Diagnostic imaging refers to a variety of non-invasive methods used by medical professionals to visualize and diagnose internal body structures or organs. These techniques allow doctors to observe and analyze conditions such as tumors, fractures, infections, or other abnormalities without the need for surgery. Common diagnostic imaging methods include X-rays, CT scans, MRI scans, ultrasounds, and PET scans. These techniques use different technologies to create images of the body's internal structures, which can then be analyzed by doctors to diagnose conditions or plan treatments.