I assume that everyone has had at some point the experience where less was more. Especially when dealing with computer based image postproduction. Software makes handy wonderful, or better: powerful, filters. Experienced artists know that only a pinch of something or homeopathy is a key to better results.
The same holds true in X-ray production. A maximum of energy does not provide better images. Let’s look closer at this point.
What is the influence of energy to X-ray images ?
Higher energies in X-rays mean shorter wavelengths and a higher resolution. Therefore it might seem reasonable to increase the energy in our X-ray tubes always to the maximum to produce incredible images based on a maximum resolution.
With four images below I show the influence of increased energy levels on X-ray images of a single rose. The applied energy levels are 40kV, 60kV, 90kV and 109kV. The steps of postproduction were the same in every image. Slight differences are owed to best contrast in each exposure.
Surprisingly to the novice we get an increasing loss of contrast (or less available contrast) in each image with higher energies. This effect of loosing contrast can easily be seen in this series of four X-rays and is highest at 109kV.