Nepedia
Back to Discover
Advanced Reader
🧬

Radiology

life science Maturity 9-11 Next article →

Radiology is a medical specialty that uses various imaging technologies to look inside the bodies of humans and animals.

Radiologist in San Diego CA 2010
Radiologist in San Diego CA 2010

These tools allow doctors to diagnose diseases and guide medical treatments. The field began with radiography, which is the use of radiation to create images. Today, radiology includes many different methods, or modalities. Some methods use ionizing electromagnetic radiation, while others do not. This diversity allows medical teams to choose the best tool for a specific health concern.

A modern radiology department relies on a specialized team of healthcare professionals. A radiologist is a medical doctor with advanced post-graduate training. They interpret the medical images and communicate their findings to other physicians through reports. Radiographers, also called radiologic technologists, perform the actual radiographic procedures. They may also provide radiation therapy to treat diseases like cancer. Nurses are also essential to the process. They care for patients before and after imaging by administering medications and monitoring vital signs.

One of the most fundamental methods is projection radiography, often called plain radiography. This process begins when an X-ray tube generates a beam of X-rays. The beam is aimed at the patient and transmitted through their body. As the rays pass through, some are absorbed or scattered by the body's tissues. The rays that pass through strike a detector to form an image. In older film-screen radiography, these rays hit a light-emitting phosphor screen and undeveloped film. Modern systems use digital radiography (DR) or the EOS system. In these digital versions, sensors convert X-ray signals into digital information for a computer screen.

X-ray of hand, where bone age is automatically found by BoneXpert software
X-ray of hand, where bone age is automatically found by BoneXpert software

Radiology also includes fluoroscopy, which allows for real-time imaging of moving structures. This is often done using radiocontrast agents to make certain anatomy easier to see. These agents are substances that strongly absorb or scatter X-rays. Patients might swallow or be injected with agents like barium sulfate or iodine. Barium sulfate is used to evaluate the gastrointestinal tract. Iodine can be used in many ways to show blood flow in arteries and veins. Doctors can even use air or carbon dioxide as contrast agents in specific situations. This helps make abnormalities like tumors or inflammation more conspicuous during the scan.

Computed tomography, or CT, revolutionized the field in the early 1970s. In a CT scan, an X-ray tube and detectors rotate in a ring around the patient. This setup produces computer-generated cross-sectional images called tomograms. While plain X-rays have higher spatial resolution, CT scans have higher contrast resolution. This means they can detect more subtle variations in how X-rays are absorbed. Modern spiral multidetector CT scans use many detectors to capture fine details very quickly.

Brain CT scan
Brain CT scan

This technology is vital for diagnosing urgent conditions like cerebral hemorrhage, appendicitis, or pulmonary embolisms.

Another major modality is ultrasonography, which uses high-frequency sound waves. Unlike X-rays, ultrasound does not use any ionizing radiation, making it very safe. This makes it a common choice for obstetrical imaging to monitor fetal growth and detect anomalies. Ultrasound is also used to visualize soft tissue in real time. It can be used to find blood clots in veins or to guide biopsies. However, ultrasound has limitations. The quality can decrease in larger patients because fat absorbs more sound waves. It also cannot image through bone or air pockets like the lungs.

Magnetic resonance imaging (MRI) provides the best soft tissue contrast of all imaging types.

MRI knee abdonrmal
MRI knee abdonrmal

This method uses strong magnetic fields to align atomic nuclei, specifically hydrogen protons, within the body. A radio signal is then used to disturb the rotation of these nuclei. As the nuclei return to their baseline state, they generate a radio frequency signal. Small antennae called coils collect these signals to create detailed images. MRI can produce images in many different planes, such as axial, coronal, or sagittal. While highly effective, some patients find the noisy, cramped space of an MRI machine difficult due to claustrophobia.

657 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (4)
File:Brain CT scan.jpg
Brain CT scan.jpg
File:MRI knee abdonrmal.jpg
MRI knee abdonrmal.jpg
File:Radiologist in San Diego CA 2010.jpg
Radiologist in San Diego CA 2010.jpg
File:X-ray of hand, where bone age is automatically found by BoneXpert software.jpg
X-ray of hand, where bone age is...
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.