For Radiology :

Radiology uses techniques such as X-ray imaging to detect and diagnose diseases and injuries, manage patient care, and guide many forms of medical treatment. Because X-rays involve ionizing radiation that can deposit energy in human cells and cause tissue changes, it is important to minimize any associated risk to the patient. This is done by limiting the radiation exposure to the minimum required to create the clinical images needed to answer the medical question.

For Dental:

X ray imaging is used extensively in dentistry to diagnose symptoms, plan and monitor treatments and to follow up pathoses.