Digital Subtraction Bowel Cleansing for CT Colonography Using Morphological and Linear Filtration Methods

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Digital Subtraction Bowel Cleansing for CT
Colonography Using Morphological and Linear
Filtration Methods

• ??
• Michael E. Zalis, James Perumpillichira, Peter
  F. Hahn
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• IEEE TRANSACTIONS ON MEDICAL IMAGINGVOL. 23, NO.
  11, NOVEMBER 2004 pp.1335-1343
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• ???????

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Outline

• Introduction
• Methods
• Experiment
• Conclusions

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Introduction(1/3)

• First description in 1994
• Computed Tomography Colonography
• What is CTC?
• Noninvasive
• Consist of Low X ray does CT
• Preparation
• Cleansing colon
• Air insufflation

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Introduction(3/3)

• Traditional
• Patients undergo a rigorous purgation cleansing
  of the colon
• Feeling
• Discomfort and inconvenience
• Digital Subtraction Bowel Cleansing (DSBC)
• Not require to
• take any bowel cathartic
• change eating habits

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Hounsfield Unit(1/2)

• Definition
• X Ray attenuation unit used in CT Scan
  interpretation
• Characterizes the relative density of a substance
  
• Each pixel is assigned a value between
• -1k to 1k

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Hounsfield Unit(2/2)

• Substance densities in Hounsfield Units
• Air -1000
• Fat -50
• Water 0
• Soft tissue such as muscle 40
• Calculus 100 to 400
• Bone 1000

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Outline

• Introduction
• Methods
• Experiment
• Conclusions

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Threshold

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• gt ,???, ?? 1
• lt ,???, ?? 0
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Artifact
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Morphology

• Dilation
• Erosion

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Artifact
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Outline

• Introduction
• Methods
• Experiment
• Conclusions

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Phantom

• Colon phantom
• specifically designed to resemble the human colon
  in terms of
• CT density
• colon contour

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Exam

• The approach is
• Use DSBC ,dilation, detection algorithm
• CT
• Range
• From
• Soft tissue of the colon wall
• To
• Colon lumen

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Exam 1
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Exam 1
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Exam 2
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Exam 2
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Exam 3
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Exam 3
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Outline

• Introduction
• Method
• Experiment
• Conclusions

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Conclusion

• DSBC offers the possibility of improving patient
  comfort for colon.
• Compared to traditionally cleansed datasets in
  human subjects ,readers rated electronically
  cleansed exams favorably.