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 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.

410 results found
Article

Grid cut off

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...
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Pulsatile portal venous flow

Pulsatile portal venous flow pattern can result from both physiological and pathological causes. Usually, mild pulsatility or in rare situations even marked pulsatility has been described, particularly in thin subjects with a venous pulsatility index of >0.5 with an inverse correlation to body ...
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Dixon method

The Dixon method is an MRI sequence based on chemical shift and designed to achieve uniform fat suppression. It has been gaining popularity as it has some advantages over other fat suppression techniques, namely:  suppression of fat signal is more uniform and less affected by artifacts than man...
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Diffusion tensor imaging

Diffusion tensor imaging (DTI) is an extension of diffusion weighted imaging (DWI) that allows data profiling based upon white matter tract orientation. DWI is based on the measurement of Brownian motion of water molecules. This motion is restricted by membranous boundaries. In white matter, di...
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FLAIR vascular hyperintensities

FLAIR vascular hyperintensities are hyperintensities encountered on FLAIR sequences within subarachnoid arteries related to impaired vascular haemodynamics 1,2. They are usually seen in the setting of acute ischaemic stroke and represent slow retrograde flow through collaterals (and not thrombus...
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CSF flow studies

CSF flow studies are performed using a variety of MRI techniques and are able to qualitatively assess and quantify pulsatile CSF flow. The most common technique used is time-resolved 2D phase contrast MRI with velocity encoding.  Note, when referring to CSF flow in the context of imaging we are...
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Black boundary artifact

Black boundary artifact (also known as India ink artifact, chemical shift artifact of the 2nd kind (or type 2), phase cancellation artifact, edging artifact or black line artifact) is an artificially-created black line located at fat-water interfaces such as those between muscle and fat. This re...
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Magnetic field gradient

Signal localisation for image construction in MR is based on adding a magnetic field gradient onto the main (constant) magnetic field. In 1973, Paul Lauterbur published the idea in Nature of deliberately superimposing linear field gradients on the main magnetic field. Along each gradient, the s...
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Effect of gradient strength and bandwidth on slice thickness

Slice thickness is dependent on gradient strength and bandwidth, to attain a slice thickness, a range of frequencies must be transmitted to produce resonance across the whole slice. This range of frequencies is the transmitter RF bandwidth (tBW). Slice thickness is determined by the slope of the...
Article

Phased array coil

Phased array coils are an example of a receive-only radiofrequency coil system which receives the radiofrequency signal in MRI. It involves the collection of multiple surface coils into a larger array whose individual signals are combined to create one image. As signal coils detect signal based ...
Article

Radiofrequency transmitter

The radiofrequency transmitter is the generator of the radiofrequency current which is delivered to the transmitting coil. This creates a signal which is used to excite protons in the imaging field. Radiofrequency coils can be both transmitters and receivers of the radiofrequency signal or recei...
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Volume coils

Volume coils are the transmit and receive radiofrequency coils which are used to both transmit and receive the radiofrequency signal in MRI. Most MRI scanners have what is called a body coil – which is a volume coil built into the bore of the magnet which transmits the radiofrequency for most ex...
Article

Magnetic shielding

Magnetic shielding refers to the attempt to isolate or block the magnetic field of the MRI magnet.  This can be done to prevent unwanted interference from the MRI magnet on nearby electronic devices.  This is different from radiofrequency shielding, which is the attempt to prevent the unwanted i...
Article

Fast spin echo

Fast or turbo spin echo (FSE/TSE) is an adaptation of conventional spin-echo (SE) acquisition technique designed to reduce imaging time. It has largely supplanted the original spin-echo technique due to vastly improved imaging speed. Basic spin echo sequence In a basic SE sequence, a single ec...
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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...
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Radiofrequency receiver

Radiofrequency coils are the radiofrequency receivers (as well as sometimes the transmitters) of the electromagnetic signal used in MRI. Radiofrequency coils can be either receive-only, or both receivers and transmitters of the radiofrequency signal. The receiver coils detect the electromagnetic...
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Dependence of magnetisation (proton density, field strength and temperature)

The dependence of magnetism is based on proton density (PD), field strength and temperature. There is a frictional interchange of energy between the protons and the lattice (spin-lattice interaction), such that a balanced exchange occurs between the two energy states and the thermal equilibrium ...
Article

Nuclear magnetisation

Nuclear magnetisation refers to the magnetic moment of an atomic nucleus. Magnetic resonance imaging (MRI) makes use of nuclear magnetic resonance (NMR). Some nuclei may have nuclear magnetisation depending on their nuclear charge distribution and the spin of its protons and neutrons. Nuclei wit...
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Chemical shift

The chemical shift is the local change in resonant frequency due to different chemical environments. The external magnetic field causes the electron cloud surrounding the nucleus to induce and electron current, which in turn produces a local magnetic field at the nucleus opposed in direction to ...
Article

Molecular tumbling rate effects on T1 and T2

The average rate at which molecules tumble (and therefore T1 and T2 time) is related to the molecular size. Small molecules (e.g. water/CSF) have a broad distribution of motional frequencies with poor matching with the Larmor frequency and therefore have long T1 values. Medium sized molecules (e...
Article

T1 values (1.5 T)

T1 values are a few hundred milliseconds for most tissues examined. The following are approximate T1 values (ms) of several tissues for B = 1.5 T fat = 260 liver = 500 muscle = 870 brain white matter = 780 brain grey matter = 920 CSF = 2500 Tissues that will have high signal in T1 weight...
Article

Electromagnetic induction

Electromagnetic induction is the induction of electric current via changing magnetic fields. Magnetic fields are generated by moving charges (equivalent to electrical current). Ampere’s law or Fleming’s right hand rule determines the magnitude and direction (i.e. clockwise or anti-clockwise) of ...
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Longitudinal and transverse magnetisation

Longitudinal magnetism and transverse magnetism are components of the net magnetism vector. Longitudinal magnetism Longitudinal magnetisation is the component of the net magnetisation vector parallel to the magnetic field (z-axis). This is due to a difference in the number of spins in parallel...
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Magnetic susceptibility

Magnetic susceptibility is the ability of external magnetic fields to affect the nuclei of an atom. This may also be thought of as the “magnetisability” of a material, or the extent to which a material becomes magnetised when placed in an external magnetic field. Magnetic susceptibility is rela...
Article

Magnetic dipole moment

The magnetic dipole moment is a quantity that represents the strength and orientation of the magnetic dipoles. This can be represented by the torque that a material experiences when added to a magnetic field. The stronger the magnetic moment, the stronger the magnetic field and stronger the torq...
Article

Magnetic dipole

Magnetic dipoles are the magnetic equivalent of an electric dipole, where the two charges are positive and negative, with a flow of electric charge and surrounding electric field. Magnets are bipolar, having two poles: north and south. The term dipole means two charges.  In a magnetic dipole, th...
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Magnetic field

The magnetic field describes the influence a magnet has on its surrounding area. Magnets create a magnetic field or line of force running from the magnetic north to the magnetic south pole of the magnet. Magnetic fields are the result of intrinsic magnetic moments and moving electric charges wit...
Article

Fringe field (MRI)

The fringe field is the peripheral magnetic field outside of the magnet core. It is important because it can cause interference with nearby electronic devices, such as pacemakers. Although the strength of the magnetic fields decreases with distance from the core of the magnet, the effect of the ...
Article

Physics curriculum

The physics curriculum is one of our curriculum articles and aims to be a collection of articles that represent core physics and imaging technology knowledge: physics and imaging technology: X-ray physics and imaging technology: Ultrasound physics and imaging technology: CT physics and imagi...
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Aliasing artifact (CT)

Aliasing artifact, otherwise known as undersampling, in CT refers to an error in the accuracy proponent of analogue to digital converter (ADC) during image digitisation.  Image digitisation has three distinct steps: scanning, sampling, and quantization.  When sampling, the brightness of each p...
Article

Aliasing in MRI

Aliasing in MRI, also known as wrap-around, is a frequently encountered MRI artifact that occurs when the field of view (FOV) is smaller than the body part being imaged. The part of the body that lies beyond the edge of the FOV is projected onto the other side of the image. This can be correcte...
Article

Becquerel (SI unit)

The becquerel (symbol: Bq) is the SI unit of radioactivity and is defined as one nuclear disintegration per second 1; it officially replaced the curie, the unit in the superseded cgs system, in 1975. Terminology One becquerel is a very small unit and is invariably used with a prefix, e.g. mega...
Article

Tesla (SI unit)

The tesla (symbol T) is the derived SI unit of magnetic flux density, which represents the strength of a magnetic field. One tesla represents one weber per square metre. The equivalent, and superseded, cgs unit is the gauss (G); one tesla equals 10,000 gauss.  Terminology As for all eponymous ...
Article

Doppler waveforms

Doppler waveforms are often misinterpreted and/or overlooked. They can provide great deal of information if carefully understood. Radiographic features Ultrasound Doppler The three basic arterial waveforms are 1,2: triphasic forward flow in systole reverse flow in late systole / early dia...
Article

Thyroid scan (Tc-99m)

Tc-99m [pertechnetate] thyroid scan is a functional nuclear medicine study used to assess the thyroid gland. Technique patient preparation fast for 4 hours prior to exam radiopharmaceutical Tc-99m pertechnetate dose and route of administration 3-5 mCi IV time of imaging 20 minutes after...
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Radiograph

Radiograph (or plain radiograph although the word plain is strictly superfluous) is the radiologist's preferred term for the static image generated following the passage of x-rays through the patient. Non-imaging clinicians and the lay population generally use the term "x-ray" to refer to a radi...
Article

Surface coil

Surface coils are a type of receive-only radiofrequency coil used in MRI to receive the radiofrequency signal (transmitted by the body coil). Surface coils are small and are shaped so that they can be placed near the part of anatomy being imaged. By their nature, surface coils have good signal-t...
Article

Gadolinium

Gadolinium is a metallic element (atomic number 64) that can be chelated into paramagnetic agents that are injected intravenously during MR imaging (see MRI contrast). The gadolinium ion is useful as an MRI agent because it has seven unpaired electrons, which is the greatest number of unpaired ...
Article

Nobel Prizes for radiology

The Nobel Prizes have been awarded since 1901, and several have been won for scientific discoveries with a direct or indirect importance for the development of radiology.  History The Nobel Prizes were originally established in the will of Alfred Nobel (1833-1896), a very wealthy Swedish weapo...
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Diffusion weighted imaging

Diffusion-weighted imaging (DWI) is a form of MR imaging based upon measuring the random Brownian motion of water molecules within a voxel of tissue. In general simplified terms, highly cellular tissues or those with cellular swelling exhibit lower diffusion coefficients. Diffusion is particular...
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Creatine peak

Creatine is one of the compounds examined in MR spectroscopy. It resonates at 3.0 ppm chemical shift and is found in metabolically active tissues (brain, muscle, heart) where it is important in storage and transfer of energy. It tends to be maintained at a relatively constant level, and is predo...
Article

MRI sequences (overview)

An MRI sequence is a number of radiofrequency pulses and gradients that result in a set of images with a particular appearance. This article presents a simplified approach to recognising common MRI sequences, but does not concern itself with the particulars of each sequence. For a more complete...
Article

T2 shine through

T2 shine-through refers to high signal on DWI images that is not due to restricted diffusion, but rather to high T2 signal which 'shines through' to the DWI image. T2 shine through occurs because of long T2 decay time in some normal tissue. This is most often seen with subacute infarctions due ...
Article

Gamma camera

Gamma cameras (also called scintillation cameras or Anger cameras) are the predominant nuclear medicine imaging machine currently in use. They permit the acquisition of planar images. Design From the exterior to interior a camera is comprised of 1: head cover: usually made from glass collima...
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 artefact.  A number of causes of tube arcing are recognized 1:  insulator surface flashover insulator breakdown va...
Article

SeHCAT

SeHCAT (23-seleno-25-homo-tauro-cholic acid) is a radiopharmaceutical used in the investigation of bile salt malabsorption, which is a cause of chronic diarrhoea.  Characteristics physical half-life: 118 days Uses, dosage and timings A capsule containing SeHCAT is ingested with water. The pa...
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Radiopharmaceuticals

Radiopharmaceuticals are drugs that are bound to radioactive substances.  The pharmaceutically active portion determines the activity that will be measured and the radioactive portion emits radiation that can be measured by the scanner. A number of radiopharmaceuticals are used in human imaging...
Article

Colour comet-tail artifact

The colour comet-tail artifact is an ultrasonographic sign seen in a number of situations when colour Doppler scanning is performed. Typically the artifact, which resembles the grey-scale comet-tail artifact, is seen in a situation when a small highly reflective (usually calcific) object is int...
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Arterial spin labelling MR perfusion

Arterial spin labelling (ASL) MR perfusion is an MR perfusion technique which does not require intravenous administration of contrast (unlike DSC perfusion and DCE perfusion). Instead it exploits the ability of MRI to magnetically label arterial blood below the imaging slab. The parameter most c...
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MRI physics

The basic process The way MR images are generated is complicated and is much harder to understand than plain radiography, CT and ultrasound. It has strong underpinnings in physics which must be understood before any real sense of 'how it works' is gained.  What follows is a very abbreviated, '...
Article

Thomas Edison

Thomas Edison (1847-1931) was a prolific inventor, considered by many to be the greatest inventor in American history. Edison holds around 1093 US patents; however, this article will focus on his work on fluoroscopy.  Early Life and career Thomas Alva Edison was born on the 11th February 1897 ...
Article

Radiofrequency shielding

Radiofrequency shielding serves to both prevent external interference and ensure signals generated by MR imaging do not escape the room.  MRI systems utilise electromagnetic waves to produce the soft tissue contrast characteristic to the modality. Given the ubiquity of similar waves in the exte...
Article

Doppler shift

Doppler shift or Doppler effect is defined as the change in frequency of sound wave due to a reflector moving towards or away from an object, which in the case of ultrasound is the transducer. Doppler equation  F = 2fo(v/c)cos(Q) where: F is Doppler frequency shift fo is transmitted frequen...
Article

Faraday cage

A Faraday cage is a conductive enclosure used to shield the inner space from electromagnetic interference. In MR imaging, this type of structure provides radiofrequency shielding to the scanning room to minimise occurrence of interference-associated imaging artifact. Operation The cage is usua...
Article

X-ray artifacts

Artifacts can present in a variety of ways including abnormal shadow noted on a radiograph or degraded image quality and have been produced by artificial means from hardware failure, operator error and software (post-processing) artifacts.  There are common and distinct artifacts for film, comp...
Article

Off focus radiation

During x-ray generation, off focus radiation refers to emission of x-ray photons which originate outside of the anode focal spot. Essentially a form of scatter, photons produced in this manner may result in blurring and are of no use for diagnostic purposes. They are shielded as much as possible...
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Multipath artifact

A multipath artefact is an ultrasound beam artefact in which the primary beam reflects off anatomy at an angle, resulting in a portion of the beam returning to the transducer, whilst another portion takes a longer duration as it reflects a second structure. This phenomenon results in a propagati...
Article

Radiofrequency coils

Radiofrequency coils (RF coils) are the "antennae" of the MRI system, broadcasting the RF signal to the patient and/or receiving the return signal. RF coils can be receive-only, in which case the body coil is used as a transmitter; or transmit and receive (transceiver). Surface coils are the si...
Article

Slew rate

Slew rate refers to the speed at which a gradient can be turned on and off, and is defined as the maximum gradient strength of the gradient divided by the rise time.  MR imaging is a product of magnetic field gradients which are created by magnetic gradient coils. The quality and performance of...
Article

MRI artifacts

MRI artifacts are numerous and give an insight into the physics behind each sequence. Some artifacts affect the quality of the MRI exam while others do not affect the diagnostic quality but may be confused with pathology. When encountering an unfamiliar artifact, it is useful to systematically ...
Article

Sievert (SI unit)

The sievert (symbol Sv) is the SI unit of dose equivalent and is dimensionally-equivalent to one joule per kilogram. The sievert represents the stochastic effects of ionising radiation as adjusted by a tissue weighting factor to account for differing responses of different human tissues to ionis...
Article

Paul Lauterbur

Paul C Lauterbur (1929-2007) is remembered as one of the co-developers of MRI, for which he was co-awarded the Nobel Prize for Medicine or Physiology in 2003, with Peter Mansfield. Early life Paul Christian Lauterbur was born on May 6th 1929 in Sidney, Ohio.In 1951 he graduated with a bachelor...
Article

Milliampere-seconds (mAs)

Milliampere-seconds more commonly known as mAs is a measure of radiation produced (milliamperage) over a set amount of time (seconds) via an x-ray tube. It directly influences the radiographic density, when all other factors are constant. An increase in current (mA) results in a higher producti...
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Units of measurement

For units of measurement the use of SI units in articles and cases on Radiopaedia.org is preferred. This is in line with best scientific practice and helps maintain consistency across the site. Terminology By scientific convention: for eponymous units, the full name is not capitalised, but t...
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Artifact

Artifacts in radiology refer to something seen on an image that is not present in reality but appears due to a quirk of the modality itself. The commonest artifact seen in radiology is image noise, which is inherent to every modality and technique, and can be mitigated but never eliminated. As...
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Godfrey Hounsfield

Sir Godfrey N Hounsfield (1919-2004) pioneered the CT scanner making him one of the greats in the history of radiology. For his work, he received the Nobel Prize in Physiology or Medicine in 1979. This was remarkable because he had had no previous experience of working in the medical field but w...
Article

Hounsfield unit

Hounsfield units (HU) are a dimensionless unit universally used in computed tomography (CT) scanning to express CT numbers in a standardised and convenient form. Hounsfield units, created by and named after Sir Godfrey Hounsfield, are obtained from a linear transformation of the measured attenua...
Article

Ring artifact

Ring artifacts are a CT phenomenon that occur due to miscalibration or failure of one or more detector elements in a CT scanner. They occur close to the isocentre of the scan and are usually visible on multiple slices at the same location. They are a common problem in cranial CT. The remedy is ...
Article

Hunter's angle

Hunter's angle (HA) is a term coined from a neurosurgeon, C Hunter Shelden, at Huntington Medical Research Institutes. He placed his comb on the spectrum at approximately a 45° angle and connected several of the peaks. If the angle and peaks roughly corresponded to the 45° angle, the curve was c...
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MR spectroscopy

MR spectroscopy (MRS) allows tissue to be interrogated for the presence and concentration of various metabolites. Grossman and Yousem said "If you need this to help you, go back to page 1; everything except Canavan has low NAA, high choline" 1. This is perhaps a little harsh, however it is fair ...
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Peter Mansfield

Sir Peter Mansfield (1933-2017) was an English physicist best known for his research into, and development of MRI, for which he was awarded the Nobel Prize in Physiology or Medicine in 2003 1. Early life Peter Mansfield was born on the 9th October, 1933 in Lambeth, London. His father, Sidney w...
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MRI contrast agents

MRI contrast agents have become an indispensable part of modern magnetic resonance imaging. Although MRI was initially hoped to provide a means of making definitive diagnoses non-invasively, it has been found that the addition of contrast agents in many cases improves sensitivity and/or specific...
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MRI contrast agent safety

Though considered safer than the frequently used iodinated contrast agents used in x-ray and CT studies, there are safety issues with MRI contrast agents as well. Paramagnetic metal ions suitable as MRI contrast agents are all potentially toxic when injected IV at or near doses needed for clinic...
Article

Fat-water swapping artifact

Fat-water swapping artifact is seen in a significant proportion of fat/water suppressed sequences using the Dixon method. The artifact follows a computational error in areas of field inhomogeneity resulting in incorrectly determining whether a voxel contains water or fat. The images have geogra...
Article

Cassette

Cassettes are rigid holders used in conventional and computed radiography (CR) for the screen film system and imaging plate respectively.  The back side of the cassette has a rubber or felt for adequate contact between screen film system or with the imaging plate. The front is made of low atomi...
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Magnetic field homogeneity

One of the key concepts in assessing the quality of a magnet is that of magnetic field homogeneity, as it will relate to image quality and the presence of artifacts.Field homogeneity refers to the uniformity of the main magnetic field when no patient is present, measured in parts per million (pp...
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PD weighted spin-echo images

Proton-density weight images are related to the number of nuclei in the area being imaged (number of hydrogen protons), as opposed to the magnetic characteristics of the hydrogen nuclei. They are produced from the first echo. PD weight images result when the contribution of both T1 and T2 contra...
Article

Magnetic shimming

Magnetic shimming refers to the process of reducing magnetic field inhomogeneities. It is an important aspect of optimising image quality. Field inhomogeneities can be the result by both intrinsic magnet properties and the surrounding environment of the MR magnet – such as the presence of nearby...
Article

MRI pulse sequence abbreviations

This article contains a list of commonly and less commonly used MRI pulse sequence abbreviations and their meaning. If available, an explanation is included in a separate article. spin echo sequences (SE) T1: T1 weighted IR: inversion recovery T2 : T2 weighted RARE: rapid acquisition with r...
Article

T2 washout

T2 washout is a phenomenon encountered on diffusion weighted imaging (DWI) which results in DWI images (e.g. B = 1000) appearing normal despite abnormal ADC maps.  For the phenomenon to occur a particular combination of ADC and T2 signal intensity is required.  increased T2 signal facilitated...
Article

Short tau inversion recovery

Short tau inversion recovery (STIR), also known as short TI inversion recovery, is a fat suppression technique with an inversion time TI = ln(2)·T1fat,where the signal of fat is zero. This equates to approximately 140 ms at 1.5 T. To distinguish two tissue components with this technique, their ...
Article

Line focus principle

Line focus principle explains the relationship between the anode surface and the effective focal spot size. Basic concept The focal spot is the area of the target upon which the electron beam impinges. The energy of the electrons in the electron beam is mostly converted into heat (approximatel...
Article

Direct digital radiography

Direct digital radiography (DDR) refers to direct digital registration of the image at the detector with no intermediate processing step required to obtain the digital signals as in computed radiography (CR). There are two primary methods of conversion are indirect and direct: Indirect convers...
Article

Rem (unit)

The rem (an acronym for roentgen equivalent man) was the cgs unit of effective dose and was officially replaced by the sievert many years ago.  One rem was a large quantity of radiation, and therefore for practical day to day use the millirem (mrem), representing one-thousandth of a rem, was us...
Article

Computed tomography

Computed tomography (CT) scanning, also known as, especially in the older literature and textbooks, computerised axial tomography (CAT) scanning, is a diagnostic imaging procedure that uses x-rays to build cross-sectional images ("slices") of the body. Cross-sections are reconstructed from measu...
Article

X-ray film

X-ray film displays the radiographic image and consists of emulsion (single or double) of silver halide (silver bromide (AgBr) is most common) which when exposed to light, produces a silver ion (Ag+) and an electron. The electrons get attached to the sensitivity specks and attract the silver ion...
Article

Intensifying screen

Intensifying screens are used in the x-ray cassette to intensify the effect of the x-ray photon by producing a larger number of light photons. It decreases the mAs required to produce a particular density and hence decreases the patient dose significantly. In cassettes, which use double emulsion...
Article

Photostimulable phosphors

Photostimulable phosphors (PSP) are materials that store absorbed energy within excited electrons and release it in the form of light on exposure to laser energy. The process can be broken up as follows 1: an x-ray or gamma photon interacts with the PSP and releases high energy secondary elect...
Article

Twinkle artifact

Twinkle artifact is the result of intrinsic machine noise seen with colour Doppler ultrasound 1. It occurs as a focus of alternating colours on Doppler signal behind a reflective object (such as calculi), which gives the appearance of turbulent blood flow 2. It appears with or without an associa...
Article

Historical aspects of ultrasound in medicine

The first written document dealing with the use of waves in spatial orientation dates back to 1794, when Lazaro Spallanzani (“Opus coli di fisica”), analyzed the basic mechanisms of spatial orientation of the bats, proposing other mechanisms of spatial orientation than the visual – ophthalmic sy...
Article

Modulation transfer function

The modulation transfer function (MTF) is the spatial frequency response of an imaging system or a component. It is the contrast at a given spatial frequency relative to low frequencies. On the radiogram, objects having different sizes and opacity are displayed with different gray-scale values....
Article

Fetal dosimetry

NB - Please consult original article(s) and discuss with you local radiology department/radiation physicist before making any clinical decision. Although exposure to the gravid uterus is to be avoided when ever possible, and only deliberately performed after careful weighing up of the pros and ...
Article

Antoine Henri Becquerel

Antoine H Becquerel (1852-1908) was a French scientist renowned for his work and subsequent discovery into the evidence of radioactivity for which he was awarded a Nobel prize. Early life Antoine Henri Becquerel was born on the 15th December 1852 in Paris, France to a family of nobility and ac...

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