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Center for Fast Ultrasound Imaging Department of Electrical Engineering
Evaluation, Q&A, and oral exam Jørgen Arendt Jensen November 30, 2015 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:
– Thursday 10/12 and Friday 11/12
• Q&A session: Monday 7/12 at 13.00 in this room • New course:
– 31548 Advanced ultrasound imaging • Help on CT assignments • MR lecture & exercise
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark 3/x
CampusNet evaluation: https://evaluering.dtu.dk/Resultpresentation?courses=C159511
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 7/12 at 13.00 in this room
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
New course: 31548 Advanced ultrasound imaging
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
General course objectives
• The course aims to: – give a thorough introduction to modern principles of
diagnostic ultrasound scanners – execution of a project with simulation and
implementation of an imaging method. – students will be familiariesed with modern ultrasound
scanners for both research and clinical use. – prepare students to engage in research and
development teams. – software and hardware facilities at the Center for Fast
Ultrasound is presented. – areas of research (system design, flow measurement,
anatomical imaging) form the basis for teaching.
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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
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Shepp-Logan phantom
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Note that the Shepp-Logan phantom is not in Hounsfield units, but the relative scaling is the same.
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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
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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
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Ram-Lak filter
Transfer function: Impulse response
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h(ω) =ρ , ρ ≤ B
0 else
"#$
%$
h(k) =
B2 k = 0
−B2
π2k
"
#$
%
&'2 k odd
0 k even
(
)
****
+
****
Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Transfer function of filters – Ram-Lak
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Shepp-Logan filter (corrected plot)
Transfer function: Impulse response
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h(ω) =ρsin 2πρ
4B2πρ4B
, ρ ≤ B
0 else
"
#
$$
%
$$
h(k) = − 8B2
π (4k2 −1)
Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Shepp-Logan filter
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Hanning weighted filter
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Hanning weighted filter
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Filter transfer functions and impulse responses
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Comparison between filters
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Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Circular convolution
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−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
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−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
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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
Center for Fast Ultrasound Imaging, Department of Electrical Engineering Technical University of Denmark
Backprojection
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Patient grid
