7/21/2014
“Partners in Solution” session
Philips CT Dose Optimization
tools and Advanced
Reconstruction
Tsvi Katchalski
Philips
July 24, 2014
1
Philips Research - Hamburg
Confidential
Content
(I) Dose Reduction and Dose Optimization Technologies
•
•
•
•
•
•
Dose Right and Tube Current Modulation (Dose Right, Z-DOM, 3D-DOM)
Special Acquisition Modes (Cardiac Dose Right, Prospective gating)
Beam Filtration and Beam Shapers
Eclipse Collimator and Clear Ray Collimator
NanoPanel Elite Detector
NEMA XR-25
– Dose check
– Dose structured reporting
(II) Advanced Reconstruction Technology
• iDose4
• IMR (Iterative Model)
2
Philips Research - Hamburg
Confidential
PART (I)
(I) Dose Reduction and Dose Optimization
Technologies
•
•
•
•
•
•
Dose Right and Tube Current Modulation (Dose Right, Z-DOM, 3D-DOM
Special Modulation Modes (Cardiac Dose Right, Prospective gating)
Beam Filtration and Beam Shapers
Eclipse Collimator and Clear Ray Collimator
NanoPanel Elite Detector
NEMA XR-25
– Dose check
– Dose structured reporting
(II) Advanced Reconstruction Technology
• iDose4
• IMR (Iterative Model)
3
Philips Research - Hamburg
Confidential
1
7/21/2014
Dose Right and Tube Current Modulation
Dose Right Index
Consistent IQ for Different Patient Size
Dose Right Index + Current Modulation
Consistent IQ for
Different Patients and at Different Z-Locations
DoseRight recommendation: 389mAs
4
Philips Research - Hamburg
DoseRight recommendation: 240mAs
Confidential
Dose Right Index – Definition (by Reference)
DRI=24
200 mAs @120 kV @ average patient size (29 cm)
Dose Right – How Does it Work
Averages patient
size is calculated
from the surview
Avg. mAs for the
patient is
calculated
according to the
DRI
Patient size is
compared to the EC
Reference size
Exponential Adaptation to Patient size
1000
900
Current x Time [mAs]
800
700
600
500
400
300
200
100
0
0
10
20
30
40
50
Average Size [cm]
5
Philips Research - Hamburg
Confidential
Increase and Decrease in DRI (Dose Right Index) - Adults
6 cm: +100% (doubled) mAs
25cm
29cm
35cm
18
71
102
202
19
80
114
226
20
90
128
254
21
101
143
284
22
113
160
317
23
127
179
355
24
142
200
400
1 DRI:
25
159
224
443
+12%
mAs
26
178
250
497
DRI
…
6 DRI:
+100%
mAs
…
6
Philips Research - Hamburg
Confidential
6
2
7/21/2014
Z- Dose Modulation (Z-DOM)
Consistent IQ Along Patient
Liver Detection
Head Detection
500
mAs
400
300
200
100
0
0
5
10
15
20
25
Z-position
7
Philips Research - Hamburg
Confidential
3D- Dose Modulation (3D-DOM)
Reduction of Streak Artifacts
Improve Noise Uniformity
8
Philips Research - Hamburg
Confidential
3D- Dose Modulation vs. Z-DOM
- Reduction of Streak
Artifacts
- Improve Noise
Uniformity
9
Philips Research - Hamburg
Confidential
3
7/21/2014
Automatic Pitch/Rotation Time Algorithm
Basic equations:
𝑠𝑐𝑎𝑛 𝑡𝑖𝑚𝑒 =
𝑏𝑒𝑑 𝑠𝑝𝑒𝑒𝑑 =
𝑚𝐴𝑠 =
mAs
Philips Research - Hamburg
𝑝𝑖𝑡𝑐ℎ × 𝑐𝑜𝑙𝑙𝑖𝑚𝑎𝑡𝑖𝑜𝑛
𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒
𝑚𝐴 × 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒
𝑝𝑖𝑡𝑐ℎ
Pitch /
rotation
time
Bed
speed
Tube
current
10
𝑠𝑐𝑎𝑛 𝑙𝑒𝑛𝑔𝑡ℎ
𝑏𝑒𝑑 𝑠𝑝𝑒𝑒𝑑
Confidential
Special Modulation Modes - Cardiac
Heart Cycle – The Heart is in Constant Motion
General motion profile:
• Relaxation: Heart is filled with blood.
• Contraction: Heart ‘pushes’ blood to the body/Lungs
“Quiet phases”: Phases with relatively less motion
• End systolic (“40%”):
• End diastolic (“75%”):
Relaxation  Expansion
Relaxation  Contraction
Diastole
Systole
“0%”
11
Philips Research - Hamburg
“40%”
“75%”
“100%”
Confidential
Cardiac Cycles
Reconstructing at Different Phases – ECG Gated
Cardiac Phase
20
12
Philips Research - Hamburg
35
75
Confidential
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7/21/2014
Special Modulation Modes
Cardiac Retrospective
• ECG triggered dose modulation in Helical/Spiral scans
Cardiac DoseRight - Prospective
Z
100 %
20 %
13
Philips Research - Hamburg
57
Confidential
34
Special Modulation Modes
Cardiac Step and Shoot – Prospective Gating
• Low dose (3–5 mSv) diagnostic scan
– Dose reduction up to 80% compared to standard
retrospectively-gated spiral scans
– Image quality comparable to that of standard retrospectivelygated spiral scans
• 3D axial cone beam reconstruction algorithm
• Real-time arrhythmia handling algorithms
14
Philips Research - Hamburg
Confidential
Special Modulation Modes
Dose Reduction
(%)
Dose Reduction from ECG Dose Modulation – Dependency on HR
90
80
70
60
50
40
30
20
10
0
60 bpm
70 bpm
80 bpm
90 bpm
100 bpm
S&SC
Compared to ECG-gated spiral scans without dose modulation
Klass O, Walker MJ, et al, Eur Rad 2008
15
Philips Research - Hamburg
Confidential
5
7/21/2014
Beam Filtration and Beam Shapers
InteliBeam Filters
SmartShape Wedge (Bowtie) Filters
-
-
16
Philips Research - Hamburg
Filtration is optimized to increase Low
Contrast and reduce Skin Dose and is
done per protocol
Three filtration modes:
“Half”/”Full”/”Off-center enabled”
Confidential
Eclipse Collimator and Clear Ray Collimator
Helical Dynamic Collimation to Reduce Over Scanning
Walker MJ, Olszewski ME, Desai MY, et al,
Intl Journal of Cardiovasc Imaging, 2009
17
Philips Research - Hamburg
Confidential
Eclipse Collimator and Clear Ray Collimator
2D Anti Scatter Grid
18
Philips Research - Hamburg
Confidential
6
7/21/2014
Clear Ray Scatter and Beam Hardening
Correction
-
19
Philips Research - Hamburg
Monte Carlo based scatter
estimation
Analytical Beam Hardening
Correction
Scatter correction is
proportional to patient size
Confidential
NanoPanel Elite New Tile Detector
Scintillator
–
–
–
–
IGOS (Gd2O2S) High Quality Ceramic Scintillator
Fast Response
High Light Output
Low Cross-Talk
PDA (Photo Diode Array)
–
–
–
–
Back Illuminated Using Thin and High purity Silicon
High Quantum efficiency.
High Shunt Resistance
Low Cross-talk
ASIC
– Very Low Noise
– Improved linearity over all the dynamic range
– Front End Electronics with 256 Channels
20
Philips Research - Hamburg
Confidential
PART (II)
(I) Dose Reduction and Dose Optimization Technologies
•
•
•
•
•
Dose Right and Tube Current Modulation (Dose Right, Z-DOM, 3D-DOM
Special Acquisition Modes (Cardiac Dose Right, Prospective gating)
Beam Filtration and Beam Shapers
Eclipse Collimator and Clear Ray Collimator
NanoPanel Elite Detector
(II) Advanced Reconstruction Technology
• iDose4
• IMR (Iterative Model)
21
Philips Research - Hamburg
Confidential
7
7/21/2014
iterative reconstruction technique: How does it work?
iDose advanced reconstruction
How it works
iDose uses the raw data output from the NanoPanel detector
to determine and remove noise while keeping structure intact
22
Philips Research - Hamburg
Confidential
iDose – Mode of Operation
Noise Reduction
– Reduce noise according to iDose Level
selection
– For each protocol the achievable iDose
Level were determined
– No degradation in Resolution and Low Contrast
(Tolerance: 10% in MTF10% and 1mm in Low Contrast)
High mA
Compensating
increase in noise
(noise
reduction %)
11 %
16 %
23 %
29 %
37 %
45 %
55 %
IQ Improvements
– Keep the Dose Level the same and improve spatial resolution and Low
Contrast
Hardware Enabler
– RapidView IR, Next Generation Intel
Multi-Core Processors
– Up to 20 Images/sec
23
Philips Research - Hamburg
Confidential
Comparison Full Dose / 50% Dose Reduction + iDose
Full Dose (250mAs) FBP
Follow up with
50% Dose Reduction
50% Dose (125mAs) FBP
24
Philips Research - Hamburg
Confidential
50% Dose (125mAs) iDose
Courtesy TU Munich, Germany
Philips Healthcare / Clinical Science & Application CT EMEA, June 6, 2008
2
4
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7/21/2014
Comparison Full Dose / 70% Dose Reduction + iDose
120 kV, 100 mAs (6.6 mGy)/ 80 kV, 100 mAs (1.9 mGy)  70% Dose Reduction
Full Dose (6.6mGy) - FBP
25
Philips Research - Hamburg
Confidential
70% Dose Reduction (1.9mGy) - iDose
Courtesy TU Munich, Germany
Philips Healthcare / Clinical Science & Application CT EMEA, June 6, 2008
2
5
Improving Image Quality: Artifact Reduction
120kV, 70mAs, 6.4mGy, Prospective Gated Aortic CTA (Step & Shoot Complete)
FBP
26
Philips Research - Hamburg
Confidential
iDose
Courtesy Cleveland Clinic,2USA
Philips Healthcare / Clinical Science & Application CT EMEA, June 6, 2008
6
Improving image quality in inherently noisy acquisitions
120kV, 280 mAs, 22.9mGy, Prospective Gated Cardiac CTA (Step & Shoot Cardiac)
FBP
27
Philips Research - Hamburg
Confidential
iDose
Philips Healthcare / Clinical Science & Application CT EMEA, June 6, 2008
Courtesy OHSU, USA
2
7
9
7/21/2014
Knowledge-Based
Iterative Reconstruction Technique
Name
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Philips Research - Hamburg
Confidential
Knowledge-Based Iterative Reconstruction
What makes this possible
Fast and compact next-gen computing devices
using GPU (under 3min for most protocols)
Integrated Workflow
User has flexibility as to the final result.
Body
Soft Tissue
Routine
Sharp Plus
29
Philips Research - Hamburg
Confidential
Performance Evaluation
Low Contrast Detectability
A measure of a person’s ability to perform a particular task: The
determination of a Low Contrast object
– Is influenced by all Physics IQ metrics (Noise, Resolution, Uniformity and
CT number)
– A statistical approach is needed
– Human observer study, 4 Alternative Forced Choice (4AFC) Study was
used
Test
Test4242out
outofof100
100
30
Philips Research - Hamburg
Test
Test 57
57 out
out of
of 100
100
Test 73 out of 100
Test
Test 77
77 out
out of
of 100
100
Test
Test94
94out
outofof100
100
Confidential
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7/21/2014
Improve low-contrast detectability
Revealing subtle differences
2.5 - 3.6x
Low-contrast Detectability Index
4
Low-contrast Detectability Index*
3
3.9
2
1
1.4
0
Standard
Reconstruction
Standard
Reconstruction
IMR
31
* Low-contrast detectability was assessed using 4-AFC test on a reference abdomen protocol, tested on the MITA CT IQ phantom. Data on file.
High resolution Imaging
Revealing fine detail
Standard Resolution MTF Measurements
100
FBP (Std Filter)
80
FBP (Sharp Filter)
Gain (%)
60
IMR (High-res setting)
40
20
0
0
2.5
5
7.5
10
12.5
Frequency (lp/cm)
32
BODY
GGO visualized on Chest CT with IMR
Chest X-Ray
0.05 mSv
Standard
Reconstruction
80 kVp, 10 mAs, 0.2 mGy, 0.11 mSv
33
Courtesy: UCL, Belgium
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7/21/2014
NEURO
71 year old man with hemorrhagic lesions not seen on FBP
1.0 mm slice thickness
3.0 mm slice thickness
Standard
Reconstruction
Standard
Reconstruction
1.0 mm slice thickness
120 kVp, 300 mAs, 14.3 mGy, 1.8 mSv, < 2 min recon time
34
Courtesy: UCL, Belgium
Non-calcified plaque visualization
FBP
iDose 4
IMR L3
Mixed plaque in
LM / LAD
in severe obese female :
130kg, 170cm, BMI 45
Step&Shoot scan !
Max tube settings 120kV,
300mAs
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7/21/2014
FBP
iDose
Excessive noise
hinders
segmentation
IMR L3
Pre-TAVI assessment
Entire ECG Gated Aorta
with ONLY 40cc’s of IV contrast
20cc @2cc/s + 20cc @ 1cc/s
Semmelweis Univ. Budapest
Video: Maimondes Medical Center
https://www.youtube.com/watch?v=X1Uk9Jvbut0
TAVI scan with only 40cc of contrast
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TAVI ISP6, annular plane
TAVI ISP6, all planes
TAVI ISP6, angle prediction
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7/21/2014
Acknowledgements
-
Scott Smith
Richard Thompson
Yoad Yagil
Igor Uman
Elazar Gerland
Shmuel Glasberg
Ami Altman
Amar Dhanantwari
Dhruv Mehta
Tom Morton
Mani Vembar
Galit Kafri
Naama Cohen-Dahan
Andrei Feldam
Mani Vembar
43
Philips Research - Hamburg
Confidential
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Philips Research - Hamburg
Confidential
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