| 摘要 |
<p>: The known computer tomography apparatus always produce a complete image of the absorption distribution in the whole slice of the body examined. However, the radiologist is often interested only in a part of the slice (diagnostic region). For second and third generation apparatus the invention enables examination in mainly only the diagnostic region, while reducing the radiation load in the part of the slice situated outside the diagnostic region. For this purpose an attenuating body is provided which allows unattenuated passage of a radiation beam for the diagnostic region and which attenuate the other radiation by a factor of 10 to 1000. This attenuating body is preferably slidable, possibly in dependence of the position and the extent of the diagnostic region and also of the angular position of the radiator/detector system, on an arc of a circle about the radiator, so that a diagnostic region which is situated outside the centre of rotation can also be covered.</p> |
