________ is a subspecialty within the field of radiology that uses radioactive substances to produce images of body anatomy and function.

Radiology

A medical specialty that uses imaging techniques such as X-rays, CT scans, and MRI to diagnose and sometimes treat diseases.

Roentgen Diagnosis

The use of X-rays to diagnose diseases or abnormalities within the body, named after Wilhelm Roentgen who discovered X-rays.

Roentgen Therapy

A form of radiation therapy using X-rays for treating diseases, named after physicist Wilhelm Röntgen.