FFD is the distance between the generator and the plate detector. On most modern generators you should have a tape measure or a laser which allows you to judge the distance and ensure it is correct. Depending on the set up you have the distance can vary - for example BCF High Frequency generators with a Cuattro plate are set at 66cm as standard.
If you find yourself varying your FFD without altering your exposure settings you will find your image quality will very accordingly.
Make sure you use your BCF exposure chart in the instance. Using the shortest time is great for hand held high frequency generators as movement is a factor which will affect your images. Typically if you want to see more contrast use a slightly lower kV and a higher mAs- remember that if you change one you must change the other. For example- reduce the kV by 10 means you must double the mAs – this is the inverse square law.
For more tricky shots through deeper tissue do not be tempted with a hand held generator to increase your mAs too much- a CC stifle of a TB will be fine at 90kv 5 mAs for example.
This is key for you to take a diagnostic image. With DR it is still advised to collimate down to the area of interest. Ensure the cross from the collimator light sits directly over the joint or area of interest. If you cannot see this cross then make sure the laser beams are around 1 inch below the area of interest (they are set slightly below the cross). Ensure the horse is on a flat surface and that the generator and plate are perpendicular and at the correct distance. You may need to take into account the angles of the joint as we know sometimes the joint is not exactly perpendicular to the floor!
For neck and stifle shots try not to leave the collimator fully open as this sill increase scatter, but instead work with your colleague to get the best possible positioning (unless you are a crack shot) to give you the best chance of capturing the area of interest. And consider the use of a grid, as this will reduce scatter and improve your image quality.
Make sure you pick the right body part and there for the right algorithm. The benefit of this is 2 fold. From a labelling perspective- you cannot change the body part once the shot has been fired with DR technology- this is for safety reasons!
Also the algorithms linked to the view enables you to achieve the best possible image for that body part. See below the difference an incorrect algorithm can make to this skyline shot.