X Ray CT

6/17/02


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Table of Contents

X Ray CT

Subject Matter

Principles of CT scanning

What is a CT scanner?

What is a CT scanner?

Advantages of CT scanning

CT scanning applications

CT applications

Construction of a CT scanner

In Practice

Tomographic imaging

CT Image

Principles of tomographic imaging

Data acquisition

What are we measuring?

Projections

Back projection

Back Projection

Filtered back projection

Filtered back projection

Filtered back projection

Filtered back projection

CT number scale

CT number window

CT Number Window

CT technology

First generation CT scanner

Second generation CT scanner

Third generation CT scanner

Re-binning fan beam data

Fourth generation CT scanners

X-ray Journey

X-ray tube

X-ray tube advances

Flat filtration

Beam Shaping Filter

Detectors

Detector Arrangement

Xenon Detectors

Ceramic Scintillators

Gantry Rotation

Slip Rings

Helical CT

Helical CT - Data Collection

Helical image reconstruction

Helical Interpolation

Helical Interpolation

Helical Pitch

Advantages of helical scanning

Disadvantages of Helical

X-ray CT, Part II

CT Scanning Parameters

Acquisition Parameters

Acquisition Parameters

Reconstruction Parameters

Reconstruction filters

CT Performance

Image Noise

Image Noise

Image Contrast

Image Contrast

Measuring Noise

Factors Affecting Noise

Factors Affecting Detector Signal

Spatial Resolution

Spatial Resolution

Expressing Spatial Resolution

Expressing Spatial Resolution

Modulation Transfer Function

Measuring Spatial Resolution

Dependence on Scanner Design

Effective Detector Width

Sampling Rate

Techniques to improve Resolution

Z-Sensitivity

Z-Axis Resolution

Expressing Z-Sensitivity

Significance

Z-Sensitivity and CT Number

Measurement of z-sensitivity

Contrast vs Spatial Resolution

Radiation Dose

CTDI

CTDI (2)

Weighted CTDI

Local, organ and effective doses

Artefacts

Streak Artefacts

Shading Artefacts

Ring Artefacts

Multi-slice CT

Multi-slice CT

Advantages of MS CT

Clinical Advantages

Clinical Advantages

Further Information

Author: Nick Keat

Email: nick@impactscan.org

Home Page: http://www.impactscan.org