radiology
The medical specialty dealing with imaging techniques such as X-rays, CT, MRI, and radiation therapy.
He is a specialist in radiology.
Advances in radiology have made early detection possible.
放射線 refers to radiation itself, while 放射線学 is the academic study or medical field of radiology.
放射線科 is the radiology department in a hospital, whereas 放射線学 is the broader academic discipline.
Compound of 放射線 (radiation) + 学 (study, -ology). The term is a direct calque from Western medical terminology.