Advanced Techniques for Computed Tomography (CT)jao/Talks/StudentTalks/openhouse.pdf ·...

Advanced Techniques for Computed Tomography (CT)

Electronic Systems and Signals Research LaboratoryDepartment of Electrical and Systems Engineering

Prof. Joseph A. O’Sullivan and Jasenka [email protected]

http://essrl.wustl.edu/~jao

Supported by a grant from NIH

CollaboratorsFaculty StudentsDonald L. SnyderJoseph A. O’SullivanJeffrey F. Williamson, VCUBruce R. WhitingDavid G. PolitteJames G. BlaineRichard LaforestMark Mintun

Ryan MurphyJasenka BenacShenyu Yan

X-ray CT Imaging

Image Artifacts:Hip Prosthesis

Data from R. Laforest and M. Mintun

CT Imaging in Presence of High Density Attenuators

Brachytherapy applicators: after-loading colpostats for radiation oncology.

Cervical cancer: 50% survival rate.Dose prediction important

Image Artifacts: BrachytherapyGoal Standard

New Alternating Minimization Algorithmfor Transmission Tomography

• Poisson distribution

• Loglikelihood function !lnln)(ln!

)(

kkkNP

ek

kNPk

−−==

== −

λλ

λ λ

)(),(),(exp),():(

):()():(

)(ln)()):(||(

):():(ln)()):(|(

0 yExxyhEyIyg

ygydyg

ydydgdI

ygygydgdl

E x

y

y

βµµ

µµ

µ

µµµ

+⎟⎠

⎞⎜⎝

⎛−=

+−=⋅

−=⋅

∑ ∑

∑

∑

∈

∈

∈

X

Y

Y

• Maximization over m equivalent to minimization of I-divergence

Derivation

⎭⎬⎫

⎩⎨⎧

==

⎟⎠

⎞⎜⎝

⎛−=

+−=

∑

∑ ∑

∑∑

∈ =

∈∈

E

x

I

iii

y Epq

ydEypEyp

ExcxyhEyIEyq

EyqEypEyqEypEypqpI

)(),(:),(

)()(),(exp),(),(

),(),(),(),(ln),()||(minmin

10

L

X

YL

µ

)(~)(ˆ

ln)(

1)(ˆ)(ˆ)(

)()()1(

xbxb

xZxcxc l

i

li

i

li

li −=+

SimulationsMetal rod phantom

Low density rods:AirTeflonWaterAluminum

High density rods:SteelAluminumBrassTeflon

Testing AM Algorithm

David G. PolitteOctober 31, 2002

Mini CT, AM Iteration 0000002

PET/CT: Combining Anatomy & Physiology

• ECAT ACCEL: High performance PET scanner

• Siemens Somatom Emotion: High performance, multislicespiral CT

• 70 cm patient port

• Optimized bed design

• Siemens syngo-based computer system

Slides and data from R. Laforest and M. Mintun.

Coregistration & Fusion• Spatial alignment and

visualization of data sets

• Choice of different registration and visualization modes

• Support for CT, MR, NM, and PET DICOM image file format

• Use of CT image to compute PET attenuation map

PETCT-211

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