Multi-slice helical CT physics and technology

9/10/03


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Table of Contents

Multi-slice helical CT physics and technology

Introduction

Why CT?

CT scanner development 1972 ? 2002

Technological advances, 1985 - 2002

Basic principles of CT scanning

Construction of a CT scanner

Basic principles of CT scanning

Data acquisition

What are we measuring?

Projections

Basic principles of CT scanning

Filtered back projection

Filtered back projection

Filtered back projection

m to CT number

Slip rings allow continuous gantry rotation

Helical scanning

Helical pitch

Image reconstruction in helical CT

360 linear interpolation

Advantages of helical scanners

Dual slice scanning

Dual slice capabilities

Sixteen slice scanners

Sixteen slice detectors

Flexible image reconstruction

Multi-slice helical reconstruction

Pitch in multi-slice

Advantages of multi-slice

Scan speed

Scan speed

Z-axis resolution

Isotropic imaging

Z-axis resolution

Larger scan volumes

Scan flexibility

Problems / difficulties with MSCT

Overbeaming in z-axis

Cone beam artefacts

Cone beam effects axial scanning

Cone beam effects helical scanning

Effect of AMPR (used by Siemens, modified ASSR)

Implications of multi-slice scanners

Dosimetry CT dose descriptors

Dosimetry measurements

Dosimetry weighted CTDI

Dosimetry CTDIvol

Dosimetry dose length product (DLP)

Dosimetry effective dose

Dosimetry typical effective doses from CT

Population doses

Testing and QC

Image noise

Spatial resolution

Spatial resolution

Measuring CT number

Artefacts

Streaking - partial volume artefact

Minimizing partial volume artefacts

Streaking photon starvation

Streaking - metal artefacts

Avoidance of metal artefacts

Metal Artefact Reduction

Motion artefact correction

Shading artefacts

Ring artefacts

CT and PET

PET / CT image registration

PET / CT image registration - couch

PET / CT attenuation correction

PET / CT attenuation correction

Conclusions

Finally

Author: David Platten

Email: david@impactscan.org

Home Page: www.impactscan.org