(a)[3]
State and explain how the hardness of the X-ray beam is controlled in an X-ray tube.
(b(i))[1]
A parallel X-rays beam of intensity $I_0$ is incident on a medium with linear absorption (attenuation) coefficient $\mu$. State an equation describing how the intensity $I$ depends on the medium thickness $x$.
(b(ii))[2]
Values of the linear absorption (attenuation) coefficient $\mu$ for an X-ray beam in blood and muscle are given in Fig. 11.1. Suggest why the image contrast would be poor if this X-ray beam were used to image blood vessels in muscle.