A pelvis and hip X-ray in a child involves exposure to radiation, which can increase the risk of cancer. However, the amount of radiation used in a pelvis and hip X-ray is generally considered to be safe. The risks and benefits of the test should be discussed with a doctor before the examination is performed. It is also important to note that an X-ray is not always able to detect all abnormalities or conditions affecting the bones or joints, and additional testing may be required if there is still concern.