Physics 9702 · AS & A Level · Production and use of X-rays
Production and use of X-rays — practice question
A basic representation of one part of a CT scan is shown in Fig. 10.1. The model contains four voxels, labelled by pixel numbers A, B, C and D. In this model, the voxels are examined one after another from four separate directions $D_1$, $D_2$, $D_3$ and $D_4$, as indicated in Fig. 10.2. The pixel readings in each of the four directions are recorded. The sum of the pixel readings for any single direction is $19$. The readings from every direction are added together to produce the pattern shown in Fig. 10.3.
(a)[1]
State the background reading for this model.
(b)[4]
Determine the values of the pixel readings for $A$, $B$, $C$ and $D$.
(c(i))[1]
Use your answers in (b) to determine the pixel readings for direction $D_3$.
(c(ii))[2]
Use your answers in (b) to determine the pixel readings for direction $D_4$.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “The background reading is $19$.” …