Modelling image profiles produced with a small field of view gamma camera with a single pinhole collimator

Abstract

Gamma cameras making use of parallel-hole collimators have a long history in medical imaging. Pinhole collimators were used in the original gamma camera instruments and have been used more recently in dedicated organ specific systems, intraoperative instruments and for small animal imaging, providing higher resolution over a smaller field of view than the traditional large field of view systems.With the resurgence of interest in the use of pinhole collimators for small field of view (SOV) medical gamma cameras, it is important to be able to accurately determine their response under various conditions. Several analytical approaches to pinhole response have been reported in the literature including models of 3D pinhole imaging systems. Success has also been reported in the use of Monte Carlo simulations; however this approach can require significant time and computing power.This report describes a 2D model that was used to investigate some common problems in pinhole imaging, the variation in resolution over the field of view and the use of 'point' sources for quantifying pinhole response.

Characterisation of a near-infrared (NIR) fluorescence imaging systems intended for hybrid gamma-NIR fluorescence image guided surgery

“…A novel small field of view (SFOV) hand-held hybrid optical gamma camera (HGC) has already been developed for scintigraphic procedures and intraoperative SLN mapping [22,23]. This camera combines gamma and optical images to provide high spatial resolution and demonstrates a new possibility for SLN identification during surgery [24].…”

Characterisation of a high resolution small field of view portable gamma camera

“…The resolution of a pinhole camera will vary across its field of view, so all phantom images were taken within the 30 FOV of the pinhole where this effect is negligible [7]. Image acquisition time was 100 s. The capillary tube was orientated at a range of angles to the detector array and this orientation was corrected for as described in Section 3.1.…”

A hybrid camera for locating sources of gamma radiation in the environment

“…Baek et al [8] stated that, although several types of collimator may be used in gamma cameras, a pinhole collimator is the most expedient for environmental imaging as it makes large area monitoring possible and offers the same angular resolution regardless of the distance between the source and the camera. However, the efficiency of pinhole collimators decreases rapidly with distance from the source and they can suffer from non-uniform spatial resolution across the field of view [12]. Although semiconductor devices can have extremely good energy resolution their stopping power can be a disadvantage at gamma ray energies used in environmental applications (typically 50 keV-1.5 MeV).…”