radiology
Meaning of radiology: The name says radiation, yet several of the field's most used methods, ultrasound and magnetic resonance among them, involve none at all.
Definition of radiology
Radiology is the branch of medicine that uses imaging to look inside the body, both to identify disease and to guide treatment through the images. Its methods rest on different physical principles: x-rays and computed tomography use ionizing radiation, ultrasound uses sound, magnetic resonance uses magnetic fields and radio waves, and nuclear medicine follows injected radioactive tracers.
How radiology is built
- radi/o Combining form · Latin x-ray, radiation
- -logy Suffix · Greek study of, body of knowledge
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
Which method answers which question?
| Method | Best suited to | Ionizing radiation |
|---|---|---|
| Plain radiography | Bones, the chest, swallowed or embedded objects, a quick first look | Yes |
| Computed tomography | Fast detail through the whole body; injury, bleeding, lung tissue | Yes |
| Ultrasound | Fluid and soft tissue, blood flow, pregnancy, use at the bedside | No |
| Magnetic resonance | Brain, spinal cord, joints, and anywhere soft tissue contrast matters | No |
| Nuclear medicine and PET | How tissue behaves rather than how it looks | Yes |
No single method wins outright. Computed tomography shows bone detail and fresh bleeding better than magnetic resonance does, magnetic resonance separates soft tissues far better, and the imaging choice therefore follows the question being asked and how quickly it has to be answered.
How do diagnostic and interventional radiology differ?
Diagnostic radiology produces and interprets the images. Interventional radiology uses them live to carry out treatment through a small opening, threading a catheter along a blood vessel or passing a needle through the skin to reach a target. Work that once demanded open surgery is now done this way as a matter of routine: opening blocked arteries, stopping internal bleeding, draining collections of fluid, placing feeding tubes, and destroying small tumors with heat or cold. The two branches share a foundation and then separate.
What limits it?
Ionizing radiation carries a small increase in long term cancer risk that grows with cumulative exposure, which is why a study using it is weighed against the information it will return, and why the amount used is kept as low as will still answer the question. Children are more sensitive to it than adults. Contrast agents that make vessels and tissues stand out can provoke reactions and can affect kidney function in some people. Magnetic resonance uses no radiation at all, but its magnet is never switched off, so implanted metal devices have to be checked for compatibility before anyone enters the room. Imaging also finds abnormalities that would never have caused harm, and separating those from findings that matter is one of the field's standing difficulties.
Used in a sentence
The patient was referred to radiology for an MRI to further evaluate the finding.
Good to know
Diagnostic radiology interprets images to identify disease while interventional radiology uses live imaging to guide treatment inside the body, and several methods grouped under radiology, including ultrasound and magnetic resonance, use no ionizing radiation at all.
Word origin
Where “radiology” comes from
Formed from Latin radius, meaning ray, and Greek logos, meaning study.