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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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Pediatric clavicle (AP view)

The anteroposterior clavicle view for pediatrics is part of a two view series examining the entirety of the clavicle and the sternoclavicular and acromioclavicular joints. This view is ideally performed erect, but supine may be necessary depending on the patient's level of distress and severity ...

Harris ring

A Harris ring is a ring-like shadow observed at the base of the odontoid process on a lateral radiograph of the cervical spine. It is formed by the superimposition of the lateral masses of the C2 vertebra (axis) on its body. Disruption of the Harris ring is seen in type III, and less commonly, ...

Virtual grid

Virtual grid softwares are a relatively new innovation utilizing no physical grid at all. Instead, the original purpose of a grid is replicated by an algorithm 1 based on fundamental mathematics (i.e. Laplace transformation, wavelet transformation and Gaussian decomposition) which iteratively re...

Clavicle series (pediatrics)

The clavicle series for pediatrics is a two view series containing an anteroposterior and a cranially angled axial radiograph. Depending on the patient's level of distress and severity of the injury, adapting the radiographic technique to suit a child sitting in bed or lying supine may be necess...

Pediatric shoulder (lateral view)

The lateral shoulder view in pediatrics is part of a two view series examining the shoulder joint, clavicle, scapula and proximal humerus. Indications This projection is an orthogonal view of the AP shoulder and is useful in pediatric imaging for identifying potential fractures or dislocation...

Foot (DP talus view)

The medial oblique axial talus view, also known as the Canale view, is a specialized projection of the talus bone, more specifically the talar neck. Indications This view is specifically indicated when assessing talar neck fracture and/or their follow-up. It is particularly useful to assess va...

Timed barium esophagogram

The timed barium esophagogram (TBO) is a simple physiologic assessment and objective method for assessing the esophageal emptying used in patients with suspected achalasia and to evaluate and follow up patients who have been treated with myotomy or pneumatic dilatation1,3. Technique Several te...

Nephrostogram

Nephrostogram, also known as antegrade pyelogram, is a special x-ray procedure that fluoroscopically evaluates the upper collecting system by introducing water-soluble contrast through the nephrostomy catheter. Indications Nephrostogram can be useful to determine tube position or assess resid...

Pediatric shoulder (AP view)

The anteroposterior shoulder view in pediatrics is part of a two view series examining the shoulder joint, clavicle, scapula and proximal humerus. Indications This projection demonstrates the shoulder joint in natural anatomical position and is used as an orthogonal view to the lateral should...

Broden's view

The Broden's view (or Broden view) is a specialized projection that accurately 1 examines the large posterior calcaneal facet and the subtalar joint 2. As technology advances, computed tomography (CT) has widely been used to better visualize and characterize fragment displacements and fracture ...

Long axial hindfoot alignment view

The long axial hindfoot alignment view is a specialized, weight-bearing radiographic view that examines the hindfoot alignment as part of a foot and ankle instability investigation. The long axial view requires no equipment and has higher inter-observer reliability compared to the standard hin...

Hindfoot alignment view

The hindfoot alignment view is a specialized, weight-bearing radiographic view that examines the hindfoot alignment as part of a foot and ankle instability investigation. The long axial view requires no equipment and has higher inter-observer reliability when measuring angular hindfoot alignme...

Foot (weight-bearing medial oblique view)

The weight-bearing medial oblique view of the foot is a specialized projection that places the foot under normal weight-bearing conditions. The projection is utilized to assess the foot under stress and better demonstrate structural and functional deformities. Indications This projection is ...

Ankle (weight-bearing mortise view)

The weight-bearing mortise (mortice is equally correct) view of the ankle is a specialized projection that places the joint under normal weight-bearing conditions. The projection is utilized to assess the joint under stress and better demonstrate structural and functional deformities. Termino...

Ankle (weight-bearing AP view)

The weight-bearing AP view of the ankle is a specialized projection that places the joint under normal weight-bearing conditions. The projection is utilized to assess the joint under stress and better demonstrate structural and functional deformities. Indications This projection is utilized ...

Ankle (weight-bearing lateral view)

The weight-bearing lateral view of the ankle is a specialized projection that places the joint under normal weight-bearing conditions. The projection is utilized to assess the joint under stress and better demonstrate structural and functional deformities. Indications This projection is util...

Bow-tie sign

"Bow-tie sign" refers to the appearance of rotated facets in unilateral facet joint dislocation. Facet joint displacement coupled with a rotational deformity gives a bow-like like appearance on a lateral view radiograph of spine 1.

CT renal mass (protocol)

The renal mass CT protocol is a multi-phasic contrast-enhanced examination for the assessment of renal masses. It is most often comprised of a non-contrast, nephrogenic phase and excretory phase. However, this article will cover the optional, corticomedullary phase too. NB: This article is inte...

Excretory phase

The excretory phase also known as the urographic phase is a postcontrast injection time range in which there is an optimal enhancement of the renal collecting systems. Technique The acquisition time depends on the intravenous device (central or peripheral), the concentration of the contrast me...

Contrast phases

Contrast phases are terms used to describe different stages of contrast enhancement to blood vessels, following the introduction of a pressure injected intravenous (IV) contrast agent such as iodine in CT. Typical phases (time from injection) include: early arterial phase 15-25 seconds pos...

CT four-phase liver (protocol)

The four-phase liver CT protocol is a useful examination in the assessment of focal liver lesions, hypervascular liver metastasis and endocrine tumors. It is a triple-phase liver with an initial non-contrast component included before the intravenous contrast medium is given, often requested if ...

CT triple-phase liver (protocol)

The triple-phase liver CT protocol is a useful examination in the assessment of focal liver lesions, hypervascular liver metastases and endocrine tumors. It involves a dedicated late arterial phase, portal venous phase and delayed phase acquisition. Not to be confused with a four-phase which in...

Shoulder series (pediatric)

The shoulder series for pediatrics is a two view series containing anteroposterior and lateral radiographs. Depending on the patient's level of distress and severity of the injury, adapting the radiographic technique to suit a child sitting in bed or lying supine may be necessary. Indications ...

Portable radiography

Portable radiography (also known as mobile radiography) is frequently performed in hospitals when patients are too unwell to transport to the imaging department. However, most health facilities endeavor to perform "departmental films", as image quality tends to be inferior when performed with a ...

Pediatric thumb (AP/PA view)

The anteroposterior (AP) or posteroanterior (PA) view of the thumb in pediatrics is part of a two view series and is orthogonal to the lateral view. Often the decision to choose between the AP or PA thumb depends on what the child can manage and how agitated they are. An AP thumb is ideal as the...

Practical radiography: A Hand-Book of the Applications of the X-Rays

The book Practical radiography: A Hand-Book of the Applications of the X-Rays was the first ever textbook on x-rays anywhere in the world. It was written by H Snowden Ward and first published in May 1896 by Dawbarn & Ward. This is a mere six months after Wilhelm Roentgen's discovery of x-rays. ...

Pediatric humerus (lateral view)

The lateral humerus view for pediatrics is part of the humerus series and is usually taken in a standing position. However, it can also be obtained in a supine position. The projection demonstrates the humerus orthogonal to the AP view, allowing for adequate radiographic examination of the enti...

Pediatric thumb (oblique view)

The oblique thumb view in pediatrics is an additional projection for thumb imaging. Typically, this view is not performed unless specified by the referring doctor or radiologist. Indications For pediatrics, this oblique view is only indicated when specifically requested. This view may help to...

Nephrogenic phase

The nephrogenic phase, also known as the nephrographic phase or the renal parenchymal phase, is a postcontrast injection time range in which there is an optimal enhancement of the renal parenchyma including the medulla. Technique The acquisition time depends on the intravenous device (central ...

Portal venous phase

The portal venous phase, also known as the late portal phase or hepatic phase, is a contrast-enhanced CT or MRI series that has the following characteristics: liver parenchyma is at its peak enhancement with a density >110 HU (an increase of at least 50 HU from the unenhanced baseline)1,2 port...

Late arterial phase

The late arterial phase, also known as the corticomedullary phase or early venous portal phase, is a contrast-enhanced CT or MRI series, in which there is an optimal enhancement of structures that get their blood supply directly from the arterial system. The standard characteristics for this ph...

Early arterial phase

The early arterial phase, also known as the early systemic arterial phase, is a contrast-enhanced CT or MRI series, in which the contrast (e.g. iodinated or gadolinium) is still in the arteries and has not reached the organs and other soft tissues. Technique The acquisition time depends on the...

Pediatric humerus (AP view)

The anteroposterior humerus view for pediatrics is part of the humerus series and is usually taken in a 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 examina...

Humerus series (pediatric)

The humerus series for pediatrics is a set of anteroposterior and lateral radiographs taken to investigate elbow joint pathology, often in the context of trauma. As the elbow joint is also imaged in this series, being familiar with the order of elbow ossification is important in assessing the e...

Pediatric thumb (lateral view)

The lateral thumb view for pediatrics is part of a two view series examining the distal metacarpal, distal and proximal phalanges. Indications This projection is useful for diagnosing fractures and localizing foreign bodies in pediatric patients. It also presents as an orthogonal view of the ...

Pediatric finger (oblique view)

The oblique finger view for pediatrics is an additional view examining the distal metacarpal, distal, middle and proximal phalanges of the finger of interest. Indications To minimize radiation dose, only the PA and lateral finger views are typically performed for pediatrics. However, the obli...

Archives of the Roentgen Ray

The Archives of the Roentgen Ray was a general radiology journal published from 1897 to 1915. In 1915, it was renamed the Archives of Radiology and Electrotherapy. The Archives was a forerunner publication of the British Journal of Radiology (BJR). History In 1897, after a single year in print...

CT transcatheter aortic valve implantation planning (protocol)

The transcatheter aortic valve implantation or TAVI planning CT protocol is used to plan for transcatheter aortic valve implantation. CT allows for the assessment of the aortic root and valve annulus in order to select an appropriate valve size and location-specific to the patient. An aortic ang...

En face

En face (pronounced /ɒ̃ ˈfas/) is a term used in radiology, mainly in plain radiography, to refer to structures or pathology that are seen front on.

Cardiac gating (CT)

Cardiac gating or ECG gated angiography in CT is an acquisition technique that triggers a scan during a specific portion of the cardiac cycle. Often this technique is conveyed to obtain high-quality scans void of pulsation artefact. Technique Via the attachment of ECG leads, cardiac gating aim...

F-18 DOPA

F-18 DOPA (3,4-dihydroxy-6-[18F]fluoro-L-phenylalanine) is a PET radiotracer primarily used in the evaluation of neuropsychiatric diseases, movement disorders, and brain malignancies 1. Production L-DOPA is the nonproteinogenic amino acid precursor to dopamine with F-18 DOPA, in recent years,...

Cardiac CT (prospective high-pitch acquisition)

The prospective ECG-gated high-pitch dual-source CT cardiac angiogram is a high pitch helical acquisition of the heart that is able to capture a single phase of the cardiac cycle, a dual-source scanner is required to perform it. Although this is the CT cardiac angiogram with the lowest dose it a...

Renal transplant scintigraphy

Renal transplant scintigraphy is a non-invasive diagnostic modality, using radioactive isotopes, to assess renal transplant related complications. Renal scintigraphy images are acquired with a dynamic planar procedure using a radioactive isotope visualized on a gamma camera. The final result is ...

Pediatric finger (lateral view)

The lateral finger view for pediatrics is part of a two view series examining the distal metacarpal, distal, middle and proximal phalanges of the finger of interest. The patient position can vary depending on which finger is being imaged. Indications This projection is useful for diagnosing f...

Shoulder (Velpeau view)

The Velpeau view of the glenohumeral joint is a modified axial projection performed in the context of shoulder immobilization. Indications This projection is performed on patients with a shoulder sling (Velpeau bandage) in place, often in the context of post-operative or a post-reduction prese...

Shoulder (West Point view)

The West Point view of the glenohumeral joint is a modified axial projection of the glenohumeral joint in which the patient is prone. Indications The West Point view is a highly specific radiographic projection to assess the anteroinferior glenoid rim often in the context of recurrent instabi...

Nasal bones (lateral view)

The lateral nasal bones view is a nonangled lateral radiograph showcasing two small oblong bones situated side by side, together forming the nasal ridge. Indications This view is often primarily used in assessing various nasal bone fractures in the trauma setting. Depending on the department, ...

Contrast-enhanced CT during extracorporeal membrane oxygenation

Contrast-enhanced CT of patients undergoing extracorporeal membrane oxygenation (ECMO) presents unique technical and diagnostic challenges. Technical considerations There are a number of factors that need to be considered to ensure contrast-enhanced CT studies of ECMO patients are both succes...

Pediatric finger (PA view)

The posteroanterior finger view for pediatrics is part of a two view series examining the distal metacarpal, distal, middle and proximal phalanges of the finger of interest. Indications This projection demonstrates the metacarpal and interphalangeal joint spaces in their natural anatomic posi...

Cervical gravity line

The cervical gravity line is a measurement made on spinal / chiropractic imaging. It is usually drawn on an erect weight bearing radiograph as plumb line drawn downwards on a sagittal image from the dens. See also lumbar gravity line

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 (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...

Noise power spectrum

The noise power spectrum (NPS), also known as the power spectral density, of a signal, is the Fourier transform of the noise autocorrelation. It gives the intensity of noise as a function of spatial frequency. It is used in all the main radiological modalities, most commonly x-ray-based, i.e. ra...

CT brain perfusion (protocol)

CT perfusion of the brain is a dynamic, contrast-enhanced study utilized in patients with suspected stroke to differentiate salvageable ischemic brain tissue (i.e. penumbra) from damaged infarcted brain. NB: This article is intended to outline some general principles of protocol design. The spe...

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...

Thumb series (pediatric)

The thumb 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 d...

Cine imaging (MRI)

Cine imaging, a.k.a. cine sequences or cine MRI, are a type of MRI sequence acquired to capture motion. Imaging technique Cine images are obtained by repeatedly imaging the area of interest for a certain time typically within a single slice, although 3D solutions already exist 3. For the hear...

Cardiac iron overload protocol (MRI)

The cardiac MRI iron overload protocol encompasses a set of different MRI sequences for the cardiac assessment in case of suspected iron overload cardiomyopathy. Note: This article aims to frame a general concept of a cardiac MRI protocol in the above setting. Protocol specifics will vary dep...

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...

Abdomen (KUB view)

The kidneys, ureters, bladder (KUB) radiograph is optimized for assessment of the urogenital system, and should not be confused with the AP supine abdomen view. However, in cases where the patient may have both gastrointestinal and urogenital abnormalities, all pathologies will still be reported...

Neuroimaging (dual-energy CT)

Dual-energy CT has a number of clinical applications in neuroimaging particularly in the realm of material composition and virtual non-contrast imaging. Differentiation of hemorrhage from iodinated contrast Contrast staining of the brain parenchyma post iodinated contrast can lead to interpret...

Musculoskeletal imaging (dual-energy CT)

Dual-energy CT has a number of clinical applications in the assessment of the musculoskeletal system particularly in the realm of artefact reduction and material composition. Detection of bone marrow edema Similar to the concept of using virtual non-contrast imaging, virtual non-calcium images...

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...

Toes (lateral view)

The lateral toe projection is part of the three view series examining the phalanges of any specified toe(s), and distal half of the associated metatarsals. Indications This view evaluates all phalanges of a specified toe(s) for any fractures or dislocation, allowing the establishment of dorsal...

Resistive index (vascular ultrasound)

The resistive index (Pourcelot index) is a calculated flow parameter in ultrasound, derived from the maximum, minimum, and mean Doppler frequency shifts during a defined cardiac cycle. Along with the pulsatility index (PI), it is typically used to assess the resistance in a pulsatile vascular sy...

CT protocol

A CT protocol is a set of parameters that specify a specific exam and contrast delivery requirements. When a CT is requested, it will be vetted by a radiologist or radiographer to determine the study is justified and what the most suitable parameters by which that CT should be performed - this m...

Ankle (stress view)

The AP stress view of the ankle is a highly specialized view used to assess the integrity of the syndesmosis and deltoid ligament. It can be performed one of two ways, with gravity or via manual external rotation. Indications In intermediate ankle injuries that have no syndesmotic widening on...

CT dose

CT dose is measured and reported via a variety of methods, put simply, it can be divided into three primary categories: exposure, absorbed dose, and effective dose. It is important to note that to accurately determine a patients dose from a CT scan one must know the patient size and the radiat...

Spine radiography

Spine radiography is utilized in both trauma and general imaging. Spine radiography explores the cervical, thoracic, lumbar, and sacral regions. In more specialized departments, full-length spine radiography via projectional, CT, or slit-beam digital radiography is still frequently utilized in t...

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...

Paranasal sinuses and facial bones (lateral view)

The lateral paranasal sinuses and facial bones view is a nonangled lateral radiograph showcasing the facial bones (i.e. mandible, maxilla, zygoma, nasal, and lacrimal bone) and paranasal sinuses. Indications This view is useful in assessing any inflammatory processes or fractures to the facial...

Pediatric wrist (lateral view)

The lateral wrist view for pediatrics is one of three views in order to examine the carpal bones, distal radioulnar joint and metacarpals. Indications This projection is an orthogonal view of the PA wrist and is used to diagnose fractures and localize foreign bodies in pediatric patients. It a...

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...

Skull (submentovertex view)

The skull submentovertex view is an angled inferosuperior radiograph of the base of skull. As this view involves radiographic positioning that is uncomfortable for the patient and with CT being more sensitive to bony detail, this view is rapidly becoming obsolete. Indications This view is usef...

Shunt series

The shunt series is a set of radiographic images performed to assess the location and integrity of a ventriculoperitoneal shunt. Indications Departmental protocols will vary but the overall goal is to image the shunt in its entirety to assess for mechanical causes of shunt failure 1,2. The sh...

Pediatric abdomen (invertogram view)

The invertogram view is an additional projection to demonstrate the pediatric abdomen and is often used exclusively in characterizing anal atresia. However, as this view may be less comfortable for the patient and result in a more technically challenging examination, a more ideal alternative tec...

Pediatric abdomen (prone cross-table lateral view)

The prone cross-table lateral view is an additional projection to demonstrate the pediatric abdomen and is a more ideal alternative to the invertogram, which may be less comfortable for the patient. This discomfort may result in a continuously crying baby, causing the puborectalis sling to contr...

Subcallosal line

The subcallosal line connects the inferior surface of the genu of the corpus callosum to the inferior surface of the splenium and is used to define an axial plane for imaging of the brain 1. The alternative AC-PC line is most commonly used, however, the subcallosal plane remains recommended fo...

Axial plane for imaging of the brain

A consistent axial plane for imaging of the brain needs to be chosen to allow for reproducible image acquisition and comparison. Unlike the sagittal plane, which is intrinsically defined by our inherent left-right plane of symmetry, axial and coronal planes need to be agreed upon and over the ye...

3D fast spin echo (MRI sequence)

3D fast spin-echo sequences are relatively recent MRI pulse sequences that are able to rapidly image relatively large volumes of tissue with high resolution whilst retaining many of the advantages of fast spin-echo sequences. They are able to create the same weightings as traditional 2D sequen...

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...

Pediatric forearm (horizontal beam lateral view)

The horizontal beam lateral forearm view for pediatrics 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 as...

Pediatric forearm (PA view)

The posteroanterior forearm view for pediatrics 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...

Pediatric forearm (lateral view)

The lateral forearm view for pediatrics 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. However, this view should no...

Pediatric forearm (AP view)

The anteroposterior forearm view for pediatrics 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 local...

Pediatric wrist (oblique view)

The oblique wrist view for pediatrics is one of three views in order to examine the carpal bones, distal radioulnar joint and metacarpals. Indications This projection is useful for diagnosing subtle wrist fractures and the location of the fracture; particularly in adults. However, the oblique...

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...

Forearm series (pediatric)

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...

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.

Pediatric immobilization

Pediatric immobilization relates to techniques used to keep children still for medical imaging examinations. Since radiation dose can affect children up to ten times more than adults 1, it is important to keep the radiation dose to a minimum. One method of achieving this is by avoiding repeat im...

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...

Ultrasound in practice

Ultrasound is a commonly used imaging tool. This is a starting page for some general articles about ultrasound in practice in including common pathology and ultrasound techniques. See also ultrasound (imaging technology) ultrasound physics

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...

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