ENGG 167 - F02 MEDICAL IMAGING
Transcript of ENGG 167 - F02 MEDICAL IMAGING
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ENGG 167 - F02MEDICAL IMAGING
Wednesday, Oct. 27
Chapter 14: Computed Tomography
Reference: Chapters 12 & 13, The Essential Physics of Medical Imaging, BushbergComputed Tomography, Kalender, Verlag, 2000.Chapter 12, Intermediate Physics for Medicine and Biology, 3rd Ed., Hobbie.Chapter 3, Principles of Computerized Tomographic Imaging, Kak and Slaney, IEEE Press
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X-ray imaging with digital subtraction
Ref: Bushberg
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Dual energy imaging
Ref: Bushberg
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Dual energy subtraction imaging
Ref: Bushberg
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Chapter 12 – Tomosynthesis – approaching computed tomography
Ref: Bushberg
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Computed Tomography – READ Chapter 13
Ref: Bushberg
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Computed Tomography: reconstruct pixelated images
Ref: Bushberg
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Computed Tomography – detection geometries
Ref: Bushberg
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Image Reconstruction : projection data
Ref: Kalendar
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Reconstruction
Ref: Kalendar
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CT – History
Ref: Kalendar
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CT – 5th generation system - fast cardiac imaging
Ref: Bushberg
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CT – 6th generation - helical or spiral CT
Ref: Bushberg
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CT – 7th generation – multiple detector slice arrays
Ref: Bushberg
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CT – slip ring input and output of voltage/current
Ref: Kalendar
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CT detectors – xenon gas – old style
Ref: Bushberg
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CT detectors – solid state detectors
Ref: Bushberg
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CT detectors – solid state multiple detector arrays
Ref: Bushberg
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CT slice thickness
Ref: Bushberg
Increasing slice thickness increasesSNR by square root of thickness ratio.This provides better contrast resolution but decreased spatial resolution in slice thickness dimension.Alternatively, the mAs can be increased for thin slices to keep the number of counts detected high.
Slice thickness is actually a sensitivity distribution
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CT slice thickness & collimators
Ref: Bushberg
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Pitch -Major factor influencing patient dose, image quality and scan time
Ref: Bushberg
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Interpolation of data in spiral CT
Ref: Bushberg
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Reconstruction - increasing # rays increases resolution
Ref: Bushberg
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Reconstruction - increasing # views increases resolution
Ref: Bushberg
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Reconstruction - effect of frequency filters
Ref: Bushberg
rampfilter
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Hounsfield units / CT Numbers
Ref: Bushberghttp://www.nobel.se/medicine/laureates/1979/hounsfield-lecture.pdf
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Hounsfield units / CT Numbers
Ref: Kalender
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Hounsfield units / CT Numbers
Ref: Kalender
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CT Numbers – windowing for display
Ref: Bushberg
CT images – 12 bitHuman vision – 6-8 bitDigital display – 8 bit
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CT geometry
Ref: Bushberg
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Radiation Dose in CT
Ref: Bushberg
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Radiation Dose in CT
Ref: Bushberg
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Radiation Dose in CT – effect of pitch
Ref: Bushberg
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Radiation Dose in Helical CT
Ref: Bushberg
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Dose versus SNR, pixel size & slice thickness
Ref: Bushberg
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Contrast Resolution vs Spatial Resolution
Ref: Bushberg
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Computed Tomography – improved contrast over projection x-ray imaging with loss of spatial resolution
Ref: Bushberg
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Contrast - Resolution analysis
Ref: Kalender
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Contrast - Resolution analysis
Ref: Kalender
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II
Ref: Bushberg
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Artifacts – beam hardening
Ref: Bushberg
energy
Inte
nsity
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Artifacts – beam hardening
Ref: Bushberg
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Artifacts – beam hardening
Ref: Bushberg
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Artifacts – partial volume effects
Ref: Bushberg
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Artifacts –
Ref: Bushberg
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Projects – schedule…
Talk to me to define project BEFORE Oct 28
Report on outline of your project BEFORE Nov 12Including – outline of literature search
(words used in search, papers found, etc)- endnote print out of all papers in search
(you read all abstracts of those listed)- list of papers skimmed in more detail.- list of papers read completely
Plan – papers to read in next two weeks- work with B. Pogue on strategic changes.
Final report written by Dec 8 or before.