Use of slices in CT scans When carrying out a CAT scan, why are pictures of slices of the respective part taken? Why can't one take the frontal area of the part of the body, and rotate the ring of detectors and X ray source?
My intuition says that it is due to increased exposure of X rays. Would that suffice, or is there more going on?
 A: The output is a series of slices because this is the clearest way to view the three dimensional tissue in sufficient detail. 
Think about a loaf of bread, if there was something inside and you didn't take appropriately thin slices then you might miss something when compared to a non-sliced imaging. 
In addition this method allows rapid reconstruction of the area when viewing on the screen. Can you think of a better way to view a three dimensional object in a more proficient way? 
A: Maybe there are some missunderstanding in question and/or answers about what "slice" means for each people.


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*At each view angle, what is theoretically taken is a 2D image, like a classical photo. 
Of course a given pixel shows the superimposition of opacities all along a column.

*Then the angle of view (+source) is turned, and numerous 2D images are progressively taken at regular view angles. Paralax of occluders chanding with depth, this allows to reconstruct every 3D voxel using some tomographic algorithm.

*In addition, the human body is long, while the captor is narrow (individual images are small), because the hardware is very constrained by the high currents and ultra-low temperatures required - and people wouldn't like that much the confinment BTW. So the source+captor keep turning as the bed translate so that the helice view finaly see all parts of the body under all angles.


A remarks that the amout of X-rays received by the body is pretty low, anyway.
