Radiology

Medical specialty using imaging to diagnose and treat disease

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Radiology

A typical radiology room

System	Various
Focus
Subdivisions
Significant diseases	Cancer, stroke, fracture, infection, cardiovascular disease, lung disease, abdominal disease, neurologic disease
Significant tests	X-ray radiography, ultrasound, computed tomography, magnetic resonance imaging, nuclear medicine, positron emission tomography, fluoroscopy, mammography
Specialist	Radiologist
Glossary	Glossary of radiology

Radiology is the branch of medicine that uses medical imaging to diagnose disease, guide treatment, monitor response to therapy, screen for selected conditions, and perform minimally invasive image-guided procedures. A physician who specializes in radiology is called a radiologist. Radiology includes diagnostic radiology, interventional radiology, neuroradiology, pediatric radiology, breast imaging, musculoskeletal radiology, thoracic radiology, abdominal imaging, emergency radiology, nuclear medicine, and related imaging sciences.ACR Appropriateness Criteria(link). American College of Radiology.

Radiology has become central to modern healthcare because it allows clinicians to visualize internal anatomy and physiology without exploratory surgery. Imaging is used in emergency diagnosis, cancer staging, trauma care, prenatal care, cardiovascular disease, neurologic disease, screening programs, surgical planning, image-guided biopsy, and minimally invasive treatment. Modern radiology also includes teleradiology, picture archiving and communication systems, radiology information systems, structured reporting, artificial intelligence in healthcare, radiomics, and clinical decision support.

Overview

Radiology combines clinical medicine, imaging technology, anatomy, pathology, physiology, radiation physics, image interpretation, procedure guidance, informatics, and patient safety. The field is practiced in hospitals, outpatient imaging centers, emergency departments, cancer centers, operating rooms, intensive care units, mobile imaging units, and telemedicine networks.

Radiologists interpret imaging studies, communicate results to referring clinicians, recommend additional imaging when needed, perform image-guided procedures, oversee imaging protocols, participate in multidisciplinary teams, and help ensure safe and appropriate imaging. Many radiologists also supervise contrast use, radiation safety, quality assurance, imaging informatics, and artificial intelligence implementation.

Major branches

Diagnostic radiology

Diagnostic radiology focuses on interpreting medical images to diagnose disease.

• X-ray radiography - Uses ionizing radiation to create projection images, commonly used for chest imaging, bone injury, and abdominal evaluation.
• Computed tomography - Uses X-rays and computer reconstruction to create cross-sectional images.
• Magnetic resonance imaging - Uses magnetic fields and radiofrequency pulses to create detailed soft-tissue images.
• Ultrasound - Uses high-frequency sound waves to image organs, vessels, fetuses, and soft tissues.
• Fluoroscopy - Uses real-time X-ray imaging for dynamic studies and procedure guidance.
• Mammography - Specialized low-dose X-ray imaging of the breast.
• Nuclear medicine - Uses radioactive tracers to evaluate organ function and disease.
• Positron emission tomography - Functional imaging commonly used in oncology, neurology, and cardiology.
• Bone densitometry - Uses dual-energy X-ray absorptiometry to assess bone mineral density.

Interventional radiology

Interventional radiology uses imaging guidance to perform minimally invasive diagnostic and therapeutic procedures. These procedures often use small incisions, catheters, needles, guidewires, balloons, stents, embolic materials, thermal ablation probes, or drainage catheters.

• Angioplasty - Balloon dilation of narrowed blood vessels.
• Stent placement - Placement of a tube-like device to keep a vessel or duct open.
• Embolization - Intentional blockage of a blood vessel to treat bleeding, tumors, or vascular malformations.
• Thrombectomy - Removal of blood clot from a vessel.
• Image-guided biopsy - Needle sampling of tissue using CT, ultrasound, fluoroscopy, or MRI guidance.
• Percutaneous drainage - Image-guided drainage of abscesses or fluid collections.
• Tumor ablation - Destruction of tumors using heat, cold, microwave, radiofrequency, or other techniques.
• Vertebroplasty - Injection of cement into a fractured vertebra in selected cases.
• Transjugular intrahepatic portosystemic shunt - Procedure to reduce portal hypertension.
• Uterine artery embolization - Treatment for selected uterine fibroids.
• Vascular access - Placement of central venous catheters, ports, and dialysis access devices.

Therapeutic and oncologic imaging

Radiology overlaps with several treatment-oriented fields.

• Radiation oncology - Medical specialty using ionizing radiation to treat cancer and selected benign conditions.
• Interventional oncology - Image-guided treatment of tumors using ablation, embolization, radioembolization, and related techniques.
• Theranostics - Combined diagnostic and therapeutic use of targeted radioactive agents.
• Image-guided surgery - Use of imaging to plan or guide surgical treatment.
• Treatment response assessment - Imaging evaluation of whether disease is improving, stable, or progressing.

Imaging modalities

X-ray radiography

X-ray radiography uses X-rays to create two-dimensional projection images. It is fast, widely available, and relatively inexpensive.

• Chest radiograph - Common test for pneumonia, heart size, lung disease, tubes, and lines.
• Skeletal radiography - Used for fractures, dislocations, arthritis, and bone lesions.
• Abdominal radiograph - Used in selected cases of obstruction, perforation, constipation, or foreign body.
• Dental radiography - Used in dentistry and oral surgery.
• Portable radiography - Bedside imaging in intensive care, emergency, or inpatient settings.
• Digital radiography - Modern digital X-ray acquisition and processing.
• Radiodensity - The degree to which a material attenuates X-rays.

Fluoroscopy

Fluoroscopy provides real-time X-ray imaging. It is used for diagnostic studies and procedures.

• Barium swallow - Evaluates swallowing, esophagus, and upper gastrointestinal tract.
• Upper gastrointestinal series - Evaluates the esophagus, stomach, and duodenum.
• Barium enema - Evaluates the colon in selected settings.
• Voiding cystourethrography - Evaluates urinary reflux and urethral anatomy.
• Hysterosalpingography - Evaluates the uterus and fallopian tubes.
• Angiography - Imaging of blood vessels using contrast.
• Fluoroscopic guidance - Used for injections, catheter placement, biopsies, and interventions.

Computed tomography

Computed tomography, also called CT scan, uses X-ray measurements and computer reconstruction to create cross-sectional images. CT is especially valuable in trauma, stroke, cancer staging, chest disease, abdominal emergencies, vascular disease, and complex anatomy.

• CT angiography - CT imaging of arteries and veins after contrast injection.
• CT pulmonary angiography - Evaluates suspected pulmonary embolism.
• CT colonography - Imaging of the colon for polyps or cancer screening in selected patients.
• CT enterography - Evaluates small bowel disease such as Crohn disease.
• Cardiac CT - Evaluates coronary arteries, calcium score, and selected structural heart disease.
• Low-dose CT - Uses dose-reduction protocols, such as lung cancer screening CT.
• Dual-energy CT - Uses two energy spectra to improve tissue characterization.
• Hounsfield unit - Quantitative CT scale of tissue radiodensity.
• Tomographic reconstruction - Computer generation of image slices from projection data.

Magnetic resonance imaging

Magnetic resonance imaging uses strong magnetic fields and radiofrequency energy to produce detailed images, especially of soft tissues. MRI does not use ionizing radiation.

• Brain MRI - Evaluates stroke, tumor, demyelination, infection, epilepsy, and neurodegenerative disease.
• Spine MRI - Evaluates disc disease, spinal cord disease, infection, tumor, and trauma.
• Musculoskeletal MRI - Evaluates joints, ligaments, cartilage, tendons, marrow, and soft-tissue tumors.
• Abdominal MRI - Evaluates liver, pancreas, biliary tree, kidneys, and pelvis.
• Breast MRI - Used in high-risk screening, staging, and problem-solving.
• Cardiac MRI - Evaluates cardiac function, cardiomyopathy, myocarditis, viability, and congenital heart disease.
• Magnetic resonance angiography - MRI-based evaluation of blood vessels.
• Diffusion-weighted imaging - MRI technique sensitive to water motion, useful in stroke and tumor imaging.
• Functional MRI - Measures brain activity by detecting blood oxygenation changes.
• Magnetic resonance cholangiopancreatography - MRI evaluation of bile ducts and pancreatic ducts.

Ultrasound

Ultrasound uses sound waves to create images. It is portable, does not use ionizing radiation, and can provide real-time imaging.

• Abdominal ultrasound - Evaluates liver, gallbladder, bile ducts, kidneys, spleen, and aorta.
• Obstetric ultrasound - Evaluates pregnancy, fetal anatomy, growth, and placental position.
• Pelvic ultrasound - Evaluates uterus, ovaries, adnexa, and pelvic pathology.
• Vascular ultrasound - Evaluates blood flow, stenosis, thrombosis, and vascular access.
• Echocardiography - Ultrasound imaging of the heart.
• Point-of-care ultrasound - Bedside ultrasound performed by clinicians in emergency, critical care, anesthesia, and other settings.
• Doppler ultrasound - Measures movement and direction of blood flow.
• Elastography - Ultrasound or MRI method estimating tissue stiffness.
• Contrast-enhanced ultrasound - Uses microbubble contrast agents to evaluate perfusion or lesions.

Nuclear medicine and molecular imaging

Nuclear medicine uses radioactive tracers to image physiology, metabolism, receptor expression, and organ function.

• Bone scintigraphy - Detects bone turnover from metastases, fracture, infection, or other disease.
• Hepatobiliary iminodiacetic acid scan - Evaluates gallbladder and biliary function.
• Ventilation-perfusion scan - Evaluates suspected pulmonary embolism.
• Myocardial perfusion imaging - Evaluates blood flow to heart muscle.
• Renal scan - Evaluates kidney function, obstruction, or scarring.
• Thyroid scan - Evaluates thyroid nodules and function.
• Single-photon emission computed tomography - Cross-sectional nuclear medicine imaging.
• Positron emission tomography - Molecular imaging using positron-emitting tracers.
• FDG PET - PET imaging with fluorodeoxyglucose, commonly used in oncology.
• PET/CT - Combined metabolic and anatomic imaging.
• PET/MRI - Combined PET and MRI imaging.

Mammography and breast imaging

Breast imaging uses mammography, ultrasound, MRI, and image-guided biopsy.

• Mammography - X-ray imaging of the breast used for screening and diagnosis.
• Digital breast tomosynthesis - Three-dimensional mammographic technique.
• Breast ultrasound - Evaluates masses, cysts, dense breasts, and biopsy guidance.
• Breast MRI - Used for high-risk screening and selected diagnostic indications.
• Stereotactic biopsy - Mammography-guided breast biopsy.
• BI-RADS - Breast Imaging Reporting and Data System for standardized reporting.

Subspecialties

Radiology is divided into several subspecialties.

• Neuroradiology - Imaging of the brain, spine, head, neck, and nervous system.
• Pediatric radiology - Imaging of infants, children, and adolescents.
• Musculoskeletal radiology - Imaging of bones, joints, muscles, tendons, ligaments, and soft tissues.
• Abdominal radiology - Imaging of the gastrointestinal, hepatobiliary, pancreatic, genitourinary, and abdominal systems.
• Thoracic radiology - Imaging of lungs, mediastinum, chest wall, and airways.
• Cardiovascular radiology - Imaging of the heart and blood vessels.
• Breast imaging - Imaging and image-guided procedures of the breast.
• Emergency radiology - Imaging of acute illness and trauma.
• Interventional radiology - Image-guided minimally invasive diagnosis and treatment.
• Nuclear medicine - Imaging and therapy using radiopharmaceuticals.
• Head and neck radiology - Imaging of the skull base, face, neck, sinuses, orbit, and aerodigestive tract.
• Genitourinary radiology - Imaging of kidneys, urinary tract, prostate, uterus, ovaries, and reproductive organs.
• Oncologic imaging - Imaging for cancer detection, staging, treatment planning, and response assessment.
• Forensic radiology - Imaging for legal investigation, identification, trauma analysis, and postmortem evaluation.
• Global radiology - Efforts to improve imaging access, safety, and training worldwide.

Radiologists and imaging professionals

Radiology is a team-based specialty.

• Radiologist - Physician trained to interpret imaging studies and perform image-guided procedures.
• Interventional radiologist - Radiologist trained in minimally invasive image-guided procedures.
• Nuclear medicine physician - Physician specializing in radiopharmaceutical imaging and therapy.
• Radiographer - Imaging professional who performs radiographic examinations.
• Radiologic technologist - Trained professional who operates imaging equipment and assists with imaging procedures.
• Sonographer - Professional trained to perform ultrasound examinations.
• MRI technologist - Technologist trained in MRI safety and image acquisition.
• CT technologist - Technologist trained in CT protocols and acquisition.
• Medical physicist - Specialist in radiation physics, imaging quality, dose optimization, and safety.
• Radiology nurse - Nurse involved in contrast administration, sedation, procedures, recovery, and patient monitoring.
• Radiology assistant - Advanced practice radiologic professional in some countries.
• PACS administrator - Specialist managing image storage, workflow, and imaging informatics.
• Medical dosimetrist - Radiation therapy professional involved in treatment planning.

Clinical workflow

Radiology workflow includes ordering, protocoling, acquisition, interpretation, communication, and follow-up.

• Imaging order - Request from a clinician for a specific imaging test.
• Clinical indication - Reason for imaging, used to choose the correct study.
• Appropriateness criteria - Evidence-based guidance used to choose imaging tests.
• Protocol - Technical plan for how an imaging study should be performed.
• Patient preparation - Instructions such as fasting, hydration, contrast precautions, or metal screening.
• Image acquisition - Performance of the imaging study by the technologist or sonographer.
• Image reconstruction - Computer processing of raw imaging data.
• Image interpretation - Radiologist analysis of imaging findings.
• Radiology report - Formal written interpretation sent to the referring clinician.
• Critical result - Urgent finding requiring timely communication.
• Structured reporting - Standardized report format to improve clarity and completeness.
• Follow-up recommendation - Imaging or clinical follow-up suggested by the radiologist.
• Peer review - Quality assurance process in image interpretation.

Appropriate imaging

Choosing the correct imaging test is essential. Unnecessary imaging can expose patients to radiation, contrast risk, incidental findings, anxiety, and cost. Underuse of imaging can delay diagnosis. The American College of Radiology publishes ACR Appropriateness Criteria, evidence-based guidelines that help clinicians select appropriate imaging or image-guided treatment for specific clinical scenarios.ACR Appropriateness Criteria(link). American College of Radiology.

• Clinical decision support - Electronic guidance to help order appropriate imaging.
• Choosing Wisely - Campaign to reduce unnecessary tests and procedures.
• Pretest probability - Estimated likelihood of disease before testing.
• Diagnostic yield - Probability that a test will provide useful diagnostic information.
• Risk-benefit analysis - Weighing diagnostic value against risks, cost, and alternatives.
• Incidental finding - Unexpected abnormality unrelated to the original reason for imaging.
• Overdiagnosis - Detection of disease that would not have caused harm.
• Underdiagnosis - Failure to detect clinically important disease.
• Repeat imaging - Imaging repeated because of interval change, poor quality, or clinical need.

Radiation safety

Some radiology tests use ionizing radiation, including radiography, fluoroscopy, CT, mammography, angiography, and nuclear medicine. Radiation protection aims to use the right test at the right time with the lowest dose that provides diagnostic quality. The World Health Organization emphasizes that ionizing radiation has medical benefits but can also cause harmful effects at sufficient doses, making justification and optimization important.Ionizing radiation and health effects(link). World Health Organization.

• Ionizing radiation - Radiation with enough energy to remove electrons from atoms.
• Radiation dose - Amount of radiation absorbed or effective biologic exposure.
• Effective dose - Dose measure reflecting risk across organs and tissues.
• Absorbed dose - Energy deposited per unit mass, measured in gray.
• Sievert - Unit used for effective dose and equivalent dose.
• ALARA - Principle of keeping radiation exposure as low as reasonably achievable.
• Justification - Imaging should have a valid medical reason.
• Optimization - Imaging should use an appropriate dose for diagnostic quality.
• Dose area product - Radiation dose measure used in radiography and fluoroscopy.
• CT dose index - CT radiation dose index used for dose monitoring.
• Diagnostic reference level - Benchmark used to compare and optimize imaging doses.
• Lead shielding - Protective shielding used in selected occupational and procedural settings.
• Pregnancy - Imaging choice should consider fetal radiation exposure, urgency, and alternatives.
• Pediatric imaging - Children require dose optimization because of greater radiosensitivity and longer life expectancy.

Contrast agents

Contrast agents improve visualization of blood vessels, organs, tumors, inflammation, and other pathology.

• Iodinated contrast - Used in CT, angiography, and fluoroscopy.
• Gadolinium-based contrast agent - Used in MRI.
• Ultrasound contrast agent - Microbubble contrast used in selected ultrasound studies.
• Barium sulfate - Oral or rectal contrast used for gastrointestinal imaging.
• Radiotracer - Radioactive agent used in nuclear medicine.
• Contrast allergy - Prior reactions should be assessed before contrast use.
• Contrast-induced nephropathy - Older term for kidney injury associated with iodinated contrast exposure; risk assessment is important in selected patients.
• Nephrogenic systemic fibrosis - Rare condition linked to some gadolinium agents in severe kidney disease.
• Extravasation - Leakage of contrast outside a vein.
• Premedication - Sometimes used for patients with prior contrast reactions.
• Hydration - May be used to reduce risk in selected patients.

Reporting systems

Structured reporting systems help standardize radiology interpretation and communication.

• BI-RADS - Breast Imaging Reporting and Data System.
• LI-RADS - Liver Imaging Reporting and Data System.
• PI-RADS - Prostate Imaging Reporting and Data System.
• Lung-RADS - Lung CT screening reporting system.
• TI-RADS - Thyroid Imaging Reporting and Data System.
• O-RADS - Ovarian-Adnexal Reporting and Data System.
• C-RADS - CT Colonography Reporting and Data System.
• CAD-RADS - Coronary Artery Disease Reporting and Data System.
• NI-RADS - Neck Imaging Reporting and Data System.
• RADS - General term for standardized reporting and data systems.

Radiology informatics

Radiology is highly dependent on digital information systems.

• Picture archiving and communication system - System for storing, retrieving, and displaying medical images.
• Radiology information system - System for scheduling, tracking, reporting, and workflow management.
• Electronic health record - Digital patient record integrated with imaging reports and orders.
• Digital Imaging and Communications in Medicine - Standard for medical image data and communication.
• Health Level Seven International - Standards organization for healthcare data exchange.
• Teleradiology - Transmission of images for remote interpretation.
• Voice recognition - Dictation software used for radiology reporting.
• Natural language processing - Computational analysis of radiology reports and text.
• Enterprise imaging - Institution-wide management of images from radiology and other specialties.
• Vendor-neutral archive - System for storing imaging data across platforms.
• Clinical decision support - Software that guides imaging selection and follow-up.

Artificial intelligence in radiology

Artificial intelligence is increasingly used in radiology for image triage, detection, segmentation, reconstruction, measurement, workflow management, quality control, and report generation. AI is not a replacement for radiologists; responsible use requires validation, monitoring, clinical oversight, explainability, privacy protection, and bias assessment. The American College of Radiology has emphasized that AI should support radiologists and that human involvement remains important for safe and effective clinical use.The Role of Radiology in AI Highlighted at ACR 2025(link). American College of Radiology.Role of AI in Medical Imaging(link). Radiological Society of North America.

• Computer-aided detection - Software that marks possible abnormalities.
• Computer-aided diagnosis - Software that assists diagnostic interpretation.
• Image segmentation - Automated outlining of organs, tumors, or structures.
• Image reconstruction - AI-enhanced reconstruction may reduce noise or scan time.
• Triage algorithm - Prioritizes studies with suspected urgent findings.
• Radiomics - Extraction of quantitative features from medical images.
• Deep learning - AI method widely used in image analysis.
• Foundation model - Large model trained on broad datasets with potential imaging applications.
• Model drift - Decline in AI performance over time or across populations.
• Algorithmic bias - Unequal performance across patient groups or imaging systems.
• Explainable artificial intelligence - AI methods that aim to show why a prediction was made.
• AI governance - Policies for safe, ethical, monitored AI deployment.
• Human-in-the-loop - Workflow in which clinicians supervise AI outputs.

Radiomics and precision imaging

Radiology is increasingly linked to precision medicine.

• Radiomics - Quantitative extraction of imaging features for research or clinical prediction.
• Radiogenomics - Study of relationships between imaging features and genetic or molecular characteristics.
• Quantitative imaging - Measurement-based imaging used for diagnosis and monitoring.
• Imaging biomarker - Imaging measurement associated with disease or treatment response.
• Theranostics - Combines targeted diagnostic imaging and targeted therapy.
• Molecular imaging - Imaging of biologic processes at molecular or cellular levels.
• Personalized medicine - Tailoring care based on patient-specific findings.
• Treatment response - Imaging assessment after therapy.
• RECIST - Response Evaluation Criteria in Solid Tumors.
• Functional imaging - Imaging that evaluates physiology, perfusion, metabolism, or diffusion.

Patient experience

Radiology affects patients before, during, and after imaging.

• Informed consent - Required for many procedures and some contrast-enhanced studies.
• Claustrophobia - Anxiety in enclosed scanners, especially MRI.
• Sedation - May be used for children, anxious patients, or painful procedures.
• Patient positioning - Important for image quality and comfort.
• Motion artifact - Movement can degrade image quality.
• Contrast reaction - Allergic-like or physiologic reaction to contrast material.
• Incidental finding - Unexpected result that may require follow-up.
• Communication - Clear explanation of preparation, risks, and results improves patient care.
• Accessibility - Imaging facilities should accommodate disability, language needs, body habitus, and mobility limitations.
• Patient portal - Many patients access reports and images electronically.

Radiology in major diseases

Cancer

Radiology is essential in oncology.

• Cancer screening - Imaging used for breast, lung, colorectal, and other cancer screening in selected populations.
• Cancer staging - Imaging defines tumor extent and spread.
• Image-guided biopsy - Confirms diagnosis with tissue sampling.
• Treatment planning - Imaging guides surgery, radiation therapy, and systemic therapy.
• Response assessment - Imaging monitors treatment effect.
• Surveillance imaging - Follow-up imaging detects recurrence.
• PET/CT - Evaluates many cancers by metabolism and anatomy.
• Tumor ablation - Interventional treatment for selected tumors.

Neurologic disease

• Stroke - CT and MRI help diagnose ischemic and hemorrhagic stroke.
• Cerebral aneurysm - CT angiography, MR angiography, or catheter angiography may evaluate aneurysms.
• Brain tumor - MRI is central to diagnosis and follow-up.
• Multiple sclerosis - MRI detects demyelinating lesions.
• Epilepsy - MRI helps identify structural causes.
• Dementia - Imaging helps evaluate atrophy, vascular disease, and selected causes.
• Traumatic brain injury - CT is often used in acute trauma.
• Spinal cord compression - MRI is often the imaging test of choice.

Cardiovascular disease

• Coronary artery disease - CT coronary angiography and calcium scoring may be used in selected patients.
• Aortic aneurysm - CT, MRI, and ultrasound assess size and complications.
• Pulmonary embolism - CT pulmonary angiography is commonly used.
• Peripheral artery disease - Ultrasound, CT angiography, MR angiography, or catheter angiography may be used.
• Heart failure - Imaging evaluates structure, function, and causes.
• Cardiomyopathy - Cardiac MRI can characterize tissue and function.
• Valvular heart disease - Echocardiography is usually central, with CT or MRI in selected cases.

Trauma and emergency care

• Trauma radiology - Imaging used in injury evaluation.
• Focused assessment with sonography for trauma - Bedside ultrasound in trauma.
• Whole-body CT - Used in selected severe trauma.
• Fracture - Radiographs and CT evaluate bone injury.
• Internal bleeding - CT and angiography identify bleeding.
• Foreign body - X-ray, CT, or ultrasound may detect retained objects.
• Emergency radiology - Rapid imaging interpretation for acute illness.

Education and training

Radiology training varies by country.

• Medical school - Basic medical education before radiology training.
• Residency - Specialty training in diagnostic radiology or related pathways.
• Fellowship - Subspecialty training after residency.
• Board certification - Credentialing process for radiologists in many countries.
• Continuing medical education - Ongoing learning required for practice.
• Simulation training - Used for procedures, emergencies, and image interpretation.
• Radiology physics - Training in radiation, imaging technology, and safety.
• Anatomy - Core knowledge for image interpretation.
• Pathology - Disease understanding needed for diagnosis.
• Quality improvement - Training in safety, communication, and workflow improvement.

Quality and safety

Radiology quality programs aim to improve diagnostic accuracy, patient safety, and communication.

• Accreditation - Formal recognition that imaging facilities meet standards.
• Quality assurance - Ongoing monitoring of equipment, protocols, and performance.
• Peer learning - Review of cases to improve interpretation and systems.
• Diagnostic error - Missed, delayed, or incorrect imaging diagnosis.
• Critical result reporting - Timely communication of urgent findings.
• Radiation dose monitoring - Tracking and optimizing patient radiation exposure.
• Contrast safety - Reducing risk of contrast reactions and kidney injury.
• MRI safety - Prevention of projectile accidents, burns, implant interactions, and acoustic injury.
• Pregnancy screening - Used before selected radiation or contrast studies.
• Infection control - Cleaning equipment and preventing procedure-related infection.
• Patient identification - Ensures the correct patient and correct examination.
• Wrong-site procedure prevention - Safety process for interventional procedures.

Global radiology

Access to radiology is uneven across the world. Many regions have limited access to imaging equipment, trained radiologists, technologists, physicists, service engineers, and maintenance. Global radiology initiatives focus on safe imaging, workforce training, teleradiology, equipment donation, quality standards, and sustainable imaging infrastructure.

• Global health - Radiology contributes to diagnosis and treatment worldwide.
• Resource-limited setting - Settings where equipment, specialists, or infrastructure are limited.
• Portable ultrasound - Important tool for low-resource and bedside imaging.
• Mobile radiography - Portable X-ray systems used in hospitals and field settings.
• Teleradiology - Can provide remote expert interpretation.
• Imaging access - Availability of appropriate imaging when clinically needed.
• Radiation protection - Essential in all settings using ionizing radiation.
• Training program - Education for radiologists, technologists, and physicists.
• Equipment maintenance - Critical for sustainable imaging services.

History

Radiology began with the discovery of X-rays by Wilhelm Conrad Röntgen in 1895. Since then, the field has expanded from plain radiography to CT, MRI, ultrasound, nuclear medicine, interventional radiology, digital imaging, molecular imaging, and AI-assisted workflows.

• Wilhelm Conrad Röntgen - Discovered X-rays in 1895.
• X-ray - First major radiologic imaging technology.
• Fluoroscopy - Early real-time X-ray imaging method.
• Computed tomography - Introduced cross-sectional X-ray imaging.
• Godfrey Hounsfield - Co-inventor of CT technology.
• Allan McLeod Cormack - Co-inventor of CT mathematical reconstruction.
• Magnetic resonance imaging - Major advance in soft-tissue imaging.
• Nuclear medicine - Developed functional imaging using radiotracers.
• Interventional radiology - Grew from angiography and catheter-based treatment.
• Digital radiography - Replaced film in many settings.
• Picture archiving and communication system - Enabled digital image storage and review.
• Teleradiology - Enabled remote interpretation.
• Artificial intelligence - Modern development in image analysis and workflow.

Glossary of radiology

• 4DCT - CT imaging that includes time as an additional dimension, often used for motion assessment in radiation therapy planning.
• Acute radiation syndrome - Illness caused by high-dose radiation exposure.
• Anti-scatter grid - Device used to reduce scattered radiation and improve image contrast.
• Aortopulmonary window - Mediastinal region evaluated on chest imaging.
• Bone age - Assessment of skeletal maturity, usually from hand and wrist radiographs.
• Bone scintigraphy - Nuclear medicine bone imaging using a radiotracer.
• Caldwell view - Skull radiographic projection used to evaluate the frontal sinuses and orbits.
• Collimator - Device that shapes and limits the radiation beam.
• Computational human phantom - Digital model of the body used in radiation and imaging simulations.
• Computed tomography enterography - CT technique used to evaluate the small bowel.
• Computer-aided diagnosis - Use of software to assist image interpretation.
• Contrast-induced nephropathy - Kidney injury historically associated with iodinated contrast exposure.
• Digital X-ray radiogrammetry - Technique for bone density assessment from hand radiographs.
• Dose area product - Measure of radiation dose and exposed area.
• Dual-energy X-ray absorptiometry - Bone mineral density imaging technique.
• EOS imaging - Low-dose biplanar X-ray imaging system used especially in spine and skeletal assessment.
• Effective dose - Radiation dose measure reflecting overall biologic risk.
• Empty delta sign - Imaging sign associated with cerebral venous sinus thrombosis.
• Forensic radiology - Use of imaging in legal and postmortem investigation.
• Hounsfield scale - CT radiodensity scale measured in Hounsfield units.
• Incidental imaging finding - Unexpected imaging finding unrelated to the original indication.
• International Day of Radiology - Annual observance on November 8 marking the discovery of X-rays.
• Magnetic resonance imaging - Imaging using magnetic fields and radiofrequency pulses.
• Mean glandular dose - Breast radiation dose measure used in mammography.
• Neuroimaging - Imaging of the brain, spine, and nervous system.
• Nuclear medicine - Imaging and therapy using radioactive tracers.
• Peak kilovoltage - Maximum voltage applied to an X-ray tube.
• Radiodensity - Degree to which material attenuates X-rays.
• Radiogenomics - Study of links between imaging findings and genomic information.
• Radiographer - Imaging professional trained to perform radiologic examinations.
• Radiology information system - Software system for radiology workflow and reporting.
• Reid base line - Anatomical reference line used in cranial radiology.
• Schuller view - Radiographic projection used for temporal bone or mastoid evaluation.
• Stenvers projection - Radiographic projection of the temporal bone.
• Surgical planning - Use of imaging to guide operative strategy.
• Teleradiology - Remote transmission and interpretation of imaging studies.
• Tomographic reconstruction - Computational creation of image slices from projection data.
• Waters view - Facial radiographic projection used to evaluate sinuses and facial bones.
• X-ray tube - Device that produces X-rays for imaging.

Patient education

Patients undergoing radiology examinations should understand why the test is being performed, what preparation is required, whether contrast will be used, and how results will be communicated.

• Ask why - Patients can ask why a particular imaging test is needed.
• Bring prior imaging - Prior images help radiologists compare old and new findings.
• Report pregnancy - Patients who are or may be pregnant should inform the care team before imaging with ionizing radiation.
• Report kidney disease - Kidney disease may affect contrast decisions.
• Report allergy - Prior contrast reactions should be discussed before contrast administration.
• Remove metal - MRI requires careful screening for metal, implants, and devices.
• Follow preparation instructions - Fasting, hydration, or medication instructions may be important.
• Ask about results - Patients should know when and how results will be available.
• Keep follow-up - Recommended follow-up imaging or clinical care should not be ignored.
• Discuss radiation concerns - Clinicians can explain the risk-benefit balance and possible alternatives.

See also

• Medical imaging
• Diagnostic radiology
• Interventional radiology
• Radiographer
• Radiologist
• X-ray radiography
• Computed tomography
• Magnetic resonance imaging
• Ultrasound
• Nuclear medicine
• Positron emission tomography
• Fluoroscopy
• Mammography
• Radiation safety
• Teleradiology
• Picture archiving and communication system
• Radiology information system
• Artificial intelligence in healthcare
• Radiomics
• Medical physics
• Radiation oncology

Further reading

• ACR Appropriateness Criteria(link). American College of Radiology.
• Ionizing radiation and health effects(link). World Health Organization.
• The Role of Radiology in AI Highlighted at ACR 2025(link). American College of Radiology.
• Role of AI in Medical Imaging(link). Radiological Society of North America.
• Radiation Safety and Protection(link). StatPearls, National Center for Biotechnology Information.

External links

• American College of Radiology
• Radiological Society of North America
• WHO - Ionizing radiation and health effects
• ACR Appropriateness Criteria
• RadiologyInfo.org
• International Atomic Energy Agency - Radiation protection of patients
• Image Wisely
• Image Gently

1. ACR Appropriateness Criteria