IEEE Transactions on Nuclear Science, B.E. Patt,, M.P. Tornai, J.S. Iwanczyk, C.S. Levin, E.J. Hoffman. 1997; 44-3(2),: 1242-48,
  • Compton Scatter and X-Ray Crosstalk and the Use of Very Thin Intercrystal Septa in High Resolution PET Detectors. IEEE Transactions on Nuclear Science C.S. Levin, M.P. Tornai, S.R. Cherry, L.R. MacDonald, E.J. Hoffman. 1997; 44-2: 18-24
  • Investigation of Crystal Geometries for Fiber Coupled Gamma Imaging Intra-Operative Probes. IEEE Transactions on Nuclear Science, M.P. Tornai, C.S. Levin, L.R. MacDonald, E.J. Hoffman, J. Park. 1997; 44-3(2),: 1254-61
  • Annihilation Gamma-Ray Background Characterization and Rejection for a Small Beta Camera Used for Tumor Localization During Surgery. IEEE Transactions on Nuclear Science C.S. Levin, M.P. Tornai, L.R. MacDonald, E.J. Hoffman. 1997; 44-4: 1120-26,
  • Discrete Scintillator Coupled Mercuric Iodide Photodetector Arrays for Breast Imaging. IEEE Transactions on Nuclear Science, M.P. Tornai, B.E. Patt, J.S. Iwanczyk, C.S. Levin, E.J. Hoffman. 1997; 44-3(2),: 1127-33,
  • PSPMT and Photodiode Designs of a Small Scintillation Camera for Imaging Malignant Breast Tumors. . IEEE Transactions on Nuclear Science, C.S. Levin, E.J. Hoffman, M.P. Tornai, L.R. MacDonald. 1997; 44-4(1),: 1513-20,
  • Design and Performance of Gamma and Beta Intra-Operative Imaging Probes. Physica Medica E.J. Hoffman, M.P. Tornai, C.S. Levin, L.R. MacDonald, S. Siegel. 1997; Vol. XIII (Suppl. 1): S243-247
  • Design Considerations and Initial Performance of a 1.2 cm2 Beta Imaging Intra-Operative Probe. IEEE Transactions on Nuclear Science, M.P. Tornai, L.R. MacDonald, C.S. Levin, S. Siegel, E.J. Hoffman. 1996; 43-4(1): 2326-2335
  • Miniature Nuclear Emission Imaging System for Intra-Operative Applications. In: Proceedings from UCLA International Conference on Imaging Detectors in High Energy & Astroparticle Physics M.P. Tornai, L.R. MacDonald, C.S. Levin, S. Siegel, E.J. Hoffman, J. Park, M. Atac, D.B. Cline. 1996: 133-47
  • Optimizing Light Collection from Thin Scintillators Used in a Beta-Ray Camera for Surgical Use. IEEE Transactions on Nuclear Science, C.S. Levin, L.R. MacDonald, M.P. Tornai, E.J. Hoffman, J. Park. 1996; 43-3(2),: 2053-60
  • Mercuric Iodide Photodetector Arrays for Gamma-Ray Imaging. Nuclear Instruments and Methods in Physics Research A, B.E. Patt, J.S. Iwanczyk, Y.J. Wang, M.P. Tornai, C.S. Levin, E.J. Hoffman. 1996; 380: 295-300
  • Characterization of Fluor Concentration and Geometry in Organic Scintillators for in situ Beta Imaging. IEEE Transactions on Nuclear Science, M.P. Tornai, E.J. Hoffman, C.S. Levin, L.R. MacDonald. 1996; 43-6(2): 3342-47
  • A Monte Carlo Correction for the Effect of Compton Scattering in 3-D PET Brain Imaging. . IEEE Transactions on Nuclear Science, C.S. Levin, M. Dahlbom, E.J. Hoffman. 1995; 42-4(1, 2): 1181-1185
  • Small Area, Fiber Coupled Scintillation Camera for Imaging Beta-Ray Distributions Intra-Operatively. In: Photoelectronic Detectors, Cameras and Systems, Eds. C.B. Johnson, E.J. Fenyves, Proceedings of SPIE, the International Society for Optical Engineering, SPIE, Bellingham, WA. L.R. MacDonald, M.P. Tornai, C.S. Levin, J. Park, M. Atac, D.B. Cline, E.J. Hoffman. 1995; 2551: 92-101
  • Development of a Mercuric Iodide Detector Array for Medical Imaging Applications. Nuclear Instruments and Methods in Physics Research A, B.E. Patt, J.S. Iwanczyk, M.P. Tornai, C.S. Levin, E.J. Hoffman 1995; 42-4(1, 2): 1181-1185
  • Development of a Mercuric Iodide Detector Array for in-vivo X-Ray Imaging. Advances in X-Ray Analysis, B.E. Patt, J.S. Iwanczyk, M.P. Tornai, C.S. Levin, E.J. Hoffman. 1995; 38: 615-24
  • A Comparison of PET Detector Modules Employing Rectangular and Round Photomultiplier Tubes. IEEE Transactions on Nuclear Science, S. R. Cherry, M.P. Tornai, C.S. Levin, S. Siegel, E.J. Hoffman. 1995; 42-4(1, 2): 1064-1068
  • Investigation of the Physical Aspects of Beta Imaging Probes Using Scintillating Fibers and Visible Light Photon Counters. IEEE Transactions on Nuclear Science, L.R. MacDonald, M.P. Tornai, C.S. Levin, J. Park, M. Atac, D.B. Cline, E.J Hoffman. 1995; 42-4(1, 2): 1351-1357

Conference Proceedings


  • Image processing algorithms to facilitate and enhance sentinel node detection using a hand-held gamma ray camera in surgical breast cancer staging Cott, P. D., Levin, C. S. IST EDITORIALI POLGRAFICI INT. 2006: 99-101

    Abstract

    We have developed a miniature scintillation camera to be used in surgical cancer staging. The availability of such a compact hand-held gamma camera may in certain cases improve localization of the sentinel lymph node and reduce the duration of a surgical breast cancer staging procedure. We have investigated image processing algorithms applied to planar images that may improve node detection capabilities for breast cancer staging. We have also studied contrast enhancement methods that may be able to identify nodes that would otherwise be missed. Exposure duration for a given camera position can be adaptively shortened or increased by using an optical flow algorithm to estimate camera motion with respect to the current frame. By determining if the camera is in motion or not, the exposure time may be increased to allow more image counts to accumulate at a given camera position. Adaptive exposure time may improve the ease of use of the hand-held camera, and allow regions of interest to be imaged more effectively. We feel that these image processing techniques can improve the utility of a hand-held gamma ray imager for sentinel lymph node detection during breast cancer staging.

    View details for Web of Science ID 000245817500027

    View details for PubMedID 17646006

  • Evaluation of a dual-panel PET camera design to breast cancer imaging Zhang, J., Chinn, G., Foudray, A. M., Habte, F., Olcott, P., Levin, C. S. IST EDITORIALI POLGRAFICI INT. 2006: 94-98

    Abstract

    We are developing a novel, portable dual-panel positron emission tomography (PET) camera dedicated to breast cancer imaging. With a sensitive area of approximately 150 cm(2), this camera is based on arrays of lutetium oxyorthosilicate (LSO) crystals (1x1x3 mm(3)) coupled to 11x11-mm(2) position-sensitive avalanche photodiodes (PSAPD). GATE open source software was used to perform Monte Carlo simulations to optimize the parameters for the camera design. The noise equivalent counting (NEC) rate, together with the true, scatter, and random counting rates were simulated at different time and energy windows. Focal plane tomography (FPT) was used for visualizing the tumors at different depths between the two detector panels. Attenuation and uniformity corrections were applied to images.

    View details for Web of Science ID 000245817500026

    View details for PubMedID 17646005

  • Impact of high energy resolution detectors on the performance of a PET system dedicated to breast cancer imaging Levin, C. S., Foudray, A. M., Habte, F. IST EDITORIALI POLGRAFICI INT. 2006: 28-34

    Abstract

    We are developing a high resolution, high sensitivity PET camera dedicated to breast cancer imaging. We are studying two novel detector technologies for this imaging system: a scintillation detector comprising layers of small lutetium oxyorthosilicate (LSO) crystals coupled to new position sensitive avalanche photodiodes (PSAPDs), and a pure semiconductor detector comprising cadmium zinc telluride (CZT) crystal slabs with thin anode and cathode strips deposited in orthogonal directions on either side of each slab. Both detectors achieve 1 mm spatial resolution with 3-5 mm directly measured photon interaction depth resolution, which promotes uniform reconstructed spatial resolution throughout a compact, breast-size field of view. Both detector types also achieve outstanding energy resolution (<3% and <12%, respectively for LSO-PSAPD and CZT at 511 keV). This paper studies the effects that this excellent energy resolution has on the expected system performance. Results indicate the importance that high energy resolution and narrow energy window settings have in reducing background random as well as scatter coincidences without compromising statistical quality of the dedicated breast PET data. Simulations predict that using either detector type the excellent performance and novel arrangement of these detectors proposed for the system facilitate approximately 20% instrument sensitivity at the system center and a peak noise-equivalent count rate of >4 kcps for 200 microCi in a simulated breast phantom.

    View details for Web of Science ID 000245817500011

    View details for PubMedID 17645990

  • Methods to extract more light from minute scintillation crystals used in an ultra-high resolution Positron Emission Tomography detector Levin, C. S., Habte, F., Foudray, A. M. ELSEVIER SCIENCE BV. 2004: 35-40

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