Treatment of disease using x-rays,radium,and other radioactive substances is:

A) ultrasonography.
B) cinematoradiography.
C) tomography.
D) radiotherapy.

Radiotherapy

A treatment using ionizing radiation, primarily used to control or kill malignant cells in cancer treatment.

Ultrasonography

A diagnostic imaging technique using ultrasound waves to visualize internal structures of the body, including organs and blood flow.

Tomography

A technique for displaying a representation of a cross section through a human body or other solid object using X-rays or ultrasound.