ct principles, basics to basic hystory of ct
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CT Principles
Back to BasicsHistory of CT
CT Principles
Back to BasicsHistory of CT
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Discovery of X-ray
• Prof. Wilhelm ConradRöntgen
(German Physicist)
• November 8, 1895 – Discovered accidently working
in his Laboratory at University
of Würzburg
– As the Nature of the Ray wasUnknown, he called it X-Ray
• Röntgen received the first
Nobel Prize in Physics in1901
• However, he refused to takeout any patents in order thatthe world could freely benefit from his work
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Inventor of X-ray Tube
• William David Coolidge
(1873-1975)
– 1905 Joined GE Research
Laboratory
– 1913 GE Engineer whodeveloped the “Coolidge” X-
Ray Tube
– Became VP & Director of GE
Research Laboratory
– 1975 Elected into National
Inventor’s Hall of Fame
– 83 Patents to His Credit
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RadiographicRadiographic IImagingmaging
Computed TomographicComputed Tomographic IImagingmaging
Conventional RadiographyConventional Radiography
Conventional TomographyConventional Tomography
X-Ray & Tomography
CTCT
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The Meaning of Tomography
• 1920 (Early) – Technique for imaging a layer of
body had been developed andcalled “Body sectionRadiography” or“Stratigraphy”(Stratum meanlayer)
• 1935 – Grossman refined the technique
and labelled it “Tomography”(From the Greek tomos meaning
section)
• Computed Tomography(CT) meaning transverse
section (cross section) ortransverse axial tomography
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Generations of CT Scanners
– 1971 First Generation – 1972 Second Generation
– 1975 - Present Third Generation
– 1977 – Present Fourth Generation
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First Generation CT
One Detector Translation/Rotation with Parallel Beam
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TranslateTranslate//Rotate with Single Detector Rotate with Single Detector
With single detector can onlyWith single detector can only
acquire one view at a timeacquire one view at a time
1st Generation CT Scanners
(Translate/Rotate)
• EMI Scanner (Prototype)
• Single Detector
• Mechanically Complex
• Long Scan Times (4-5Mins)
• Extremely Slow
• Head Scan Limited
• Required Water Bath
• Fixed Anode X-Ray Tube – Low mA
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Second Generation CTMultiple Detectors Translation/Rotation with Small Fan Beam
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TranslateTranslate//Rotate withRotate with MultipleMultiple Detector Detector ss
Significant ImprovementSignificant Improvement
Over 1st GenerationOver 1st Generation
2nd Generation CT Scanners
(Translate/Rotate)
• EMI 1010 & 5005 Scanner
(1972)• Multiple Detectors
• Mechanically Complex
• Shorter Scan Times – 20 to 90 Sec
• Head/Body Scan Capable
• Required Water Bath forHead Only Scanner
• Rotating Anode X-RayTube
– Low mA, Long Scan Time – Poor Tube Life, 350 KHU
Tube
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Third Generation CT
Multiple Detectors Rotation/Rotation with Large Fan Beam
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TranslateTranslate//Rotate withRotate with MultipleMultiple Detector Detector ss
Current Geometry of ChoiceCurrent Geometry of Choice
for All Manufacturersfor All Manufacturers
3rd Generation CT Scanners (Rotate/Rotate)
•GE 8800 (1975) – Multiple Detectors in “Fan Beam”
– Array of detectors and tube rotatearound the patient for fasterscanning
– High mechanical stability
– Detectors always in x-ray beam,allow good utilization of the x-ray beam
– Good tube-patient-detectorsgeometry
• Faster Scan Times – 4.9 Sec
– Long Recon Times
•Rotating Anode X-Ray Tube – Higher Pulsed mA – Poor Tube Life, 500 KHU Tube
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LightSpeedLightSpeed1616with Xtream Technologywith Xtream Technology
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Fourth Generation CTDetector Ring Source/Rotation with Large Fan Beam
LightSpeed Continuum LightSpeed Platform
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9 Productsin 7 Years
on 1 platform!
LightSpeed16LightSpeed
Plus
Our commitment to our Customer is our Continuum.
LightSpeed
Ultra
HiSpeed
QX/i
LightSpeed
QX/i
1998 2000 2001 2002 2002 2003 2003
LightSpeed
Pro16LightSpeed
RT
LightSpeed
VCT
2004
LightSpeed Continuum…LightSpeed Platform
LightSpeed
Pro32
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Can All Scanners do
this?
1. Can you do a Coronary CTA in 5 heartbeats?
2. Can you perform a gated study of the chest in 10-12 seconds?
3. Can you scan the whole body in 10 seconds with sub-millimeter resolution?
4. Can your detector read out a full 64 channels per rotation?
5. Does your CT detector feature backlit diode technology?6. Does your system have an isotropic detector that delivers 0.35mm resolution?
7. Can you acquire a coronary CT image with a temporal resolution of 43 milliseconds
and an actual-not effective-mAs of 280?
8. Does your system deliver up to 800 mA?
9. What is the maximum table weight and scannable range?
10. Is all recon and transfer on your system performed at 16 images per second?