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Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

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CT pulmonary angiogram (technique)

The computed tomography pulmonary angiogram (CTPA/CTPE) is a commonly performed diagnostic examination to exclude pulmonary emboli. Each radiology department will have a slightly different method for achieving the same outcome, i.e. adequate enhancement of the pulmonary trunk and its branches. ...

Dacryocystography

Dacryocystography (DCG) is a fluoroscopic contrast examination of the nasolacrimal apparatus. The nasolacrimal duct is cannulated enabling iodinated contrast to be instilled into the nasolacrimal system. Indications The most frequent indication is epiphora: excessive tearing or watering of the...

Deep endometriosis (transvaginal ultrasound)

Transvaginal ultrasound (TV) for deep endometriosis is a specialized ultrasound technique used for the detection of deep endometriosis (DE). It differs from a traditional pelvic ultrasound in that the scan is extended beyond the uterus and ovaries to assess the anterior and posterior pelvic comp...

Densitometric vertebral fracture assessment

Densitometric vertebral fracture assessment (VFA) is an image of the lumbar and thoracic spine acquired on dual energy x-ray absorptiometry (DXA) scanners, for the purpose of diagnosing osteoporotic vertebral fractures. Terminology The technique is available on DXA scanners under a variety of...

Developer solution

Developer solution is used in the darkroom for developing (i.e. converting latent image to visible image) x-ray films used in conventional (screen film) radiography. Components developer: hydroquinone (for high contrast) + Metol or phenidone (for low contrast) the developer itself gets oxidis...

Digital breast tomosynthesis

Digital breast tomosynthesis (DBT) is an imaging technique that allows a volumetric reconstruction of the whole breast from a finite number of low-dose two-dimensional projections obtained by different X-ray tube angles, with a geometric principle very similar to that applied in stratigraphic te...

Digital image

A digital image is a numerical representation of an image via a set of picture elements known as pixels. This simplified article lists three parameters of a digital image that moderate spatial and contrast resolution. Image matrix The image matrix is comprised of columns (M) and rows (N) that ...

Digital Imaging and Communications in Medicine (DICOM)

Digital Imaging and Communications in Medicine (DICOM) is a worldwide standard for the storage and transmission of medical imaging. The standard therefore defines both a file format and a networking protocol. The standard also has some specifications in terms of file storage on some types of med...

Digital radiography

Digital radiography is based on the use of discrete values in comparison to conventional radiography which uses analog/continuous values. It removes the requirement of dark room procedures. Types computed radiography (CR) uses photostimulable phosphor plates (PSP) in cassettes direct digital...

Double spot compression view

A double spot compression view is obtained by focal compression of both sides of the breast to produce higher spatial and contrast resolution. This is made possible due to the increased amount of breast thinning and a significant decreased incidence of blurring because of decreased exposure time...

Dual energy CT

Dual energy CT, also known as spectral CT, is a computed tomography technique that uses two separate x-ray photon energy spectra, allowing the interrogation of materials that have different attenuation properties at different energies. Whereas conventional single energy CT produces a single imag...

Dual-energy CT (clinical applications)

Dual-energy CT or multispectral CT is becoming increasingly more common in clinical practice due to the rapid rise in computer technology and expanding literature exhibiting vast advantages over conventional single energy CT. Clinical applications The clinical practice, adaptation and techniq...

Dual-energy x-ray absorptiometry

Dual-energy x-ray absorptiometry (DEXA or DXA) is a technique used to aid in the diagnosis of osteopenia and osteoporosis. Radiographic features Values are calculated for the lumbar vertebrae and femur preferentially, and if one of those sites is not suitable (e.g. artifact, patient mobility)...

Ducroquet view of hip

The Ducroquet view is a radiographic projection of the femoral neck with flexed and abducted affected hip joint.1,4 The view can be used for examining cam-type femoroacetabular impingement (FAI). Patient position Patient is supine; the affected hip joint is flexed on pelvis of 90° and abducted...

Effect of isolated pronation-supination (lateral wrist radiograph)

The wrist series is comprised of a posteroanterior, oblique, and lateral projection. The series examines the carpal bones (namely, the scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate and hamate). It also examines the radiocarpal joint along with the distal radius and ulna....

Eklund technique

Eklund modified compression technique is a technique which can be used for patients with augmented or reconstructed breasts post mastectomy. Technique It consists of posterosuperior displacement of the implants simultaneously to an anterior traction of the breast, pushing the implants towards...

Elbow (acute flexion AP)

The elbow acute flexion AP is a modified elbow AP projection for patients who cannot straighten their arm for examination. It is comprised of two views demonstrating the distal humerus and proximal forearm structures Indications This is a modified projection (chosen by the radiographer when a...

Elbow (AP view)

The elbow AP view is part of the two view elbow series, examining the distal humerus, proximal radius and ulna. The projection demonstrates the elbow joint in its natural anatomical position allowing for adequate radiographic examination of the articulations of the elbow including the radiohum...

Elbow (Coyle's view)

The Coyle's view or trauma oblique view of the elbow is an axial projection that is performed in addition to the standard elbow series when there is suspicion of a radial head or capitellum fracture. Indications The Coyle's view is performed for any patient with a suspected radial head fractur...

Elbow (external oblique view)

The elbow external oblique view is an additional projection of the elbow often used to better demonstrate the radial head free from superposition. Indications This external oblique view is an additional projection often used to separate the proximal radius from the ulna for closer inspection o...

Elbow (lateral view)

The lateral elbow view is part of the two view elbow series, examining the distal humerus, proximal radius and ulna. It is deceptively one of the more technically demanding projections in radiography 1-3. The projection is the orthogonal view of the AP elbow allowing for examination of the ulna...

Elbow (medial oblique view)

The elbow medial oblique view is a specialized projection, utilized to demonstrate both the coronoid process in profile and the olecranon process sitting within the olecranon fossa of the humerus. Indications The medial oblique view is not a standard projection of the elbow, however helpful wh...

Elbow series

The elbow series is a set of radiographs taken to investigate elbow joint pathology, often in the context of trauma. It usually comprises an AP and lateral projection, although other non-standard, modified projections are utilized for specific indications. Indications Elbow x-rays are indicate...

Elbow series (pediatrics)

The elbow series for pediatrics is a set of radiographs taken to investigate elbow joint pathology, often in the context of trauma. It usually comprises an anteroposterior and lateral projection in order to minimize radiation dose to the patient. Depending on the department and clinical indicati...

Elevated craniocaudal projection

Elevated craniocaudal projection is an additional trouble shooting view. Technique direct beam superiorly to inferiroly face patient towards unit, feet forward lean patient inward, relaxing the shoulders bring inferior aspect of breast onto the image receptor pull breast outward and forwar...

EOS imaging systems

EOS® imaging system (also known as a slot-scanning device or slit-beam digital radiography system) is an x-ray technology that allows simultaneous acquisition of AP and lateral images of the entire body in a natural, erect position, and is also capable of performing three-dimensional reconstruct...

F-18 fluorodeoxyglucose (FDG) embolism

F-18 fluorodeoxyglucose (FDG) embolism is a condition which results in a uniform intense FDG-avid pulmonary focus without any underlying structural CT correlate with an unremarkable follow-up PET-CT scan 1. It is thought to occur as a result of clumping of FDG with blood when the blood is withdr...

Facial bones (reverse Waters)

The acanthioparietal or reverse water's view modified Water's view used in trauma. It can be used to assess for facial fractures, as well as for acute sinusitis. Skull radiographs, in general, are rapidly becoming obsolete, being replaced by much more sensitive CT scans. Patient position the ...

Femoral torsion analysis

Femoral torsion analysis is used to assess the alignment of a femur post-surgery. If one side has been operated on it can be compared to the non-operated side. Method Superimpose axial images of ref: femoral heads the neck of femurs femoral condyles Draw a line from the center of the femor...

Femur (AP view)

The anteroposterior femur view is part of a standard series examining the femur in its entirety, including the hip and knee joint. Due to the limitations of the image detector, these projections are often performed in two images per view to ensure inclusion of both knee and hip joints. Indicati...

Femur (lateral view)

The lateral femur view is part of a standard series examining the femur in its entirety, including the hip and knee joint. Due to the limitations of the image detector, these projections are often performed in two images per view to ensure inclusion of both knee and hip joints. Indications Thi...

Femur series

The femur series is comprised of an anteroposterior (AP), and lateral radiograph. The series is utilized to asses for abnormalities pertaining to the shaft of the femur (often requested when fringe abnormality is seen on hip or knee radiographs). It is not an effective series to assess for a nec...

Finger (oblique view)

Finger oblique view is a standard projection for radiographic assessment of the fingers. Indications The oblique view s not required for follow-up studies, or 'query foreign body' unless specifically requested. It is, however, a very useful projection in the acute setting and should be includ...

Finger (PA view)

Finger PA view is a standard projection for radiographic assessment of the fingers; it is one of three views of the finger series. Indications This projection is best to access the joint spaces and distal, middle and proximal phalanx in the AP plane. It is not advisable to only obtain one vie...

Finger series

The finger series is comprised, conventionally of a posteroanterior, oblique and a lateral view. The series examines in detail the distal, middle and proximal phalanx as well as the interphalangeal, metacarpophalangeal and carpometacarpal joints. Note: the thumb (first digit) reviewed under th...

Finger series (pediatric)

The finger series for pediatrics often consist of a posteroanterior and lateral view only in order to minimize radiation dose to the patient. Depending on the department and clinical indication, an additional oblique view may also be done. Indications trauma with suspected fracture suspected...

Fingers (lateral view)

Finger lateral view is a standard projection for radiographic assessment of the fingers; it is one of three views of the finger series. it is divided into: lateral index and middle fingers lateral of ring and little fingers Indications The lateral projection is an ideal projection to assess ...

Flat panel CT

Flat panel computed tomography (FPCT), otherwise, know as flat panel volume tomography are multidetector computed tomography scanners that utilize a large area detector rather than a fixed array of detectors 1,3. Flat panels have a significantly wider z-axis area coverage that can cover larger ...

Foot (dorsoplantar view)

The dorsoplantar view is part of a three view series examining the phalanges, metatarsals and tarsal bones that make up the foot. Indications This view demonstrates the location and extent of fractures in the foot, joint space abnormalities, soft tissue effusions and is the frontal view for t...

Foot (lateral view)

The lateral foot projection is part of the three view series examining the phalanges, metatarsals and tarsal bones that make up the foot. This view additionally examines the talocrural joint. Indications This view is useful in the assessment for joint abnormalities, determining the degree of d...

Foot (medial oblique view)

The medial oblique projection is part of the three view series examining the phalanges, metatarsals and tarsal bones that make up the foot. Indications This view demonstrates the location and extent of fractures in the foot and joint space abnormalities. It is also used in the determination o...

Foot series

The foot series is comprised of a dorsoplantar (DP), medial oblique, and a lateral projection. The series is often utilized in emergency departments after trauma or sports related injuries 2,4. See: approach to foot series. Indications Foot radiographs are performed for a variety of indicatio...

Foot (weightbearing dorsoplantar view)

The weightbearing dorsoplantar foot radiograph is a specialized projection of the foot. Nonweightbearing views (e.g. DP foot) are inadequate for the assessment of alignment because the bones of the feet are not in a functional position. Indications This view is key to the assessment of foot a...

Foot (weightbearing lateral view)

The weightbearing lateral foot radiograph is important in the assessment of foot alignment and the diagnosis of abnormalities that cause malalignment and foot pain. Nonweightbearing views (e.g. lateral foot) would be inadequate for the assessment of alignment as the bones of the feet are not in ...

Forearm (AP view)

The forearm AP view is one of two standard projections in the forearm series to assess the radius and ulna. Indications This view demonstrates the elbow joint in its natural anatomical position allowing for assessment of suspected dislocations or fractures and localizing foreign bodies within ...

Forearm (horizontal beam lateral view)

The horizontal beam lateral forearm view is one of two modified trauma projections in the forearm series, examining the radius and ulna. Indications This view is ideal for patients who are unable to move their arm as per the standard forearm positioning technique but require assessment of sus...

Forearm (lateral view)

Forearm lateral view is one of two standard projections in the forearm series to assess the radius and ulna. Indications This view allows for the assessment of suspected dislocations or fractures and localizing foreign bodies within the forearm. Patient position patient is seated alongside t...

Forearm (PA view)

The posteroanterior forearm view is one of two modified trauma projections in the forearm series, examining the radius and ulna. Indications This view is ideal for patients who are unable to move their arm as per the standard forearm positioning technique but require assessment of suspected r...

Forearm series

The forearm series is comprised of an anteroposterior and lateral projection. The series examines the entire radius and ulna including articulations distally and proximal. Typically requested for midshaft injuries, the forearm series is not a 'two-for-one' projection of the wrist and the elbow j...

Forearm series (pediatrics)

The forearm series for pediatrics comprises an anteroposterior and lateral projection. These projections examine the entire radius and ulna including the distal and proximal articulations. Indications Forearm x-rays are indicated for a variety of settings including: trauma bony tenderness s...

Foreign body ingestion series (pediatric)

The suspected foreign body ingestion series is a set of radiographs utilized to detect and identify foreign bodies in the gastrointestinal tract. It involves an AP and lateral radiograph of the neck, chest, and abdomen ensuring adequate coverage of the entire gastrointestinal tract 1. Patient p...

Foreign body inhalation series (pediatric)

The suspected foreign body inhalation series although not a primary port of investigation aims to detect and identify both foreign bodies or the secondary signs of inhaled foreign bodies 1. It involves a frontal chest radiograph in both the inspiration and expiratory phases and, in some cases, b...

Frontal oblique approach mammography

Background Mammographic technique is very important to obtain diagnostic mammograms, to reduce the number of false negatives and to increase the sensitivity of the procedure. As widely noted in literature, most breast pathology occurs in the upper outer quadrant and is very important that this ...

General radiography

General radiography, also known as plain film radiography, is the specialty within medical imaging that utilizes projectional radiography to examine anatomy. It is often referred to as simply ‘x-ray’ within medical imaging departments. Due to the differences in pediatric projectional radiography...

General radiography article structure

There are two main types of general radiography articles, which require a different set of subheadings as the usual epidemiology, clinical presentation, pathology etc. are not relevant. ======================================================================= Radiographic series These articles...

General radiography curriculum

The general radiography section covers in detail the various clinical presentations that require specific plain radiographic investigation, the anatomy covered, and how it is displayed via the chosen view. It outlines standard and modified radiographic technique to accommodate for a wide range o...

Ghost image (orthopantomogram)

A ghost image is a commonly observed artifact in an orthopantomogram whereby a dense, often metallic object is located between the source of x-ray and the focal center, resulting in a duplicate 'ghost' image at the contralateral aspect of the image. Real image vs ghost image In panoramic imag...

Gluteoplasty

A gluteoplasty, also called gluteal augmentation, is a surgical procedure performed to improve the shape and the size of the buttocks. Indications A cosmetic desire to boost the volume and shape of the buttocks. Surgical technique Many types of procedures are performed 1: subfascial gluteal...

Grid cutoff

Grid cutoff is an unwanted absorption of x-rays via an x-ray grid, observed when a grid is employed incorrectly, most often seen with parallel grids. The term cutoff stems from the phenomenon in which the primary x-ray beam is 'cut off' by grid lines, leading to an overall decrease in optical de...

Gustav Bucky

Gustav Bucky (1880-1963) was a German-born, American radiologist who pioneered the development of anti-scatter grids in projectional radiography with his invention, the Bucky diaphragm. Early life Gustav Peter Bucky was born in the city of Leipzig, Germany on 3 September 1880 2,3,5. He had a k...

Hair artifact

Hair artifact and hair-product artifacts are artifacts produced by the presence of the patient's hair, hair accessories (e.g. hair clip) and hair products (e.g. shampoo) within the field of view during acquisition of an image, which can affect all modalities to varying degrees. For example, in m...

Hand (ball-catcher view)

The ball-catcher view, Nørgaard projection, or posterior oblique view of both hands is an additional projection of the routine hand series. Indications The ball-catcher view is typically undertaken to assess for erosive arthropathies such as rheumatoid arthritis. It often complements the bilat...

Hand (bilateral PA view)

The bilateral PA view is merely a single film that includes both hands, side by side. Indications This view often complements the ball-catcher view and is performed almost exclusively to examine for evidence of rheumatological disorders (e.g. rheumatoid arthritis, osteoarthritis, psoriatic ar...

Hand (lateral view)

The lateral hand view is an orthogonal view taken along with the PA view of the hand. Indications The lateral hand view is requested for diagnosing a variety of clinical indications such as rheumatoid arthritis, osteoarthritis, suspected fracture or dislocation and localizing foreign bodies. ...

Hand (oblique view)

The hand oblique view is part of a two view series metacarpals, phalanges, carpal bones and distal radial ulnar joint. Indications The oblique hand view is requested for diagnosing a variety of clinical indications such as rheumatoid arthritis, osteoarthritis, suspected fracture or dislocatio...

Hand (PA view)

The Hand PA view is part of a two view series metacarpals, phalanges, carpal bones and distal radial ulnar joint. Indications The PA hand view is requested for diagnosing a variety of clinical indications such as rheumatoid arthritis, osteoarthritis, suspected fracture or dislocation and loca...

Hand series

The hand series consists of posteroanterior, oblique, and lateral projections. Although additional radiographs can be taken for specific indications. The series primarily examines the radiocarpal and distal radioulnar joints, the carpals, metacarpals, and phalanges. Indications Hand x-rays ar...

Hand series (pediatric)

The hand series for pediatrics often consist of a posteroanterior and lateral view only in order to minimize radiation dose to the patient. Depending on the department and clinical indication, an additional oblique view may also be done. Indications trauma with suspected fracture suspected di...

Hip (AP view)

The AP hip is part of a radiographic series examining the anatomy of the hip joint and proximal femur. Indications This view helps to visualize any potential fractures, dislocations, bone lesions or degenerative diseases to the hip joint. It is also often requested in post-operative examinatio...

Hip (Clements-Nakayama view)

The Clements-Nakayama view of the hip is a highly specialized lateral projection utilized on patients with bilateral femoral fractures, or patients unable to mobilize due to postoperative requirements. When performed correctly the projection can yield images of a high diagnostic quality comparab...

Hip (Dunn view)

The Dunn view is a radiographic projection of the hip that demonstrates and examines the hip joint, femoral head, acetabulum, and particularly the relationship of the femoral head and acetabulum. Indications The Dunn view is the preferred projection to aid in the diagnosis of femoroacetabular ...

Hip (horizontal beam lateral view)

The horizontal beam lateral hip radiograph or shoot through hip is in the purest terms the orthogonal view of the neck of the femur to the AP projection 1. Indications The projection is used to assess the neck of the femur in profile during the investigation of a suspected neck of femur fractu...

Hip (lateral view)

The lateral hip view is a radiographic projection assessing the relationship of the femoral head to the acetabulum. Indications This view assesses the hip joint for any potential fractures, dislocations, bone lesions or degenerative diseases (i.e. suspected osteoarthritis of the hip) in an ort...

Hip series

The hip series is comprised of an anteroposterior (AP) and lateral radiograph of the hip joint. The series is requested for a myriad of reasons from trauma to atraumatic hip pain. Indications Hip radiographs are performed for a variety of indications including 1-3: trauma hip pain abnormal...

Hip (Von Rosen view)

The Von Rosen view also known as the abduction-internal rotation view (AIR view) is a radiographic projection of the hip that demonstrates the relationship between the femoral head and the acetabulum. Indications The von Rosen view is used in the diagnosis of developmental dysplasia of the hip...

Humeral neck (AP view)

AP view for neck of humerus is taken to look for fracture in the neck of humerus. Patient position patient can stand or lay down facing the X-ray tube the dorsal aspect of shoulder of the affected side is kept in contact with the cassette (placed on a vertical stand) X-ray beam features a ...

Humerus (AP view)

The AP view of the humerus is part of the humerus series and is usually taken in standing position. However, it can also be obtained in a supine position. The projection demonstrates the humerus in its natural anatomical position allowing for adequate radiographic examination of the entire hume...

Humerus (lateral view)

The lateral view of the humerus is part of the humerus series and is usually taken in a standing position. However, it can also be taken in the supine position in the acute, trauma setting. The projection demonstrates the humerus in the lateral position allowing for adequate radiographic examin...

Humerus radiographic series

The humerus series is comprised of an AP and lateral radiograph, utilized primarily in trauma, but also in the evaluation of bone tumors. Indications trauma: fracture neck of humerus/shaft of humerus fractures bone tumor detection Projections The two standard projections allow two views of ...

Humerus series

The humerus series is usually used for the detection of traumatic injury to the shaft of the humerus. Indications Humerus radiographs are performed for a variety of indications including: trauma bony tenderness at the glenohumeral joint/region restriction of abduction suspected disloca...

Humerus (supracondylar AP view)

AP view for supracondylar aspect of humerus may be taken to look for supracondylar fracture. Patient position patient stands facing the X-ray tube with the posterior aspect of arm in contact with cassette (placed on a vertical stand) X-ray beam features a horizontal beam is employed centere...

Imaging in practice

Imaging in practice is home to all diagnostic and therapeutic investigations/interventions conducted in a typical radiology department. Each article below outlines clinical indications and practical information regarding each respective modality. general radiography (adult) general radiography...

Inferomedial superolateral oblique projection

Inferomedial superolateral oblique projection is useful for stereotactic biopsy positioning. This projection allows access to the inferior aspect of the breast to achieve shortest skin to abnormality distance. It is also useful in the nonconforming patient. Technique Rotate C arm to about 125°...

Interventional radiology in practice

Interventional radiology procedures within medical imaging span multiple subspecialties and modalities. This is a collection of articles exploring indications, techniques and practice applications of interventional procedures withing radiology.

Iodinated contrast media

Iodinated contrast media are contrast agents that contain iodine atoms used for x-ray-based imaging modalities such as computed tomography (CT). They can also used in fluoroscopy, angiography and venography, and even occasionally, plain radiography. Although the intravenous route of administrati...

Iterative reconstruction (CT)

Iterative reconstruction refers to an image reconstruction algorithm used in CT that begins with an image assumption, and compares it to real time measured values while making constant adjustments until the two are in agreement. Computer technology limited early scanners in their ability to per...

K-absorption edge

The K-absorption edge (K-edge) refers to the abrupt increase in the photoelectric absorption of x-ray photons observed at an energy level just beyond the binding energy of the k-shell electrons of the absorbing atom. K-shell binding energies are specific to each element. As the atomic number (Z...

Key figures in the history of radiology

In the history of radiology certain key figures stand out for their groundbreaking contributions to the establishment and development of radiology as a science, medical specialty and major advance in patient care. This list is by necessity arbitrary, although we (the editors) hope that the major...

Knee (AP view)

The knee anteroposterior view is a standard projection to assess the knee joint, distal femur, proximal tibia and fibula and the patella. Indications This view demonstrates the distal femur and proximal tibia/fibula in their natural anatomical position allowing for assessment of suspected disl...

Knee (AP weight-bearing view)

The knee AP weight-bearing view is a specialized projection to assess the knee joint, distal femur, proximal tibia and fibula and the patella. Indications Knee AP weight-bearing views will often be used in the context of orthopedic appointments to assess the alignment and degree of arthropath...

Knee (Beclere method intercondylar view)

The Béclere method intercondylar view is an additional projection of the knee, used to better examine the tibial plateau and femoral intercondylar spaces. It is anecdotally known as a 'notch view'. Indication The commonest indications for this additional knee view is for the assessment of a lo...

Knee (horizontal beam lateral view)

The horizontal beam lateral view (cross-table lateral) is an orthogonal view of the AP view of the knee requiring little to no patient movement and is hence the lateral projection of choice for acute knee injuries. Indications This view is the ideal projection to assess for lipohemarthrosis as...

Knee (lateral view)

The lateral knee view is an orthogonal view of the AP view of the knee. The projection requires the patient to 'roll' onto the side of their knee, hence it is not an appropriate projection in trauma, in all suspected traumatic injuries of the knee, the horizontal beam lateral method should be ut...

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