Articles
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 continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
More than 200 results
Article
Speckle artifact
Speckle artifact may be encountered in ultrasound. It is caused by the scattering of waves from the surface of small structures within a certain tissue. The artifact produces a textured appearance.
Because speckle can make it harder to distinguish soft tissue differences, modern ultrasound mac...
Article
Thallium-201 scintigraphy
Thallium-201 (Tl-201) is a radiopharmaceutical used for scintigraphy, primarily of the myocardium. The element thallium is treated by the body as an analog of potassium; it is produced in a cyclotron by bombarding thallium-203 with protons.
Characteristics
thallium is a monovalent cation
usua...
Article
Dose limits
Dose limits are recommended by the International Commission on Radiological Protection (ICRP). They are in place to ensure that individuals are not exposed to an unnecessarily high amount of ionizing radiation. Dose limits are a fundamental component of radiation protection, and breaching these ...
Article
Gadolinium contrast agents
Gadolinium-based contrast media (GBCM), gadolinium-based contrast agents (GBCAs), or simply gadolinium contrast agents, are molecular complexes containing the rare earth metal gadolinium, chelated to a carrier ligand. They are a type of paramagnetic contrast agent, which are the primary class of...
Article
Superb microvascular imaging (ultrasound)
Superb microvascular imaging (SMI) or microvascular flow imaging (MVI/MV-flow - the name varying by manufacturers) is a ultrasound imaging technique that aims to visualize low velocity and small diameter blood vessel flow. Unlike conventional color and power Doppler imaging, superb microvascular...
Article
T1 rho
T1 rho, also known as T1ρ or "spin lock" ('ρ' is the symbol for the Greek letter rho), is an MRI sequence that is being developed for use in musculoskeletal imaging. At the moment it is mostly investigational and does not yet have widespread clinical use.
The "rho" in the sequence name refers t...
Article
Wilhelm Roentgen
Wilhelm C Roentgen (1845-1923) was a German physicist who is celebrated globally for his discovery of x-rays on 8 November 1895.
Early life
Wilhelm Conrad Roentgen (Röntgen in German) was born on 27 March 1845 in Lennep, Germany. He attended the primary and secondary school run by Martinus Her...
Article
Magnetic particle imaging
Magnetic particle imaging (MPI) is an emerging cross-sectional imaging technique that in the future may be a new clinical imaging modality offering high resolution, dynamic functional imaging without utilizing ionizing radiation.
Physics
Magnetic particle imaging is a tracer imaging technique...
Article
Factors affecting T1
Factors affecting T1 and T2 relaxation times of different tissues are generally based on molecular motion, size and interactions.
The protons giving rise to an NMR signal are mainly those in cell water and lipids (i.e. protons that are free to move), while those in protein and solids usually do...
Article
Adrenal glands ultrasound
Adrenal glands ultrasound, is an imaging method that can provide valuable information regarding their size, shape, and structure. As a result, it can aid in diagnosing various pathological conditions related to adrenal gland function.
Techniques
Several ultrasound techniques can be employed to...
Article
Nuclear medicine
Nuclear medicine in vivo is the practice of utilizing small amounts of radioactive substances (unsealed radioactive sources) to diagnose, monitor and treat disease. The utilization of radiopharmaceuticals (radionuclide + pharmaceutical) offers a unique perspective on both disease and cancer trea...
Article
Lead equivalent personal protection equipment
Lead equivalent personal protection equipment (PPE) should be available in all radiology departments and operating suites. There are three traditional principles for ionizing radiation safety: time, distance, and shielding. It is important to remember that all three principles have a part to pla...
Article
Shear wave elastography
Shear wave elastography is a developing variation of ultrasound imaging.
The concept is similar to strain elastography, but instead of using transducer pressure to compare a shift in an ultrasound A-line (thereby measuring changes in strain), a higher intensity pulse is transmitted to produce s...
Article
Enteric contrast medium (CT)
Enteric contrast media can be given to patients before their CT exam to improve its diagnostic accuracy. Historically, a combination of oral and intravenous contrast media were always given prior to a CT abdomen. Contemporaneously, improved CT scanners mean that oral contrast agents are no longe...
Article
Tube arcing
Tube arcing occurs when there is a short-circuit within the tube, typically from the cathode to the tube envelope. The result is a temporary loss of x-ray output and a localized artifact.
A number of causes of tube arcing are recognized 1:
insulator surface flashover
insulator breakdown
va...
Article
Brown adipose tissue
Brown adipose tissue (BAT) (also known as brown fat) is one of two types of adipose tissue (the other one being white fat) important for producing thermal energy (heat, non-shivering thermogenesis), especially in the newborn. It constitutes ~5% of body mass in the newborn and tends to reduce mar...
Article
X-ray tube
An x-ray tube functions as a specific energy converter, receiving electrical energy and converting it into two other forms of energy: x-radiation (1%) and heat (99%). Heat is considered the undesirable product of this conversion process; therefore x-radiation is created by taking the energy from...
Article
Cone beam effect
Cone beam effect artifacts are seen in multidetector row CT (cone beam CT) acquisitions 1. Modern CT scanners use more detector arrays to increase the number of sections acquired per rotation. This causes the x-ray beams to become cone-shaped as opposed to fan-shaped 2. As a result instead of co...
Article
Mass attenuation coefficient
The mass attenuation coefficient (also known as the mass absorption coefficient) is a constant describing the fraction of photons removed from a monochromatic x-ray beam by a homogeneous absorber per unit mass.
It is equivalent to the linear attenuation coefficient divided by the density of the...
Article
O-arm
The O-arm is a movable CT imaging structure developed for intraoperative 3D fluoroscopic imaging. It is utilized during surgery for the identification of bony details in complex procedures such as spinal fixation or microdiscectomy.
See also
C-arm
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