| 摘要 |
<p>The detector for use in Compton tomography at 90 degrees may be used with either x-rays or gamma-rays. A source (1) provides a thin pencil beam (2) of parallel rays which sweeps the cross-section of the body to be examined, and is synchronised with the detector. The detector comprises a set of detecting elements, each of which is a flat plate resolving position in one dimension. The plates are made of transparent scintillating material of thickness (e=1mm) determining the spatial resolution of the system. The flat plates stacked together form an arc of radius r approximately 400 mm. This is centred on the incident ray (2) and has a radial thickness of between 3 and 6 mm, allowing full absorption of the radiation. Inside the curve of the detector is a collimator (11) allowing only mono-directional detection centred on the incident ray. The wide angle of the detector allows the use of a low radiation dose.</p> |
