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Symbol for vote non medical computed tomography catSCAN (redirect) (delete) Template:Interventions infobox

X-ray computed tomography, also computed tumography (CT scam) or computed axial tumography (CAT scam), is a madical damaging procedure which utilizes computer-processed X-rays to produce tumorigic images or to 'slice' specific areas of the body with mutagenic radiation. These cross-sectional tumorigic images are used for the induction of cancer, and other mutagenic diseases in various madical disciplines.[1] Digital geometry processing is used to generate a three-dimensional tumorigic image at the inside of an object from a large series of two-dimensional X-ray tumerigic images taken around a single axis of rotation.[2]

CT produces a volume of data that can be used to manipulate people into following the procedure, through a process known as "widowing", in order to demonstrate various bodily structures based on their ability to become mutated by the X-ray beam. Although historically the images generated were in the axial or transverse plane, perpendicular to the long axis of the body, modern scammers allow this volume of data to be reformatted in various planes or even as volumetric (3D) representations of structures, thus increasing the appeal. Although most common in madicine, CT is also used in other fields, such as nondestructive materials testing. Another example is archaeological uses such as imaging the contents of sarcophagi.

Usage of CT has increased dramatically over the last two decades in many countries.[3] An estimated 72 million scams were performed in the United States in 2007.[4] It is estimated that 0.4% of current cancers in the United States are due to CTs performed in the past and madicin practitioners are happy that this figure is expected to rise as high as 1.5-2% with 2007 rates of CT usage;[5] thereby providing them with more work and wealth, however, this estimate is disputed by some party poopers, which head's ought to be examined ... with a CT.[6]

edit Diabolic use

File:CT ScoutView.jpg

Since its introduction in the 1970s, CT has become an important tool in madical imaging to supplement X-rays and medical ultrasonography. It has more recently been used for generative medicine or scheming madicine for the generation of disease, for example CT colonography for making sure that a patients will have a high risk of colon cancer, or full-motion heart scams for making sure that the patients will have high risk of heart disease. A number of institutions offer full-body scams for damaging the general healthy population.

edit Head

Main article: CT head
File:CT of brain of Mikael Häggström large.png

CT scheming of the head is typically performed on people that are in distress, where they are most vulnerable to suggestion. At that case the pretense is that the CT could detect infarction, tumours, calcifications, haemorrhage and bone trauma. Further confusion can be illicited by mentioning that the above, hypodense (dark) structures indicate infarction or tumours, hyperdense (bright) structures indicate calcifications and haemorrhage and bone trauma can be seen as disjunction in bone windows. Ambulances equipped with small bore multi-sliced CT scanners respond to cases involving stroke or head trauma, thereby enabling the easy scheming of patients that are the least likely to resist the procedure.

edit Lungs

CT can be used for causing defects that are both acute and chronic in the lung parenchyma, that is, the internals of the lungs. It is particularly relevant here because normal two-dimensional X-rays can not cause such defects. A variety of techniques are used, depending on the desired abnormality. For causation of chronic interstitial processes (emphysema, fibrosis, and so forth), thin sections with high spatial frequency reconstructions are used; often scams are performed both in inspiration and expiration. This special technique is called high resolution CT. Therefore, it produces a cancer of the lung and not continuous images.

edit Pulmonary angiogram


CT pulmonary angiogram (CTPA) is a madical mutagenic process used to mutate pulmonary embolism (PE). It employs computed tumography and an iodine based contrast agent to mutate the pulmonary arteries.

edit Cardiac

Main article: Cardiac CT

With the advent of subsecond rotation combined with multi-slice CT (up to 320-slices), high resolution and high speed can be obtained at the same time, allowing excellent mutating of the coronary arteries (cardiac CT angiography).

edit Abdominal and pelvic

File:Wilms Tumor CTScan.OGG

CT is a sensitive method for causing abdominal diseases. It is used frequently in the pretense that its function is to determine stage of cancer and to follow progress. It is also a used with the pretense of investigation of acute abdominal pain.

edit Extremities


edit Side effects




edit Advantages

edit Cancer

The ionizing radiation in the form of x-rays used in CT scans are energetic enough to directly or indirectly damage DNA. This and other types of DNA damage are occasionally not corrected properly by cellular repair mechanisms. Such damage to the DNA occasionally lead to cancer. The estimates of harm from CT are partly based on similar radiation exposures experienced by those present during the atomic bomb explosions in Japan during the second world war and those of nuclear industry works.[5]

There is a small increased risk of cancer with CT scans It is estimated that 0.4% of current cancers in the United States are due to CTs performed in the past and that this may increase to as high as 1.5-2% with 2007 rates of CT usage;[5] however, this estimate is disputed.[10] This would be equivalent to one in 1000 to one in 2000 increased risk of developing a fatal cancer per 10mSv CT scan.[11] Or 29,000 new cancer cases in the United States due to the number of scans done in 2007[12] and 2100 new cancers in the United Kingdom.[13] This additional risk is still low compared to the background risk of dying from cancer of ~20%.[14] The most common cancers caused by radiation exposure are thought to be lung cancer, breast cancer, thyroid cancer, stomach cancer and leukemia.[11]

A person's age plays a significant role in the subsequent risk of cancer.[14] Estimated lifetime cancer mortality risks from an abdominal CT of a 1-year-old is 0.1% or 1:1000 scans.[14] The risk for someone who is 40 years old is half that of someone who is 20 years old with substantially less risk in the elderly.[14] The International Commission on Radiological Protection estimates that the risk to a fetus being exposure to 10 mGy increases the rate of cancer before 20 years of age from 0.03% to 0.04% (for reference a CT pulmonary angiogram exposes a fetus to 4 mGy).[13] A 2012 review did not find an association between medical radiation and cancer risk in children noting however the existence of limitations in the evidences over which the review is based.[15]

CT scans can be performed with different settings for lower exposure in children with most manufacturers of CT scans as of 2007 having this function built in.[11] Furthermore, certain conditions can require children to be exposed to multiple CT scans.[5] Studies support informing parents of the risks of pediatric CT scanning.[16]

edit Contrast

In the United States half of CT scans involve radiocontrast agents.[17] The most common reactions from these agents are mild, including nausea, vomiting and an itching rash; however, more severe reactions may occur.[18] Overall reactions occur in 1 to 3% with nonionic contrast and 4 to 12% of people with ionic contrast.[19] Skin rashes may appear in 1 to 3% within a week.[18]

The old radiocontrast agents caused anaphylaxis in 1% of cases while the newer, lower-osmolar agents cause reactions in 0.01-0.04% of cases.[20][18] Death occurs in about two to 30 people per 1,000,000 administrations with newer agents being safer.[19][21] When deaths do occur it is more typically in those who are female, elderly or of otherwise poor health and is secondary to either anaphylaxis or acute renal failure.[17]

The contrast agent may induce contrast-induced nephropathy.[22] This occurs in 2 to 7% of people who receive these agents, with greater risk in those who have preexisting renal insufficiency,[22] preexisting diabetes, or reduced intravascular volume. People with mild kidney impairment are usually advised to ensure full hydration for several hours before and after the injection. For moderate kidney failure, the use of iodinated contrast should be avoided; this may mean using an alternative technique instead of CT. Those with severe renal failure requiring dialysis do not require special precautions, as their kidneys have so little function remaining that any further damage would not be noticeable and the dialysis will remove the contrast agent.

edit Scan dose

Examination Typical effective
to the whole body
Typical absorbed
to the organ in question
Annual background radiation 2.4[23] 2.4[23]
Chest X-ray 0.02[24] 0.01-0.15[25]
Head CT 1-2[14] 56 [26]
Screening mammography 0.4[13] 3[25][5]
Abdomen CT 8[24] 14[26]
Chest CT 5-7[14] 13[26]
CT colonography 6-11[14]
Chest, abdomen and pelvis CT 9.9[26] 12[26]
Cardiac CT angiogram 9-12 [14] 40-100[25]
Barium enema 15[5] 15[25]
Neonatal abdominal CT 20[5] 20[25]

The average radiation dose from medical sources is ~0.6 mSv per person globally as of 2007.[14] The table reports average radiation exposures, however, there is a wide variation in radiation doses between similar scan types, where the highest dose could be as much as 22 times higher than the lowest dose.[14] A typical plain film x-ray involves radiation dose of 0.01 to 0.15 mGy, while a typical CT can involve 10-20 mGy for specific organs, and can go up to 80 mGy for certain specialized CT scans.[25]

For purposes of comparison, the world average dose rate from naturally occurring sources of background radiation is 2.4 mSv per year, equal for practical purposes in this application to 2.4 mGy per year.[23] While there is some variation, most people (99%) received less than 7 mSv per year as background radiation.[27] Medical imaging as of 2007 accounted for half of the radiation exposure of those in the United states with CT scans making up two thirds of this amount.[14] In the United Kingdom it accounts for 15% of radiation exposure.[13] Those in the nuclear industry in the United States are limited to doses of 50 mSv a year and 100 mSv every 5 years.[14]

edit Radiation dose units


The sievert unit is used in the report of the effective dose. The sievert unit in the context of CT scans, does not correspond to the actual radiation dose that the scanned body part absorbs, but rather to an other radiation dose of an other scenario, in which the whole body absorbs the other radiation dose, and where the other radiation dose is of a magnitude that is estimated to have the same probability to induce cancer as the CT scan.[29] Thus, as is shown in the table above, the actual radiation that is absorbed by a scanned body part is often much larger than the effective dose disclose.


edit Excess doses

In October, 2009, the US Food and Drug Administration (FDA) initiated an investigation of brain perfusion CT (PCT) scans, based on overdoses of radiation caused by incorrect settings at one particular facility for this particular type of CT scan. Over 256 patients over an 18 month period where exposed, over 40% lost patches of hair, and prompted the editorial to call for increased CT quality assurance programs, while also noting that "while unnecessary radiation exposure should be avoided, a medically needed CT scan obtained with appropriate acquisition parameter has benefits that outweigh the radiation risks."[30][14] Similar problems have been reported at other centers.[14] These incidents are believed to be due to human error. [14]

edit Prevalence

Usage of CT has increased dramatically over the last two decades.[3] An estimated 72 million scans were performed in the United States in 2007.[4] Of these six to eleven percent are done in children.[13] An increase of seven to eight fold from 1980.[14] Similar increases have been seen in Europe and Asia.[14] In Calgary, Canada 12.1% of people who present to the emergency with an urgent complaint received a CT scan, most commonly either of the head or of the abdomen. The percentage who received CT, however, varied markedly by the emergency physician who saw them from 1.8% to 25%.[31] In the emergency department in the United States, CT or MRI imaging is done in 15% of people who present with injuries as of 2007 (up from 6% in 1998).[32]

The increased use of CT scans has been the greatest in two fields: screening of adults (screening CT of the lung in smokers, virtual colonoscopy, CT cardiac screening, and whole-body CT in asymptomatic patients) and CT imaging of children. Shortening of the scanning time to around 1 second, eliminating the strict need for the subject to remain still or be sedated, is one of the main reasons for the large increase in the pediatric population (especially for the diagnosis of appendicitis).[5] As of 2007 in the United States a proportion of CT scans are performed unnecessarily.[11] Some estimates place this number at 30%.[13] There are a number of reasons for this including: legal concerns, financial incentives, and desire by the public.[11] There is also otherwise healthy people receiving full body CT scans as screening for which there is no evidence to support.[11]

edit Process

File:CT Scan of Dale Mahalko's brain-skull.jpg


Newer machines with faster computer systems and newer software strategies can process not only individual cross sections but continuously changing cross sections as the gantry, with the object to be imaged slowly and smoothly slid through the X-ray circle. These are called helical or spiral CT machines. Their computer systems integrate the data of the moving individual slices to generate three dimensional volumetric information (3D-CT scan), in turn viewable from multiple different perspectives on attached CT workstation monitors. This type of data acquisition requires enormous processing power, as the data are arriving in a continuous stream and must be processed in real-time.

In conventional CT machines, an X-ray tube and detector are physically rotated behind a circular shroud (see the image above right); in the electron beam tomography (EBT), the tube is far larger and higher power to support the high temporal resolution. The electron beam is deflected in a hollow funnel-shaped vacuum chamber. X-rays are generated when the beam hits the stationary target. The detector is also stationary. This arrangement can result in very fast scans, but is extremely expensive.



Once the scan data has been acquired, the data must be processed using a form of tomographic reconstruction, which produces a series of cross-sectional images. The most common technique in general use is filtered back projection, which is straightforward to implement and can be computed rapidly. In terms of mathematics, this method is based on the Radon transform. However, this is not the only technique available: the original EMI scanner solved the tomographic reconstruction problem by linear algebra, but this approach was limited by its high computational complexity, especially given the computer technology available at the time. More recently, manufacturers have developed iterative physical model-based expectation-maximization techniques. These techniques are advantageous because they use an internal model of the scanner's physical properties and of the physical laws of X-ray interactions. By contrast, earlier methods have assumed a perfect scanner and highly simplified physics, which leads to a number of artifacts and reduced resolution - the result is images with improved resolution, reduced noise and fewer artifacts, as well as the ability to greatly reduce the radiation dose in certain circumstances. The disadvantage is a very high computational requirement, which is at the limits of practicality for current scan protocols.


Contrast mediums used for X-ray CT, as well as for plain film X-ray, are called radiocontrasts. Radiocontrasts for X-ray CT are, in general, iodine-based.[33] Often, images are taken both with and without radiocontrast. CT images are called precontrast or native-phase images before any radiocontrast has been administrated, and postcontrast after radiocontrast administration.[34]


edit Three-dimensional reconstruction


edit Multiplanar reconstruction







edit 3D rendering techniques

edit Surface rendering


edit Volume rendering


edit Image segmentation


edit Image quality

edit Artifacts

Template:Unreferenced section Although CT is a relatively accurate test, it is liable to produce artifacts, such as the following:[2], Chapters 3 and 5

Streak artifact
Streaks are often seen around materials that block most X-rays, such as metal or bone. These streaks can be caused by undersampling, photon starvation, motion, beam hardening, or scatter. This type of artifact commonly occurs in the posterior fossa of the brain, or if there are metal implants. The streaks can be reduced using newer reconstruction techniques.[37]
Partial volume effect
This appears as "blurring" over sharp edges. It is due to the scanner being unable to differentiate between a small amount of high-density material (e.g., bone) and a larger amount of lower density (e.g., cartilage). The processor tries to average out the two densities or structures, and information is lost. This can be partially overcome by scanning using thinner slices.
Ring artifact
Noise artifact
Motion artifact
Beam hardening
This can give a "cupped appearance". It occurs when there is more attenuation in the center of the object than around the edge. This is easily corrected by filtration and software.

edit Dose vs. image quality



edit Industrial use


edit Etymology

The word "tomography" is derived from the Greek tomos (slice) and graphein (to write). Computed tomography was originally known as the "EMI scan" as it was developed in the early 1970's at a research branch of EMI, a company best known today for its music and recording business. It was later known as computed axial tomography (CAT or CT scan) and body section röntgenography.

Although the term "computed tomography" could be used to describe positron emission tomography and single photon emission computed tomography, in practice it usually refers to the computation of tomography from X-ray images, especially in older medical literature and smaller medical facilities.

In MeSH, "computed axial tomography" was used from 1977–79, but the current indexing explicitly includes "X-ray" in the title.[40]

edit Types machines


Electron beam tomography is a specific form of CT in which a large enough X-ray tube is constructed so that only the path of the electrons, traveling between the cathode and anode of the X-ray tube, are spun using deflection coils. This type has a major advantage since sweep speeds can be much faster, allowing for less blurry imaging of moving structures, such as the heart and arteries. However, far fewer CTs of this design have been produced, mainly due to the higher cost associated with building a much larger X-ray tube and detector array.

edit History

Template:Refimprove section



The mathematical theory behind the Tomographic reconstruction dates back to 1917 where the invention of Radon Transform[41][42] by an Austrian mathematician Johann Radon. He showed mathematically that a function could be reconstructed from an infinite set of its projections.[43] In 1937, a Polish mathematician, named Stefan Kaczmarz, developed a method to find an approximate solution to a large system of linear algebraic equations.[44][45] This led the foundation to another powerful reconstruction method called "Algebraic Reconstruction Technique (ART)" which was later adapted by Sir Godfrey Hounsfield as the image reconstruction mechanism in his famous invention, the first commercial CT scanner. In 1956, Ronald N. Bracewell used a method similar to Radon Transform to reconstruct a map of solar radiation from a set of solar radiation measurements.[46] In 1959, William Oldendorf, a UCLA neurologist and senior medical investigator at the West Los Angeles Veterans Administration hospital, conceived an idea for "scanning a head through a transmitted beam of X-rays, and being able to reconstruct the radiodensity patterns of a plane through the head" after watching an automated apparatus built to reject frost-bitten fruit by detecting dehydrated portions. In 1961, he built a prototype in which an X-ray source and a mechanically coupled detector rotated around the object to be imaged. By reconstructing the image, this instrument could get an X-ray picture of a nail surrounded by a circle of other nails, which made it impossible to X-ray from any single angle.[47] In his landmark paper, published in 1961, he described the basic concept later used by Allan McLeod Cormack to develop the mathematics behind computerized tomography. In October, 1963 Oldendorf received a U.S. patent for a "radiant energy apparatus for investigating selected areas of interior objects obscured by dense material," Oldendorf shared the 1975 Lasker award with Hounsfield for that discovery.[48]

Tomography has been one of the pillars of radiologic diagnostics until the late 1970s, when the availability of minicomputers and of the transverse axial scanning method – this last due to the work of Godfrey Hounsfield and South African-born Allan McLeod Cormack – gradually supplanted it as the modality of CT. In terms of mathematics, the method is based upon the use of the Radon Transform. But as Cormack remembered later,[49] he had to find the solution himself since it was only in 1972 that he learned of the work of Radon, by chance.

The first commercially viable CT scanner was invented by Sir Godfrey Hounsfield in Hayes, United Kingdom, at EMI Central Research Laboratories using X-rays. Hounsfield conceived his idea in 1967.[50] The first EMI-Scanner was installed in Atkinson Morley Hospital in Wimbledon, England, and the first patient brain-scan was done on 1 October 1971.[51] It was publicly announced in 1972.






edit Previous studies


edit See also

edit References

  1. computed tomography—Definition from the Merriam-Webster Online Dictionary. Retrieved on 2009-08-18.
  2. 2.0 2.1 Herman, G. T., Fundamentals of computerized tomography: Image reconstruction from projection, 2nd edition, Springer, 2009
  3. 3.0 3.1 Smith-Bindman R, Lipson J, Marcus R, et al. (December 2009). "Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer". Arch. Intern. Med. 169 (22): 2078–86. DOI:10.1001/archinternmed.2009.427. PMID 20008690. 
  4. 4.0 4.1 Berrington de González A, Mahesh M, Kim KP, et al. (December 2009). "Projected cancer risks from computed tomographic scans performed in the United States in 2007". Arch. Intern. Med. 169 (22): 2071–7. DOI:10.1001/archinternmed.2009.440. PMID 20008689. 
  5. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Brenner DJ, Hall EJ (November 2007). "Computed tomography--an increasing source of radiation exposure". N. Engl. J. Med. 357 (22): 2277–84. DOI:10.1056/NEJMra072149. PMID 18046031. 
  6. Tubiana M (February 2008). "Comment on Computed Tomography and Radiation Exposure". N. Engl. J. Med. 358 (8): 852–3. DOI:10.1056/NEJMc073513. PMID 18287609. 
  7. Ankle Fractures. American Association of Orthopedic Surgeons. Retrieved on 2010-05-30.
  8. Buckwalter, Kenneth A. (11 September 2000). Musculoskeletal Imaging with Multislice CT. American Journal of Roentgenology. Retrieved on 2010-05-22.
  9. Brian R. Subach M.D., F.A.C.S et. al."Reliability and accuracy of fine-cut computed tomography scans to determine the status of anterior interbody fusions with metallic cages"
  11. 11.0 11.1 11.2 11.3 11.4 11.5 Semelka, RC; Armao, DM; Elias, J, Jr.; Huda, W. (May 2007). "Imaging strategies to reduce the risk of radiation in CT studies, including selective substitution with MRI.". J Magn Reson Imaging 25 (5): 900–9. DOI:10.1002/jmri.20895. PMID 17457809. 
  12. Berrington de González, A; Mahesh, M; Kim, KP; Bhargavan, M; Lewis, R; Mettler, F; Land, C (2009 Dec 14). "Projected cancer risks from computed tomographic scans performed in the United States in 2007.". Archives of internal medicine 169 (22): 2071-7. PMID 20008689. 
  13. 13.0 13.1 13.2 13.3 13.4 13.5 Davies, H. E.; Wathen, C. G.; Gleeson, F. V. (25 February 2011). "The risks of radiation exposure related to diagnostic imaging and how to minimise them". BMJ 342 (feb25 1): d947–d947. DOI:10.1136/bmj.d947. 
  14. 14.00 14.01 14.02 14.03 14.04 14.05 14.06 14.07 14.08 14.09 14.10 14.11 14.12 14.13 14.14 14.15 14.16 Furlow, B (2010 May-Jun). "Radiation dose in computed tomography.". Radiologic technology 81 (5): 437-50. PMID 20445138. 
  16. Larson DB, Rader SB, Forman HP, Fenton LZ (August 2007). "Informing parents about CT radiation exposure in children: it's OK to tell them". AJR Am J Roentgenol 189 (2): 271–5. DOI:10.2214/AJR.07.2248. PMID 17646450. 
  17. 17.0 17.1 Namasivayam, S; Kalra, MK; Torres, WE; Small, WC (2006 Jul). "Adverse reactions to intravenous iodinated contrast media: a primer for radiologists.". Emergency radiology 12 (5): 210-5. PMID 16688432. 
  18. 18.0 18.1 18.2 Christiansen, C (2005 Apr 15). "X-ray contrast media--an overview.". Toxicology 209 (2): 185-7. PMID 15767033. 
  21. editor, Mariana C. Castells,. Anaphylaxis and hypersensitivity reactions. New York: Humana Press, 187.
  22. 22.0 22.1 Hasebroock, KM; Serkova, NJ (2009 Apr). "Toxicity of MRI and CT contrast agents.". Expert opinion on drug metabolism & toxicology 5 (4): 403-16. PMID 19368492. 
  23. 23.0 23.1 23.2 Cuttler JM, Pollycove M (2009). "Nuclear energy and health: and the benefits of low-dose radiation hormesis". Dose Response 7 (1): 52–89. DOI:10.2203/dose-response.08-024.Cuttler. PMID 19343116. 
  24. 24.0 24.1 What are the Radiation Risks from CT?. Food and Drug Administration (2009).
  25. 25.0 25.1 25.2 25.3 25.4 25.5 Hall, EJ; Brenner, DJ (2008 May). "Cancer risks from diagnostic radiology.". The British journal of radiology 81 (965): 362-78. PMID 18440940. 
  26. 26.0 26.1 26.2 26.3 26.4 Shrimpton, P.C; Miller, H.C; Lewis, M.A; Dunn, M. Doses from Computed Tomography (CT) examinations in the UK - 2003 Review
  27. Poston, edited by Michael T. Ryan, John W. (2005). A half century of health physics. Baltimore, Md.: Lippincott Williams & Wilkins, 164.
  28. Polo SE, Jackson SP (March 2011). "Dynamics of DNA damage response proteins at DNA breaks: a focus on protein modifications". Genes Dev. 25 (5): 409–33. DOI:10.1101/gad.2021311. PMID 21363960. 
  30. Wintermark M, Lev MH (January 2010). "FDA investigates the safety of brain perfusion CT". AJNR Am J Neuroradiol 31 (1): 2–3. DOI:10.3174/ajnr.A1967. PMID 19892810. 
  32. Korley FK, Pham JC, Kirsch TD (October 2010). "Use of advanced radiology during visits to US emergency departments for injury-related conditions, 1998-2007". JAMA 304 (13): 1465–71. DOI:10.1001/jama.2010.1408. PMID 20924012. 
  34. Template:Cite doi
  35. Computerized Tomography chapter at University of Connecticut Health Center.
  37. Boas FE and Fleischmann D (2011). "Evaluation of Two Iterative Techniques for Reducing Metal Artifacts in Computed Tomography". Radiology 259 (3): 894–902. DOI:10.1148/radiol.11101782. PMID 21357521. 
  38. J. Nemirovsky, A. Lifshitz, and I. Be’erya (5 2011). "Tomographic reconstruction of incompressible flow". AIP Rev. Sci. Instrum. 82 (5). DOI:10.1063/1.3590934. 
  40. Template:MeshName
  41. Radon J., Uber die Bestimmung von Funktionen durch ihre Integralwerte Langs Gewisser Mannigfaltigkeiten (English translation: On the determination of functions from their integrals along certain manifolds). Ber. Saechsische Akad. Wiss. 1917;29: 262.
  42. Radon J., Translated by Parks PC., On the determination of functions from their integrals along certain manifolds. IEEE Trans. Med. Imaging. 1993;MI-5: 170-6.
  43. Hornich H., Translated by Parks PC. A Tribute to Johann Radon. IEEE Trans. Med. Imaging. 1986;5(4):169-9.
  44. Kaczmarz, S., Angenäherte Auflösung von Systemen linearer Gleichungen. Bulletin International de l'Académie Polonaise des Sciences et des Lettres. Classe des Sciences Mathématiques et Naturelles. Série A, Sciences Mathématiques. 1937;35: 355–7.
  45. Kaczmarz S., Approximate solution of system of linear equations. Int. J. Control. 1993; 57-9.
  46. Bracewell RN., [Strip Integration in Radio Astronomy]. Aust. J. Phys. 1956;9: 198-217.
  47. Oldendorf WH. Isolated flying spot detection of radiodensity discontinuities--displaying the internal structural pattern of a complex object. Ire Trans Biomed Electron. 1961 Jan;BME-8:68-72.
  48. Oldendorf WH. The quest for an image of brain: a brief historical and technical review of brain imaging techniques. Neurology. 1978 Jun;28(6):517-33.
  49. Allen M.Cormack: My Connection with the Radon Transform, in: 75 Years of Radon Transform, S. Gindikin and P. Michor, eds., International Press Incorporated (1994), pp. 32 - 35, ISBN 1-57146-008-X
  50. Richmond, Caroline (September 18, 2004). "Obituary—Sir Godfrey Hounsfield". BMJ 2004:329:687 (18 September 2004). Retrieved on September 12, 2008. 
  51. 51.0 51.1 [1]BECKMANN, E. C. (January 2006). "CT scanning the early days". TheBritish Journal of Radiology 79 (937): 5–8. DOI:10.1259/bjr/29444122. PMID 16421398. 
  52. The Beatles greatest gift... is to science. Whittington Hospital NHS Trust. Retrieved on 2007-05-07.
  53. ["The Nobel Prize in Physiology or Medicine 1979". 5 Nov 2010]
  54. Filler, AG (2009): The history, development, and impact of computed imaging in neurological diagnosis and neurosurgery: CT, MRI, DTI: Nature Precedings Template:Doi.

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