Diagnostic radiology involves one or more medical imaging technologies to diagnose and sometimes treat disease. A diagnostic radiologist is a physician who works with X-rays, ultrasound, MRI (Magnetic Resonance Imaging), CT scans (Computed Tomography), and other imaging technology to diagnose and sometimes treat diseases or disorders, such as breast cancer, tumors, lung disorders or heart disease.

Doctor density varies by specialty and location. Washington, D.C. has 176 practicing diagnostic radiologists. Broken out by city, diagnostic radiology doctor density in Washingon is 1 and in Washington is 176.

According to 2005 Census estimates, Washington, D.C. has a population of 550,521. Of this population, 110,240 are under the age of 18 and 66,591 are at or above the age of 65.