Characterisation of the latest Birmingham modular positron camera

T.W. Leadbeater, D.J. Parker

Positron Imaging Centre, University of Birmingham, Edgbaston, Birmingham, B15 2TT

Positron imaging techniques rely on the detection of the back-to-back annihilation photons arising from positron decay within the field of view of a positron camera. A standard technique, called Positron Emitting Particle Tracking (PEPT) [1], uses a number of these detected events to rapidly determine the position of a positron emitting tracer particle introduced into the system under study.

Conventionally PEPT is performed using detectors which are fixed in position in the laboratory. Recently however, a more flexible detection system has been developed which allows customisation of the detection geometry (i.e. allowed field-of-view) for specific applications.

The modular camera performance has been improved allowing data rates up to 4MHz (and therefore particle locations accurate to 0.05mm to be made every 0.25ms). Variants of the modular camera concept have been increasingly used campus wide at The University of Birmingham and a number of different applications are currently being studied using these devices.

Presented in this paper are studies into the performance of the modular camera system, performed using a mixture of both Monte Carlo techniques and experimental validation. Studies into the stored event rate (and therefore particle location rate and location precision) have been performed and show a maximum data rate of 2.5MHz, leading to particle location rates of 10kHz with location precision of 0.25mm in 3 dimensions. The field of view for this camera geometry is discontinuous, thus efficiency profiles as a function of position have been determined; peak measured efficiency for genuine coincidences is around 15% with an average of 5% across the entire field of view.

Keywords Positron imaging, Particle tracking.