Analytic Determination of the Resolution-Equivalent Effective Diameter of a Pinhole Collimator

Accorsi, Roberto; Metzler, S.

doi:10.1109/tmi.2004.826951

Cited by 122 publications

(94 citation statements)

References 28 publications

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“…17 and 18. For large pinholes ͑with a diameter larger than 1 mm͒, Anger's effective pinhole diameter is acceptable, 17,18 and will be adopted in this article for its simplicity. Similarly, for the divergent-beam geometry, we have Divergent-beam collimator resolution:…”

Section: Iie a More Realistic Comparison Between The Divergent-beammentioning

confidence: 99%

Multidivergent‐beam stationary cardiac SPECT

Zeng

Stevens

2009

Medical Physics

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This article develops a stationary cardiac single photon emission computed tomography ͑SPECT͒ system using a novel multidivergent-beam collimator. This stationary SPECT system is inexpensive to build, small, and able to acquire true dynamic SPECT data. Stationary cardiac SPECT systems with multipinhole technology already exist. The proposed approach is to replace the multipinhole collimators with the originally designed multidivergent-beam collimators. The motivation for replacing the pinhole technology by divergent-beam technology is based on the following facts. The resolution/sensitivity trade-off for the pinhole is excellent ͑good resolution and good sensitivity͒ only in small object ͑e.g., small animal͒ imaging when it operates in the image magnifying mode. However, in large object ͑e.g., human͒ imaging, the resolution/sensitivity trade-off is poor ͑poor resolution and poor sensitivity͒ when the pinhole operates in the image reducing mode. In a stationary system, the number of angular views is limited; thus, image reduction is necessary to obtain more view angles. In this image reducing situation, divergent-beam collimation is able to provide better resolution and detection sensitivity than pinhole collimation. Computer simulations are carried out to verified the claims.

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Section: Iie a More Realistic Comparison Between The Divergent-beammentioning

confidence: 99%

Multidivergent‐beam stationary cardiac SPECT

Zeng

Stevens

2009

Medical Physics

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“…These systems use large magnifications to provide superior spatial resolution with relatively poor intrinsic spatial [16]. If detectors having higher intrinsic spatial resolutions are used for pinhole systems, they could offer higher resolutions without magnification.…”

Section: Introductionmentioning

confidence: 99%

“…This 9-pinhole collimator indicates the possibility of improving detection efficiency and spatial resolution compared to parallel-hole collimators [13], [14]. Most multi-pinhole systems employ a conventional gamma camera with 3~5 mm intrinsic spatial resolution.These systems use large magnifications to provide superior spatial resolution with relatively poor intrinsic spatial [16]. If detectors having higher intrinsic spatial resolutions are used for pinhole systems, they could offer higher resolutions without magnification.…”

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confidence: 99%

Design and Development of a High Performance Pinhole Array Dual Head SPECT Using Monte Carlo Simulation

Rahman¹

2015

IJIEE

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Abstract-The Purpose of this study is to investigate the performance of a dual head SPECT system having an array of pinholes as a collimator. Several analytical methods are used to evaluate the performance of the given pinhole array detector module design. Monte Carlo simulation studies using Geant4 Application for Tomographic Emission (GATE) validate the performance of this novel dual head SPECT where a cylindrical water phantom is imaged. We are proposing a pinhole array detector module with 48mm by 48mm of active area behind an array of 100 pinholes laid out in a 10 by 10 lattice. This configuration allows high detection efficiency and excellent sensitivity in SPECT imaging. The system is based on a pixelated array of NaI crystals (100 × 100 × 10mm elements) coupled with an array of position sensitive photomultiplier tubes (PSPMTs). The basic characteristics of this system were evaluated with pinhole apertures of 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm and 3mm respectively. A conventional filtered back projection algorithm was used to reconstruct the images. Performance evaluation of this system indicates that high quality images can be obtained for in vivo imaging.Index Terms-Dual head SPECT, SPECT instrumentation, pinhole SPECT and GATE. I. INTRODUCTIONIn the past several years, SPECT has developed significantly and is now considered to be an imperative modality in the nuclear emission field. SPECT is a physiological imaging tool that is commonly used for visualizing or measuring the function of specific organs. There are definite advantages for improved SPECT devices [1]. Higher sensitivity and resolution are necessary for small animal imaging than for human imaging to achieve a level of anatomic detail that is comparable to human studies. Dedicated small animal imaging systems are being developed in several modalities. In spite of the requirement for higher spatial resolution, SPECT is most often based on the Anger camera principle: a collimator is placed in front of a NaI (Tl) scintillation crystal associated with a set of photomultipliers. Conventional collimators used for SPECT imaging cannot provide better detection efficiency and result in poor image quality. SPECT is a rapidly changing field, and the past several years have produced new developments in both hardware technology and image processing algorithms [2]. At the component level, there have been improvements in scintillators and photon transducers as well as in the greater availability of semiconductor technology. The current Manuscript received September 10, 2014; revised November 25, 2014 state-of-the-art of SPECT has been developing from many fronts and there is still scope to see improvements in instrumentation and innovative image reconstruction algorithms. Despite the readily available isotopes, unlike PET, SPECT suffers from low detection efficiency and low resolution; therefore, many investigations have focused on increasing its sensitivity without degrading spatial resolution [3]- [5]. A pinhole approach for SPECT is envisaged for superior spa...

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“…In this case, the collection efficiency is minimal due to the fact that the system sensitivity and system spatial resolution operate as opposing magnitudes. 2,[6][7][8] The spatial resolution also depends on the source-collimator distance. As this distance increases, the spatial resolution severely worsens.…”

Section: Introductionmentioning

confidence: 99%

Stereoscopic full aperture imaging in nuclear medicine

Strocovsky

Otero

2011

AIP Advances

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Images of planar scintigraphy and single photon emission computerized tomography (SPECT) used in nuclear medicine are often low quality. They usually appear to be blurred and noisy. This problem is due to the low spatial resolution and poor sensitivity of the acquisition technique with the gamma camera (GC). Other techniques, such as coded aperture imaging (CAI) reach higher spatial resolutions than GC. However, CAI is not frequently used for imaging in nuclear medicine, due to the decoding complexity of some images and the difficulty in controlling the noise magnitude. Summing up, the images obtained through GC are low quality and it is still difficult to implement CAI technique. A novel technique, full aperture Imaging (FAI), also uses gamma ray-encoding to obtain images, but the coding system and the method of images reconstruction are simpler than those used in CAI. In addition, FAI also reaches higher spatial resolution than GC. In this work, the principles of FAI technique and the method of images reconstruction are explained in detail. The FAI technique is tested by means of Monte Carlo simulations with filiform and spherical sources. Spatial resolution tests of GC versus FAI were performed using two different sourcedetector distances. First, simulations were made without interposing any material between the sources and the detector. Then, other more realistic simulations were made. In these, the sources were placed in the centre of a rectangular prismatic region, filled with water. A rigorous comparison was made between GC and FAI images of the linear filiform sources, by means of two methods: mean fluence profile graphs and correlation tests. Finally, three-dimensional capacity of FAI was tested with two spherical sources. The results show that FAI technique has greater sensitivity (>100 times) and greater spatial resolution (>2.6 times) than that of GC with LEHR collimator, in both cases, with and without attenuating material and long and shortdistance configurations. The FAI decoding algorithm reconstructs simultaneously four different projections which are located in separate image fields on the detector plane, while GC produces only one projection per acquisition. Simulations have allowed comparison of both techniques under ideal identical conditions. Our results show it is possible to apply an extremely simple encoded imaging technique, and get three-dimensional radioactivity information for simplistic geometry sources. The results are promising enough to evaluate the possibility of future research with more complex sources typical of nuclear medicine imaging.

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Analytic Determination of the Resolution-Equivalent Effective Diameter of a Pinhole Collimator

Cited by 122 publications

References 28 publications

Multidivergent‐beam stationary cardiac SPECT

Multidivergent‐beam stationary cardiac SPECT

Design and Development of a High Performance Pinhole Array Dual Head SPECT Using Monte Carlo Simulation

Stereoscopic full aperture imaging in nuclear medicine

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