A correction method of the spatial distortion in planar images from γ-Camera systems

Abstract

A methodology for correcting spatial distortions in planar images for small Field Of View (FOV) γ-Camera systems based on Position Sensitive Photomultiplier Tubes (PSPMT) and pixelated scintillation crystals is described. The process utilizes a correction matrix whose elements are derived from a prototyped planar image obtained through irradiation of the scintillation crystal by a 60 Co point source and without a collimator. The method was applied to several planar images of a SPECT experiment with a simple phantom construction at different detection angles. The tomographic images are obtained using the Maximum-Likelihood Expectation-Maximization (MLEM) reconstruction technique. Corrected and uncorrected images are compared and the applied correction methodology is discussed.

Sensitivity and Resolution Study of a Small-Field γ-Camera System on a Tomographic Level

“…The Gel-Phantom is placed on a small rotating support and a total of 24 projections with 15 0 -step covering the full angle region (0 0°3 60 0 ) are obtained with the ∞-Camera system under examination. The planar information is further analyzed to reconstruct the tomographic images, taking into account all oAE-line corrections needed to remove barreloid deformations appearing at the edges of the Field-of-View, as they have been described in [1].…”

“…A small-field ∞-Camera system, based on the HAMAMATSU R2486 Position Sensitive Photomultiplier Tube (PSPMT) and utilizing the resistive chain readout technique, is being, in the last years, developed in our laboratory. Attention has been paid to the removal of the spatial distortion appearing at the edges of the system's Field-of-View [1]. On a planar level the spatial resolution has been found to be ae X = (0.95 ± 0.05)mm and ae Y = (1.07 ± 0.07)mm with respect to the X-and Y-direction of the PSPMT's multi-anode grid [2].…”

A real time motion correction technique for a small-field γ-Camera system

“…In the past years, in our laboratory a prototype small field ,-Camera system based on the R2486 (HAMAMATSU) Position Sensitive PhotoMultiplier Tube has been developed [1], [2], [3].…”

Phantom Experimentation on SPECT, Infrared and Optical Tomography

“…The extra load of ionizing radiation (CT), the high cost (MRI) and also the mobility of such devises make those methods superfluous. Our SPECT-Lab has recently developed and evaluated on a tomographic level, a small-field γ-Camera system based on Position Sensitive PhotoMultiplier Tubes (PSPMT) [1]. Therefore, in order to gain the necessary anatomic information two different, non invasive, non-ionizing, low cost and portable modalities are proposed in the current project.…”

“…The main goal of the present study is to experimentally define the capabilities of the infrared emission tomography at the scale of mammal's core temperatures, as well as the optical tomography fluorescence light emission, by means of appropriate phantom experimentation. This will also serve as a feasibility study in the design of a dual-modality imaging system with the existing portable γ-Camera system of our Lab [1] by incorporating a future infrared and optical tomography additionally to the existing SPECT option. Therefore, the tasks posed in this study require a reasonable selection of the appropriate phantoms and imaging conditions, as well as an efficient reconstruction technique.…”