Outline briefly the principles of computed tomography (CT scanning).

1. (a)Outline briefly the principles of computed tomography (CT scanning).[5]
2. (b)One section of a model designed to illustrate CT scanning is divided into four voxels. The pixel numbers K, L, M and N of the voxels are shown in Fig. 10.1. [Figure 10.1]. The section is viewed, in turn, from four different directions D1, D2, D3 and D4, as shown in Fig. 10.1. The detector readings for each direction are noted and these are summed to give the values shown in Fig. 10.2. [Figure 10.2]. The background reading is 24. Determine the pixel numbers K, L, M and N shown in Fig. 10.1.[3]

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