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Center for Fast Ultrasound Imaging Department of Electrical Engineering

Evaluation, Q&A, and oral exam Jørgen Arendt Jensen December 4, 2017 Center for Fast Ultrasound Imaging, Build 349 Department of Electrical Engineering Technical University of Denmark

Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Topics for today

• Course evaluation on CampusNet and comments • Oral exam and time slots:

– Wednesday 13/12, 2017

– Thursday 14/12, 2017 • Q&A session: Monday 11/12, 2017 at 13.30 in this room

• Help on CT assignments • MR lecture & exercise

2/x

Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark 3/x

CampusNet evaluation: When is the deadline? Only 8 have filled it out, so we will look at this Monday

Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Oral exam

• 20 min time slots in room 214, building 349 • Take one question, explain on black board • No books or notes in the room • Reading list and questions on CampusNet • Time slots are listed on CampusNet and list is here

• Q&A session: – Monday 11/12, 2017 at 13.30 in this room

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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

CT assignments

• Usual hand-in of reports • Standard pdf, readable in Urkund • Remember to include the code

• Grade will be available before the exam

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Shepp-Logan phantom

6/x

Note that the Shepp-Logan phantom is not in Hounsfield units, but the relative scaling is the same.

Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Hounsfield units

From

: W. A

. Kal

ende

r; C

ompu

ted

Tom

ogra

phy,

Pub

licis

, 200

5

Note that the in-vivo data on the website is off-set by 1000 HU (-1000 is off-set to 0)

Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Influence from number of projections

8/x

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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Comparison between filters

9/x Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Circular convolution

10/x

−100 −80 −60 −40 −20 0 20 40 60 800

0.01

0.02

h(n)

Filter

−100 −80 −60 −40 −20 0 20 40 60 800

5

10

15

20

g 1(n)

Periodic time signal

−100 −80 −60 −40 −20 0 20 40 60 800

2

4

g 1(n)

Resulting periodic time signal with overlap

Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Circular convolution

11/x

−100 −80 −60 −40 −20 0 20 40 60 800

2

4

Sample number (n)

g 2(n)

Periodic time signal without overlap

−100 −80 −60 −40 −20 0 20 40 60 800

0.01

0.02

h(n)

Filter

−100 −80 −60 −40 −20 0 20 40 60 800

5

10

15

20

g 1(n)

Periodic time signal

Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Circular convolution – Shepp-Logan

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Ideal Shepp−logan phantom, 512 x 512 pixels, Range: [0.95 1.1]

Relative x−coordinate

Rel

ativ

e y−

coor

dina

te

−3 −2 −1 0 1 2

−3

−2

−1

0

1

2

4

Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark

Backprojection

13/x

Patient grid

Projec

tion