Topic: 4. Developments in Medical CT Equipments

Tuya Erdenejargal

APPM 4380September 14, 2015

Word Origin

CT Scan

Computed Tomography (CT) orComputed Axial Tomography (CAT) scanning

Tomography = Tomos + graphia (Greek)

Tomos means ”slice” or ”section”graphia means ”describe”

Types of CT Scan

Depending on the type of emission

• X-Ray CTMost common. 72 million scans were performed in the United States (2007)

• Positron Emission Tomography [PET]

• Single-Photon Emission Computed Tomography [SPECT]

Why CT Scan?

Tradition X-Ray Image

• 1895 (William Roentgen)

• First non-invasive tool

• 3D reduced to 2D :(

CT Image

• 1970s

• Cross-section of body parts

• More contrast in the soft tissues

Nobel Prize 1979

The Nobel Prize in Physiology or Medicine 1979 was awarded jointly to Allan M.Cormack and Godfrey N. Hounsfield ”for the development of computer assistedtomography.”

The First Commercial CT Scanner

Very first scan

1971, Atkinson Morley Hospital,London, UK- Cerebral cyst patient

The First Commercial CT Scanner

• Widely installed between 1974 and1976

• Only for head imaging

• Whole body scan by 1980

Now 6000 CT scanners installed in theU.S. and about 30,000 installedworldwide.

Improvement

Brain Image

Circa 1975, in the early days of the CTscan

A present-day scan, showing the six-foldincrease in detail

Improvement

SpecificationFirst CT Scanner(circa 1970)

State-of-The-Art

Time to acquire image 5 minutes 350 ms

Pixel Size 3 mm x 3 mm 0.5 mm x 0.5 mm

Number of Pixels inImage

80 x 80 512 x 512

Principles of CT Scanning

Johann Radon (1887-1956) Radon Transformation

Image of an unknown object could beproduced given an infinite number ofprojections through the object.

Principles of CT Scanning

Radon Transformation in Medical Imaging

M(r , θ) = The total attenuationµ(x , y) = The attenuation map

M(r , θ) =

∫ ∞−∞

µ(x , y)ds

RM(r , θ) = µ(x , y) ,

where R is Radon Transformation.

Principles of CT Scanning

Principles of CT Scanning

Principles of CT Scanning

Principles of CT Scanning

Principles of CT Scanning

Evolution of Different CT Scanners

Research and Development

Types of RD

• Increase Resolution

• Decrease Radiation Dosage

• Decrease Cost

Reference

• http://www.physicscentral.com/explore/action/scans.cfm

• http://pathology.jhu.edu/pc/ctscan.php

• http://www.nobelprize.org/nobelprizes/medicine/laureates/1979/http ://www .imaginis.com/ct − scan/brief − history − of − ct

•• http://thatsmaths.com/2013/03/07/ct-scans-and-the-radon-transform/

• http://www.impactscan.org/slides/impactcourse/basicprincipleso fct/img8.html