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7/21/2014
1
Philips Research - Hamburg Confidential 1
“Partners in Solution” session
Philips CT Dose Optimization tools and Advanced
Reconstruction
Tsvi Katchalski Philips
July 24, 2014
Philips Research - Hamburg Confidential 2
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)
Philips Research - Hamburg Confidential 3
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)
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Philips Research - Hamburg Confidential 4
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 DoseRight recommendation: 240mAs
Philips Research - Hamburg Confidential 5
Dose Right Index – Definition (by Reference)
Dose Right – How Does it Work
Averages patient size is calculated from the surview
Patient size is compared to the EC
Reference size
Avg. mAs for the patient is calculated
according to the DRI
DRI=24 200 mAs @120 kV @ average patient size (29 cm)
0
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300
400
500
600
700
800
900
1000
0 10 20 30 40 50
Cu
rren
t x
Tim
e [m
As]
Average Size [cm]
Exponential Adaptation to Patient size
Philips Research - Hamburg Confidential 6
Increase and Decrease in DRI (Dose Right Index) - Adults
DRI 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
25 159 224 443
26 178 250 497
…
1 DRI:
+12% mAs
6 cm: +100% (doubled) mAs
6 DRI:
+100% mAs
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Philips Research - Hamburg Confidential 7
Z- Dose Modulation (Z-DOM) Consistent IQ Along Patient Liver Detection Head Detection
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200
300
400
500
0 5 10 15 20 25
mA
s
Z-position
Philips Research - Hamburg Confidential 8
3D- Dose Modulation (3D-DOM) Reduction of Streak Artifacts Improve Noise Uniformity
Philips Research - Hamburg Confidential 9
3D- Dose Modulation vs. Z-DOM - Reduction of Streak Artifacts - Improve Noise Uniformity
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Philips Research - Hamburg Confidential 10
Automatic Pitch/Rotation Time Algorithm Basic equations:
𝑠𝑐𝑎𝑛 𝑡𝑖𝑚𝑒 =𝑠𝑐𝑎𝑛 𝑙𝑒𝑛𝑔𝑡ℎ
𝑏𝑒𝑑 𝑠𝑝𝑒𝑒𝑑
𝑏𝑒𝑑 𝑠𝑝𝑒𝑒𝑑 =𝑝𝑖𝑡𝑐ℎ × 𝑐𝑜𝑙𝑙𝑖𝑚𝑎𝑡𝑖𝑜𝑛
𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒
𝑚𝐴𝑠 =𝑚𝐴 × 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒
𝑝𝑖𝑡𝑐ℎ
Bed speed
Pitch / rotation
time
mAs
Tube current
Philips Research - Hamburg Confidential 11
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%”): Relaxation Expansion
• End diastolic (“75%”): Relaxation Contraction
Systole Diastole
“40%” “75%” “0%” “100%”
Philips Research - Hamburg Confidential 12
Cardiac Cycles Reconstructing at Different Phases – ECG Gated
20 35 75
Cardiac Phase
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Philips Research - Hamburg Confidential 13
Special Modulation Modes Cardiac Retrospective
• ECG triggered dose modulation in Helical/Spiral scans
57 34
Z
20 %
Cardiac DoseRight - Prospective
100 %
Philips Research - Hamburg Confidential 14
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 retrospectively-
gated spiral scans
• 3D axial cone beam reconstruction algorithm
• Real-time arrhythmia handling algorithms
Philips Research - Hamburg Confidential 15
Special Modulation Modes Dose Reduction from ECG Dose Modulation – Dependency on HR
Compared to ECG-gated spiral scans without dose modulation
0
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80
90
60 bpm 70 bpm 80 bpm 90 bpm 100 bpm S&SC
Do
se R
ed
uct
ion
(%
)
Klass O, Walker MJ, et al, Eur Rad 2008
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Philips Research - Hamburg Confidential 16
Beam Filtration and Beam Shapers InteliBeam Filters SmartShape Wedge (Bowtie) Filters
- Filtration is optimized to increase Low Contrast and reduce Skin Dose and is done per protocol
- Three filtration modes: “Half”/”Full”/”Off-center enabled”
Philips Research - Hamburg Confidential 17
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
Philips Research - Hamburg Confidential 18
Eclipse Collimator and Clear Ray Collimator 2D Anti Scatter Grid
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Philips Research - Hamburg Confidential 19
Clear Ray Scatter and Beam Hardening Correction
- Monte Carlo based scatter estimation
- Analytical Beam Hardening Correction
- Scatter correction is proportional to patient size
Philips Research - Hamburg Confidential 20
NanoPanel Elite New Tile Detector Scintillator
– IGOS (Gd2O2S) High Quality Ceramic Scintillator
– Fast Response
– High Light Output
– Low Cross-Talk
ASIC
– Very Low Noise
– Improved linearity over all the dynamic range
– Front End Electronics with 256 Channels
PDA (Photo Diode Array)
– Back Illuminated Using Thin and High purity Silicon
– High Quantum efficiency.
– High Shunt Resistance
– Low Cross-talk
Philips Research - Hamburg Confidential 21
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)
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Philips Research - Hamburg Confidential 22
iDose advanced reconstruction How it works
iterative reconstruction technique: How does it work?
iDose uses the raw data output from the NanoPanel detector
to determine and remove noise while keeping structure intact
Philips Research - Hamburg Confidential 23
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 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
Compensating increase in noise
(noise reduction %)
11 %
16 %
23 %
29 %
37 %
45 %
55 %
Philips Research - Hamburg Confidential 24 Philips Healthcare / Clinical Science & Application CT EMEA, June 6, 2008
2
4
50% Dose (125mAs) FBP 50% Dose (125mAs) iDose
Courtesy TU Munich, Germany
Follow up with
50% Dose Reduction
Comparison Full Dose / 50% Dose Reduction + iDose Full Dose (250mAs) FBP
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Philips Research - Hamburg Confidential 25 Philips Healthcare / Clinical Science & Application CT EMEA, June 6, 2008
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120 kV, 100 mAs (6.6 mGy)/ 80 kV, 100 mAs (1.9 mGy) 70% Dose Reduction
70% Dose Reduction (1.9mGy) - iDose
Courtesy TU Munich, Germany
Full Dose (6.6mGy) - FBP
Comparison Full Dose / 70% Dose Reduction + iDose
Philips Research - Hamburg Confidential 26 Philips Healthcare / Clinical Science & Application CT EMEA, June 6, 2008
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6
120kV, 70mAs, 6.4mGy, Prospective Gated Aortic CTA (Step & Shoot Complete)
iDose FBP
Courtesy Cleveland Clinic, USA
Improving Image Quality: Artifact Reduction
Philips Research - Hamburg Confidential 27 Philips Healthcare / Clinical Science & Application CT EMEA, June 6, 2008
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7
Courtesy OHSU, USA
120kV, 280 mAs, 22.9mGy, Prospective Gated Cardiac CTA (Step & Shoot Cardiac)
iDose FBP
Improving image quality in inherently noisy acquisitions
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Philips Research - Hamburg Confidential 28
Knowledge-Based Iterative Reconstruction Technique
Name
Philips Research - Hamburg Confidential 29
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
Philips Research - Hamburg Confidential 30
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 42 out of 100 Test 57 out of 100 Test 73 out of 100 Test 77 out of 100 Test 94 out of 100
Test 57 out of 100Test 42 out of 100 Test 94 out of 100Test 77 out of 100Test 73 out of 100
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0
1
2
3
4
StandardReconstruction
IMR
1.4
3.9
Low
-con
trast
Dete
cta
bili
ty I
ndex 2.5 - 3.6x
Low-contrast Detectability Index*
Standard
Reconstruction
* Low-contrast detectability was assessed using 4-AFC test on a reference abdomen protocol, tested on the MITA CT IQ phantom. Data on file.
Improve low-contrast detectability Revealing subtle differences
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0
20
40
60
80
100
0 2.5 5 7.5 10 12.5
Gain
(%
)
Frequency (lp/cm)
Standard Resolution MTF Measurements
FBP (Std Filter)
FBP (Sharp Filter)
IMR (High-res setting)
Revealing fine detail
High resolution Imaging
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GGO visualized on Chest CT with IMR
80 kVp, 10 mAs, 0.2 mGy, 0.11 mSv
Chest X-Ray
0.05 mSv
Standard
Reconstruction
BODY
Courtesy: UCL, Belgium
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Standard
Reconstruction
120 kVp, 300 mAs, 14.3 mGy, 1.8 mSv, < 2 min recon time
71 year old man with hemorrhagic lesions not seen on FBP
NEURO
1.0 mm slice thickness
Courtesy: UCL, Belgium
3.0 mm slice thickness 1.0 mm slice thickness
Standard
Reconstruction
FBP iDose 4 IMR L3
Non-calcified plaque visualization
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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FBP iDose
IMR L3
Excessive noise hinders
segmentation
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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Philips Research - Hamburg Confidential 43
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
Philips Research - Hamburg Confidential 44