Which field utilizes radioactive materials for medical imaging?

Nuclear medicine is the field that specifically utilizes radioactive materials for medical imaging. This specialty involves the use of small amounts of radioactive substances to diagnose and treat diseases. The imaging techniques in nuclear medicine, such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT), allow for the visualization of the function and metabolism of organs and tissues in the body.

In contrast, while radiology does involve imaging techniques, it primarily focuses on X-rays, ultrasound, and magnetic resonance imaging (MRI), which do not use radioactive materials in the same way. Oncology, being the field concerned with cancer treatment and research, may utilize radiological techniques in treatment but doesn't directly involve radioactive imaging as its primary method. Cardiology focuses on the study of the heart and its function, typically employing ultrasound or electrocardiograms rather than radioactive materials.