case study computed tomography (ct) non-invasive medical imaging techniques
TRANSCRIPT
Ultrasound (B超 )
Use very high frequency sound (MHz)Safe Image in real timeEquipment is not
expensive
LimitationStrong sound
absorption by bonesHard in brain studies,
or anywhere with bones
基本原理(物理的):波的折射与反射
Computed Tomography A parallel sheet of X-ray Mathematical tools needed for successful
computed tomography (CT) imaging Basic principle is discovered more once 1979 Nobel Prize in Physiology and Medicine
was awarded to G. Hounsfield & A.M. Cormack jointly for realizing and bringing to medical use
Computed Tomography
Not expensive to use Some drawbacks
Possible tissue damage from ionization
Low contrasts between different type of soft tissues
Computed Tomography
There are many applications other than medical tomography:Astronomy---binary stars, coronal studyOceangraphy---acoustic probing of ocean
conditionsGeophysics---mantle flow, atmospheric studiesPorous Media---
Radon Transformation
Assume the density function of the test object is given by
The scan data can be written as
Question: how to recover from
Least Square Method To understand the idea
behind, consider3*3 small objectHomogenous blocksThe block densities
either 0 or 1 How to achieve the
reconstruction?