Digital Image: From 1 Different Sources
an image made up of *pixels. Each pixel has numbers (digits) to describe its position and shade on the *grey scale. The more shades available, described by the number of computer bits required to store the shade of grey, the more accurately the image represents the original tissue contrast. An 8-bit computer image shows 28 (256) possible shades of grey, close to the maximum the human eye can differentiate. 12-bit (4096 levels of grey) images are of much higher quality and take up more memory. They can be manipulated more easily by computer using image enhancement techniques. Compare analogue image.
A radiological technique for detecting osteoporosis (see BONE, DISORDERS OF) in which a beam of X-rays is directed at the bone-area under investigation – normally the spine and hip – and the CALCIUM density measured. If the calcium content is low, preventive treatment can be started to reduce the likelihood of fractures occurring.... quantitative digital radiography
A person’s perception of the different parts of his or her own body.... body image
See angiography.... digital subtraction angiography
n. an impression of an image that is registered by the brain for a brief moment after an object is removed from in front of the eye, or after the eye is closed. A positive afterimage, which lasts a few seconds, retains the colour and brightness of the original image; the more common negative afterimage lasts longer and has colours and brightness that are complementary to the original.... after-image
a traditional X-ray image on film that is in shades that range smoothly from black to white with no appreciable steps from one shade of grey to the next (see grey scale). Analogue images can be converted to digital format (see digitization) for manipulation and storage by computers and other electronic devices.... analogue image
adj. 1. (in anatomy) relating to a digit. 2. (in radiology) relating to or utilizing *digitization.... digital
see hearing aid.... digital hearing aid
(DR) an alternative to film radiography, by acquiring X-ray images from a large number of individual X-ray detectors on a matrix in a digital format directly. This contrasts with *computerized radiography, in which an *analogue image is taken and then put into a reader to be converted into a *digital image. The technique allows the storage of images and their subsequent retrieval, manipulation, and interpretation using computers (see PACS).... digital radiography
(DSI) the production of static images using an *image intensifier, usually during a fluoroscopic examination. The images can be stored digitally (see digitization) and either transferred to photographic film or viewed on a TV monitor.... digital spot imaging
a radiological technique that enhances visualization of blood vessels (see angiography). A digitized image is taken before the contrast medium (a ‘mask’) is injected, and this is subtracted by computer from the images taken after contrast injection. Only the blood vessels remain on the image. The technique enables blood-vessel anatomy and blood supply to an organ to be demonstrated more clearly. The quality of the image is very dependent on the patient remaining still, since movement causes severe loss of image (movement *artifact). The technique can also be used in nuclear medicine using two different tracers to look for parathyroid gland tumours.... digital subtraction
(IGRT) the process of imaging during a course of radiation treatment to verify the internal position of the target in comparison to the initial planning scan. This enables adjustment of *treatment fields to improve coverage and allows the use of smaller treatment volumes. The possible methods for IGRT include cone beam CT, *tomotherapy, *cyberknife, and ultrasound and kilovoltage X-rays of implanted fiducial markers.... image-guided radiotherapy
see computer-assisted surgery.... image-guided surgery
n. the production of vivid mental representations by the normal processes of thought. Eidetic imagery, more common in children than adults, is the production of images of exceptional clarity, which may be recalled long after being first experienced.... imagery
see 3-D magnetic imager.... magnetic imager
the trading name of the *Health and Social Care Information Centre (HSCIC) since 1 August 2016. It is the national provider of information, data, and IT systems for commissioners, analysts, and clinicians for the National Health Service (England). It also runs the *NHS Choices website.... nhs digital
an electronic image taken during radiotherapy treatment to verify the position of radiation beams.... portal image
an instrument that harnesses magnetic technology to give a virtual image of an endoscope during colonoscopy. It aids steering and minimalizes looping of the endoscope. An external antenna tracks the magnetic field generated by coils built inside the endoscope, enabling real-time 3D imaging of this instrument. Trade name: ScopeGuide.... 3-d magnetic imager
an electronic device that provides a TV image from an X-ray source. The X-rays strike a fluorescent screen after passing through the patient, giving off electrons, which are accelerated using an electron lens before striking a second fluorescent screen, which is usually attached to a video camera. The acceleration of the electrons amplifies the signal from the original image, giving a brighter picture, so that the radiation dose can be reduced. Images can be taken from the camera to be observed in real time on a video monitor or, using a brief higher-dose exposure, to provide a more detailed static image (see digital spot imaging).... image intensifier
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