Ehsan Samei, PhD
Duke University
Duke CIPG
Clinical Imaging Physics Group
Medical Physics 2.0?
• A bold vision for an existential transition of
clinical imaging physics
• 12 hrs didactic lectures on CT, MRI, NM,
Fluoroscopy, Rad, Mammo, US, IT
– RSNA 2013
– RSNA 2014
– RSNA 2015
– AAPM 2014
– AAPM 2015
– Clinical Imaging Physics. Wiley and Sons, 2015
Overarching presuppositions
• Imaging should render relevant state of
health/disease accurately and precisely
enough so that it can lead to definitive clinical
decisions
• Images should be more reflective of the state
of the patient than the technique used
Reality checks
• Clinical activities are
heterogeneous/compounded/complex
operations
• Increased scrutiny
• Limited resources
• How imaging physics can add value in the
quality of imaging operation?
4 Key formative questions
1. Where is imaging in medicine
enterprise?
• Transformative technology
• The “face” of modern medicine
2. Where medical imaging is going?
• Evidence-based medicine
– Practice informed by science
• Precision medicine
– Quantification and personalization of care
• Value-based medicine
– Scrutiny on safety, performance, consistency,
stewardship, ethics
• Comparative effectiveness and meaningful use
– Enhanced focus on actual utility
3. What has been the role of
imaging physics in medicine?
• Remember Roentgen!
• Medical physics is the foundational discipline
behind Radiology and Radiation Oncology
4. What has been the clinical role
of imaging physics?
• Ensuing quality and safety of clinical imaging
systems
• We have done a GREAT job using engineering
and physics concepts to
– Design systems with superior performance
– Ensure minimum intrinsic performance
– Claim compliance
• But…
Imaging physics enterprise
Education
Research
Clinical Practice
Imaging physics enterprise
Research
Education
Clinical
Practice
Why 1.0 is not enough
• Not translatable, historically, to clinical care,
mostly equipment-focused
– Relevance?
• Outdated science and technology
– Compliance lags behind clinical needs and
innovations
Why 1.0 is not enough
•
•
•
•
•
Clinical performance?
Optimization of use?
Consistency of quality?
Changing technology?
Value-based healthcare?
1.0 to 2.0
• Clinical imaging physics extending from
compliance
intrinsic
Equipment
Specifications
Quality
Assumption
Promises
to
to
to
to
to
to
to
excellence
extrinsic
operation
performance
consistency
actual utility
implementation
Inspiring practices of
Medical Physics 2.0
1. Science: Practices that are scientifically-informed by
latest findings and methods
2. Relevance: Objectives that are oriented towards the
actual clinical practice
3. Stewardship: Approaches that are pragmatic in the
meaningful and efficient use of resources
4. Integration: Solutions that are comprehensive and
holistic in view of clinical operation
5. Empowerment: Education enabling others to be
their best in their domain of care
Clinical role of medical physics
Applying the science of imaging physics
to ensure quality, safety,
consistency, and optimum utilization
in the clinical practice of medical imaging
Ensuring quality, safety, consistency, optimality
18
Ensuring quality, safety, consistency, optimality
Prospective performance assessment
Quality by inference
Prospective protocol definition
Retrospective quality assessment
Quality by prescription
Quality by outcome
Ensuring quality, safety, consistency, optimality
Prospective performance assessment
Quality by inference
• Devising better metrics
• Automated characterization
Prospective protocol definition
Retrospective quality assessment
Quality by prescription
Quality by outcome
Nuclear Medicine non-uniformity
Crosshatched artifact pattern
(system has square PMT’s)
Nuclear Medicine non-uniformity
N max - N min
Integral Uniformity =
´100%
N max + N min
2.87%
Action limit = > 5.00%
2.81%
Nelson JS, et al, JNM, 2014
Structured Noise Index (SNI)
Eye Filter
NPSS
FT
Filtered NPSS
Subtract
Quantum
Noise
Eye Filter
Flood Image
NPST
Filtered NPST
Artifact Image
Flood Image
Filtered NPS
Artifact Image
Is SNI valid?
• Observer study: 55 images, 5 observers, 2 settings
Sensitivity
Estimated
Integral
UFOV
62%
Estimated
Integral
CFOV
54%
Specificity
PPV
NPV
Accuracy
R2
90%
67%
88%
84%
0.426
83%
50%
85%
76%
0.462
Structured
Noise Index
100%
95%
87%
100%
96%
0.766
Integral Uniformity vs SNI
CFOV IU = 2.81%
Action limit = > 5.00%
SNI= 0.78
Action limit = > 0.5
SNI Tracking and Analytics
• Scanners can send QC data to physics server
Physics Server
SNI Tracking and Analytics
• Scanners can send QC data to physics server
Physics Server
Improved consistency across NM fleet
29
SNI Tracking and Analytics
• Improved consistency across systems
• Decreased the time technologists and
physicists spent analyzing QC
• Successfully alerted staff to issues which
would have been overlooked
• Expedited communication between clinical
staff, physicist, and clinical engineers
30
What is image quality?
ICRU Report 54, 1996
“Any general definition of image quality must address
the effectiveness with which the image can be used for
its intended task.”
CNR vs observer performance
Christianson, et al, Radiology, 2015
Parameters that affect taskbased image quality
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Contrast
Lesion size
Lesion shape
Lesion edge
Resolution
Viewing distance
Display
Noise magnitude
Noise texture
Operator noise
Feature of
interest
Image
details
Distractors
Parameters that affect taskbased image quality
CNR
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Contrast
Lesion size
Lesion shape
Lesion edge
Resolution
Viewing distance
Display
Noise magnitude
Noise texture
Operator noise
Feature of
interest
Image
details
Distractors
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Contrast
Lesion size
Lesion shape
Lesion edge
Resolution
Viewing distance
Display
Noise magnitude
Noise texture
Operator noise
FBP
Reconstruction
Iterative
Reconstruction
Noise
texture?
IR
FBP
Low Dose CT @ 114 DLP, 1.9 mSv
Images courtesy of Dr de Mey and Dr Nieboer, UZ Brussel, Belgium
Noise Power Spectrum
Noise Power Spectrum
Resolution and noise, eg 1
Lower noise but
different texture
Comparable
resolution
x 10
1
-FBP
-IRIS
-SAFIRE
-FBP
-IRIS
-SAFIRE
2.5
2
0.6
NPS
MTF
0.8
-6
1.5
0.4
1
0.2
0
0.5
0
0.2
0.4
0.6
Spatial frequency
0.8
0
0
0.2
0.4
0.6
Spatial frequency
0.8
Resolution and noise, eg 2
Lower noise but
different texture
Higher resolution
1
0.5
0.9
0.45
0.8
0.4
0.7
0.35
0.6
0.3
NPS
MTF
x 10-5
-MBIR
-ASIR
-FBP
0.5
0.4
0.3
0.25
0.2
0.15
0.2
0.1
0.1
0.05
0
0
0.2
0.4
0.6
Spatial frequency
-MBIR
-ASIR
-FBP
0.8
0
0
0.2
0.4
Spatial frequency
0.6
0.8
Task-based quality index
Resolution and contrast
transfer
×
Attributes of image
feature of interest
Image noise magnitude and
texture
(d )
2
'
NPWE
[ òò MTF (u,v)W
2
=
2
Task
(u,v)E (u,v)dudv
2
]
2
2
2
4
2
2
MTF
(u,v)W
(u,v)
NPS(u,v)E
(u,v)
+
MTF
(u,v)W
òò
Task
Task (u,v)N i dudv
Richard, and E. Samei, Quantitative breast tomosynthesis: from detectability to estimability. Med Phys, 37(12), 6157-65 (2010).
Chen et al., Relevance of MTF and NPS in quantitative CT: towards developing a predictable model of quantitative... SPIE2012
CNR vs observer performance
Christianson, et al, Radiology, 2015
d’ vs observer performance
Christianson, et al, Radiology, 2015
Simple Metrics
Detection Accuracy
CNR
1
0.9
Fourier-Based
NPW
CHO
R = 0.726
E = 0.25
CI9 5 % = 3.32e-03
R2 = 0.603
E = 0.4
CI9 5 % = 4.25e-02
Humans vs. Models
2
R 2 = 0.114
E = 0.3
CI9 5 % = 5.60e-03
1
0.9
1
0.9
0.8
0.8
0.8
0.7
0.7
0.7
0.6
0.6
0.6
0.5
0.5
0.5
0.5
0.6
0.7
A
0.8
0.9
0.5
1
0.6
1
0.9
0.7
A
CNR
0.8
0.9
1
0.5
1
0.9
NPW
R = 0.77
E = 0.3
CI9 5 % = 5.83e-03
1
0.9
0.8
0.8
0.7
0.7
0.7
0.6
0.6
0.6
0.5
0.5
0.5
0.7
A
0.8
CNRa
0.9
1
0.5
0.6
0.7
A
0.8
NPWE
0.8
0.9
1
0.9
1
CHO
CHOi
0.8
0.6
0.7
A
2
R 2 = 0.707
E = 0.15
CI9 5 % = 1.20e-02
0.5
0.6
NPWE
CNRa
Detection Accuracy
Image Based
0.9
1
R2 = 0.72
E = 0.45
CI
= 4.59e-02
95%
0.5
0.6
0.7
A
0.8
CHOi
Task-based measurements
Mercury Phantom 3.0
• Diameters matching population cohorts
• Depths consistent with cone angles
• Designed for size, AEC, and d’ evaluations
44
Design: Resolution, HU, noise
•
•
•
•
•
Representation of abnormality-relevant HUs
Sizes large enough for resolution sampling
Maximum margin for individual assessment
Iso-radius resolution properties
Matching uniform section
for noise assessment
45
Wilson et al, MedPhys 2012
imQuest
(image quality evaluation software)
HU, Contrast, Noise, CNR, MTF, NPS, and d’ per patient size, mA modulation profile
Wilson et al, MedPhys 2012
Detectability index across systems
12
All Systems
System 1
System 2
System 3
System 4
System 5
System 6
System 7
System 8
System 9
System 10
System 11
System 12
System 13
Detectability
10
8
6
6
8
10
12
Date
Intra system variability: 1-4%
Inter system variability: 6%
Winslow et al, AAPM, 2014
Image quality in the presence of
anatomical heterogeneity
48
Truth
Truth
System A
System B
System C
System D
System E
Ensuring quality, safety, consistency, optimality
Prospective performance assessment
Quality by inference
• Protocol optimization
• Protocol consistency
Prospective protocol definition
Retrospective quality assessment
Quality by prescription
Quality by outcome
Optimization
framework
Be
fit
e
n
Quality indices
(d’, Az, …)
Different patients
and indications
e
m
i
g
re
Optimization regime
Scan factors
(mAs, kVp, pitch, recon,
kernel, …)
sk
i
R
im
g
re
e
Safety indices
(organ dose,
eff. dose, …)
Optimization of kVp-recon
Feature with no iodine
1
Feature with iodine
1
0.9
0.8
0.8
AZ
AZ
0.9
0.7
0.7
0.6
0.6
0.5
0
2
4
6
Eff dose (mSv)
8
10
0.5
0
2
4
6
Eff dose (mSv)
8
10
Patient size?
54
for-your-child.blogspot.com
http://www.pedrad.org
Optimization of dose per size
Iso-gradient optimization points to define ALARA
Size
Optimization for quantification
Quantitative CT volumetry
PRC: Relative difference between any two repeated
quantifications of a nodule with 95% confidence
Texture similarity
Sharpness
Solomon, Samei, Med Phys, 2012
Texture similarity – matched recons
Minimum
RMSD
(mm2)
Minimum
|PFD| (mm1)
GE
Siemens
SOFT
B35f
0.01
0.00
STANDARD B43f
0.01
0.00
CHEST
B41f
0.01
0.01
DETAIL
B46f
0.04
0.01
LUNG
B80f
0.03
0.00
BONE
B75f
0.10
0.13
BONE+
B75f
0.09
0.12
EDGE
B75f
0.18
0.41
Solomon, Samei, Med Phys, 2012
Texture similarity – matched recons
Minimum
|PFD| (mm1)
GE
Siemens
SOFT
B35f
0.01
0.00
STANDARD B43f
0.01
0.00
CHEST
0.01
0.01
B41f
Standard
B43f
~50 mm
Minimum
RMSD
(mm2)
0.8
STANDARD
B43f
0.7
0.04
0.01
LUNG
B80f
0.03
0.00
BONE
B75f
0.10
0.13
BONE+
B75f
0.09
0.12
0.6
2
B46f
nNPSf (mm )
DETAIL
0.5
0.4
0.3
0.2
0.1
EDGE
B75f
0.18
0.41
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Spatial Frequency (mm−1)
0.8
0.9
1
Solomon, Samei, Med Phys, 2012
Texture similarity – matched recons
Minimum
|PFD| (mm1)
GE
Siemens
SOFT
B35f
0.01
0.00
STANDARD B43f
0.01
0.00
CHEST
0.01
0.01
B41f
Lung
B80f
~50 mm
Minimum
RMSD
(mm2)
0.8
LUNG
B80f
0.7
0.04
0.01
LUNG
B80f
0.03
0.00
BONE
B75f
0.10
0.13
BONE+
B75f
0.09
0.12
0.6
2
B46f
nNPSf (mm )
DETAIL
0.5
0.4
0.3
0.2
0.1
EDGE
B75f
0.18
0.41
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Spatial Frequency (mm−1)
0.8
0.9
1
Solomon, Samei, Med Phys, 2012
Resolution/noise across recons
Resolution/noise across recons
Ensuring quality, safety, consistency, optimality
Prospective performance assessment
Quality by inference
• Dose monitoring - analytics
• Quality tracking - analytics
Prospective protocol definition
Retrospective quality assessment
Quality by prescription
Quality by outcome
Dose monitoring components
A. Access: Connection and collection of doserelevant data
B. Integrity: Data quality and accuracy
C. Metrology: Meaningful quantities to monitor
D. Analytics: From data to knowledge
E. Informatics: Dose monitoring as a secure,
integrated solution
Dose analytics
1.
2.
3.
4.
5.
6.
7.
8.
Benchmarking institution against national DRLs
Defining protocol- and size-specific DRLs
Identifying outliers
Ascertaining trends over time
Ascertaining inter-system variability
Tracking protocol discrepancy
Investigating individual doses
Improving operational consistency
Frush, Samei, Medscape Radiology, in print 2015
Benchmarking institution against
national DRLs
60
50
CTDI
40
30
20
10
0
Institution
DIR
Size (cm)
25
30
35
40
Upper
10
17
31
55
Lower
3
6
10
18
55
31
17
18
10
10
6
3
Dose monitoring in mammo
Chest exposures by operator and Clinic
CR
DR
CT Table
Height
71
PE Chest Protocol
60
50
CTDIvol (mGy)
40
30
VCT - Old
SOMATOM Definition
20
10
0
20
25
30
35
Effective Diameter (mGy)
40
45
PE Chest Protocol
60
50
CTDIvol (mGy)
40
VCT - Old
30
SOMATOM Definition
VCT - New
20
10
0
20
25
30
35
Effective Diameter (mGy)
40
45
Clinical image quality?
Clinical image quality monitoring
Laplacian Pyramid Decomposition
1. Lung grey level
2. Lung detail
3. Lung noise
4. Rib-lung contrast
5. Rib sharpness
6. Mediastinum detail
7. Mediastinum noise
8. Mediastinum alignment
Thorax linear landmark detection
9. Subdiaphragm-lung contrast
10. Subdiaphragm area
Lin et al, Med Phys 2012
Samei et al, Med Phys 2014
Mediastinum noise
Image quality reference levels – lung noise
Quality
Acceptable
Poor
Lung detail
Average Lung Noise
40
35
Acceptable
Quality
30
25
20
15
10
5
0
Average Lung Detail
35
30
25
20
15
10
5
0
13 - 42
19 - 31
0.00
AJ19
AK151
AM235
BARWI003
BPS12
DAVIS090
DG97
DW77
ED108
HITE0001
JACOB074
KCG24
KMD48
KS324
LAM41
LB111
LH154
MALES003
MCG
MH225
MOORE237
MW187
NA
RICKM005
SC134
TA34
TE45
TML113
VJ28
0.08 – 0.49
0.17 – 0.27
Average Subdiaphragm Area
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
Overall operational consistency - CT
Abdomen Pelvis Exams (n=2358)
50
Scanner 1
45
Scanner 2
40
Scanner 1
45
Scanner 2
40
Scanner 3
Scanner 3
35
Noise (HU)
35
SSDE (mGy)
50
30
25
20
30
25
20
15
15
10
10
5
5
0
0
20
30
40
Effective Diameter (cm)
20
30
40
Effective Diameter (cm)
Christianson et al, AAPM, 2014
Protocol Report Cards
STANDARD CHEST 5 mm
n = 4229 annually
Protocol Definition
Scan parameter
Definition
Flash
750 HD
VCT
LS 16
23_ST A NDA RD_CHE ST _WIT HOU T _I V22_FLASH_P E_CHEST5.1STA NDA RD CHEST5.1STA NDA RD CHEST5.1STA NDA RD CHEST
Pro to co l name
Scan type
Helical
Helical
Helical
Helical
Helical
Ro tatio n time
0.5
0.285
0.4
0.4
0.5
n = 4229 annually
Flash
750 HD
VCT
P itch
0.8 LS 16
3
1.375
1.375
1.375
22_FLA SH_P E_CHEST5.1STA NDARD CHEST5.1STA NDARD CHEST5.1STA NDARD CHEST
Table speed
61.4Helical
404.2
137.5
137.5
55
Helical
Helical
Helical
0.285
0.4
0.4
0.5
B eam width
38.4 1.375
38.4
40
40
20
3
1.375
1.375
404.2
137.5
kVp137.5
120 55
120
120
120
120
38.4
40
40
20
Slice thickness
5 120
5
5
5
5
120
120
120
5
5
5
5
A uto mA
On On
On
On
On
On
On
On
On
150
19.2
16
mA /NI/mAsref
150 16
150
19.2
16
16
Wedge_2
Bo dy
Bo dy
Bo dy
SFOV
Wedge_3
Wedge_2
B o dy
B o dy
B o dy
B 31f
Standard
Standard
Standard
FB P
A SiR 30%
FB P
FB P
Kernel
B 31f
B 31f
Standard
Standard
Standard
No
Yes
Iterative Yes
Level
FB P Yes
FB P
A SiR 30%
FB P
FBP
Protocol Definition
STANDARD CHEST 5 mm
Scan parameter
Definition
P ro to co l name
Scan type
Ro tatio n time
Pitch
Table speed
Beam width
kVp
Slice thickness
A uto mA
mA /NI/mA sref
SFOV
Kernel
Iterative Level
23_ST A N D AR D _CH E ST _WIT H OUT _IV
Helical
0.5
0.8
61.4
38.4
120
5
On
150
Wedge_3
B 31f
FB P
M atches e-pro to co l
% o f STA NDA RD CHEST exams
Yes
14.3%
Kernel/IR
47.9%
5.3%
MTF50
d' (5mm)
STD/40%
Current Flash
B31/0
Current VCT
STD/0
0.3
0.43
35.6
Current LS16
STD/0
0.3
0.43
35.6
0.3
0.43
Recommended Flash
i40/3
Recommended VCT
STD/0
Recommended LS16
5.2%
M atches e-pro
to co l
0.261
0.45
40
% o0.293
f STANDA RD0.412
CHEST exams
33.2
Target
(CT 750HD)
0.265
0.432
Image Quality
(Prospective)
Image Quality
(Prospective)
Target (CT 750HD)
27.4%
NPSavg
STD/0
15
10
Yes
5.2%
No
Kernel/IR
NPSavg
MTF50
d' (5mm)
5% Match
STD/40%
Yes
0.45
40
N/A
0.293
0.412
33.2
No
Current VCT
STD/0
0.3
0.43
35.6
No
Current LS16
STD/0
0.3
0.43
35.6
No
50
Recommended
Flash
45
Definit ion
i40/3
0.265
0.432
40.7
Yes
STD/0
0.3
0.43
35.6
No
STD/0Fla sh
0.3
0.43
35.6
No
35.6
No
35.6
40
Flash
Recommended
VCT
35
750 HD
Definit ion
30
25
Recommended
LS16
VCT
20
750 HD
16
15
ToLSmatch
noise
magnitude of 750HD,
VCT increase ref mAs to 155
10
DIR 75th %
LS 16
5
If STD
DIR 50th%behaves on VCT as on 750HD, , decrease VCT NI to 11.8
0
5
0
25-30cm 30-35cm 35-40cm 40-45cm
(27%)
(51%)
(21%)
(1%)
25
DIR 25th%
30
35
40
45
Patient diameter (cm)
30
25
50
35
30
Definit ion
Definit ion
15
Fla sh
750 HD
10
VCT
5
LS 16
Global Noise Level
20
Global Noise Level
Noise
(Retrospective)
Yes
5.3%
0.261
CTDIvol (mGy)
CTDIvol (mGy)
Radiation Dose
20
Yes
47.9%
B31/0No
40.7
Current
Flash
0.3
0.43
If STD behaves on VCT as on 750HD, , decrease VCT NI to 11.8
25
No
27.4%
No
To match noise magnitude of 750HD, increase ref mAs to 155
30
5% Match
Yes N/A
14.3%No
45
25
Definit ion
20
Fla sh
15
750 HD
10
VCT
5
LS 16
0
0
25
25-30cm
(27%)
30-35cm
(51%)
35-40cm
(21%)
40-45cm
(1%)
30
35
40
45
Patient diameter (cm)
82
Image Quality
(Prospective)
Protocol Report Cards
Recommended LS16
STD/0
0.3
0.43
35.6
No
To match noise magnitude of 750HD, increase ref mAs to 155
If STD behaves on VCT as on 750HD, , decrease VCT NI to 11.8
STANDARD CHEST
5 mm
30
50
P ro to co l name
Scan type
Ro tatio n time
Pitch
Table speed
Beam width
kVp
Slice thickness
A uto mA
mA /NI/mA sref
SFOV
Kernel
Iterative Level
23_ST A N D AR D _CH E ST _WIT H OUT _IV
Target (CT 750HD)
750 HD
25
VCT
Yes
14.3%
No
27.4%
Kernel/IR
NPSavg
STD/40%
0.261
Current Flash
B31/0
0.293
Current VCT
STD/0
0.3
Current LS16
STD/0
0.3
Recommended Flash
i40/3
0.265
Recommended VCT
STD/0
0.3
Recommended LS16
STD/0
0.3
20
15
10
5
0
Yes
5.3%
Yes
5.2%
MTF50
d' (5mm)
5% Match
0.45
40
N/A
33.2
No
25
0.43
35.6
No
40.7
Yes
0.43
35.6
No
0.43
35.6
No
750 HD
VCT
LS 16
Definition
30
25
Fla sh
20
750 HD
15
VCT
10
DIR 50th%
LS 16
0
25
DIR 25th%
30
35
40
45
Patient diameter (cm)
35
To match noise magnitude of 750HD, increase ref mAs to 155
Noise
(Retrospective)
35
5
25-30cm 30-35cm 35-40cm 40-45cm
0.43
No
(27%)
(51%) 35.6 (21%)
(1%)
0.432
40
Flash
DIR 75th %
Yes
47.9%
0.412
45
Definit ion
LS 16
22_FLA SH_P E_CHEST5.1STA NDARD CHEST5.1STA NDARD CHEST5.1STA NDARD CHEST
Helical
Helical
Helical
Helical
0.285
0.4
0.4
0.5
3
1.375
1.375
1.375
404.2
137.5
137.5
55
38.4
40
40
20
120
120
120
120
5
5
5
5
On
On
On
On
150
19.2
16
16
Wedge_2
Bo dy
Bo dy
Bo dy
B 31f
Standard
Standard
Standard
FB P
A SiR 30%
FB P
FB P
CTDIvol (mGy)
Helical
0.5
0.8
61.4
38.4
120
5
On
150
Wedge_3
B 31f
FB P
M atches e-pro to co l
% o f STA NDA RD CHEST exams
Image Quality
(Prospective)
Flash
CTDIvol (mGy)
Definition
Radiation Dose
Protocol Definition
n = 4229 annually
Scan parameter
30
15
10
5
0
25-30cm 30-35cm 35-40cm 40-45cm
(27%)
(51%)
(21%)
(1%)
Flash
750 HD
Flash
40
10
VCT
LS 16
DIR 75th % 5
35
Definit ion
30
20
VCT
750 HD
15
VCT
LS 16
LS 16
5
DIR 25th%
750 HD
Fla sh
25
10
DIR 50th%
0
25
0
30
35
40
30-35cm
(51%)
25
Definition
20
Flash
15
750 HD
10
VCT
5
LS 16
0
45
25
Patient diameter (cm)
25-30cm
(27%)
35
25
35-40cm
(21%)
40-45cm
(1%)
30
35
40
45
Patient diameter (cm)
30
Definit ion
15
Fla sh
750 HD
10
VCT
5
LS 16
Global Noise Level
20
Global Noise Level
Noise
(Retrospective)
45
Global Noise Level
20
Definition
50
15
Definit ion
CTDIvol (mGy)
25
CTDIvol (mGy)
Radiation Dose
30
Global Noise Level
If STD behaves on VCT as on 750HD, , decrease VCT NI to 20
11.8
25
Definit ion
20
Fla sh
15
750 HD
10
VCT
5
LS 16
0
0
25
25-30cm
(27%)
30-35cm
(51%)
35-40cm
(21%)
40-45cm
(1%)
30
35
40
45
Patient diameter (cm)
83
Challenges on the path to MP2.0
•
•
•
•
•
•
•
Cultural inertia
Availability of effective tools
Availability of QA informatics
Lagging guidelines, accreditations, regulations
Lagging certification requirements
Lagging education
Effective model(s) of practice
Conclusions 1
• Clinical Imaging physics is a severely untapped
resource insufficiently integrated into the
patient care process.
• We need a new paradigm to define and enact
how the clinical physicist can engage as an
active, effective, and integral member of the
clinical team.
Medical Physics 2.0
• An existential transition of clinical physics in
face of the new realities of value-based,
evidence-based, personalized medicine.
• Clinical imaging physics expanding beyond
insular models of inspection and acceptance
testing, oriented toward compliance, towards
– Team-based models of operational engagement
– Prospective assurance of effective use
– Retrospective evaluation of clinical performance
Conclusions 3
• Skilled expertise in imaging physics is needed
to understand the nuances of modern imaging
equipment to
–
–
–
–
–
–
–
Ensure quality (with relevant metrology)
Ensure consistency
Define and ensure conformance
Inform effective use, at outset and continually
Optimize quality and safety
Monitor and ensure their continued performance
Enable quantitative and personlized utilization