Press this button to normalise the CBV values of the entire volume to the value of a voxel which is 100% blood. In order to calculate this value, a maximum intensity projection (MIP) image of the entire volume is created. The square-root image of this undergoes tangential smoothing to remove potential fit-failures (please see Tina Memo 2002-001 for more details) and this image is displayed on the Imcalc Tool Tv. The square-root of the value of the 100% voxel is displayed in the Tina Tool text window. This value should be somewhere in the region of 1000-2000. If it is very much greater than that, check through the CBV volume and delete any high-valued pixels which are fit failures.