Flat Detectors are an alternative to Image Intensifiers. The advantages of this technology include: lower patient dose and increased image quality because the X-rays are always pulsed, and no deterioration of the image quality over time.  Despite FPD being at a higher cost than II/TV systems, the noteworthy changes in the physical size and accessibility for the patients is worth it, especially when dealing with paediatric patients. [ 9 ]


X-ray Markers , also known as: anatomical side markers, [ 1 ]   Pb  markers,  lead  markers,  x-ray  lead markers, or radiographic film identification markers, are used to mark x-ray films, both in  hospitals  and in industrial workplaces (such as on  aeroplane  parts and  motors ). They are used on radiographic images to determine anatomical side of body, date of the procedure, and may include patients name.


Most X-ray markers consist of a right and a left letter with the  radiographer's  initials. There are also available markers to indicate positioning of the body e.g. supine, or as to time when performing procedures such as an  Intravenous pyelogram .


It has been suggested that radiographic markers are a potential  fomite  for harmful bacteria such as  MRSA , and that they should be cleaned on a regular basis; this, however, is not always done. [ 2 ]


X-ray motion analysis  is a technique used to track the movement of objects using  X-rays . This is done by placing the subject to be imaged in the center of the X-ray beam and recording the motion using an  image intensifier  and a  high-speed camera , allowing for high quality videos sampled many times per second. Depending on the settings of the X-rays, this technique can visualize specific structures in an object, such as  bones  or  cartilage . X-ray motion analysis can be used to perform  gait analysis , analyze  joint  movement, or record the motion of bones obscured by  soft tissue . The ability to measure skeletal motions is a key aspect to one's understanding of vertebrate  biomechanics ,  energetics , and  motor control . [ 1 ]


Many X-ray studies are performed with a single X-ray emitter and camera. This type of imaging allows for tracking movements in the two-dimensional plane of the X-ray. Movements are performed parallel to the camera's imaging plane in order for the motion to be accurately tracked. [ 2 ]  In  gait analysis , planar X-ray studies are done in the  sagittal plane  to allow for highly accurate tracking of large movements. [ 3 ]  Methods have been developed to allow for estimating all  six degrees of freedom  of movement from a planar X-ray and a model of the tracked object. [ 4 ] [ 5 ]


Few movements are truly planar; [ 2 ]  planar X-ray imaging can capture the majority of movement, but not all of it. Accurately capturing and quantifying all three dimensions of movement requires a biplanar imaging system. [ 2 ]  Biplanar imaging is difficult to perform because many facilities have access to only one X-ray emitter. [ 1 ]  With the addition of a second X-ray and camera system, the 2-D plane of imaging expands to a 3-D volume of imaging at the intersection of the X-ray beams. Because the volume of imaging is at the intersection of two X-ray beams, the overall size of it is limited by the area of the X-ray emitters.


Motion capture techniques often use reflective markers for the image capturing. In X-ray imaging, markers that appear opaque in the X-ray images are utilized. [ 2 ]  This frequently involves using radio-opaque spheres attached to the subject. Markers can be implanted in the subject's bones, which would then appear visible in the X-ray images. [ 6 ]  This method requires surgical procedures for implanting and a healing period before the subject can undergo a motion analysis. For accurate 3-D tracking, at least three markers need to be implanted onto each bone to be tracked. [ 7 ]  Markers can also be placed on the subject's skin to track the motion of the underlying bones, though markers placed on the skin are sensitive to skin movement artifacts. These are errors in the measurement of the location of a skin-placed marker compared to a bone-implanted marker. This occurs at locations where soft tissue moves more freely than the overlaying skin. [ 2 ] [ 4 ] [ 6 ] [ 8 ]  The markers are then tracked relative to the X-ray camera(s) and the motions are mapped to the local anatomical bodies.


Emerging techniques and software are allowing for motion to be tracked without the need for radio-opaque markers. By using a 3-D model of the object being tracked, the object can be overlaid on the images of the X-ray video at each frame. [ 7 ]  The translations and rotations of the model, as opposed to a set of markers, are then tracked relative to the X-ray camera(s). [ 7 ]  Using a local coordinate system, these translations and rotations can then be mapped to standard anatomical movements. The 3-D model of the object is generated from any 3-D imaging technique, such as an MRI or CT scan. Markerless tracking has the benefit of being a non-invasive tracking method, avoiding any complications due to surgeries. One difficulty comes from generating the 3-D model in animal studies, as the animals are required to be sedated or sacrificed for the scan.


In planar X-ray imaging, the motions of the markers or bodies are tracked in a specialized software. An initial location guess is supplied by the user for the markers or bodies. The software, depending on its capabilities, requires the user to manually locate the markers or bodies for each frame of the video, or can automatically track the locations throughout the video. The automatic tracking has to be monitored for accuracy and may require manually relocating the markers or bodies. After the tracking data is generated for each marker or body of interest, the tracking is applied to the local anatomical bodies. For example, markers placed at the hip and knee would track the motion of the femur. Using knowledge of the local anatomy, these motions can then be translated into  anatomical terms of motion  in the plane of the X-ray. [ 2 ]


In biplanar X-ray imaging, the motions are also tracked in a specialized software. Similar to planar analysis, the user provides an initial location guess and either tracks the markers or bodies manually or the software can automatically track them. However, biplanar analysis requires that all tracking be done on both video frames at the same time, positioning the object in free space. Both X-ray cameras have to be calibrated using an object of known volume. This allows the software to locate the cameras' positions relative to each other and then allows the user to position the 3-D model of the object in line with both video frames. The tracking data is generated for each marker or body and then applied to the local anatomical bodies. The tracking data is then further defined as  anatomical terms of motion  in free space. [ 7 ]


X-ray motion analysis can be used in  human gait analysis  to measure the  kinematics  of the lower limbs. Treadmill gait or overground gait [ 9 ]  can be measured depending on the mobility of the X-ray system. Other types of movements, such as a jump-cut maneuver, [ 10 ]  have also been recorded. By combining X-ray motion analysis with  force platforms , a  joint torque analysis  can be performed. [ 10 ] [ 11 ]   Rehabilitation  is an important application of X-ray motion analysis. X-ray imaging has been used for medical diagnostic purposes since shortly after its discovery in 1895. [ 12 ]  X-ray motion analysis can be utilized in joint imaging or analyzing joint-related diseases. It has been used to quantify  osteoarthritis  in the knee, [ 13 ]  estimate  knee cartilage  contact areas, [ 14 ]  and analyze the results of rotator cuff repair by imaging the  shoulder joint , [ 15 ]  among other applications.


Animal locomotion  can also be analyzed with X-ray imaging. As long as the animal can be placed between the X-ray emitter and the camera, the subject can be imaged. Examples of gaits that have been studied are rats, [ 8 ] [ 16 ]  guineafowl, [ 17 ]  horses, [ 6 ]  bipedal birds, [ 18 ]  and frogs, [ 11 ]  among others. Aside from locomotion, X-ray motion analysis has been utilized in the study and research of other moving morphology analyses, such as pig mastication [ 2 ]  and movement of the  temporomandibular joint  in rabbits. [ 19 ]


X-ray optics  is the branch of  optics  dealing with  X-rays , rather than  visible light . It deals with focusing and other ways of manipulating the X-ray beams for research techniques such as  X-ray diffraction ,  X-ray crystallography ,  X-ray fluorescence ,  small-angle X-ray scattering ,  X-ray microscopy ,  X-ray phase-contrast imaging , and  X-ray astronomy .


X-rays and visible light are both  electromagnetic waves , and propagate in space in the same way, but because of the much higher  frequency  and  photon  energy of X-rays they interact with matter very differently. Visible light is easily redirected using  lenses  and  mirrors , but because the real part of the  complex refractive index  of all materials is very close to 1 for X-rays, [ 1 ]  they instead tend to initially penetrate and eventually get absorbed in most materials without significant change of direction.


There are many different techniques used to redirect X-rays, most of them changing the directions by only minute angles. The most common principle used is  reflection  at  grazing incidence  angles, either using  total external reflection  at very small angles or  multilayer coatings . Other principles used include  diffraction  and  interference  in the form of  zone plates ,  refraction  in  compound refractive lenses  that use many small X-ray lenses in series to compensate by their number for the minute index of refraction, and  Bragg reflection  from a crystal plane in flat or bent  crystals .


X-ray beams are often  collimated  (reduced in size) using pinholes or movable slits typically made of tungsten or some other high- Z  material. Narrow parts of an X-ray spectrum can be selected with  monochromators  based on one or multiple Bragg reflections by crystals. X-ray spectra can also be manipulated by passing the X-rays through a  filter  that typically reduces the low-energy part of the spectrum, and possibly parts above  absorption edges  of the  elements  used for the filter.


Analytical X-ray techniques such as X-ray crystallography, small-angle X-ray scattering,  wide-angle X-ray scattering , X-ray fluorescence,  X-ray spectroscopy  and  X-ray photoelectron spectroscopy  all benefit from high X-ray flux densities on the samples being investigated. This is achieved by focusing the divergent beam from the  X-ray source  onto the sample using one of several possible focusing optical components. This is also useful for  scanning probe  techniques such as  scanning transmission X-ray microscopy  and scanning X-ray fluorescence imaging.


Polycapillary lenses are arrays of small hollow glass tubes that guide the X-rays with many  total external reflections  on the inside of the tubes. [ 2 ]
The array is tapered so that one end of the capillaries points at the X-ray source and the other at the sample. Polycapillary optics are achromatic and thus suitable for scanning fluorescence imaging and other applications where a broad X-ray spectrum is useful. They collect X-rays efficiently for  photon energies  of 0.1 to 30  keV  and can achieve gains of 100 to 10000 in flux over using a  pinhole  at 100 mm from the X-ray source. [ 3 ]
Since only X-rays entering the capillaries within a very narrow angle will be totally internally reflected, only X-rays coming from a small spot will be transmitted through the optic. Polycapillary optics cannot image more than one point to another, so they are used for illumination and collection of X-rays.


Zone plates consist of a substrate with concentric zones of a phase-shifting or absorbing material with zones getting narrower the larger their radius. The zone widths are designed so that a transmitted wave gets  constructive interference  in a single point giving a focus. [ 4 ]  Zone plates can be used as  condensers  to collect light, but also for direct full-field imaging in e.g. an X-ray microscope. Zone plates are highly  chromatic  and usually designed only for a narrow energy span, making it necessary to have  monochromatic  X-rays for efficient collection and high-resolution imaging.


Since refractive indices at X-ray wavelengths are so close to 1, the  focal lengths  of normal  lenses  get impractically long. To overcome this, lenses with very small  radii of curvature  are used, and they are stacked in long rows, so that the combined  focusing power  becomes appreciable. [ 5 ]  Since the refractive index is less than 1 for X-rays, these  lenses must be concave  to achieve focusing, contrary to visible-light lenses, which are  convex  for a focusing effect. Radii of curvature are typically less than one millimeter, making the usable X-ray beam width at most about 1 mm. [ 6 ]  To reduce the  absorption  of X-rays in these stacks, materials with very low atomic number such as  beryllium  or  lithium  are often used. Lenses from other materials are also available: radiation-resistant polymer (Epoxy based) such as  SU-8 ,  nickel  and  silicon . Since the refractive index depends strongly on X-ray wavelength, these lenses are highly  chromatic , and the variation of the focal length with wavelength must be taken into account for any application.


The basic idea is to  reflect  a beam of X-rays from a surface and to measure the intensity of X-rays reflected in the specular direction (reflected angle equal to incident angle). It has been shown that a reflection off a parabolic mirror followed by a reflection off a hyperbolic mirror leads to the focusing of X-rays. [ 7 ]  Since the incoming X-rays must strike the tilted surface of the mirror, the collecting area is small. It can, however, be increased by nesting arrangements of mirrors inside each other. [ 8 ]


The ratio of reflected intensity to incident intensity is the  X-ray reflectivity  for the surface. If the interface is not perfectly sharp and smooth, the reflected intensity will deviate from that predicted by the  Fresnel reflectivity  law; the deviations can be analyzed to obtain the density profile of the interface normal to the surface. For films with multiple layers, X-ray reflectivity may show oscillations with wavelength, analogous to the  Fabry–Pérot effect . These oscillations can be used to infer layer thicknesses and other properties.


In X-ray diffraction a beam strikes a crystal and  diffracts  into many specific directions. The angles and intensities of the diffracted beams indicate a three-dimensional density of  electrons  within the crystal. X-rays produce a diffraction pattern because their  wavelength  typically has the same  order of magnitude  (0.1–10.0 nm) as the spacing between the atomic planes in the crystal.


Each atom re-radiates a small portion of an incoming beam's intensity as a spherical wave. If the atoms are arranged symmetrically (as is found in a crystal) with a separation  d , these spherical waves will be  in phase  (add constructively) only in directions where their path-length difference 2 d  sin  θ  is equal to an integer multiple of the wavelength  λ . The incoming beam therefore appears to have been deflected by an angle 2 θ , producing a  reflection  spot in the  diffraction pattern .


X-ray diffraction is a form of  elastic scattering  in the forward direction; the outgoing X-rays have the same energy, and thus the same wavelength, as the incoming X-rays, only with altered direction. By contrast,  inelastic scattering  occurs when energy is transferred from the incoming X-ray to an inner-shell electron, exciting it to a higher  energy level . Such inelastic scattering reduces the energy (or increases the wavelength) of the outgoing beam. Inelastic scattering is useful for probing such  electron excitation , but not in determining the distribution of atoms within the crystal.


Longer-wavelength photons (such as  ultraviolet   radiation ) would not have sufficient resolution to determine the atomic positions. At the other extreme, shorter-wavelength photons such as  gamma rays  are difficult to produce in large numbers, difficult to focus, and interact too strongly with matter, producing  particle–antiparticle pairs .


Similar diffraction patterns can be produced by scattering electrons or  neutrons . X-rays are usually not diffracted from atomic nuclei, but only from the electrons surrounding them.


X-ray  interference  due to the  superposition  of two or more X-ray  waves  produces a new wave pattern. X-ray interference usually refers to the interaction of waves that are correlated or  coherent  with each other, either because they come from the same source or because they have the same or nearly the same  frequency .


Two non- monochromatic  X-ray waves are only fully coherent with each other if they both have exactly the same range of  wavelengths  and the same  phase  differences at each of the constituent wavelengths.


The total phase difference is derived from the sum of the path difference and the initial phase difference (if the X-ray waves are generated from two or more different sources). It can then be concluded whether the X-ray waves reaching a point are  in phase  (constructive interference) or  out of phase  (destructive interference).


There are a variety of techniques used to funnel X-ray photons to the appropriate location on an X-ray detector:


Most X-ray optical elements (with the exception of grazing-incidence mirrors) are very small and must be designed for a particular  incident angle  and energy, thus limiting their applications in divergent  radiation . As of 2009 [update] , although the technology had advanced rapidly, its practical uses outside research were limited. Efforts were ongoing to introduce X-ray optics in medical  X-ray imaging . For instance, one of the applications showing greater promise is in enhancing both the  contrast  and  resolution  of  mammographic  images, compared to conventional  anti-scatter grids . [ 16 ]  Another application is to optimize the energy distribution of the X-ray beam to improve  contrast-to-noise ratio  over conventional energy filtering. [ 17 ]


X-ray mirrors can be made of glass, ceramic, or metal foil, coated by a reflective layer. [ 1 ]  The most commonly used reflective materials for X-ray mirrors are  gold  and  iridium . Even with these the critical reflection angle is energy-dependent. For gold at 1 keV, the critical reflection angle is 2.4°. [ 18 ]


The use of X-ray mirrors simultaneously requires:


No material has substantial reflection for X-rays, except at very small grazing angles. Multilayers enhance the small reflectivity from a single boundary by adding the small reflected amplitudes from many boundaries coherently in phase. For example, if a single boundary has a reflectivity of  R  = 10 −4  (amplitude  r  = 10 −2 ), then the addition of 100 amplitudes from 100 boundaries can give reflectivity  R  close to one. The period Λ of the multilayer that provides the in-phase addition is that of the standing wave produced by the input and output beam, Λ =  λ /2 sin  θ , where  λ  is the wavelength, and 2 θ  the half angle between the two beams. For  θ  = 90°, or reflection at normal incidence, the period of the multilayer is Λ =  λ /2. The shortest period that can be used in a multilayer is limited by the size of the atoms to about 2 nm, corresponding to wavelengths above 4 nm. For shorter wavelength a reduction of the incidence angle  θ  toward more grazing has to be used.


The materials for multilayers are selected to give the highest possible reflection at each boundary and the smallest absorption or the propagation through the structure. This is usually achieved by light, low-density materials for the spacer layer and a heavier material that produces high contrast. The absorption in the heavier material can be reduced by positioning it close to the nodes of the standing-wave field inside the structure. Good low-absorption spacer materials are Be, C, B, B 4 C and Si. Some examples of the heavier materials with good contrast are W, Rh, Ru and Mo.


Applications include:


Mo/Si is the material selection used for the near-normal incidence reflectors for EUV lithography.


An X-ray mirror optic for the  NuSTAR  space telescope working at 79 keV (hard, i.e. high-energy X-radiation) was made using multilayered coatings, computer-aided manufacturing, and other techniques. [ 19 ]  The mirrors use a  tungsten / silicon  (W/Si) or  platinum / silicon-carbide  (Pt/SiC) multicoating on  slumped  glass, allowing a  Wolter telescope  design. [ 19 ]


An  X-ray telescope  ( XRT ) is a  telescope  that is designed to observe remote objects in the  X-ray  spectrum. X-rays are absorbed by the  Earth's atmosphere , so instruments to detect X-rays must be taken to high altitude by  balloons ,  sounding rockets , and  satellites .


The basic elements of the telescope are the  optics  (focusing or  collimating ), that collects the  radiation  entering the telescope, and the  detector , on which the radiation is collected and measured. A variety of different designs and technologies have been used for these elements.


Many X-ray telescopes on satellites are compounded of multiple small detector-telescope systems whose capabilities add up or complement each other, and additional fixed or removable elements [ 1 ] [ 2 ]  (filters, spectrometers) that add functionalities to the instrument.


X-ray telescopes were first used for astronomy to observe the  Sun , which was the only source in the sky bright enough in X-rays for those early telescopes to detect. Because the Sun is so bright in X-rays, early X-ray telescopes could use a small focusing element and the X-rays would be detected with photographic film. The first X-ray picture of the Sun from a rocket-borne telescope was taken by John V. Lindsay of the NASA  Goddard Space Flight Center  and collaborators in 1963. The first orbiting X-ray telescope flew on  Skylab  in the early 1970s and recorded more than 35,000 full-disk images of the Sun over a 9-month period. [ 3 ]


First specialised X-ray satellite,  Uhuru , was launched by  NASA  in 1970. It detected 339 X-ray sources in its 2.5-year lifetime. [ 4 ]


The  Einstein Observatory , launched in 1978, was the first imaging X-ray observatory. It obtained high-resolution X-ray images in the energy range from 0.1 to 4 keV of stars of all types, supernova remnants, galaxies, and clusters of galaxies. Another large project was  ROSAT  (active from 1990 to 1999), which was a heavy X-ray space observatory with focusing X-ray optics, and European  EXOSAT . [ 4 ]


The  Chandra X-Ray Observatory  was launched by NASA in 1999 and is operated for more than 25 years in a high elliptical orbit, returning thousands 0.5 arc-second images and high-resolution spectra of all kinds of astronomical objects in the energy range from 0.5 to 8.0 keV. Chandra's resolution is about 50 times superior to that of ROSAT. [ 3 ]


Satellites in use today include  ESA 's  XMM-Newton observatory  (low to mid energy X-rays 0.1-15 keV),  NASA 's  Swift  observatory,  Chandra  observatory and  IXPE  telescope.  JAXA  has launched the  XRISM  telescope, while  ISRO  has launched  Aditya-L1  and  XPoSat .


The  GOES 14  spacecraft carries on board a Solar X-ray Imager to monitor the Sun's X-rays for the early detection of solar flares, coronal mass ejections, and other phenomena that impact the geospace environment. [ 5 ]  It was launched into orbit on June 27, 2009, at 22:51 GMT from  Space Launch Complex 37B  at the  Cape Canaveral Air Force Station .


The Chinese  Hard X-ray Modulation Telescope  was launched on June 15, 2017 to observe black holes, neutron stars, active galactic nuclei and other phenomena based on their X-ray and gamma-ray emissions. [ 6 ]


The  Lobster-Eye X-ray Satellite  was launched on 25 July 2020 by  CNSA  making it is the first in-orbit telescope to utilize the  lobster-eye  imaging technology of ultra-large field of view imaging to search for dark matter signals in the x-ray energy range. [ 7 ]   Lobster Eye Imager for Astronomy  was launched on 27 July 2022 as a technology demonstrator for  Einstein Probe , launched on January 9, 2024, dedicated to time-domain  high-energy astrophysics . [ 8 ]  The  Space Variable Objects Monitor  observatory launched on 22 June 2024 is directed towards studying the explosions of massive stars and analysis of  gamma-ray bursts . [ 9 ]


A  soft X-ray  solar imaging telescope is on board the  GOES-13  weather satellite launched using a  Delta IV  from  Cape Canaveral  LC37B on May 24, 2006. [ 10 ]  However, there have been no GOES 13 SXI images since December 2006.


The Russian-German  Spektr-RG  carries the  eROSITA  telescope array as well as the  ART-XC  telescope. It was launched by  Roscosmos  on 13 July 2019 from  Baikonur  and began collecting data in October 2019.


The most common methods used in X-ray optics are  grazing incidence mirrors  and  collimated apertures . Only three geometries that use  grazing incidence reflection  of X-rays to produce X-ray images are known:  Wolter system ,  Kirkpatrick-Baez system , and  lobster-eye optics . [ 11 ]


A simple parabolic mirror was originally proposed in 1960 by  Riccardo Giacconi  and  Bruno Rossi , the founders of extrasolar X-ray astronomy. This type of mirror is often used as the primary reflector in an optical telescope. However, images of off-axis objects would be severely blurred. The German physicist  Hans Wolter  showed in 1952 that the reflection off a combination of two elements, a paraboloid followed by a hyperboloid, would work far better for X-ray astronomy applications. Wolter described three different imaging configurations, the  Types I, II, and III . The design most commonly used by X-ray astronomers is the Type I since it has the simplest mechanical configuration. In addition, the Type I design offers the possibility of nesting several telescopes inside one another, thereby increasing the useful reflecting area. The Wolter Type II is useful only as a narrow-field imager or as the optic for a dispersive spectrometer. The Wolter Type III has never been employed for X-ray astronomy. [ 12 ]


With respect to collimated optics, focusing optics allow:


The mirrors can be made of  ceramic  or  metal foil [ 13 ]  coated with a thin layer of a reflective material (typically  gold  or  iridium ). Mirrors based on this construction work on the basis of  total reflection  of light at grazing incidence.


This technology is limited in energy range by the inverse relation between critical angle for total reflection and radiation energy. The limit in the early 2000s with  Chandra  and  XMM-Newton  X-ray  observatories  was about 15 kilo- electronvolt  (keV) light. [ 14 ]  Using new multi-layered coated mirrors, the X-ray mirror for the  NuSTAR  telescope pushed this up to 79 keV light. [ 14 ]  To reflect at this level, glass layers were multi-coated with  tungsten  (W)/ silicon  (Si) or  platinum  (Pt)/ silicon carbide (SiC). [ 14 ]


While earlier X-ray telescopes were using simple collimating techniques (e.g. rotating collimators, wire collimators), [ 15 ]  the technology most used in the present day employs coded aperture masks. This technique uses a flat aperture patterned grille in front of the detector. This design gives results that are less sensitive than focusing optics; also the imaging quality and identification of source position is much poorer. Though this design offers a larger  field of view  and can be employed at higher energies, where grazing incidence optics become ineffective. Also the imaging is not direct, but the image is rather reconstructed by post-processing of the signal.


X-rays has a huge span in wavelength (~8 nm - 8 pm), frequency (~50 PHz - 50 EHz) and energy (~0.12 - 120 keV). In terms of temperature, 1 eV = 11,604 K. Thus X-rays (0.12 to 120 keV) correspond to 1.39 × 10 6  to 1.39 × 10 9  K. From 10 to 0.1 nanometers (nm) (about 0.12 to 12  keV ) they are classified as soft X-rays, and from 0.1 nm to 0.01 nm (about 12 to 120 keV) as hard X-rays.


Closer to the visible range of the electromagnetic spectrum is the  ultraviolet . The draft ISO standard on determining solar  irradiances  (ISO-DIS-21348) [ 16 ]  describes the ultraviolet as ranging from ~10 nm to ~400 nm. That portion closest to X-rays is often referred to as the "extreme ultraviolet" ( EUV  or XUV). When an EUV photon is absorbed,  photoelectrons  and  secondary electrons  are generated by  ionization , much like what happens when X-rays or electron beams are absorbed by matter. [ 17 ]


The distinction between X-rays and  gamma rays  has changed in recent decades. Originally, the electromagnetic radiation emitted by  X-ray tubes  had a longer  wavelength  than the radiation emitted by  radioactive   nuclei  (gamma rays). [ 18 ]  So older literature distinguished between X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10 −11  m, defined as gamma rays. [ 19 ]  However, as shorter wavelength continuous spectrum "X-ray" sources such as  linear accelerators  and longer wavelength "gamma ray" emitters were discovered, the wavelength bands largely overlapped. The two types of radiation are now usually distinguished by their origin: X-rays are emitted by electrons outside the nucleus, while gamma rays are emitted by the  nucleus . [ 18 ] [ 20 ] [ 21 ] [ 22 ]


Although the more energetic X-rays,  photons  with an energy greater than 30  keV  (4,800  a J), can penetrate the  Earth's atmosphere  at least for distances of a few meters, the Earth's atmosphere is thick enough that virtually none are able to penetrate from outer space all the way to the Earth's surface. X-rays in the 0.5 to 5 keV (80 to 800 aJ) range, where most celestial sources give off the bulk of their energy, can be stopped by a few sheets of paper; 90% of the photons in a beam of 3 keV (480 aJ) X-rays are absorbed by traveling through just 10 cm of air.


A  proportional counter  is a type of  gaseous ionization detector  that counts  particles  of  ionizing radiation  and measures their energy. It works on the same principle as the  Geiger-Müller counter , but uses a lower operating  voltage . All X-ray proportional counters consist of a windowed gas cell. [ 23 ]  Often this cell is subdivided into a number of low- and high-electric field regions by some arrangement of electrodes.


Proportional counters were used on  EXOSAT , [ 24 ]  on the US portion of the  Apollo–Soyuz  mission (July 1975), and on French  TOURNESOL  instrument. [ 25 ]


Monitoring generally means to be aware of the state of a system. A device that displays or sends a signal for displaying X-ray output from an X-ray generating source so as to be aware of the state of the source is referred to as an X-ray monitor in space applications.
On  Apollo 15  in orbit above the  Moon , for example, an X-ray monitor was used to follow the possible variation in solar X-ray intensity and spectral shape while mapping the lunar surface with respect to its chemical composition due to the production of  secondary X-rays . [ 26 ]


The X-ray monitor of  Solwind , designated NRL-608 or XMON, was a collaboration between the  Naval Research Laboratory  and  Los Alamos National Laboratory . The monitor consisted of 2 collimated argon proportional counters.


A scintillator is a material which exhibits the property of  luminescence [ 27 ]  when excited by  ionizing radiation . Luminescent materials, when struck by an incoming particle, such as an X-ray photon, absorb its energy and scintillate, i.e. reemit the absorbed energy in the form of a small flash of light, typically in the visible range.


The scintillation X-ray detector were used on  Vela 5A  and its twin  Vela 5B ; [ 28 ]  the X-ray telescope onboard  OSO 4  consisted of a single thin NaI(Tl) scintillation crystal plus phototube assembly enclosed in a CsI(Tl) anti-coincidence shield.  OSO 5  carried a CsI crystal scintillator. The central crystal was 0.635 cm thick, had a sensitive area of 70 cm 2 , and was viewed from behind by a pair of photomultiplier tubes.


The  PHEBUS  had two independent detectors, each detector consisted of a bismuth germinate (BGO) crystal 78 mm in  diameter  by 120 mm thick. [ 25 ]  The  KONUS-B  instrument consisted of seven detectors distributed around the spacecraft that responded to  photons  of 10 keV to 8 MeV energy. They consisted of  NaI (Tl) scintillator crystals 200 mm in diameter by 50 mm thick behind a  Be  entrance window.  Kvant-1  carried the HEXE, or High Energy X-ray Experiment, which employed a  phoswich  of sodium iodide and caesium iodide.


In  electronics ,  modulation  is the process of varying one waveform in relation to another waveform. With a 'modulation collimator' the amplitude (intensity) of the incoming X-rays is reduced by the presence of two or more 'diffraction gratings' of parallel wires that block or greatly reduce that portion of the signal incident upon the wires.


An  X-ray collimator  is a device that filters a stream of X-rays so that only those traveling parallel to a specified direction are allowed through.


Minoru Oda , President of Tokyo University of Information Sciences, invented the modulation collimator, first used to identify the counterpart of Sco X-1 in 1966, which led to the most accurate positions for X-ray sources available, prior to the launch of X-ray imaging telescopes. [ 29 ]


SAS 3  carried modulation collimators (2-11 keV) and Slat and Tube collimators (1 up to 60keV). [ 30 ]


On board the  Granat  Observatory were four  WATCH  instruments that could localize bright sources in the 6 to 180 keV range to within 0.5° using a Rotation Modulation Collimator. Taken together, the instruments' three fields of view covered approximately 75% of the sky. [ 25 ]


The  Reuven Ramaty High Energy Solar Spectroscopic Imager  (RHESSI), Explorer 81, images solar flares from soft X-rays to gamma rays (~3 keV to ~20 MeV). Its imaging capability is based on a Fourier-transform technique using a set of 9  Rotational Modulation Collimators .


OSO 8  had on board a Graphite Crystal X-ray Spectrometer, with energy range of 2-8 keV, FOV 3°.


The  Granat   ART-S X-ray spectrometer  covered the energy range 3 to 100 keV, FOV 2° × 2°. The instrument consisted of four detectors based on  spectroscopic   MWPCs , making an effective area of 2,400 cm 2  at 10 keV and 800 cm 2  at 100 keV. The time resolution was 200  microseconds . [ 25 ]


The X-ray spectrometer aboard  ISEE-3  was designed to study both solar flares and cosmic gamma-ray bursts over the energy range 5-228 keV. The experiment consisted of 2 cylindrical X-ray detectors: a Xenon filled proportional counter covering 5-14 keV, and a NaI(Tl) scintillator covering 12-1250 keV.


Most existing X-ray telescopes use  CCD  detectors, similar to those in visible-light cameras. In visible-light, a single photon can produce a single electron of charge in a pixel, and an image is built up by accumulating many such charges from many photons during the exposure time. When an X-ray photon hits a CCD, it produces enough charge (hundreds to thousands of electrons, proportional to its energy) that the individual X-rays have their energies measured on read-out.


Microcalorimeters  can only detect X-rays one photon at a time (but can measure the energy of each).


Transition-edge sensors  are the next step in microcalorimetry. In essence they are super-conducting metals kept as close as possible to their transition temperature. This is the temperature at which these metals become super-conductors and their resistance drops to zero. These transition temperatures are usually just a few degrees above absolute zero (usually less than 10  K ).


Xeromammography  is a  photoelectric  method of recording an  x-ray  image on a coated metal plate, using low-energy  photon  beams, long  exposure time , and dry  chemical developers .


It is a form of  xeroradiography . [ 1 ]


This process was developed in the late 1960s by  Jerry Hedstrom , and used to image  soft tissue , and later focused on using the process to detect  breast cancer .


Xeroradiography  is a type of X-ray imaging in which a picture of the body is recorded on paper rather than on  film . In this technique, a plate of selenium, which rests on a thin layer of aluminium oxide, is charged uniformly by passing it in front of a  scorotron . [ 1 ]
The process was developed by engineer Dr. Robert C. McMaster in 1950. [ 2 ]


As X-ray photon impinges on this amorphous coat of selenium, charges diffuse out, in proportion to energy content of the X-ray. This occurs as a result of  photoconduction . The resulting imprint, in the form of charge distribution on the plate, attracts toner particles, which is then transferred to reusable paper plates. In contrast to conventional X-rays,  photographic developers  are not needed. Hence the term xeroradiography; 'xero' meaning dry in Greek.
It requires more radiation exposure. Historically used in mammography prior to the advent of digital mammography.


Xeromammography  is a form of xeroradiography. [ 3 ]


Celedonio Calatayud Costa  ( Spanish pronunciation:   [θeleˈðonjo   kalataˈʝuð   ˈkosta] ; October 29, 1880 in  Pedreguer  – January 24, 1931 in  Madrid ) was a Spanish  scientist  and  radiologist , remembered for his achievements on  radiology ,  radiotherapy , and electrology. He pioneered the use of radiology and electrology in Europe for both diagnostics and therapeutical purposes, introducing  radiotherapy  in Spain in 1906. He founded the Spanish Medical Electrology and Radiology Society (Sociedad Española de Radiología y Electrología Médicas), [ 1 ]  promoted the doctoral chair of Electro-radiology and was elected as the first professor to chair it [ 2 ]  at the Universidad Central (later renamed  Complutense University of Madrid ). He also was the driving force behind and creator of the  First National Medical Congress  that took place in  Madrid  in 1919, [ 3 ] [ 4 ]  precursor of the use of  diathermy  in gynecologic therapy, founder of the  Spanish Journal of Medical Electrology and Radiology  ( Revista Española de Radiología y Electrología Médicas ) and  Tribuna Médica , as well as author of many papers on electrodiagnosis,  electrotherapy ,  roentgenology , and  radiotherapy .


Michael Grace Kawooya  (born 1958) is a  Ugandan   physician ,  academic ,  researcher  and  academic administrator , who serves as Director at the  Ernest Cook Ultrasound Research and Education Institute  (ECUREI). He is a Professor (emeritus) of Radiology at  Makerere University College of Health Sciences . [ 1 ]


He was born in the  Buganda Region  of Uganda circa 1958. After attending local elementary and secondary schools, he was admitted to  Makerere University Medical School  in 1978. [ 2 ]


He graduated with a  Bachelor of Medicine and Bachelor of Surgery  degree, in 1983. He went on to obtain a  Master of Medicine  degree in  Radiology  from the same university, in 1988. [ 2 ]


He followed that with a two-year fellowship in radiology from the  University of Tübingen  in  Tübingen , Germany. In 2001, he studied at the  Thomas Jefferson University , in  Philadelphia , Pennsylvania, United States in a fellowship in ultrasound. [ 1 ]


He started his teaching career in the Department of Radiology at  Makerere University Medical School , as a lecturer to undergraduate and postgraduate students. Over the years he was promoted and given more responsibilities, as his experience increased and broadened. He has supervised over forty radiologists at the Master of Medicine level and above. He attained full professorship in radiology at  Makerere University . [ 3 ]


Professor Kawooya’s area of super-specialization is  ultrasound . He has in excess of fifty-five published articles in peer-reviewed journals, and five chapters in books on different topics, including imaging of tropical diseases. He has many professional awards including as an Honorary Fellow of the  American Institute of Ultrasound in Medicine , awarded in 2015, and as an Honorary Member of the  European Society of Radiology , awarded in 2019. [ 4 ]


In 2002, with the support of  Thomas Jefferson University , in  Philadelphia , Pennsylvania, United States, Professor Kawooya, with other Ugandan radiologists, founded the  Ernest Cook Ultrasound Research And Education Institute (ECUREI) , based at  Mengo Hospital , in  Kampala , Uganda's capital city. [ 2 ] [ 5 ]


ECUREI, which also receives partial funding from the  Fontys University of Applied Sciences , in the Netherlands trains students for the  Diploma in Ultrasound  qualification. Trainees come from  Uganda ,  Kenya ,  Tanzania , the  Democratic Republic of the Congo  and  Zambia . [ 6 ]


Robert Kienböck  (11 January 1871 – 8 September 1953) was an Austrian  radiologist  who was a native of  Vienna .


In 1895 he earned his medical doctorate at the  University of Vienna , and spent the next year abroad ( London  and  Paris ). He returned to Vienna as an assistant to  Leopold von Schrötter  (1837–1908), a  laryngologist , and began working in the new science of  radiology . Several years later, he became head of the radiological department at  Vienna General Hospital . In 1926 he became an associate professor of radiology.


In June 1923, along with  Guido Holzknecht  (1872-1931), he was co-founder of the  Wiener Gesellschaft für Röntgenkunde  (Vienna Radiology Society). He was elected president of the  Österreichische Gesellschaft für Röntgenkunde  (Austrian Radiology Society) in 1934 and honorary president of that body after the  Second World War . [ 1 ] [ 2 ]  With Holzknecht, he published the two-part  Röntgenologie. Eine Revision ihrer technischen Einrichtungen und praktische Methoden  ( Roentgenology . A review of its technical facilities and practical methods). [ 3 ]


Kienböck was a pioneer in the use of  x-ray  technology for medical diagnosis and therapy. He specialized in research of  skeletal  diseases and its treatment through radiology. In 1910 he described a disorder which consisted of breakdown of the  lunate bone  in the wrist. He called the disorder "lunatomalacia", which is now known as  Kienböck's disease . [ 4 ]
Kienböck published his findings in a treatise titled  Über traumatische Malazie des Mondbeins und ihre Folgezustände  (Traumatic  malacia  of the lunate and its consequences). [ 5 ]


This biographical article related to medicine in Austria is a  stub . You can help Wikipedia by  expanding it .


Sergey Pavlovich Morozov  ( Russian :  Сергей Павлович Морозов ; born 10 March 1979) is a Russian radiologist and healthcare official.


Sergey Morozov was born in Moscow on March 10, 1979. In 2002, he graduated from  I.M. Sechenov First Moscow State Medical University  with honors with a degree in Internal Medicine. In 2002–2004, he completed postgraduate training in Diagnostic Imaging and Radiography at Sechenov University and the  Moscow State University of Medicine and Dentistry  and fellowship programs at the University of Illinois in Chicago, Memorial Sloan-Kettering Cancer Center ( USA ), Oslo University ( Norway ), and Universita La Sapienza ( Italy ).


In 2004, Sergey Morozov completed his  candidate  thesis working on functional  magnetic resonance imaging ; his  doctoral  thesis on diagnostic imaging in  orthopedics  was accepted in 2010. [ 1 ]  Sergey Morozov received the master's degree from the Harvard School of Public Health (Boston, USA) in 2006, followed by another master's degree from the  Russian Presidential Academy of National Economy and Public Administration  in Economics and Business Administration in 2013. Sergey Morozov became a professor of Radiology and Radiotherapy in 2015 and a Certified Imaging Informatics Professional (CIIP) in 2017, completing a certification program at the Society for Imaging Informatics in Medicine (SIIM). During his early career, Morozov was a radiologist at the Radiology Department of I.M. Sechenov Moscow Medical Academy. In 2007–2013, he headed the Department of X-Ray and MR Diagnostics at the  Moscow Central Clinical Hospital . Since 2004, Morozov has been a lecturer at the Department of Radiology and Radiotherapy of  Sechenov University , holding the positions of a teaching assistant, associate professor, and later becoming a professor. From 2013, Morozov was the medical school rector and radiology department head at the European Medical Center. [ 2 ]  In December 2015, he was appointed CEO of the Moscow Center for Diagnostics & Telemedicine of the Moscow Healthcare Department. [ 3 ]


In 2016–2018, Morozov was the president of the European Society of Medical Imaging Informatics (EuSoMII). [ 4 ]  He became the Chief External Officer for Radiology of the Moscow Healthcare Department in 2015 and the Chief External Officer for Radiology and Instrumental Diagnostics in 2019 to chair the expert  certification  panel in Radiology, Diagnostic Ultrasonography, and Radiography. [ 5 ]  In 2017, he was promoted to Chief Regional Radiology and Instrumental Diagnostics Officer of the Ministry of Health of the Russian Federation for the Central Federal District. Morozov is the chair of the Moscow Regional Office of the Russian Society of Radiologists and Radiotherapists (MRO of RSRR) and the founder of Management in  Radiology  (MIR) national school and MIR international summit. He is a member of ESR committees, organizer and Chair of Artificial Intelligence in Healthcare subcommittee, and member of the Expert Council of the  Moscow International Medical Cluster  (Skolkovo). [ 6 ]


Morozov is a co-organizer and academic director of Healthcare Management: Leaders of Change graduation program at the  Moscow School of Management SKOLKOVO . He founded Digital Diagnostics peer-reviewed  scientific journal  and is its Deputy Editor-In-Chief. [ 7 ]  Moreover, Morozov is an editorial board member at Diagnostic and Interventional Radiology, Journal of Telemedicine and E-Health, [ 8 ]  and Medical Visualization. [ 9 ]
After the beginning of the special operation in February 2022, he left [ 10 ]  Russia and accepted [ 11 ]  a position of Innovations Director in a Belgian company, [ 12 ]  specializing in IT solutions for radiology.


Morozov is an author and co-author of more than 250 papers,  monographs , and books. He owns 28  patents  and certificates of invention and has supervised five PhD thesis.  Russian Science Citation Index  (SPIN) 8542-1720. [ 13 ]


Morozov co-initiated and developed Radiography Guidelines (effective in Russia from 2021) and took part in the development of the new Ultrasound Guidelines, Occupational Standards for Radiographers, and Diagnostic Imaging Guidelines in  COVID-19 . He organized the pilot projects on Moscow LDCT  Lung Cancer  Screening and Moscow  Breast Cancer  Screening and created the National Ranking of Radiology Departments, which has been calculated annually since 2018. In 2016–2018, he promoted the creation of a  PET/CT  imaging system that can be accessible to general public.


Morozov is a co-author and co-editor of Artificial Intelligence in Medical Imaging published by  Springer Science+Business Media , which provides a historical overview of  artificial intelligence  use in radiology, its technical background, and discusses the impact of new and emerging technologies on medical imaging. Morozov is an initiator and co-author of the Fundamentals of Management in Radiology.


As a strong supporter of  digitalization  of healthcare,  automation  of diagnostic imaging, development of innovative technologies and methods, their incorporation into clinical practice, and  big data  use in healthcare, Morozov initiated the creation of the Unified Radiological Information Service and the launch of the Moscow Experiment on the Use of Innovative Computer Vision Technologies for Analysis of Medical Images. In 2019, he piloted a project to equip outpatient radiology departments with  speech recognition  systems. In 2020, at the Moscow Center for Diagnostics & Telemedicine, Morozov facilitated the foundation of Moscow Radiology Reference Center, the first teleradiology center in the Russian public healthcare sector.


At the Moscow Center for Diagnostics and Telemedicine, Morozov supervises a research team that managed to collect the world's largest dataset of anonymized chest CT scans of patients with confirmed  COVID-19 .


Sydney Domville Rowland  (29 March 1872 – 6 March 1917) was an English physician and the world's first editor of a  radiology  journal. He coined the term " skiagraphy " and wrote some of the first works on  X-rays  in the  Archives of Clinical Skiagraphy  that preceded the  British Journal of Radiology .


Rowland worked in India and helped confirm how  plague  is spread by rats carrying fleas, and later joined the  Royal Army Medical Corps  in the  First World War  as a bacteriologist in France, where he worked on septic wounds,  typhoid  carriers and  gas gangrene , and set up No. 1 Mobile Laboratory, the  first of its kind . He died at the age of 44 years after contracting  meningitis  during his work.


Sydney Rowland was born in  Cornwall , the United Kingdom, on 29 March 1872, [ 2 ]  the eldest son of the Reverend William J. Rowland and Margaret Domville. [ 3 ]  He had one sister, Agnes, and two brothers, William and Cecil. [ 3 ]   Ernest Hart , editor of the  British Medical Journal  ( BMJ ), was his uncle. [ 3 ]  In 1873, he moved to India with his family and lived in  Jabalpur ,  Calcutta  (now Kolkata), and  Darjeeling . [ 3 ]  In 1880 he returned to England and attended  Berkhamsted School , where he held a scholarship. [ 3 ] [ 4 ]  He won a  natural sciences  scholarship to  Downing College , Cambridge, [ 5 ]  where he was president of the Natural History Society, and from where he graduated in 1892 with a 1st Class in Natural Sciences Tripos Part I, and in 1893 with a 2nd Class in Part II. [ 3 ] [ 4 ]  He passed his first and second M.B. at Cambridge and won the Shuter scholarship at  St Bartholomew's Hospital , London, from where he graduated M.R.C.S., L.R.C.P. in 1897. [ 4 ]


Rowland's career began in medical journalism while he was still a medical student when, in 1896, as Hart's intern, the year following the  discovery of X-rays , [ 6 ]  the  BMJ  appointed Rowland as "Special Commissioner" to produce a report on the clinical use of X-rays titled "Report on the Application of the New Photography in Medicine and Surgery." [ 3 ] [ 6 ] [ a ]  It was published in 17 parts between 8 February 1896 and 12 June 1897. [ 3 ]  In May 1896, he founded the world's first X-ray journal, the  Archives of Clinical Skiagraph , a radiology journal that preceded the  British Journal of Radiology . [ 3 ] [ 6 ]  In the preface to the first issue, written in April 1896, he wrote that "the object of this publication is to put on record in permanent form some sort of the most striking applications of the new photography to the needs of medicine and surgery". [ 6 ]  He coined the term " skiagraphy " to describe the making of X-ray pictures and wrote some of the early works on  radiology . [ 3 ]  Without any radiology experts or X-ray departments at the time, his journal became an essential reading. [ 6 ]


He stopped studying X-rays in 1897 and moved into the field of laboratory medicine. [ 4 ]  The following year, he became an assistant bacteriologist at the  Lister Hospital . [ 3 ] [ 4 ]  In 1905, the Lister sent him to India to investigate and confirm the theory that plague is spread by rats carrying fleas. [ 4 ]  He returned to England in 1908 and 1909 and was sent to the Plague Commission again. Still, this time to investigate plague prevention in the UK and later to find out how an outbreak of plague appeared in  Freston  village, East Suffolk. [ 4 ]


Later, he joined the  Royal Army Medical Corps  in the  First World War  as a bacteriologist. [ 3 ]  In 1914, he bought a large motor caravan in England and set up  No. 1 Mobile Laboratory , which he drove to the army area in France himself. [ 7 ]  The first of its kind, it formed the model for later mobile laboratories. [ 7 ]  During the war, he also worked on septic wounds, typhoid carriers, and gas gangrene. [ 4 ] [ 8 ]  In 1915 he rose to the rank of Major and worked with the 26th General Hospital Royal Army Medical Corps. [ 4 ]


Rowland died on 6 March 1917, at age 44, after contracting  meningitis . He is buried at  Étaples Military Cemetery . [ 4 ] [ 9 ]


Jalal Jalal Shokouhi  (born 1950,  Miandoab ,  West Azerbaijan ) is an Iranian radiologist, writer and historical and cultural researcher. He is the chief of  Iranian Society of Radiology  and also the first person who made polymer samples of  Saltman . [ 1 ]  He was one of the candidates for president election of  Iranian Medical Council . [ 2 ]


Jalal Jalal Shokouhi was born in 1950 in Miandoab a city in West Azerbaijan province of  Iran . He attended elementary school and high school there and then traveled to  Mashhad  to study as a  general practitioner . In 1977 he graduated from  Mashhad University of Medical Sciences  and then continued his studies to his doctorate degree from  Shahid Beheshti University of Medical Sciences .


After completing his academic educations in Iran, he also attended many courses such as Advanced  Radiology ,  Ultrasound ,  MRI  and intervention in Germany. He also earned his PhD degree in "Head and Neck" field. [ 3 ]


Through his working years he taught as a professor in  Shahid Chamran Hospital ,  Shahid Beheshti University of Medical Sciences ,  Islamic Azad University  of Medical Science and also he cooperated with  Loghman Hakim Hospital . [ 4 ]


Now Jalal Shokouhi is the chief of Iranian Society of Radiology and years of activity in this field made him one of the well-known figures in radiology science.


Activities of Jalal Jalal Shokouhi contain a wide range of medical to cultural ones. Besides decades in medical science and radiology, which is his special field, he also wrote a number of books in history and culture.


One of the most well-known activities of Jalal Shokouhi is his project in partnership with the Iranian  Cultural Heritage, Handcrafts and Tourism Organization ,  National Museum of Iran
and  Zanjan Museum  about Radiology and CT Scan of  Saltman  and also some crafts and Pottery, determining their antiquity and properties. [ 5 ]  This project started in 2005 and resulted in building  polymer  samples of Saltman's skull.


In this case he presented many articles in different conferences and made interviews in many TV programs as a science,  anthropology  and sociology expert in  Iran  and Japan, like "Saltman Documentary" directed by "Hassan Dehghan". Today, he also cooperates with Iran's Heritage Organization as an adviser in radiography.


Shokouhi also had done completed many projects as a radiologist. He is the chief of Iranian Society of Radiology and presented many papers in journals like "Ettelaat Elmi", " Biomedical Engineering " and "Radiology Management". He also cooperates with Iranian  Medical jurisprudence  in its commissions.


Jalal Shokouhi also wrote a number of books in Radiology and Culture. "Radiography Made Simple" and " Orthopedic surgery  and  MRI " are two of his books which are also referred to by academics. [ 7 ]


He was the manager of Iran Radiology Conference for several years and Middle East and Europe Conference on spinal cord, in 2007 and 2009 at  Abu Dhabi  and  Kish Island . [ 8 ]  He was also selected as the premier doctor of Iranian Medical Council.


In terms of cultural activities, he published some books in history and  travel literature . Moreover, he is the chief of Shokouhi's Foundation which publishes and revives old books and  manuscripts . [ 9 ]


Objection to Arresting Radiologists


After that incident, Jalal Jalal Shokouhi as the chief of Iranian Society of Radiology, wrote a letter to the Iranian Ministry of Health and expressed his willingness to solve the problem using reason and conversation. [ 13 ]


Fang-Fang Yin  is a Chinese-born radiologist.


Yin earned a Bachelor of Science degree from  Zhejiang University  in 1982. He subsequently moved to the United States, completing a Master of Science degree at  Bowling Green State University  in 1987, followed by a doctorate at the  University of Chicago  in 1992. [ 1 ] [ 2 ]  Yin teaches at  Duke University , where he is affiliated with the  Duke Cancer Institute , [ 3 ]  and was appointed the Gustavo S. Montana Professor of Radiation Oncology in 2021. [ 4 ] [ 5 ]


As early as the 1990s, there was discussion in the literature regarding the usefulness of ultrasound in the rapid assessment of blunt trauma.[3] The natural advantage of ultrasound over pure clinical intervention is the accuracy of visualization, sensitivity (49–99% versus 27–45%), and specificity (95–100%). The advantage of ultrasound over CT scanning is the rapidity of the exam and the fact that the physician may remain at the bedside to make critical decisions regarding the potential rapidly changing condition of the patient. In a patient who has received blunt trauma (often from a motor vehicle accident) or penetrating trauma (such as a gunshot wound), the presence of free blood or free air in the abdomen may be seen within a few minutes by an experienced clinician.[4]


The original basis of trauma ultrasound was that the blood that escaped the vascular system due to trauma (e.g., bleeding inside the abdomen) would be seen as an abnormal hypoechoic entity in the abdomen. This concept is greatly aided by the fact that there are anatomic “potential spaces” where fluid, mostly extravascular blood, collects. Potential spaces had been known for centuries as locations where abnormal fluid collections could be reliably found and removed. It is with the more sophisticated radiology modalities that the fluid can be located before surgery and used diagnostically to help determine if surgery is necessary. Ultrasound imaging quickly and reliably indicates emergent surgery to stop the bleeding from a liver laceration, a splenic laceration, an ectopic pregnancy rupture, a bladder rupture, an injury to a major blood vessel, or less frequent injuries to other organs.


The FAST exam evaluates the right upper quadrant, the left upper quadrant, and the pelvis, as shown in Figure 11-1.[5] Most famous because of the more defined areas are Morrison’s pouch (in the right upper quadrant, highlighted by the contrasting bright, hyperechoic Gerota’s fascia) and the pouch of Douglas (in the low midline of the pelvis between the hyperechoic borders of the bladder in males or vagina in females superiorly and the rectum inferiorly). The splenic-renal recess in the left upper quadrants and the paracolic gutters in both the right and left lower quadrants are important to access but less easy to navigate.


The rapid ultrasound exam for trauma has extended to areas above the diaphragm as ultrasound has progressed. The eFAST (the extended FAST exam) also evaluates the lungs and heart[6] in addition to the abdomen, as shown in Figure 11-1. The probe is pointed superiorly from the xiphoid area to gain views of the heart and lungs. Again, the hypoechoic reflection of free, abnormal fluid is used as an indication of emergent surgery.


Above the diaphragm, this fluid collection indicates emergent action in the form of a pericardial or pleural effusion. In the case of pericardial effusion, cardiac tamponade can occur and must be treated immediately. Cardiac tamponade is a medical condition that causes the restriction of ventricular filling due to pressure of fluid in the pericardium. In the case of pleural effusion, the restriction is not the initial problem. However, there may be ongoing bleeding contributing to the effusion that must be stopped. Cardiac imaging is used to evaluate pericardial effusion. There are two different cardiac views. The parasternal long-axis view is obtained by placing the transducer just left of the sternum in the fourth or fifth intercostal space oriented to the right shoulder, as shown in Figure 11-2. The parasternal sagittal ultrasound view of the heart is shown in Figure 11-3. The abbreviations LV, RV, LA, RA, and A have been used for the left ventricle, right ventricle, left atrium, right ventricle, and aorta, respectively, in some of the following ultrasound images.


The subxiphoid view can sometimes be challenging in a patient who is considered obese. First, locate the xiphoid process, place the transducer down in a transverse position with the indicator facing toward the right, and aim between the head and left shoulder, as shown in Figure 11-4. Gently apply pressure downward, and visualize the cardiac contractility during respiration to identify the best visualization. Figure 11-5 shows the four-chamber view of the heart during this evaluation. Assess for hemopericardium, or fluid around the heart.


Pulmonary imaging in trauma has evolved over the years. Most recently, with the COVID-19 pandemic, it has become a more detailed and important part of the evaluation addressed in Chapter 8.


Peritoneal imaging of the abdomen/pelvis evaluates fluid in the hepatorenal recess (also referred to as Morrison’s pouch), splenorenal recess, and pelvic cavity. Figure 11-6 shows a cross-sectional diagram of the abdomen, demonstrating Morrison’s pouch (hepatorenal recess) and the splenorenal recess. The most straightforward abdominal view is to place the transducer in the midaxillary line at the 8th to 11th intercostal space with cephalad orientation.


First, start on the right abdominal region in the midaxillary line between the 8th to 11th intercostal spaces, as shown in Figure 11-7. Maneuver the transducer by sliding, fanning, angling, and rotating until you can visualize the liver and kidney well. The abbreviations L, R, K, P, and S have been labeled in some of the following ultrasound images, representing liver, recess (hepatorenal and splenorenal), kidney, pleura, and spleen, respectively. Figure 11-8 represents the hepatorenal view, showing the liver, hepatorenal recess, kidney, and pleura.


Next, place the transducer in the longitudinal plane with the indicator facing the patient’s head, evaluating between the fifth to ninth intercostal spaces, as shown in Figure 11-9. Again, maneuver the transducer until you can visualize the spleen and kidney well. Figure 11-10 represents the splenorenal view, showing the spleen, splenorenal recess, and kidney.


The pelvic cavity also has an area where peritoneal fluid can collect within the pouch. In women, it is called the rectouterine pouch or pouch of Douglas (peritoneum between the rectum and uterus). In men, it is referred to as the rectovesical pouch (peritoneum between the rectum and bladder), as shown in Figure 11-11.


Figure 11-12 shows an ultrasound image of the bladder (abbreviated B on the image) obtained by placing the transducer in the patient’s midline, right above the pubic symphysis. This concludes the eFAST exam.


The best time to stop bleeding is as soon as possible. When the bleeding is not apparent or external, ultrasound has made leaps of progress regarding rapid diagnosis. The first hour after trauma, known as the “Golden Hour of Trauma,” is a recognized time entity in which medical professionals aim to provide definitive care. In the future, it may well be a standard of care for paramedics to perform ultrasound on the scene. In this case, the image will be transmitted to an emergency department and a trauma surgeon’s cell phone so that preparations for emergent surgery may be made before the patient arrives. Perhaps in the future, the patient will be taken immediately off the ambulance and directly to surgery. Trials of this technology are ongoing all over the world.


The primary physiologic functions of the venous system are to return the deoxygenated blood to the heart, thermoregulate, store blood (at any instance, the venous system contains up to 70% of the circulating blood), and regulate the cardiac output. It is divided into three systems: superficial, perforating, and deep veins. Figure 10-1 shows the anatomy of the venous system. Blood flows from the superficial to deep veins through branching perforating veins. The deep veins usually follow the arteries in the same areas and often have similar names. For example, the femoral vein is beside the femoral artery. The deep venous system eventually returns blood to the right side of the heart. Since the venous system is usually a low-pressure system, veins have bicuspid valves to allow flow in one direction from superficial to deep (the foot is the exception) and from distal to proximal. Muscular contraction helps with venous flow, such as in the calf muscle pump in the leg.[1]


Venous pathophysiology has many etiologies, such as trauma and genetic predisposition, and can occur when outflow is impaired by dysfunctional valves, resulting in retrograde flow and causing a condition known as chronic venous insufficiency. Vein thrombosis is another condition with many hereditary and acquired etiologies, such as trauma or prolonged immobilization. Deep vein thrombosis is especially important to evaluate and treat.[2]


The great saphenous vein (GSV) is the longest vein in the human body, as shown in Figure 10-2. It originates in the medial aspect of the foot as part of the dorsal arch. It continues proximally along the medial aspect of the foot and passes anterior to the medial malleolus on the tibia. It ascends along the medial aspect of the leg between the superficial and deep fascia. It typically has 10–20 valves and terminates at the saphenofemoral junction (SFJ). Once flow enters the femoral vein, it is in the deep venous system. Venous anatomy can vary from individual to individual. However, the GSV typically has branching superficial veins, such as the anterior and posterior accessory saphenous veins in the thigh.[3]


The small saphenous vein (SSV) is the second most significant superficial vein that joins the dorsal venous arch in the lateral aspect of the foot. It ascends proximally behind the lateral malleolus and terminates into the deep popliteal vein, although this is highly variable and can extend into the thigh. The SSV typically has 9–12 valves. Like the GSV, the SSV lies between the superficial and deep fascia and can have many branching superficial veins. Perforating veins connect superficial to deep veins. They usually contain a bicuspid valve.[4]


The deep venous system includes the common femoral vein, profunda femoral vein, deep femoral vein, popliteal vein, gastrocnemius veins, soleus veins, anterior tibial veins, posterior tibial veins, and peroneal veins. The direction of venous flow is described as antegrade, retrograde, or absent. In both the deep and superficial venous systems, it is essential to check for the following characteristics: compressibility, spontaneous flow, respiratory variation, augmentation, intraluminal defects, and venous reflux.


Compressibility evaluates if the vein collapses by applying downward pressure with the transducer. Typically, it should compress, since it is a low-pressure vessel. A thrombus can occlude the lumen and prevent compression. Spontaneous flow is observed when the blood flow moves actively without external influences, such as an augmentation maneuver. Respiratory variation, also known as phasicity, refers to regular venous flow changes that occur secondary to intrathoracic pressure during breathing cycles. Augmentation is a maneuver that is used to evaluate possible abnormal flow patterns. For example, by squeezing a distal portion in the calf, an increase in venous flow should be observed just proximal to this area. Absent or diminished flow could suggest obstruction, such as in a thrombus formation, and reversal of flow could indicate incompetent venous valves, such as in venous reflux disease.


Intraluminal defects usually describe a thrombus formation within the lumen of the vein. It is crucial to describe the details of the thrombus formation and whether it is obstructive.


Finally, venous reflux describes blood flow going in the wrong direction, usually from incompetent valves. Maneuvers are usually done to augment blood flow to test for reflux, which is significant if it exceeds seconds in the superficial venous system, seconds in perforators, and 1 second in the deep venous system.


A complete venous duplex ultrasound of the lower extremities starts with a proximal to distal evaluation of the deep venous system in a transverse (TRV) side-by-side image without compression and with compression (COMP). This is followed by a sagittal (SAG) view with augmentation (AUG) using the color Doppler. The veins that are evaluated in succession include the common femoral vein (CFV), profunda femoral vein (PROF V), femoral vein (FV), popliteal vein (POP V), gastrocnemius vein (GASTROC V), posterior tibial vein (PTV), peroneal vein (PERO V), anterior tibial vein (ATV), great saphenous vein (GSV), and small saphenous vein (SSV). The abbreviations given in parentheses in the last few sentences have been labeled in some of the following ultrasound images for venous system discussion. Figure 10-3 shows a side-by-side transverse ultrasound view of the right common femoral vein without compression and with compression, while Figure 10-4 represents the sagittal view of the right common femoral vein with augmentation.


Figure 10-5 shows a side-by-side transverse ultrasound view of the right profunda femoral vein without compression and with compression, while Figure 10-6 represents the sagittal view of the right profunda femoral vein with augmentation.


Figure 10-7 shows a side-by-side transverse ultrasound view of the right femoral vein without compression and with compression, while Figure 10-8 represents the sagittal view of the right femoral vein with augmentation.


Figure 10-9 shows a side-by-side transverse ultrasound view of the right popliteal vein without compression and with compression, while Figure 10-10 represents the sagittal view of the right popliteal vein with augmentation.


Figure 10-11 shows a side-by-side transverse ultrasound view of the right gastrocnemius vein without compression and with compression, while Figure 10-12 represents the sagittal view of the right gastrocnemius vein with augmentation.


Figure 10-13 shows a side-by-side transverse ultrasound view of the right posterior tibial vein without compression and with compression, while Figure 10-14 represents the sagittal view of the right posterior tibial vein with augmentation.


Figure 10-15 shows a side-by-side transverse ultrasound view of the right peroneal vein without compression and with compression, while Figure 10-16 represents the sagittal view of the right peroneal vein with augmentation.


Figure 10-17 shows a side-by-side transverse ultrasound view of the anterior tibial vein without compression and with compression, while Figure 10-18 represents the sagittal view of the right anterior tibial vein with augmentation.


Next, in the complete venous duplex ultrasound, we look at the superficial venous system from proximal to distal, starting with the GSV at the SFJ in the transverse plane with a side-by-side image without and with color Doppler, followed by a sagittal image with augmentation with color Doppler. Figure 10-19 shows a side-by-side transverse ultrasound view of the right GSV at the SFJ, while Figure 10-20 represents the sagittal view of the right GSV at the SFJ with augmentation.


Next, we continue to follow and evaluate the GSV distally from above the knee (AK) to below the knee (BK) in the transverse plane without color, followed by the sagittal plane with augmentation with color Doppler. The abbreviations AK and BK have been used in the ultrasound images discussed here. Figure 10-21 shows a side-by-side transverse ultrasound view of the right GSV above the knee. Figure 10-22 represents the sagittal view of the right GSV above the knee with augmentation.


Figure 10-23 shows a transverse ultrasound view of the right GSV below the knee, while Figure 10-24 represents the sagittal view of the right GSV below the knee with augmentation.


The next superficial vein to be evaluated is the SSV, starting in the popliteal area of the lower extremity and using the same approach as the great saphenous vein. We first start with a transverse image at the saphenopopliteal junction (SPJ) without color Doppler, followed by a sagittal image with augmentation with color Doppler. Figure 10-25 shows a side-by-side transverse ultrasound view of the right SSV at the SPJ, while Figure 10-26 represents the sagittal view of the right SSV at the SPJ with augmentation.


Also, anterior and posterior accessory saphenous veins are often evaluated as part of the superficial venous system, and perforating veins that connect superficial to deep veins are often evaluated during the study.


The template shown in the next couple of pages can be used to perform a complete venous duplex Doppler ultrasound examination of the lower extremities.


Figure 10-27 shows the anatomy of the arterial system, which will be helpful in discussing and understanding various ultrasonography images of the arteries.


Norwegian physicist Rune Aaslid developed intracranial ultrasound in 1982. Transcranial imaging was subsequently developed by a German neurologist, Ulrich Bogdahn, in 1990. It was the first noninvasive way to evaluate the circle of Willis using a low-frequency transducer (2 MHz).[5],[6]


Transcranial Doppler (TCD) can detect intracranial stenosis, vasospasm secondary to subarachnoid hemorrhage, and arteriovenous malformations and assess suspected brain death. A TCD system usually has a 2 MHz pulsed Doppler with a spectrum analyzer. A typical TCD probe is shown in Figure 10-28. Blood flow in TCD is usually measured in cm/sec, and Figure 10-29 represents a TCD velocity distribution. When evaluating intracranial vessels, it is vital to know the acoustic window, depth, direction of blood flow, velocity, and angle of insonation. One important principle when evaluating pathology is the pulsatility index (PI).


A high PI (>) can indicate increased intracranial pressure, microvascular disease, or distal vasospasm. Also, a low PI (<) can be seen with carotid stenosis or occlusion as well as arteriovenous malformations.[7],[8]


The three most common acoustic windows that provide direction to evaluate the intracranial vessels are the transtemporal, transorbital, and transforaminal windows, as shown in Figure 10-30. The transcranial evaluation begins with the transtemporal approach on each side to identify the anterior, middle, and posterior cerebral arteries, and sometimes, the most distal aspect of the internal carotid artery (ICA) may also be evaluated.[9],[10]


When evaluating the anterior cerebral artery, normal flow is away from the probe, the depth is 60–70 mm, and the velocity ranges from 41–76 cm/sec. The middle cerebral artery has normal flow toward the probe, a depth of 30–60 mm, and a velocity that ranges from 46–86 cm/sec. The posterior cerebral artery typically has flow toward the probe, a depth of 60–70 mm, and a velocity range of 33–64 cm/sec, as shown in Figure 10-31.[11],[12],[13]


The transorbital approach is followed and used to evaluate the ophthalmic artery and carotid siphon on each side, as shown in Figure 10-32. The location for of obtaining flow patterns is essential in this window, since it is difficult to determine the anatomic structure, as in the transtemporal approach demonstrating the circle of Willis. Comparisons can be made between different flow patterns.


The transforaminal approach is then used to evaluate the intracranial vertebral arteries and the basilar arteries, as shown in Figure 10-33.


In the vertebral arteries, normal blood flow is away from the probe, the depth is 60–70 mm, and the velocity ranges from 27–55 cm/sec. In the basilar arteries, normal blood flow is away from the probe, the depth is 80–120 mm, and the velocity is 30–57 cm/sec.


Figure 10-34 shows the positioning of the ultrasound probe for carotid artery evaluations. A high-frequency linear transducer (–10 MHz) is most appropriate for carotid sonography. Transverse and longitudinal views are both imaged in B-mode, color, and spectral Doppler. In the sagittal plane, the ICA, external carotid artery (ECA), and right common carotid artery (CCA) are followed from the clavicle to the mandible with anterior, oblique, lateral, and posterior projections to identify plaque formation. Comparison flow characteristics are made from one side to the other as well as from proximal to distal segments of the ICA, ECA, and CCA.[14] In the transverse plane, the ICA and CCA are followed to evaluate plaque formations. The percentage of stenosis can then be evaluated by looking at the diameter reduction. Plaque characteristics can be evaluated for calcification, thrombosis, and fibrosis.


Figure 10-35 shows the CCA in the proximal transverse plane with the jugular vein on top, demonstrating blood flow in the opposite direction following the BART principle. Prox is the abbreviation used for proximal in the image for Figure 10-35 and some of the other following ones. Pulsed Doppler with spectral analysis is the primary tool for evaluating blood flow in the vascular study.


Figure 10-36 shows the pulsed wave (PW) Doppler with spectral analysis of the right CCA in the distal sagittal plane. Spectral analysis is a method of displaying the variety of frequencies of blood flow during systole and diastole. The scanner technology automatically analyzes and displays the individual frequencies of the returned signals, creating a velocity profile consisting of time on the horizontal axis, frequency shifts on the vertical axis, and amplitude as brightness. This combination of blood flow analysis and anatomic information is the basis of duplex ultrasonography,[15] as discussed in Chapter 2.


The Doppler characteristics of the carotid artery system are different. The ICA and CCA usually have low flow resistance, as shown in Figures 10-37 and 10-38, respectively. Flow occurs throughout the cardiac cycle. The diastolic segment does not touch the baseline. The ECA has high flow resistance with little or no diastolic or reversed diastolic flow. Reproducible and consistent velocity measurements require an angle of 60 degrees or less. Although a zero-degree angle of insonation provides the most remarkable Doppler shift because this depends on the angle’s cosine, this would be difficult with most vessels. The criteria used for the interpretation of velocity measurements were established using a 60-degree angle.[16],[17]


Since the brain is a low-resistance vascular bed, the ICA is less pulsatile with increased flow during diastole. The typical waveform of the ICA has a rapid upstroke during systole and a high diastolic component with a possible dicrotic notch and gradual downslope.


With the common carotid artery in the longitudinal plane, the transducer is angled more posterolaterally to identify the vertebral artery. Vertical shadows will appear running through the vertebral arteries, which are the transverse processes of the vertebrae, as shown in Figure 10-39. Vert in the image represents the vertebral artery. Flow direction is documented.


The ECA supplies blood to vascular areas with higher resistance, such as the scalp. It has a rapid upstroke in systole and rapid downstroke in diastole with a dicrotic notch, as shown in Figure 10-40.


Both the CCA and vertebral arteries have low flow resistance. The flow characteristics are similar to the ICA. Multiple guidelines and trials are used to determine the percentage of diameter stenosis and clinically relevant stenosis. The ICA is of the most importance for surgical intervention. The Society of Radiologists in Ultrasound Consensus, one of the most widely used guidelines to assess ICA stenosis, is presented in Table 10-1 the table below.[18]


The North American Symptomatic Endarterectomy Trial was published in the journal Stroke in 1991.[19] The results concluded that patients with 70–99% stenosis of the ICA benefit from surgical intervention in the appropriate clinical setting.


The aorta is the largest artery in humans. It branches off the heart’s left ventricle into the thoracic and abdominal cavities, as shown in Figure 10-41. The abdominal aorta branches into the right and left iliac arteries at the level of the umbilicus, where it carries oxygenated blood to each lower extremity. When the wall of the aorta weakens and expands, an aneurysm develops (with an increased risk of rupture under this high-pressure system).


Each year, 200,000 people in the United States are diagnosed with an abdominal aortic aneurysm (AAA). Of these, nearly % have a life-threatening risk of rupture. The majority of patients with AAA are asymptomatic. The aorta’s diameter must be greater less than 3 cm to be diagnosed as an aneurysm. When it reaches 5 cm or greater, very close monitoring and surgical options are entertained. Risk factors for an AAA include hypertension, smoking, and genetic factors, especially involving immediate relatives with AAA. Men over the age of 60 are also at greater risk.[20]


The ultrasound evaluation of the abdominal aorta (A or AA) should include the proximal, mid, and distal aorta to the bifurcation in the transverse and longitudinal planes, as shown in Figure 10-42. Evaluation of the branches of the aorta should include the celiac artery (C), superior mesenteric artery (SMA), and renal artery branches, as shown in Figures 10-43 and 10-44, without and with color Doppler, respectively.[21] The abbreviations given in parentheses in this paragraph have been labeled in some of the ultrasound images discussed below.


Figure 10-45 shows the normal anatomical branches of the arterial system in the lower extremity. Peripheral artery disease (PAD) is a condition in which the arteries of the lower extremities are narrowed primarily from atherosclerosis. Approximately 8 million people in the United States have PAD. Men and women are affected equally. Risk factors include smoking, diabetes, hypertension, high cholesterol, and being over 60 years of age. A classic symptom of PAD is claudication, or pain when walking. Lower-extremity arterial duplex scanning is a noninvasive way to identify the presence and severity of arterial occlusive disease.


It can also be used to follow the progression of the disease. The patient must rest for at least 20 minutes before testing, since this can affect the results, especially if the patient has PAD. The patient is then positioned supine with the lower extremities at the heart level so the hydrostatic pressure cannot falsely elevate the measurements.


During an arterial Doppler exam, various cuffs are placed on the patient’s legs and arms. This exam uses color wave (CW) Doppler. CW Doppler employs two crystals contained in the same probe: one that transmits the signal and one that receives the reflected sound wave of the blood cells. The reflected frequency is either higher or lower than the transmitted frequency, depending on the flow direction. This change in frequency is called the Doppler shift. The ankle brachial index (ABI) is recorded, and the waveforms are analyzed. The ABI is a simple test that compares the blood pressure in the upper and lower limbs. The ABI is calculated by dividing the blood pressure in an ankle artery by the blood pressure in an arm artery. An ABI value of less than indicates PAD.


An arterial duplex is another type of evaluation that uses ultrasound. It starts proximally at the common femoral artery with a side-by-side transverse image without and with color Doppler, followed by a sagittal image of the artery in red and sometimes the corresponding vein(s) in blue, and finally, a sagittal image of the artery with waveform analysis, which includes peak systolic velocity (PSV) and end-diastolic velocity (EDV). As the arterial study is performed from proximal to distal, the same approach is obtained with each artery, including, in succession, the common femoral artery (CFA), profunda femoral artery (Prof A), superficial femoral artery (SFA), popliteal artery (Pop A), posterior tibial artery (PTA), peroneal artery (Pero A), anterior tibial artery (ATA), and dorsalis pedis artery (DPA). The abbreviations given in parentheses in the previous sentence have been labeled in some of the ultrasound images discussed below. The abbreviation Trans used in some of these images is for transverse. Figures 10-46 and 10-47 show the transverse and sagittal views, respectively, of the side-by-side images of the right common femoral artery without and with color Doppler. Figure 10-48 shows the sagittal view of the right common femoral artery with color Doppler and waveform analysis.


Figures 10-49 and 10-50 show the transverse and sagittal views, respectively, of the right profunda femoral artery without and with color Doppler. Figure 10-51 shows the sagittal view of the right profunda femoral artery with color Doppler and waveform analysis.


Figures 10-52 and 10-53 show the transverse and sagittal views, respectively, of the right proximal superficial femoral artery without and with color Doppler. Figure 10-54 shows the sagittal view of the right proximal superficial femoral artery with color Doppler and waveform analysis.


Figures 10-55 and 10-56 show the transverse and sagittal views, respectively, of the right middle superficial femoral artery without and with color Doppler. Figure 10-57 shows the sagittal view of the right middle superficial femoral artery with color Doppler and waveform analysis.


Figures 10-58 and 10-59 show the transverse and sagittal views of the right distal superficial femoral artery without and with color Doppler. Figure 10-60 shows the sagittal view of the right distal superficial femoral artery with color Doppler and waveform analysis.


Figures 10-61 and 10-62 show the transverse and sagittal views, respectively, of the right popliteal artery without and with color Doppler. Figure 10-63 shows the sagittal view of the right popliteal artery with color Doppler and waveform analysis.


Figures 10-64 and 10-65 show the transverse and sagittal views, respectively, of the right posterior tibial artery without and with color Doppler. Figure 10-66 shows the sagittal view of the right posterior tibial artery with color Doppler and waveform analysis.


Figures 10-67 and 10-68 show the transverse and sagittal views, respectively, of the right peroneal artery without and with color Doppler. Figure 10-69 shows the sagittal view of the right peroneal artery with color Doppler and waveform analysis.


Figure 10-70 shows the side-by-side sagittal view of the right anterior tibial artery without and with color Doppler. Figure 10-71 shows the sagittal view of the right anterior tibial artery with color Doppler and waveform analysis.


Figure 10-72 shows the transverse view of the right dorsalis pedis artery without and with color Doppler. Figure 10-73 shows the sagittal view of the right dorsalis pedis artery with color Doppler and waveform analysis.


Figure 10-73: Sagittal image of the right dorsalis pedis artery with color Doppler.


When evaluating the lower extremities for diagnostic criteria for PAD, the PSV and velocity ratio (VR) are often used. The VR is defined as the ratio of the PSV of the stenotic area to the PSV of the standard proximal segment. The degree of stenosis is determined by these values of the PSV and VR, as illustrated in Table 10-2.[22]


Kidneys are interesting because understanding renal function and disease involves several disciplines, including chemistry, biology, and physics. In clinical medicine, we often analyze renal function using standard lab tests such as urinalysis, serum creatinine, and serum blood urea nitrogen (BUN). These tests give us clues about both normal function and etiologies of pathology. Examples of how the three tests help us begin abound: too much protein in the urine in the shape of a glomerulus (called “casts”) may indicate immune-mediated glomerulonephritis, too-high creatinine alone may indicate diffuse renal failure and intravascular fluid overload, and an altered creatinine-BUN ratio may indicate intravascular fluid depletion.


In a typical ultrasound fashion, we will look at the end anatomic result of renal function and formulate a theory of a patient’s condition. Figure 9-1 shows an ultrasonography scan of the longitudinal view of the usual left kidney.


Although it might be challenging to view a nephron or its functional parts on ultrasound, we can observe the results of renal malfunction with our gross anatomic view and make some rapid observations that may help a patient. The fascia is the outer fibrous covering of many organs, and Gerota’s fascia is the one that surrounds the kidneys and adrenal glands. This fascia is particularly dense and hyperechoic, most often producing a bright reflection (white) back onto the screen in the B-mode. From this distinct outline, we can determine the size, shape, location, and consistency of the surrounding structures near the kidney. The kidney measures approximately 11–14 cm in length, 6 cm in width, and 4 cm in thickness. You may measure these at first, but you may soon only estimate the size visually. Other hyperechoic structures typically surround the kidney. The liver is located superior to the right kidney, and the spleen is located superior to the left kidney. The kidneys are retroperitoneal, or behind the peritoneal cavity. Difficulties in visualizing a kidney are due to the presence of air-filled lungs superior to it as well as the ribs. Air, of course, disperses the ultrasound waves so that reflection is complex. Ribs cause shadowing, which may completely prohibit your initial viewing attempts. Because the liver does not fully extend to the left side, the left kidney is often partially covered by the thoracic cavity and more challenging to visualize.


Other than size and shape, a general clinician ultrasound exam may include lobules, evaluation of cortex thickness, evaluation of the renal pelvis, a survey to evaluate hyperechoic renal calculi (kidney stones), and observation of the vessels entering and leaving the renal pelvis (renal arteries, renal veins, and ureters). If atrophy is noted or a patient has marked hypertension, renal artery blood flow velocity is calculated via Doppler technology to determine if there is renal artery stenosis. This latter exam is usually outside the realm of general clinical ultrasound. It may be best for the general ultrasound clinician to refer this exam to those who do the exam often.


Large kidneys, or hydronephrosis, may be due to congenital variation, but this most often is a condition due to distal obstruction. Figure 9-2 shows an ultrasound image of end-stage hydronephrosis. Most often, there is only unilateral obstruction of the ureter. As the kidney continues to make urine in the presence of ureteral obstruction, there is backflow pressure and renal swelling. This is often seen in patient care with ureteral calculi obstructing a ureter. Hematuria (blood in the urine), unilateral pain, and unilateral hydronephrosis are diagnostic of ureteral calculi, even if a calculus is too small to be seen (usually less than 3 mm). Treatment is begun based on this clinical presumption.


Choices to diagnose kidney and ureteral stones include intravenous pyelogram (IVP), plain radiographs, CT scans (which allow the synthesis of a 3D picture from multiple radiologic views), and ultrasound. Plain radiography, or shooting an X-ray through the abdomen, is the oldest evaluation method but is still used. Often hydronephrosis and occasionally an actual stone may be visualized. This method is often used to follow a visible stone over several days. IVP production involves injecting dye into a patient’s vein and taking serial plain X-rays to observe the flow of dye through the kidney and ureter. This method has lost great popularity due to the dye load on the kidney occasionally causing renal malfunction and less accuracy in diagnosis. CT technology is fast, does not require dye in this particular study, and is most accurate. The clarity of this technology is evident to the most inexperienced patient. Even a very small stone with a typical size of 1 mm may be measured more accurately. The stone may be more easily seen even if it does not contain calcium to reflect ultrasound waves. CT is used most often, but ultrasound is becoming more popular due to cost and the lack of ionizing radiation. Figure 9-3 shows an ultrasound image of a renal stone located at the pyeloureteral junction.


Over 70 million CT scans are performed in the United States every year.[1] The malignant potential of CT scans was most famously brought to the forefront in 2007 by David Brenner and Eric Hall in the New England Journal of Medicine.[2] Determining the medical cost of a CT scan is also a complex issue. There is a wide range of costs for CT imaging, typically running from $900 to $3,000. It is conceded by most that clinician-generated ultrasound avoids both of these menacing issues.


Clinically, significantly small bilateral kidneys with a thin cortex may indicate chronic renal disease from a diffuse process such as glomerulonephritis or chronic urinary tract infections causing scarring. This condition is distinct from a single small kidney and indicates a localized problem, such as decreased blood flow to only one kidney, known as renal artery stenosis.


Gallbladder ultrasounds are standard diagnostic investigations that can be done by primary care and emergency providers. The capsule of the gallbladder, with its fluid-filled contents, often makes a very clearly defined reflective surface. Figure 9-4 shows an ultrasound image of a gallbladder stone. Calculi, often called “gallstones,” may be seen within the gallbladder because of the high density and reflectivity of the discrete objects sitting in often clear fluid. Another feature called “shadowing” is helpful in diagnosis. Shadowing refers to the sharply demarcated darkness that is under the gallstone. Not all gallstones cause disease or need to be addressed. Other features that can be noted on ultrasound and can indicate pathology or a diseased state in a patient include the location of the calculi, the size of the gallbladder, inflammation of the gallbladder, and acute cholecystitis.


Gallstones close to the gallbladder neck are speculated to have more potential to eventually migrate through the gallbladder neck, into the cystic duct, and even into the common bile duct. Gallstones are often more challenging to visualize in the cystic duct or common bile duct due to their small size and coexisting bowel gas reflecting the ultrasound beam before it can reach the gallbladder. Other modalities are often needed to assist in diagnosis.


The gallbladder contracts with cholecystokinin hormone, stimulating the vagus nerve in the parasympathetic nervous system. A small gallbladder may indicate chronic inflammation and scarring. A large gallbladder may also be pathological, even indicating rare gallbladder cancer. The gallbladder size is recorded by manipulating the measurement function on the machine.


The wall of the gallbladder can be thickened from inflammation. Greater than cm wall thickness is often defined as being pathologically thickened.


Surrounding a thickened wall can also be inflammatory fluid, indicating an acute inflammatory response or “acute cholecystitis.” This inflammatory fluid will be seen as a dark area outside the (usually thickened) gallbladder wall, as shown in Figure 9-5.


Figure 9-6 is an abdominal ultrasound showing the right lobe of the liver and right kidney. Compared to the gallbladder, kidney, intestine, or bladder, the liver’s thin covering makes it less distinctive. Distinctive features include the following:


While both systems are housed in the thorax, pulmonary and cardiac ultrasound approaches and findings can be strikingly different. As briefly discussed in the previous chapter, cardiac ultrasound has specific measures used for valves, blood velocity, and cardiac muscle contractility. The operators’ abilities can adversely affect measurement accuracy on such subtle issues as the angle at which the probe is held and, subsequently, the angle at which measurements are obtained. One of the productive uses of artificial intelligence in the ultrasound field allows the operator to know when the best angle of insonation is obtained before the image is captured. Clear imaging is partially achieved by filtering raw images and removing portions of the images that are confusing to obtain the measurements. These measurements then determine important treatment routes, including choosing medication for the patient and even deciding if cardiac surgery is necessary.


In many ways, pulmonary ultrasound is the antithesis of cardiac ultrasound. The motion cycle of the lungs is less dramatic and less frequent, and the “snow patterns” on the screen caused by a lung consolidation or other conditions allow health care providers to make rapid, critical, and often lifesaving decisions about patients who are most ill. The total picture of the reflections of an ultrasound beam that is received from the same beam-emitting probe is often blurred. The “artifacts” are often distracting and even prohibitive in making the exact measurements. Figure 8-1 shows an ultrasound image of the intercostal space. Daniel Lichtenstein, known by many as the father of critical care ultrasound, was one of the first experts to recognize that the artifacts emitted in the lungs were not the problem but part of the solution in determining the pulmonary and vascular status of the patient.[3] The notion of lung ultrasound was possible and pertinent through Dr. Lichtenstein and his colleagues’ recognition and hard work.


Successful respiratory cycles are controlled at many levels, from the brain to the alveoli. Clinically, we focus on what we can change to improve our patients’ conditions. The brain’s complex mechanisms and primary circuits, such as the autonomic nervous system and vagus nerve, are often out of our reach to meaningfully control for the long-term. We can mimic respiratory control by completely paralyzing our muscles and forcing air with oxygen concentrations into the lungs at a rate determined to be optimal by the clinician. This action is almost always temporary, such as for patients needing general anesthesia for surgery or patients in respiratory failure needing intensive care unit (ICU) attention. Lung ultrasound is most often used to help diagnose the cause of acute respiratory failure or evaluate continuing critical care efforts on patients already being actively treated for respiratory failure.