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The scale Hounsfield or CT , named after Sir Godfrey Hounsfield, is a quantitative scale for describing radiodensity.


Video Hounsfield scale


Definisi

The Hounsfield (HU) scale is a linear transformation of the measurement of the original linear attenuation coefficient into one where the radiodensity of distilled water at standard pressure and temperature (STP) is defined as the Hounsfield (HU) zero unit, while the airborne radiodity in STP is defined as -1000 HU. In voxel with the average linear attenuation coefficient               ?               {\ displaystyle \ mu} , the corresponding HU value is given by:

              H          U         =         1000        ÃÆ' -                                             ?      Â     Â                ?                                             Â water//mtext>     ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ,        ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ,       Â                            Â                ?                                             Â water//mtext>     ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ,        ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ,       Â      Â     Â                ?                                          ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ, Air     ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ,        ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ,       Â                                            {\ displaystyle HU = 1000 \ times {\ frac {\ mu - \ mu _ {\ textrm {water}}} {\ mu_ {\ textrm {water }} - \ mu_ {\ textrm {water}}}}}  Â

Di                            ?                                     air                                          {\ displaystyle \ mu _ {\ textrm {water}}}  dan                            ?                                     udara                                          {\ displaystyle \ mu_ {\ textrm {air}}}  masing-masing adalah koefisien atenuasi linier air dan udara.

Thus, a change of one Hounsfield (HU) unit represents a 0.1% change of the water attenuation coefficient because the air attenuation coefficient is almost zero.

This is the definition for a calibrated CT scanner with reference to water.

Rationale

The above standards are chosen because they are universally available and suitable for key applications for developed axial tomography are developed: internal anatomical imaging of living things based on organized water structures and mostly living in the air, for example humans.

Maps Hounsfield scale



Value in body parts

The Hounsfield scale applies to medical grade CT scans but not for CT (computed tomography computed tomography) scans.

This practical application is a tumor evaluation, in which, for example, adrenal tumors with less than 10 HU radiodensity are somewhat fatty in composition and almost certainly benign adrenal adenomas.

ASPECTS (Alberta Stroke Program Early CT Score) Measurement Using ...
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History

The CT machine was the first imaging device for detailed visualization of the internal three-dimensional anatomy of living things, initially only as a tomographic reconstruction of the sights or sections. Since the early 1990s, with advances in computer technology and scanners using spiral CT technology, the three-dimensional internal anatomy can be seen with the reconstruction of three-dimensional software, from multiple perspectives, on computer monitors. For comparison, conventional X-ray images are the correct three-dimensional projection of true three-dimensional anatomy, the radiodent shadow. It was founded by Sir Godfrey Newbold Hounsfield, one of the major engineers and developers of computed axial tomography (CAT, or CT scan).

Hounsfield unit value and clot length in the acutely occluded ...
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See also

  • Cone beam computed tomography # Bone density and Hounsfield scale

Functional computed tomography using energy resolved photon ...
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References

  • Feeman, Timothy G. (2010). Mathematical Medical Imaging: Beginner's Guide . Springer Undergraduate Text in Mathematics and Technology. Jumper. ISBN: 978-0387927114.

Quantification of Thrombus Hounsfield Units on Noncontrast CT ...
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Note


CT of the chest with model-based, fully iterative reconstruction ...
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External links

  • "Hounsfield unit". Medcyclopaedia . GE.
  • Hounsfield Unit - fpnotebook.com
  • "Introduction to CT physics" (PDF) . elsevierhealth.com. Archived from the original (PDF) in 2007-09-26.
  • Brain stimulation in the brain leads using an extended Hounsfield CT unit. Stereotact Funct Neurosurg. 2009; 87 (3): 155-60. doi: 10.1159/000209296

Source of the article : Wikipedia