A high resolution Small Field Of View (SFOV) gamma camera: a columnar scintillator coated CCD imager for medical applications

Abstract

We describe a high resolution, small field of view (SFOV), Charge Coupled Device (CCD) based camera for imaging small volumes of radionuclide uptake in tissues. The Mini Gamma Ray Camera (MGRC) is a collimated, scintillator-coated, low cost, high performance imager using low noise CCDs. The prototype MGRC has a 600 µm thick layer of columnar CsI(Tl) and operates in photon counting mode using a thermoelectric cooler to achieve an operating temperature of -10 ˚C. Collimation was performed using a pin hole collimator. We have measured the spatial resolution, energy resolution and efficiency using a number of radioisotope sources including 140 keV gamma-rays from 99m Tc in a specially designed phantom. We also describe our first imaging of a volunteer patient.

Quantitative investigation of a novel small field of view hybrid gamma camera (HGC) capability for sentinel lymph node detection

“…This preservation of spatial resolution was due to the light-guiding that is provided by the needle structure of the scintillation layer. 10 …”

Assessment of Spatial Resolution on SPECT using Image Processing

“…The benefit of a consistent approach across all gamma cameras outweighs the effects of a finite source and the standard LFOV method, with a 0.5 mm diameter line source, may be used.It may be possible to use a point or line source of a known diameter and then deconvolve the expected profile from the resultant image to determine the resolution; this is not ideal and requires specific knowledge of the expected profile of the source [21] and so may produce inconsistent results for different systems.Many SFOV cameras use pinhole collimators rather than the more widely used parallel-hole collimator. This means that a line source imaged at the collimator face would appear to be a floodsource in the resultant image.…”

A scheme for assessing the performance characteristics of small field-of-view gamma cameras

“…It may be possible to use a point or line source of a known diameter and then deconvolve the expected profile from the resultant image to determine the resolution; this is not ideal and requires specific knowledge of the expected profile of the source [10] and so may produce inconsistent results for different systems.…”

“…These aim to combine the advantages of large field-of-view (LFOV) gamma cameras and nonimaging gamma probes while addressing some of the limitations of these devices. Designs for SFOV systems include: scintillationbased detectors -with scintillators coupled to position sensitive photomultiplier tubes (PSPMTs) [5e8], electron multiplying charge coupled detectors (EMCCDs) [9,10] or silicon drift arrays [11] -and solid state detectors such as cadmium telluride (CdTe) [12e14] and cadmium zinc telluride (CdZnTe) [15].…”

“…These aim to combine the advantages of large field-of-view (LFOV) gamma cameras and nonimaging gamma probes while addressing some of the limitations of these devices. Designs for SFOV systems include: scintillationbased detectors -with scintillators coupled to position sensitive photomultiplier tubes (PSPMTs) [5e8], electron multiplying charge coupled detectors (EMCCDs) [9,10] or silicon drift arrays [11] -and solid state detectors such as cadmium telluride (CdTe) [12e14] and cadmium zinc telluride (CdZnTe) [15].Manufacturers of LFOV gamma cameras routinely use standardised protocols such as the NEMA Standard NU1-2007 [16] to assess performance and provide specifications. In the clinical environment, modified protocols arising from these standards have been developed for ease of use, for example, IPEM Report 86 in the UK [17].…”