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Papers by Neal Clinthorne

International Congress Series, 2001

2002 IEEE Nuclear Science Symposium Conference Record

... IEEE, Trans. Nuclear science, vol. 44, June 1997. [2] S. Weber et al. “Evaluation of the Tier... more ... IEEE, Trans. Nuclear science, vol. 44, June 1997. [2] S. Weber et al. “Evaluation of the TierPET system”. IEEE, Trans. Nuclear science, vol. 46, 1999. [3] NH Clinthorne, “Very High Resolution Animal PET”. J. Nucl. Med. Supp., 2000. ...

Medical physics, 2018

Application of advanced imaging techniques, such as PET and x ray CT, can potentially improve det... more Application of advanced imaging techniques, such as PET and x ray CT, can potentially improve detection of breast cancer. Unfortunately, both modalities have challenges in the detection of some lesions. The combination of the two techniques, however, could potentially lead to an overall improvement in diagnostic breast imaging. The purpose of this investigation is to test the basic performance of a new dedicated breast-PET/CT. The PET component consists of a rotating pair of detectors. Its performance was evaluated using the NEMA NU4-2008 protocols. The CT component utilizes a pulsed x ray source and flat panel detector mounted on the same gantry as the PET scanner. Its performance was assessed using specialized phantoms. The radiation dose to a breast during CT imaging was explored by the measurement of free-in-air kerma and air kerma measured at the center of a 16 cm-diameter PMMA cylinder. Finally, the combined capabilities of the system were demonstrated by imaging of a micro-ho...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

In order to estimate and correct Compton scattering m nuclear-medicine Anger-camera imaging, we h... more In order to estimate and correct Compton scattering m nuclear-medicine Anger-camera imaging, we have previously required the least-mean-square error between the locally measured energy spectrum and one dependent on a model. The model assumes a fixed-order polynomial for the spectrum of scatter and fits the data over a specified energy range In this study, a Monte Carlo simulation program produces spectra at specified locations in a projection image of a 99-Tc "hot" sphere in a "cold" cylinder. Poisson noise is subsequently added to each spectral channel, modelling a given count level within the acceptance window. Tests were done at two pixel locations, one at the center of the sphere and the other near the edge. Without noise, we find that the calculated-to-true ratio for unscattered counts is reasonably close to 1.0 (average 1 .03, range 0.85 to 1.16) for all of the 16 order-range combinations that were tested Tests on expenmental data yield comparable results. For comparison, without any Compton-scatter correction the average ratio is 1 .39. Optimizing the fitting parameters is difficult because, for example, the best set for location 1 is the worst for location 2. With noisy data, the relative standard deviation, and sometimes the bias for the estimate of direct (i .e. unscattered) counts, increases as the statistical noise increases. The average relative error for the estimate is 10% for the 3 cases measured with about 5000 unscattered counts but increases to 20% if that number decreases to 700.

International Congress Series, 2003

2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515), 2000

The effect of intercrystal Compton scatter in a small animal PET module was investigated using el... more The effect of intercrystal Compton scatter in a small animal PET module was investigated using electron-gamma shower code (EGS4) simulations. The size of detector module is fixed at a 16 mm×16 mm crystal array. Monte Carlo simulations were performed to estimate the effect of intercrystal scatter considering scintillation materials (BGO, LSO, and NaI), detector energy threshold, crystal size, and interaction

Nuclear Instruments and Methods in Physics Research, 1984

A circular ring tomograph, designated SPRINT, is under development for single photon emission tom... more A circular ring tomograph, designated SPRINT, is under development for single photon emission tomography of the human head. Most data to date have been gathered using a single rotating slit inside the detector ring to define ray directions. As an alternative method, we have also investigated the use of multiplexed slit patterns consisting of a pseudorandom binary code. From theoretical considerations, one would expect that the substitution of the code for the single slit would have potential advantages in reducing statistical noise in tomographic images of small objects. It has been our experience that this improvement is marginal at best for the types of source distributions encountered in clinical brain imaging. However, the code shows substantial advantage in suppressing uncorrelated backgrounds and the effects of highly penetrating gamma ray components in the source.

International Congress Series, 2001

2002 IEEE Nuclear Science Symposium Conference Record

... IEEE, Trans. Nuclear science, vol. 44, June 1997. [2] S. Weber et al. “Evaluation of the Tier... more ... IEEE, Trans. Nuclear science, vol. 44, June 1997. [2] S. Weber et al. “Evaluation of the TierPET system”. IEEE, Trans. Nuclear science, vol. 46, 1999. [3] NH Clinthorne, “Very High Resolution Animal PET”. J. Nucl. Med. Supp., 2000. ...

Medical physics, 2018

Application of advanced imaging techniques, such as PET and x ray CT, can potentially improve det... more Application of advanced imaging techniques, such as PET and x ray CT, can potentially improve detection of breast cancer. Unfortunately, both modalities have challenges in the detection of some lesions. The combination of the two techniques, however, could potentially lead to an overall improvement in diagnostic breast imaging. The purpose of this investigation is to test the basic performance of a new dedicated breast-PET/CT. The PET component consists of a rotating pair of detectors. Its performance was evaluated using the NEMA NU4-2008 protocols. The CT component utilizes a pulsed x ray source and flat panel detector mounted on the same gantry as the PET scanner. Its performance was assessed using specialized phantoms. The radiation dose to a breast during CT imaging was explored by the measurement of free-in-air kerma and air kerma measured at the center of a 16 cm-diameter PMMA cylinder. Finally, the combined capabilities of the system were demonstrated by imaging of a micro-ho...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

In order to estimate and correct Compton scattering m nuclear-medicine Anger-camera imaging, we h... more In order to estimate and correct Compton scattering m nuclear-medicine Anger-camera imaging, we have previously required the least-mean-square error between the locally measured energy spectrum and one dependent on a model. The model assumes a fixed-order polynomial for the spectrum of scatter and fits the data over a specified energy range In this study, a Monte Carlo simulation program produces spectra at specified locations in a projection image of a 99-Tc "hot" sphere in a "cold" cylinder. Poisson noise is subsequently added to each spectral channel, modelling a given count level within the acceptance window. Tests were done at two pixel locations, one at the center of the sphere and the other near the edge. Without noise, we find that the calculated-to-true ratio for unscattered counts is reasonably close to 1.0 (average 1 .03, range 0.85 to 1.16) for all of the 16 order-range combinations that were tested Tests on expenmental data yield comparable results. For comparison, without any Compton-scatter correction the average ratio is 1 .39. Optimizing the fitting parameters is difficult because, for example, the best set for location 1 is the worst for location 2. With noisy data, the relative standard deviation, and sometimes the bias for the estimate of direct (i .e. unscattered) counts, increases as the statistical noise increases. The average relative error for the estimate is 10% for the 3 cases measured with about 5000 unscattered counts but increases to 20% if that number decreases to 700.

International Congress Series, 2003

2003 IEEE Nuclear Science Symposium. Conference Record (IEEE Cat. No.03CH37515), 2000

The effect of intercrystal Compton scatter in a small animal PET module was investigated using el... more The effect of intercrystal Compton scatter in a small animal PET module was investigated using electron-gamma shower code (EGS4) simulations. The size of detector module is fixed at a 16 mm×16 mm crystal array. Monte Carlo simulations were performed to estimate the effect of intercrystal scatter considering scintillation materials (BGO, LSO, and NaI), detector energy threshold, crystal size, and interaction

Nuclear Instruments and Methods in Physics Research, 1984

A circular ring tomograph, designated SPRINT, is under development for single photon emission tom... more A circular ring tomograph, designated SPRINT, is under development for single photon emission tomography of the human head. Most data to date have been gathered using a single rotating slit inside the detector ring to define ray directions. As an alternative method, we have also investigated the use of multiplexed slit patterns consisting of a pseudorandom binary code. From theoretical considerations, one would expect that the substitution of the code for the single slit would have potential advantages in reducing statistical noise in tomographic images of small objects. It has been our experience that this improvement is marginal at best for the types of source distributions encountered in clinical brain imaging. However, the code shows substantial advantage in suppressing uncorrelated backgrounds and the effects of highly penetrating gamma ray components in the source.