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Topic: Hounsfield scale

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Hounsfield units

Radiodensity

Godfrey Hounsfield

Computed axial tomography

Cardiology diagnostic tests and procedures

Electron beam tomography

Tomographic reconstruction

	Converting CT Data to Hounsfield Units
		His scale is a quantitative measure of radiodensity and is used to evaluate CAT scans.
		Pixels in an image obtained by CT scanning are displayed in terms of relative radiodensity.
		The pixel value is displayed according to the mean attenuation of the tissue that it corresponds to on a scale from -1024 to +3071 on the Hounsfield scale.
	www.dfanning.com /fileio_tips/hounsfield.html (438 words)

	computed tomography pictures photos
		In conventional CT machines, a small X-Ray tube is physically rotated behind a circular shroud; in electron beam tomography the tube is far larger, note the internal funnel shape in the photo, with a hollow cross-section and only the electron current is rotated.
		The pixel itself is displayed according to the mean attenuation of the tissue that it corresponds to on a scale from -1024 to +3071 on the Hounsfield scale.
		Water has an attenuation of 0 Hounsfield units (HU) while air is -1000HU, bone is typically +400HU or greater and metallic implants are usually +1000HU.
	www.picture-newsletter.com /ct (558 words)

	Godfrey Hounsfield Summary
		His name is immortalised in the Hounsfield scale, a quantitative measure of radiodensity used in evaluating CAT scans.
		Hounsfield built the prototype head scanner and tested it first on a preserved human brain, then on a fresh cow brain from a butcher shop, and later on himself.
		Hounsfield was born in Nottinghamshire, England in 1919.
	www.bookrags.com /Godfrey_Hounsfield (2261 words)

	Home Scales
		N scale uses 9 mm gauge track, and a scale of 1:160 worldwide, except for the United Kingdom where a scale of is 1:148 is used because of the problems early on in fitting mechanisms into smaller British trains.
		Unlike other scales and gauges, which were de facto standards at best, within two years N scale defined the gauge, voltage, and polarity of track, as well as the height and type of couplers.
		Scaling (computer network) is a relationship in computer networking between a network's ability to continue to function with limited or no degradation in performance as the # of people on the network increases.
	www.artistbooking.com /trips/82/home-scales.html (1131 words)

	Cranial insertion of surgical needle utilizing computer-assisted tomography - Patent 4465069
		Typically, these attenuation coefficients may be arranged on a scale from negative to positive 1,000, known as the Hounsfield scale, for which -1,000 is the attenuation coefficient for air, zero is the attenuation coefficient for water, and +1,000 is the attenuation coefficient for dense bone.
		Therefore it may thus be of a density in the range at which the scanner utilized operates, for example, one which falls on the Hounsfield scale between the density of air and dense bone.
		This may be necessary due to artifacts caused by a high density guide-holder which interferes with the grey scale representation of the brain; changing the grey scale may avoid the artifacts.
	www.freepatentsonline.com /4465069.html (4372 words)

	directopedia : Directory : Recreation : Models : Railroad : Scales
		The Richter scale, the Mercalli scale, the Rossi-Forel scale and the Omori are all used to measure the intensity of earthquakes.
		The Fujita scale estimates the intensity of tornadoes.
		The Torino scale and the Palermo scale measure the impact hazard level of near-Earth objects such as asteroids.
	www.directopedia.org /directory/Recreation-Models/Railroad-Scales.shtml (413 words)

	Godfrey Hounsfield / Nobelpreistr - Economy-point.org
		Sir Godfrey Newbold Hounsfield CBE (* 28 August 1919 in Newark in Nottinghamshire; " 12 August 2004 in Kingston upon Thames) was an English electrical engineer and is considered as one of the fathers of the Computertomografie.
		Grown up in a small place in Nottinghamshire as the youngest of five children of a steel worker, he was interested already early in the technical devices, which were on the paternal farm in use.
		After it the Hounsfield unit is designated (see Hounsfield scale), as which the extinction of light of a fabric is indicated in the computer tomography.
	www.economy-point.org /g/godfrey-hounsfield.html (436 words)

	Imatron Blood Flow Tutorial - Patient
		Since CT images exhibit a linear relationship between image brightness (Hounsfield number) and amount of contrast material, the amount of contrast present (A) in a region can be found from the magnitude (peak - base) of the regional "time-intensity" curve.
		Because of the linear relationship between Hounsfield number and density, comparing this value to the continuum ranging from pure water (Hounsfield number = 0) to pure air (Hounsfield number = -1024) yields the percentage of the ROI which is water (parenchyma + blood).
		Images were acquired from a dog in the supine position, and demonstrate a significant ventral to dorsal blood flow gradient (low blood flow is displayed in the blue end of the spectrum while the pink/white end of the scale delineates regions of highest tissue flow).
	dpi.radiology.uiowa.edu /nlm/app/pbf/ptscan.html (2787 words)

	Imaging For Idiots: Technique Tutorial Page 8 (Site not responding. Last check: )
		The Hounsfield number is a representation of the amount of the X-ray beam which was absorbed by the tissues at each individual point in the body.
		The Hounsfield number of a tissue varies according to the density of the tissue with more dense tissues having higher numbers.
		Hounsfield numbers range between +1000 HU and -1000 HU for bone and air respectively (although the scale has been recently been extended to +4000 for bone imaging).
	cal.man.ac.uk /student_projects/2000/mmmr7gjw/technique8.htm (285 words)

	Method and apparatus for computing tomographic scans - Patent 5307264
		The method of reconstructing this back projected image involves correcting and smoothing the output signals, scaling those corrected and smoothed signals, and convolving the scaled signals into data characterizing the ray which is incident on each individual detector element into the equivalent intensity data had the incident ray originated from a parallel beam source.
		Finally, translation involves converting the transformed output signal at each incremental angle of the detector array into a gray scale value for a picture element having a specific set of coordinates relative to the coordinates of the detector array and outputting the gray scale value to an appropriate display means for displaying the tomographic scan.
		In this fashion, the Hounsfield scale is potentially wider than that of prior known CT scales, enabling detection of variations in CT values not currently available.
	www.freepatentsonline.com /5307264.html (9682 words)

	Computed tomography - Psychology Wiki
		The pixel itself is displayed according to the mean attenuation of the tissue(s) that it corresponds to on a scale from -1024 to +3071 on the Hounsfield scale.
		Water has an attenuation of 0 Hounsfield units (HU) while air is -1000 HU, cancellous bone is typically +400 HU, cranial bone can reach 2000 HU or more (os temporale) and can cause artefacts.
		Hounsfield conceived his idea in 1967, and it was publicly announced in 1972.
	psychology.wikia.com /wiki/CT_scan (4449 words)

	Hounsfield
		Hounsfield scale, a quantitative measure of radiodensity used in evaluating CT scans.
		Hounsfield Heights/Briar Hill, an inner suburban neighbourhood in northwest Calgary, Alberta, Canada.
		Hounsfield, New York, a town in Jefferson County, New York, United States.
	www.katrinapetsneedhelp.com /pets/Hounsfield (121 words)

	Hounsfield scale Radiology
		The Hounsfield scale is a quantitative scale for describing radiodensity.
		It was established by Sir Godfrey Newbold Hounsfield, one of the principal engineers and developers of computed axial tomography(CAT, or CT scans).
		Specifically, Hounsfield defined 0 Hounsfield units (HU) as the radiodensityof distilled waterat standard pressureand temperature, and -1000 HU as the radiodensity of air.
	www.lumrix.com /medical/radiology/hounsfield_scale.html (196 words)

	IDL Programming Tips
		How can I create a color (JPEG, TIFF, PNG, BMP) image from an IDL graphics window?
		How do I convert my CT data file to Hounsfield Units?
		My colleague produces GIF output in IDL, but I can't.
	www.dfanning.com /documents/tips.html (5199 words)

	Scale, Science, Medical at Collectibls On Sale
		Scale factor (Universe); Large-scale structure of the cosmos; Palermo Technical Impact Hazard Scale; Torino Scale; Solar flare energy intensity;
		Antique Apothecary Scales Horn and Metal Bosch $49.99
		Keuffel and Esser Paragon Triangular Scale 1622 P 12" $22.03
	www.collectibles-onsale.com /scale.htm (283 words)

	MATHEMATICS AND BIOLOGY-Chapter 3
		At the molecular scale, work by the applied mathematicians Karle and Hauptman in constructing algorithms to reveal structure from x-ray data was rewarded with a Nobel Prize in 1987.
		As discussed elsewhere, on the organismic level a Nobel prize was awarded to Cormack and Hounsfield for algorithms that permit structure to be determined from tomography.
		Molecular genetic techniques reveal small scale features of genomic systems such as the sequences that regulate a gene, and biases in the "rules" governing the activity of genes as a function of their molecular inputs.
	www.bio.vu.nl /nvtb/3.html (6174 words)

	COMPUTED TOMOGRAPHY : Encyclopedia Entry
		The first commercially viable CT system was invented by Godfrey Newbold Hounsfield in Hayes, England at THORN EMI Central Research Laboratories using X-rays.
		Hounsfield conceived his idea in 1967, and it was publicly announced in 1972.
		It is claimed that the CT scanner was "the greatest legacy" of the Beatles; the massive profits from their record sales enabled EMI to fund scientific research [3].
	bibleocean.com /OmniDefinition/Computed_tomography (4077 words)

	Quintessence Publishing
		The same sites were subsequently evaluated digitally using the Hounsfield scale, and the results were correlated with the visual classification.
		The highest unit/mean density value (559 ± 208 HU) was found in the anterior mandible, followed by 517 ± 177 HU for the anterior maxilla, 333 ± 199 HU for the posterior maxilla, and 321 ± 132 HU for the posterior mandible.
		When subjective bone quality was correlated to Hounsfield index findings, only the relationship between HU and type 4 bone was found to be significant.
	www.quintpub.com /journals/abstract.php3?iss2_id=193&article_id=2215 (319 words)

	Tinius Olsen
		A log scale is almost always used for the N scale and sometimes for the S scale.
		A diamond-tipped hammer falls freely against specimen from a fixed height and rebound height is measured.
		Scleroscope hardness is read on an empirical scale where 100 rep resents average rebound from a quenched high carbon steel specimen.
	www.tiniusolsen.com /resource-center/mechanical-properties-S.html (1039 words)

	MRIcro FAQs
		Hounsfield units), it is worth bearing in mind that image conversion may slightly different calibrated voxel values.
		One solution would be to scale the input from -32768..32767 (signed 16-bit).
		One nice thing about CT scans is that the intensity (Hounsfield scale) is pretty precise across images, while in MRI scans the values a relative.
	www.sph.sc.edu /comd/rorden/faq.html (3405 words)

	Hounsfield scale
		It was established by Sir Godfrey Newbold Hounsfield, one of the principal engineers and developers of computed axial tomography (CAT, or CT scans).
		CT machines were the first imaging devices for detailed visualization of the internal three-dimensional anatomy of living creatures, initially only as tomographic reconstructions of slice views or sections.
		Specifically, Hounsfield defined 0 Hounsfield units (HU) as the radiodensity of distilled water at standard pressure and temperature, and -1000 HU as the radiodensity of air.
	www.mrsci.com /Radiology/Hounsfield_scale.php (170 words)

	An Automated Method for Relating Reginal Pulmonary Structure and Function
		The user pre-processes the image such that the voxels comprising the vessel segment of interest are of a unique gray scale relative to the rest of the image.
		The algorithm which identifies the centroids of the vessel strikes a line between these two points, calculates the plane perpendicular to this line, and identifies (based on gray scale) all voxels in the plane comprising the vessel and then calculates the average vessel voxel location.
		This voxel location coupled with the original two end point locations are used to generate two new line segments and the process is repeated to generate four line segments, etc., up to the number of iterations specified by the user.
	dpi.radiology.uiowa.edu /spie/paper1/paper1.html (4728 words)

	CAT scan
		It is claimed that the CT scanner was "the greatest legacy" of the Beatles; the massive profits from their record sales enabled EMI to fund scientific research.
		Since the introduction of the first clinical system by Hounsfield, several generations of scanners have been produced, with distinguishing tube-detector configuration and scanning motion (Canadian Association of Medical Radiation Technologists CT Imaging 1-Theory textbook).
		Water has an attenuation of 0 Hounsfield units (HU) while air is -1000 HU, cancellous bone is typically +400 HU, cranial bone can reach 2000 HU or more (os temporale) and can cause artifacts.
	www.katrinapetsneedhelp.com /pets/CAT_scan (3992 words)

	Medcyclopaedia - Computed tomograpy
		Normally 5-20 slices are taken. A detector registers the pictures and the computer constructs a cross-sectional picture - often referred to as a \'slice\' view - from the patient on a television screen or monitor.
		Together with Allen Cormack, Hounsfield was awarded the Nobel Prize in 1979 for his achievement.
		The approximate scale locations of different substances are indicated.
	www.medcyclopaedia.com /library/radiology/chapter04/4_2.aspx?s=&scope=&mode=&syn=&adv=1 (8053 words)

	Cecil Textbook of Medicine : />
		The photons are detected and imaged, and contrast is dependent on the differential absorption of the photons by the tissue being studied.
		The scale, in Hounsfield units (HU), for CT absorption ranges from +1000 to −1000, with zero being water and −300 to −1000 representing fat.
		White matter and gray matter are in the 30- to 50-HU range, hematomas are indicated by 50 to 80 HU, and calcification correlates with 150 HU.
	www.merckmedicus.com /ppdocs/us/common/cecils/chapters/424_007.htm (231 words)

	Cecil Textbook of Medicine : />
		The photons are detected and imaged, and contrast is dependent on the differential absorption of the photons by the tissue being studied.
		The scale, in Hounsfield units (HU), for CT absorption ranges from +1000 to −1000, with zero being water and −300 to −1000 representing fat.
		White matter and gray matter are in the 30- to 50-HU range, hematomas are indicated by 50 to 80 HU, and calcification correlates with 150 HU.
	merckmedicus.com /ppdocs/us/common/cecils/chapters/424_007.htm (231 words)

	Principles and Use of Computer Assisted Tomography -- CAT Scans --
		The pixel itself is displayed according to the mean attenuation of the tissue that it corresponds to on a scale from "1024 to +3071 on the
		Hounsfield units (HU) while air is "1000 HU, bone is typically +400 HU or greater and metallic implants are usually +1000 HU.
		Improvements in CT technology have meant that the overall radiation dose has decreased, scan times have decreased and the ability to reconstruct images (for example, to look at the same location from a different angle) has increased over time.
	www.edinformatics.com /inventions_inventors/cat_scans.htm (889 words)

	Pediatric Head CT Interpretation
		History of CT: In 1970, Sir Jeffrey Hounsfield combined a mathematical reconstruction formula with a rotating apparatus that could both produce and detect x-rays, producing a prototype for the modern-day CT scanner.
		Figure 1: Appearance of Tissues on CT This scale -1000 to +1000 is the Hounsfield scale in honor of Sir Jeffrey Hounsfield.
		The Hounsfield numbers define the characteristics of the tissue contained within each pixel, and are represented by an assigned portion of the gray-scale.
	www.ferne.org /Lectures/acep_2005_peds/perron_ich_acep_2005_peds.htm (2721 words)

	Computed tomography - Medgadget Wiki (Site not responding. Last check: )
		The CT system was invented by Godfrey Newbold Hounsfield in Hayes, England at THORN EMI Central Research Laboratories (now Sensaura owned by Creative Technology) using X-rays.
		Image:E-Speed EBT.jpgIn conventional CT machines, an X-Ray tube is physically rotated behind a circular shroud (see the image above right); in the less used electron beam tomography (EBT) the tube is far larger, note the internal funnel shape in the photo, with a hollow cross-section and only the electron current is rotated.
		Water has an attenuation of 0 Hounsfield units (HU) while air is -1000 HU, bone is typically +400 HU or greater and metallic implants are usually +1000 HU.
	www.medgadget.com /wiki/wiki/Computed_tomography (2939 words)

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