Pinhole imaging of gamma rays

Paix, D

doi:10.1088/0031-9155/12/4/004

Cited by 60 publications

(29 citation statements)

References 4 publications

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“…The pencil beam was created by positioning the sources one meter from a 0.5 mm diameter lead pinhole located 15 mm over the crystal surface. The effective diameter of the pinhole [6], taking into account penetration through its edges, was 0.51, 0.515 and 0.52 mm for 241 Am, 57 Co and 99m Tc respectively. For 125 I, a 0.1 mm pinhole in a lead sheet was placed directly over the crystal, and edge penetration was negligible.…”

Section: B Spatial Resolutionmentioning

confidence: 99%

Investigation of a continuous crystal PSAPD-based gamma camera

Després

Barber

Funk

et al. 2006

IEEE Trans. Nucl. Sci.

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Abstract-Position-sensitive avalanche photodiodes (PSAPDs) have recently been proposed as optical light detectors in scintillation based gamma cameras. They are compact solid-state devices that provide high quantum efficiency and gain, and they can achieve precise positioning over relatively large surfaces with few readout channels. In previous studies, PSAPDs were coupled to scintillator arrays and the imaging task consisted in identifying the crystal of interaction. In this work, we investigate the possibility of using a PSAPD to read the light of a single continuous crystal. Such a configuration has the potential to reduce the cost and simplify the construction of a PSAPD-based gamma camera while maintaining good overall performance. The spatial resolution of a small imaging unit having a continuous scintillator coupled to an 8x8 mm

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Section: B Spatial Resolutionmentioning

confidence: 99%

Investigation of a continuous crystal PSAPD-based gamma camera

Després

Barber

Funk

et al. 2006

IEEE Trans. Nucl. Sci.

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“…The localization of the source in absolute coordinates is of lesser importance since it would be difficult to relate them to target volume due to movements of patient during treatment. The question about pinhole geometry and materials has been addressed many times [3], [5], [6], [7] since the introduction of first Anger gamma camera [8]. For our application 2 cm thick lead shield with interchangeable pinhole insert was chosen.…”

Section: Methodsmentioning

confidence: 99%

A system for localization of high dose rate¹⁹²Ir source during brachytherapy treatment with silicon detectors

Batič

Burger

Cindro

et al. 2009

2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)

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A system for in-vivo tracking of 192 Ir source during high dose rate or pulsed dose rate brachytherapy treatment was built using 1 mm thick silicon pad detectors as image sensors and knife-edge lead pinholes as collimators. With source self-images obtained from a dual-pinhole system location of the source could be reconstructed in three dimensions in real time. The system was tested with 1 Ci 192 Ir clinical source in air and plexi-glass phantom. The locations of the source were tracked from a distance of 40 cm in a field of view of 20 × 20 × 20 cm 3 . Reconstruction precision, defined as the average distance between true and reconstructed source positions, with data collected in less than 1 second with 1 Ci 192 Ir source was about 5 mm. The reconstruction precision was in our case mainly limited by imperfect alignment of detectors and pinholes. With perfect alignment the statistical error would allow precision of about 1 mm which could further be improved with larger detector placed at larger distance from the pinhole. However also the modest precision of few millimeters is sufficient for in-vivo detection of larger deviations from planned treatment caused by various misadministrations or malfunctioning of the brachytherapy treatment apparatus. Usage of silicon detectors offers a possibility for building a compact device which could be used as an independent online quality assurance system. In this paper details about sensors, readout system and reconstruction algorithm are described. Results from measurements with clinical source are presented.

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“…Pinhole collimation was one of the first techniques used in gamma ray imaging (Anger and Rosenthal 1959, Mallard and Myers 1963, Paix 1967). Pinhole collimators are widely used for small animal single photon emission computed tomography (SPECT) imaging (Jaszczak et al 1994, Weber et al 1994, Meikle et al 2005, Beekman and van der Have 2007).…”

Section: Introductionmentioning

confidence: 99%

Analytic derivation of pinhole collimation sensitivity for a general source model using spherical harmonics

Li¹,

Oldendick²,

Chang³

2010

Phys. Med. Biol.

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Pinhole collimators are widely used for SPECT imaging of small organs and animals. There also has been renewed interest in using pinhole arrays for clinical cardiac SPECT imaging to achieve high sensitivity and complete data sampling. Overall sensitivity of a pinhole array is critical in determining a system’s performance. Conventionally, a point source model has been used to evaluate the sensitivity and optimize the system design. This model is simple but far from realistic. This work addresses the use of more realistic source models to assess the sensitivity performance of pinhole collimation. We have derived an analytical formula for pinhole collimation sensitivity with a general source distribution model using spherical harmonics. As special cases of this general model, we provided the pinhole sensitivity formulae for line, disk and sphere sources. These results show that the point source model is just the zeroth-order approximation of the other source models. The point source model overestimates or underestimates the sensitivity relative to the more realistic model. The sphere source model yields the same sensitivity as a point source located at the center of the sphere when attenuation is not taken into account. In the presence of attenuation, the average path length of emitted gamma-rays is 3/4 of the radius of the sphere source. The calculated sensitivities based on these formulae show good agreement with separate Monte Carlo simulations in simple cases. The general and special sensitivity formulae derived here can be useful for the design and optimization of SPECT systems that utilize pinhole collimators.

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Pinhole imaging of gamma rays

Cited by 60 publications

References 4 publications

Investigation of a continuous crystal PSAPD-based gamma camera

Investigation of a continuous crystal PSAPD-based gamma camera

A system for localization of high dose rate¹⁹²Ir source during brachytherapy treatment with silicon detectors

Analytic derivation of pinhole collimation sensitivity for a general source model using spherical harmonics

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Pinhole imaging of gamma rays

Cited by 60 publications

References 4 publications

Investigation of a continuous crystal PSAPD-based gamma camera

Investigation of a continuous crystal PSAPD-based gamma camera

A system for localization of high dose rate192Ir source during brachytherapy treatment with silicon detectors

Analytic derivation of pinhole collimation sensitivity for a general source model using spherical harmonics

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A system for localization of high dose rate¹⁹²Ir source during brachytherapy treatment with silicon detectors