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(b) The radiographer recovers insufficient detail in the X-ray image produced with an accelerating voltage of 70 kV to make a diagnosis, so they increase the accelerating voltage to 200 kV. To their surprise, this leads to an X-ray image with less contrast. (i) X-ray contrast relies on differential absorption. Given the mass attenuateon coefficients provided in panel (C), briefly explain why there would be high contrast in a 70 kV X-ray image of the skull and not the 200 kV X-ray image. (ii) Differential absorption depends on the average X-ray photon energy of the accelerating voltage employed. Explain why the mass attenuateon coefficients for bone and muscle provided in panel (C) change with the average X-ray photon energy (E) of the accelerating voltage (AVV).