Fig. 1.

Illustration of the reduced FOV and the lack of MRI coverage for a H&N patient. The original CT outline is represented in red and the missing imaged tissue in pink. Area outside the MRI FOV and inside the red contour was filled-in with a water equivalent density for both the CT and sCTs. Area in pink was assumed to have an air equivalent density for all sCTs. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)