Developments in Medical Computed Tomography Equipment

1
Developments in Medical Computed Tomography
Equipment

• Kevin Ryan
• Modeling in Applied Mathematics
• February 13, 2008

2
Invention

• Godfrey Newbold Hounsfield
• 1972
• EMI Central Research Laboratories
• Allan McLeod Cormack
• 1963
• Tufts University
• Nobel Prize in medicine in 1979.
• CT Scan machine is the great legacy of the
  Beatles

3
First CT Scanner

• EMI Scanner
• 1971
• Atkinson Morleys Hospital in Wimbledon
• 300 seconds to scan
• 20 minutes to analyze
• Translate and Rotate
• Single X-ray Source
• Single Detector
• Only Scanned Head

Original "Siretom" dedicated head CT scanner,
circa 1974
4
First Generation
X-ray tube

• 1971
• Pencil Thin Beam of Radiation
• Translate and Rotate
• X-ray source and detector fixed relative position
• One degree of rotation possible
• Scan Time (Single Image)
• 5 min
• 128 x 128 images

Patient
Detector
5
Second Generation

• 1974
• X-rays
• Multiple Pencil
• Fan Shaped 3 - 26 degrees
• Still Translate and Rotate
• X-ray source and detector still fixed relative
  position
• Rotation increased from one to three degrees
• Scan time (Single Image)
• 3.5 min
• Eventually 5.3 sec

X-ray tube
Detectors
6
Third Generation
X-ray tube

• 1977
• X-ray
• Fan Shaped
• 21 - 45 degrees
• Rotation Only
• Array of Detectors
• Scan Time (Single Image)
• 4.8 sec
• Eventually reduced to 2.5 seconds

Detectors
7
Fourth Generation
X-ray tube

• 1980
• X-ray
• Wide Fan
• 48 - 120 degrees
• Rotation Only
• Full Ring of Detectors
• Scan Time (Single Image)
• 5 Sec
• Eventually reduced to 1 sec

Ring of Detectors
8
Improvements

• 1989 - Spiral CT
• Rotation and patient motion
• Scan in single breath hold
• 1mm - 10mm Slice Thickness
• 1991 - Dual Spiral
• 2003 - 64 Multislice CT
• Single scan in 0.33 sec
• Entire scan in 20-60 sec
• Resolution - 0.4 mm
• 512 x 512 images
• 2007 - 256 Multislice CT

9
Display

• 2-D
• Mainly Transverse
• Other Orientations - Constructed
• Windowing (Hounsfield units)
• 3-D
• Suited to
• Skeletal System
• Contrast-filled Vessels
• Fly-through

10
Range of Applications

• One Section of Body
• Head, Neck, Spine, Thorax, Abdomen, Extremities
  
• Find
• Cancer
• Aneurysm
• Bleeding
• Infection
• Blockage
• Herniated Disc
• Foreign objects
• Guide a needle during biopsy

• Drawbacks
• Expensive
• High Dose of Radiation
• Promotes Laziness
• Misinterpretation

11
Movies
12
References

• Cormack AM. Early two-dimensional reconstruction
  and recent topics stemming from it. Nobel
  Lecture. December 8, 1979.
• Hendee, William R, The physical principles of
  computed tomography, Boston Little, Brown,
  c1983
• The Beatles greatest gift... is to science.
  Whittington Hospital NHS Trust.
• Supplement to Applied Radiology, "Cardiac CT
  Where are we today and where are we going?".
• Websites
• http//en.wikipedia.org/wiki/Computed_tomography
• http//www.imaginis.com/ct-scan/history.asp
• http//www.medical.siemens.com
• http//www.pubmedcentral.nih.gov/articlerender.fcg
  i?artid548232
• http//www.radiology.uiowa.edu

13
Future

• Computer Capabilities
• Faster Image Production
• Better 3-D Displays
• Better Controlled X-ray
• Lower Dosage
• Detector Technology
• More Accurate
• More Stable
• Patient Comfort
• Less time