Monte Carlo modelling of the performance of a rotating slit-collimator for improved planar gamma-camera imaging.
Planar imaging with a gamma camera is currently limited by the performance of the collimator. Spatial resolution and sensitivity trade off against each other; it is not possible with conventional parallel-hole collimation to have high geometric sensitivity and at the same time excellent spatial resolution unless field-of-view is sacrificed by using fan- or cone-beam collimators. We propose a rotating slit-collimator which collects one-dimensional projections from which the planar image may be reconstructed by the theory of computed tomography. The performance of such a collimator is modelled by Monte Carlo methods and images are reconstructed by a convolution and backprojection technique. The performance is compared with that of a conventional parallel-hole collimator and it is shown that higher spatial resolution with increased sensitivity is possible with the slit-collimator. For a point source a spatial resolution of some 6 mm at a distance of 100 mm from the collimator with a x7 sensitivity compared with a parallel-hole collimator was achieved. Applications to bone scintigraphy are modelled and an improved performance in hot-spot imaging is demonstrated. The expected performance in cold-spot imaging is analytically investigated. The slit-collimator is not expected to improve cold-spot imaging. Practical design considerations are discussed.
Webb
S
S
Joint Department of Physics, Institute of Cancer Research, Sutton, Surrey, UK.
Binnie
D M
DM
Flower
M A
MA
Ott
R J
RJ
D004867:Equipment Design; D015902:Gamma Cameras; D006801:Humans; D008961:Models, Structural; D009010:Monte Carlo Method; D011877:Radionuclide Imaging / Q000295:instrumentation*