Radiology - Technology Information PortalSaturday, 1 November 2014
Info
  Sheets

Out-
      side





 
 'Intensifying Screen' 
SEARCH   
 
  ABCDEFGHIJKLMNOPQRSTUVWXYZ
Result : Searchterm 'Intensifying Screen' found in 1 term [] and 7 definitions []
1 - 5 (of 8)     next
Result Pages : [1]  [2]
Radiology Resources 
 pointMusculoskeletal System    pointPediatrics    pointSupplies and Accessories    pointEquipment and Parts    pointCT Scanners    pointBioinformatics    
 
Intensifying Screen
 
An intensifying screen is used to intensify the x-ray effect during radiation exposure of the x-ray film. Approximately 5% of the x-ray photons will be absorbed by the film only. Intensifying screens consist of a sheet of inorganic salts that emits fluorescent light when stroked by x-rays. The fluorescent input and output screens of the image intensifier are very similar to intensifying screens.
Calcium tungstate and rare earths are two common salts (also called phosphors) used for intensifying screens. For example, a calcium tungstate (CaWo4) screen can absorb around 40% of the x-ray photons and convert the radiation into light photons. A basic feature of this screen types is related to the position of the k-edge on the energy axis. Tungsten (W) is a heavy element has a k-edge at 69.5 keV, while that for rare earth elements is in around 50 keV.
The fraction of x-rays absorbed by a screen is depending on the speed. Factors affecting the speed of a screen:
point the phosphor type;
point the x-ray radiation absorption efficiency;
point the radiation to light intrinsic conversion efficiency;
point the thickness of the screen.

Mammography cassettes contain usually one intensifying screen, but most others use two screens per film cassette. The intensifying screen as part of a film screen system has been an important component in radiology to reduce the radiation dose of the patient. Today, the conventional film cassette is being replaced by an imaging plate used in digital systems.
See also Actinides, Cinefluorography and Added Filtration.
 
• Share the entry 'Intensifying Screen':  Facebook  Twitter  LinkedIn  
Radiology Resources 
 pointPET/CT    pointHeart, Cardiac    pointDirectories    pointService and Repair    pointMolecular Imaging    pointVascular System    
 
Cassette
 
A cassette is a thin, low x-ray absorption plastic case, for holding the x-ray film. Inside the cassette are intensifying screens for the conversion of x-rays to visible light photons. The intensifying screens are mounted in close contact with the film. Mammography cassettes are equipped with single screens.
Radiology Resources 
 pointImage Libraries    pointCase Studies    pointPediatrics    pointVascular System    pointBioinformatics    pointRadiopharmaceuticals    
 
X-Ray Film
 
An x-ray film is a photographic film used to generate a visual x-ray image. X-ray films are rarely used as the only radiation detector. Commonly they are used in conjunction with intensifying screens placed in the film cassette, because high resolution films have a poor sensitivity to x-rays. At direct film exposure, only a small amount of x-ray photons will be absorbed and react with the film emulsion. An intensifying screen contains scintillating materials to convert x-ray radiation into light or lows electromagnetic energies.
X-ray films provide very good spatial resolution and contrast, but need long exposures times and chemical processing.
See also Conventional Radiography and Digital Radiography.

• View the NEWS results for 'X-Ray Film' (3).Open this link in a new window. 


  Further Reading:
  Basics:
The Photographic Process and Film SensitivityOpen this link in a new window
'Medical images are recorded either in digital format on some form of digital media or on photographic film. Here we consider the ...'
by www.sprawls.org    
Radiology Resources 
 pointContrast Agents    pointGuidelines    pointLung, Pulmonary System    pointDosimetry    pointSafety pool    pointPACS    
 
Conventional Radiography
 
Conventional (also called analog, plain-film or projectional) radiography is a fundamental diagnostic imaging tool in the detection and diagnosis of diseases. X-rays reveal differences in tissue structures using attenuation or absorption of x-ray photons by materials with high density (like calcium-rich bones).
Basically, a projection or conventional radiograph shows differences between bones, air and sometimes fat, which makes it particularly useful to asses bone conditions and chest pathologies. Low natural contrast between adjacent structures of similar radiographic density requires the use of contrast media to enhance the contrast.
In conventional radiography, the patient is placed between an x-ray tube and a film or detector, sensitive for x-rays. The choice of film and intensifying screen (which indirectly exposes the film) influence the contrast resolution and spatial resolution. Chemicals are needed to process the film and are often the source of errors and retakes. The result is a fixed image that is difficult to manipulate after radiation exposure. The images may be also visualized on fluoroscopic screens, movies or computer monitors.
X-rays emerge as a diverging conical beam from the focal spot of the x-ray tube. For this reason, the radiographic projection produces a variable degree of distortion. This effect decreases with increased source to object distance relative to the object to film distance, and by using a collimator, which let through parallel x-rays only.
Conventional radiography has the disadvantage of a lower contrast resolution. Compared with computed tomography (CT) and magnetic resonance imaging (MRI), it has the advantage of a higher spatial resolution, is inexpensive, easy to use, and widely available. Conventional radiography can give high quality results if the technique selected is proper and adequate. X-ray systems and radioactive isotopes such as Iridium-192 and Cobalt-60 for generating penetrating radiation, are also used in non-destructive testing.
See also Computed Radiography and Digital Radiography.


  Further Reading:
  Basics:
Medical radiographyOpen this link in a new window
'Radiography is the use of ionizing electromagnetic radiation such as X-rays to view objects. Although not technically ...'
by en.wikipedia.org    
Radiology Resources 
 pointEncyclopaedias    pointLung, Pulmonary System    pointImage Interpretation pool    pointCT Scanners    pointRadiopharmaceuticals    pointJournals and Magazines    
 
Direct Exposure Film
 
Direct exposure films are highly sensitive to the direct effect of x-rays rather than in combination with an intensifying screen. However, a film is a relatively inefficient radiation detector and requires relatively high radiation exposure. The use of rectangular collimation and the highest speed films reduce radiation exposure.
See also Conventional Radiography.


  Further Reading:
  Basics:
The Photographic Process and Film SensitivityOpen this link in a new window
'Medical images are recorded either in digital format on some form of digital media or on photographic film. Here we consider the ...'
by www.sprawls.org    
Radiology Resources 
 pointAtlases    pointSPECT    pointHospitals    pointHumor    pointPortals    pointLung, Pulmonary System    
 
Radiology Resources 
 pointContrast Enhanced CT    pointNon-English    pointService and Repair    pointArtifacts    pointReimbursement    pointCT Scanners    
 
     1 - 5 (of 8)     next
Result Pages : [1]  [2]
 Random Page
 
Share This Page
FacebookTwitterLinkedIn

Radiology-TIP
Community
User
Pass
Forgot your UserID/Password ?  


Look
      Ups






Radiology - Technology Information Portal
Member of SoftWays' Medical Imaging Group - MR-TIP • Radiology-TIP • US-TIP • The-Medical-Market
Copyright © 2008 - 2014 SoftWays. All rights reserved.
Terms of Use | Privacy Policy | Advertising
 [last update: 2014-07-21 03:53:52]