Back in the 1950s, when it wasn't known that X-rays could be harmful (and the machines emitted much more radiation than they do today), it wasn't unusual for XLHers to have full-body, head-to-toe sets of X-rays done at regular intervals.
Fortunately, today they're done more cautiously, using less radiation, so the benefits generally outweigh the risks. Still, there is some risk from X-ray exposure, which may be of particular concern for children. A recent journal article reminded doctors of this fact. You can read the abstract of "Children, medical radiation and the environment: an important dialogue" from the April 2017 issue of Environmental Research here: https://www.ncbi.nlm.nih.gov/pubmed/28391175
Researchers are looking into the possibility of using Magnetic Resonance Imaging, which do not use radiation, instead of X-rays. Doctors already knew what rickets looked like in an X-ray, but not what it looks like in an MRI.
According to a recent journal article, researchers appear to have figured out a way to identify rickets in an MRI. In an article published in April in Hormone Research in Pediatrics, researchers concluded, "MRI of the knee provides precise rickets patterns that are correlated with ALP, an established biochemical marker of the disease, avoiding X-ray exposure and providing surrogate quantitative markers of disease activity." You can read the abstract here: https://www.ncbi.nlm.nih.gov/pubmed/28376474