x imaging t advancedx-ray tomographic xtmedica.fisica.edu.uy/docs/is/day 2 mammo and tomo.pdf ·...
TRANSCRIPT
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Fundamentos físicos de la mamografía y tomosintesisIoannis Sechopoulos, PhD, DABRAssociate ProfessorAdvanced X‐Ray Tomographic Imaging (AXTI) LaboratoryDepartment of Radiology and Nuclear MedicineRadboud University Medical CenterandDutch Reference Center for Screening (LRCB)Nijmegen the Netherlands
Tx T advancedx-raytomographicimagingx
Nijmegen, the Netherlands BREAST CANCER IMAGING
Tx
BREAST CANCER IMAGING
2
MicrocalcificationsMasses Architectural Dist.
Tx 3 Courtesy of Dr. Carl J. D’Orsi
Clinical Application ‐ Screening
ScreeningScreening
Diagnostic work‐up
Tx
Biopsy
4
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Clinical Application ‐ Concern
Di iDiagnostic work‐up
Tx
Biopsy
5
Mammographic Screening ViewsCranio Caudal (CC) view Medio‐Lateral Oblique (MLO) view
Tx
Tx 7
Mammographic Work‐up ViewsMagnificationMagnificationSpot compressionRollsLateral (90°)
Tx
…
Ultrasound
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BI‐RADS® ‐ Breast Imaging Reporting and Data System
ning
Scree
gnostic
work‐up
Tx 9
Diag THE MAMMOGRAPHY SYSTEM
Tx
THE MAMMOGRAPHY SYSTEM
10
A typical mammography system
Tx © Bushberg, Seibert, Leidholdt and Boone
A typical mammography system
Tx 12 Courtesy GE Medical Systems
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Why a dedicated machine?
Tx
MAMMOGRAPHY SPECTRA
Tx
MAMMOGRAPHY SPECTRA
14
Tx © Bushberg, Seibert, Leidholdt and Boone
What is needed for lower energy?
Lower tube voltage (kVp)Lower tube voltage (kVp)Different target material?Higher tube current‐exposure time product (mAs) (why?)
Higher quantum efficiency (why?)
Tx
Higher quantum efficiency (why?)
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Optimal energies
Monochromatic energy between 15 and 25 keV.
Tx
Drawbacks of using low energy
Tx
Low energy Higher doseLow energy Higher dose
Tx
Low energy Longer exposuresLow energy Longer exposures
Tx
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How?
Tx
Molybdenum
Tx
Molybdenum
Tx
Molybdenum
Melting point: 2896 K
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Rhodium
Tx By Alchemist‐hp (talk) www.pse‐mendelejew.dederivative work: Purpy Pupple (talk) ‐ Own work, CC BY‐SA 3.0 de, https://commons.wikimedia.org/w/index.php?curid=7636785
Rhodium
Tx
Rhodium
Melting point: 2237 K
Tx Tx
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Add filtration
Tx
Inherent tube filtration
Exit port:Exit port: ~0.8 mm Beryllium (Z=4)
No oil
Tx
Ideal choice for added filtration?Ideal choice for added filtration?
Tx
Mo and Rh Linear Attenuation Coefficients
Mo Characteristic Energies
Tx © Bushberg, Seibert, Leidholdt and Boone
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Mo and Rh FilteringMolybdenum Target Rhodium Target
Tx 33
0.030 mm (30 µm) is the thickness of Molybdenum filtration used.0.025 mm (25 µm) is the thickness of Rhodium filtration used.
Target‐Filter MixingRh filters can be used with Mo targets.
Tx
Target‐Filter MixingMo filters can NOT be used with Rh
targets!!targets!!
Tx
TungstenMore bremsstrahlung x‐raysMore bremsstrahlung x rays Z is higherLower exposure times
Tx
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TungstenNo characteristic emissionsNo characteristic emissionsRh, Al, Ag filters used to shape
Tx
W Spectra – Rh Filter
Tx
W Spectra – Al Filter
Tx
HALF VALUE LAYERS
Tx
HALF VALUE LAYERS
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Half Value Layers
Increases:Increases: Z of target Z of filters T b lt
Tx
Tube voltage
Half Value Layers ‐ Examples
Mo/Mo 25 kVp: 0.322 mm AlRh/Rh 35 kVp: 0.509 mm AlW/Rh 35 kVp: 0.575 mm Al
Tx
Tissue HVLE.g. Tissue HVL of 1.5 cm:E.g. Tissue HVL of 1.5 cm:Only half the x‐rays make it through the first 1.5 cm of breast.
After a 6 cm breast (4 HVL), only ~6% of x‐rays exit the breast.
Tx
y FIELD GEOMETRY
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FIELD GEOMETRY
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Why half‐field geometry?
Tx Yaffe et al, Radiology 1995.
Breast positioning and the heel effect
Tx © Bushberg, Seibert, Leidholdt and Boone
BREAST COMPRESSION
Tx
BREAST COMPRESSION
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Why breast compression?Reduce:M tiMotionDoseSuperpositionGeometric unsharpnessX‐ray scatter.
Tx
Pull breast tissueIncrease exposure uniformity
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Scatter Reduction
Tx © Bushberg, Seibert, Leidholdt and Boone
Exposure uniformity
Tx © Bushberg, Seibert, Leidholdt and Boone
Spot compression
Tx © Bushberg, Seibert, Leidholdt and Boone
Spot compression confirms there is no mass…
Tx © Bushberg, Seibert, Leidholdt and Boone
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SPATIAL RESOLUTION
Tx
SPATIAL RESOLUTION
53
Why high resolution?
Tx Courtesy of Dr. Carl J. D’Orsi
What is needed for high resolution?Small focal spotSmall focal spotThin scintillating screensSmall pixels in digital detectorsFast acquisition
Tx
Two Focal Spots
Tx © Bushberg, Seibert, Leidholdt and Boone
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Anode Angle –Effective Focal Spot
Tx 57 © Bushberg, Seibert, Leidholdt and Boone
Scintillating Screen in Screen‐Film Mammography
Screen
Film
Tx
Screen
…so in screen‐film mammography we use only one screen under the film.
Scintillating Screen in Digital Mammography X‐rays
Diffusing scintillations
Tx
CsI:Tl structured scintillator Detector
Microcolumnar CsI(Tl) film with a needle diameter of 3‐5 m.
Tx Courtesy of RMD Inc., Watertown, MA
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MTF Comparison
Tx © Bushberg, Seibert, Leidholdt and Boone
MTF Comparison79 µm (direct)
200 µm (indirect DR)
54 µm (scanning indirect)79 µm (direct)
100 µm (indirect)85 µm (direct)
Tx
µ ( )
Lazzari et al, Medical Physics, 2007.Granfors et al, Medical Physics, 2000.
X RAY SCATTER
Tx
X‐RAY SCATTER
X‐Ray Scatter in MammographyContrast is reduced by:Contrast is reduced by:
0
1CCSPR
Tx
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SPR as a function of compressed breast thickness and breast size
TxSPR doesn’t vary significantly with target/filter combination or tube voltage
© Bushberg, Seibert, Leidholdt and Boone
Mammographic anti‐scatter grids
Tx 66 © Bushberg, Seibert, Leidholdt and Boone
MAGNIFICATION VIEWS
Tx
MAGNIFICATION VIEWS
What changes?0.1 mm focal spot
Tx
No scatter grid
© Bushberg, Seibert, Leidholdt and Boone
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Why no anti‐scatter grid?
Tx © Bushberg, Seibert, Leidholdt and Boone
Focal Spot MTF Comparison
Tx © Bushberg, Seibert, Leidholdt and Boone
ARTIFACTS
Tx
ARTIFACTS
Motion
Tx Ayyala R S et al. Radiographics 2008;28:1999-2008
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Antiperspirant
Tx Ayyala R S et al. Radiographics 2008;28:1999-2008
Ghosting
Tx Ayyala R S et al. Radiographics 2008;28:1999-2008
Collimator misalignment
Tx Ayyala R S et al. Radiographics 2008;28:1999-2008
Underexposure
Tx 76 Ayyala R S et al. Radiographics 2008;28:1999-2008
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Grid Artifact
Tx Ayyala R S et al. Radiographics 2008;28:1999-2008
Detector Line Artifacts
Tx http://www.upstate.edu/radiology/education/rsna/mammography/artifact/
Static
Tx 79
?So?Tx
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Dutch Screening Performance
Cancer Detection Rate0.68%
Tx NETB Monitor 2014
Dutch Screening Performance
< 20 mm:61.2%
Tx NETB Monitor 2014
Dutch Screening Performance
Recall Rate2.54%
Tx NETB Monitor 2014 Tx
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Dutch Screening Performance
Negative Recalls2.6 per positive recall
Tx NETB Monitor 2014
Dutch Screening Performance
Program Sensitivity74.9%
Tx NETB Monitor 2013
Dutch Screening Performance
Cancers Missed1 out of 4
Tx NETB Monitor 2013
Cancer Detection vs. Density14% 22% 30% 39%
86% 78% 70% 61%
30% 39%
Tx
VDG 1 VDG 2 VDG 3 VDG 4Screening Interval
Wanders et al, Breast Cancer Res Treat (2016)
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29% of missed cancers were missed due towere missed due to being “obscured by overlying tissue”
Tx 89 Birdwell et al, Radiology 219, 192‐202 (2001).
We needWe need tomographic i i !
Tx
imaging!
DIGITAL TOMOSYNTHESIS
Tx
DIGITAL TOMOSYNTHESIS
91
Translated X‐ray source
X‐ray beam
Tx 92
Detector
Lesions of Interest
This information is used to reconstruct the volume
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Recall
TxCourtesy of Hologic Inc.
93
Recall
TxCourtesy of Hologic Inc.
CC view .IDC
Tx 95Courtesy of Hologic Inc. Tx 96Courtesy of Hologic Inc.
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BenefitsSimilar to Radiography/Mammographyg p y/ g p ySystemWorkflowInterpretationDose
Tx
…but with some discrimination of vertical position!
97
FFDM System Breast Tomo System
Tx 98
TxCourtesy Joseph Lo (via youtube) Tx
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Tx280 slices 72 slices
Tx
slice 140/280 slice 36/72
Tx
slice 7/14 = 5.46 mm thick slice 36/72
SYSTEM DESIGN
Tx
SYSTEM DESIGN
104
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Translated X‐ray source
X‐ray beam
Tx 105
Detector
Tx 106 Otto Zhou, Applied Nanotechnology Laboratory, UNC at Chapel Hill
Tx 107 Courtesy of Philips Digital Mammography AB TxXcounter AB
108
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Tx 109 Zhang and Yu, Medical Physics, 2010, 37(8), 4186–4192
FURTHER DESIGN CONSIDERATIONS
Tx
FURTHER DESIGN CONSIDERATIONS
110
Acquisition GeometryMammography:
h f1 position, 1 shot, fast
CT:full revolution, 1000 shots, as fast as
possible
Tx
Tomosynthesis:???
111
Design decisions…Detector TypeypDetector MotionX‐Ray Tube MotionCenter of RotationAngular Range Number of Projections
Tx
Number of ProjectionsScan TimeReconstruction Method
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SystemFuji
AMULET Innovality
GE EssentialHologicSelenia
Dimensions
IMS Giotto TOMO
Philips MicroDose
Planmed Nuance Excel
DBT
Siemens MAMMOMAT Inspiration
Detector Motion
Static Static Rotating StaticContinuous Slit
ScanRotating during
exposureStatic
X‐Ray Tube Motion
Continuous Step‐and‐Shoot Continuous Step‐and‐Shoot Continuous Continuous Continuous
Tx Tx Zhao and Zhao, Medical Physics, 35(5), 2008
Tx 115 http://2014.bhpa.eu/wp‐content/uploads/formidable/Marshall_Nicolas.pdf
Total Angular Range ‐ Oblique Incidence
(20 deg)(20 deg)
Tx Acciavatti and Maidment, Medical Physics, 38(11), 2011
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Oblique Incidence – Direct Detectors
Tx 117 Zhao and Zhao, Medical Physics, 35(5), 2008
Oblique Incidence – Indirect Detectors
Tx 118Mainprize et al, Medical Physics, 33(9), 2006
Oblique Incidence
Tx 119
Image Acquisition OptimizationAcquisition parameters:q p
Angular rangeNumber of projection anglesTube voltageTube current‐exposure time productSource to object distance (SOD)
Prior knowledge
Tx
Source to object distance (SOD)Source to imager distance (SID)
120
g
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A priori thoughts:
↑ angular range ↑ vertical resolution
↑ ver cal resolu on↑ # of projections ↓ exposure per proj
Tx
↑ # of projections ↓ exposure per proj.↑ scan me
121 Tx 122Maidment et al, Proceedings of SPIE, 5745, 2005
Artifact Spread Function
s BG
s 0 BG 0
I z -I zASF z =
I z -I z
Tx 123Wu et al, Medical Physics, 31(9), 2004 Tx 124 Hu et al, Medical Physics, 35(12), 2008
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Image Acquisition OptimizationComputer simulated breast volumeComputer simulated breast volume and lesions
63 different acquisition geometries
Tx
In‐plane quality and vertical resolution
125Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207. Tx
Realistic mammogramIdeal 0° projection
126 Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207.
Tx
0° tomosynthesis proj.Acquisition: 13 proj. over 60°
angular range.
127
0° tomosynthesis proj.Acquisition: 41 proj. over 60°
angular range.
Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207. Tx
Central reconstructed sliceAcquisition: 13 proj. over 60°
angular range.
128
Central reconstructed sliceAcquisition: 41 proj. over 60°
angular range.
Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207.
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NR
Nor
mal
ized
CN
Tx 129
(a) Mass
Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207. Tx 130Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207.
Tx 131Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207. Tx 132Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207.
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Tx 133
aSubstantial artifacts due to narrow angular range
Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207.
Summary Metric
Tx 134Sechopoulos and Ghetti, Medical Physics 2009, 36, 1199‐1207.
SystemFuji
AMULET Innovality
GE EssentialHologic Selenia
Dimensions
IMS Giotto TOMO
Philips MicroDose
Planmed Nuance Excel
DBT
Siemens MAMMOMAT Inspiration
Angular Range 15 25 15 40 11 30 50Number of Projections
15 9 15 13 21 15 25
Tx
Does the exposure distribution have to be uniform?
x mAs
x mAs x mAs x mAs
x mAs
X‐ray beam
Tx 137
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How about:x mAs
x mAs y mAs x mAs
x mAs
X‐ray beam y < x ?
y > x ?
Tx 138
Or even:x mAs
x mAsy mAs
x mAsx mAs
X‐ray beam y < x ?
y > x ?
Tx 139
Mammo Tomo Proposal
Tx 140 Nishikawa, Reiser et al, Proceedings of SPIE 6510, 65103C–65108C (2007).
μCa detectability: center projection < single center slicecenter projection < single center slice
of reconstruction
Mass detectability: no statistically significant difference
Tx
no statistically significant difference
Das et al, Medical Physics 2009, 36(6), 2009
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IMS GiottoVariable dose and angles
Tx 142 http://www.tomosynthesis‐giotto.com/3/technical‐specifications
What if??Improved
lx kVp
y kVp x kVp y kVp
x kVp
image quality?Dose reduction?Single‐pass
Tx
contrast enhanced imaging?
ACQUISITION TECHNIQUE
Tx
ACQUISITION TECHNIQUE
144
Tube Voltage SelectionMultiple studies reported higher kV than mammo optimal for tomo
One study reported lower energies beneficial
Ren et al, Proceedings of SPIE 5745, 550–561 (2005).Zhao et al, Proceedings of SPIE 5745, 1272–1281 (2005).Wu et al, Proceedings of SPIE 6142, 61425E (2006)
Tx
One study reported lower energies beneficial
145
Glick and Gong, Proceedings of SPIE 6142, 61421L–61429L (2006).
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Technique and Dosimetric Characterization of a Clinical System
Tx 146
Feng and Sechopoulos, Radiology, 2012; 263(3): 35‐42
Breast
Thickness Filter
Tube
Voltage 1st HVL
(mm Al)Filter
Tube
Voltage
1st HVL
(mm Al)
Tomosynthesis Mammography
(cm)
2
3
4
5
(kVp)
Rh 25 0.453
Rh 26 0.494
Rh 28 0.517
Rh 29 0.551
(kVp)Al)
Al 26 0.441
Al 28 0.476
Al 29 0.490
Al 31 0.541
Tx
6
7
8
Rh 31 0.567
Ag 30 0.586
Ag 32 0.611
147
Al 33 0.572
Al 35 0.600
Al 38 0.660
Feng and Sechopoulos, Radiology, 2012; 263(3): 35‐42
TOMOSYNTHESIS RECONSTRUCTION
Tx
TOMOSYNTHESIS RECONSTRUCTION
148
SystemFuji
AMULET Innovality
GE EssentialHologic Selenia
Dimensions
IMS Giotto TOMO
Philips MicroDose
Planmed Nuance Excel
DBT
Siemens MAMMOMAT Inspiration
Reconstruction Method
Modified FBP
Iterative FBPIterative with Total Variation Regularization
Iterative Iterative FBP
Tx 149
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BACKPROJECTION
Tx
BACKPROJECTION
150
Projection Acquisition
1 1 1 1 1
1 1 1 1 1
1 1 10 1 1
1 1 1 1 1
1 1 1 1 1
Tx
Projection Acquisition
1 1 1 1 1
1 1 1 1 1
1 1 10 1 1
1 1 1 1 1
1 1 1 1 1
Tx
5 5 14 5 5
Projection Acquisition
1 1 1 1 1
1 1 1 1 1
1 1 10 1 1
1 1 1 1 1
1 1 1 1 1
5
5
14
5
5
Tx
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Projection Acquisition5 5 14 5 5
1 1 1 1 1
1 1 1 1 1
1 1 10 1 1
1 1 1 1 1
1 1 1 1 1
5 5 14 5 5
Tx
Projection Acquisition
1 1 1 1 1
1 1 1 1 1
1 1 10 1 1
1 1 1 1 1
1 1 1 1 1
5
5
14
5
5
Tx
Backprojection
5 5 14 5 5
5 5 14 5 5
5 5 14 5 5
5 5 14 5 5
5 5 14 5 5
Tx
5 5 14 5 5
Backprojection
10 10 19 10 10
10 10 19 10 10
19 19 28 19 19
10 10 19 10 10
10 10 19 10 10
5
5
14
5
5
Tx
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Backprojection5 5 14 5 5
15 15 33 15 15
15 15 33 15 15
24 24 42 24 24
15 15 33 15 15
15 15 33 15 15
Tx
Backprojection
20 20 38 20 20
20 20 38 20 20
38 38 56 38 38
20 20 38 20 20
20 20 38 20 20
5
5
14
5
5
Tx
BackprojectionDividing all pixels by 4 to compute the average
5 5 9.5 5 5
5 5 9.5 5 5
9.5 9.5 14 9.5 9.5
5 5 9.5 5 5
5 5 9.5 5 5
Tx
Acquisition
Tx
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Backprojection
Tx
Backprojection
TxTomosynthesis
Backprojection
TxCT
Backprojection
Tx 165
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FILTERED BACKPROJECTION
Tx
FILTERED BACKPROJECTION
166
1/r Blurring
Tx © Bushberg, Seibert, Leidholdt and Boone
Filtered Backprojection
Tx 168 © Bushberg, Seibert, Leidholdt and Boone
Filtered Backprojection
Tx 169 © Bushberg, Seibert, Leidholdt and Boone
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Tx © Bushberg, Seibert, Leidholdt and Boone
(really) Filtered Back ProjectionHfilter (ωy, ωz) = Hspectrum(ωy) ⋅ Hprofile(ωz) ⋅ Hinverse(ωy, ωz)filter y z spectrum y profile z inverse y z
Hspectrum(ωy): Hanning filter to control noise
Tx
Hinverse(ωy, ωz): Ramp‐type filter
Hprofile(ωz): Slice profile filter for constant depth resolution
Mertelmeier et al, SPIE 6142, 61420F (2006)
Tx Mertelmeier et al, SPIE 6142, 61420F (2006) Tx 173Mertelmeier et al, SPIE 6142, 61420F (2006)
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Tx Zhou et al, Medical Physics, Vol. 34, No. 3, March 2007
FBP w/ramp only + Hanning & thickness filter + Hanning & thickness filter 2
Tx Zhou et al, Medical Physics, Vol. 34, No. 3, March 2007
+ modified ramp SBP Iterative
ITERATIVE RECONSTRUCTION
Tx
ITERATIVE RECONSTRUCTION
Guess the reconstructed
volumeAdjust guess
1
iv vp p
pi i
l E Y
Simulate the projections that would result from the guessed volume
N=N0e‐ΣµTAcquired projections
v v
vpp
l R E
Tx177
Simulated projections of guessed volume
Compare
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Other Reconstruction MethodsSIRTSARTARTMLEM
Tx
TVR
178 Tx 179 Van de Sompel et al, Medical Image Analysis 2011, 15, 53–70
Comparison of ReconstructionsOptimal acquisition might differ forOptimal acquisition might differ for different recons
Challenging for a single group to implement and optimize all recons
Tx
implement and optimize all recons
Most appropriate metric(s)?
2.5
3.0
3.5
0.05
0.06
m‐1)
W/Al 32 kVp
W/Al 32 kVp + 6 cm of breast tissue
µ Breast Tissue (cm^‐1)µ = 25.2 keV
1.0
1.5
2.0
0.02
0.03
0.04
Line
ar Atten
uation
Coe
fficient (cm
Normalized
Spe
ctrum
µ = 21.7 keV
Tx
0.0
0.5
0.00
0.01
0 5 10 15 20 25 30 35 40
X‐Ray Energy (keV)
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Homogeneous Phantom + MassesFBP MLEM Spectral
0% 80%
60% 40% 20%
0% 80%
60% 40% 20%
0% 80%
60% 40% 20%
Tx 182
100% 100% 100%
10
12
14
Spectral
MLEM
FBP
2
4
6
8
SDNR
FBP
Tx
‐2
0
2
0 20 40 60 80 100
Lesion Glandular Density (%)
Homogeneous Phantom + Microcalcifications
FBP Spectral
Tx 184
Homogeneous Phantom + Microcalcifications
FBP Spectral
Tx 185
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Dual Spectrum Single Pass Tomo
AEC kVp
49 kVp + Cu AEC kVp 49 kVp + Cu
AEC kVp
Tx Sechopoulos et al, European Congress of Radiology, 2015
8 cm Homogeneous Phantom + Masses
AEC (38 kVp, 84 mAs) AEC + 49 kVp/0.254 mm Cu
Tx 187 Sechopoulos et al, European Congress of Radiology, 2015
p = 0.412826
Tx Sechopoulos et al, European Congress of Radiology, 2015
p = 0.232631
Tx Sechopoulos et al, European Congress of Radiology, 2015
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8 cm Homogeneous Phantom + MassesAEC (38 kVp, 84 mAs) AEC + 49 kVp/0.254 mm Cu
80% 40%
20%
100%
80% 40%
20%
100%
AGD = 1.43 mGy AGD = 1.03 mGy
Tx 190
0%60%
0%60%
Sechopoulos et al, European Congress of Radiology, 2015
ResultsThickness SDNR Difference Dose
5 cm ‐16.0 ± 9.25% (p>0.08)
‐48%
8 cm ‐3.2 ± 19.9% (p>0.41)
‐28%
Tx Sechopoulos et al, European Congress of Radiology, 2015
BREAST COMPRESSION
Tx
BREAST COMPRESSION
192
Why compress the breast?Reduce:Tissue superpositionX‐ray scatterMotionGeometric distortionRadiation dose
Tx
Increase: Tissue coverageImage homogeneity
193
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Monte Carlo study with phantomsDetectability of lesions at full andDetectability of lesions at full and reduced compression
Various conditions: iso‐dose, iso‐SNR, iso mAs
Tx
iso‐mAs
194Saunders et al, Radiology, 251(3), 2009 Tx 195 Saunders et al, Radiology, 251(3), 2009
Assumed iso‐dose and:4 cm 4.5 cm6 cm 6.75 cm
Patient Study (N = 46)Mean Breast
Thickness (mm)Range (mm)
Thickness (mm)Full compression 45.4 23‐83Half compression 51.3 28‐92
Tx Fornvik et al, Radiation Protection Dosimetry (2010), Vol. 139, No. 1–3, pp. 118–123
Full Compression Rated Superior
Tx 197
glandular tissue and fibrous strands (n=15)
Fornvik et al, Radiation Protection Dosimetry (2010), Vol. 139, No. 1–3, pp. 118–123
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Patient Study at EmoryBreast thicknessBreast thicknessTissue coverageCompression forcePerceived pain
Tx Agasthya et al, AJR, in press
P 1Part 1
Tx 199
Tx 200Agasthya et al, AJR, in press Tx 201Agasthya et al, AJR, in press
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Tx 202Agasthya et al, AJR, in press
P 2Part 2
Tx 203
Tx 204Agasthya et al, AJR, in press Tx 205Agasthya et al, AJR, in press
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Tx 206Agasthya et al, AJR, in press
MLO Tomosynthesis
Blurring Tissue Coverage
Yes with Yes with MLO Tomosynthesis images No
Blurringadequate
diagnostic quality
poor diagnostic
quality
Adequate Inadequate
Radiologist 1
SC 22 21 8 47 4RC 18 26 7 49 2
Radiologist 2
SC 20 20 11 32 19RC 22 19 10 32 19
Tx
Radiologist 3
SC 14 24 13 48 3RC 8 23 20 47 4
Agasthya et al, AJR, in press
Tx
TOMOSYNTHESIS ARTIFACTS
Tx
TOMOSYNTHESIS ARTIFACTS
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High contrast off‐plane objects introduce artifacts
“Voting” strategy to identify projections inidentify projections in which appropriate information is included, others ignored
Especially important for acquisitions with low
Tx 210 Wu et al, Medical Physics. 33(7), 2461–2471 (2006).
acquisitions with low number of projections
Breast tissue
Breast tissue outside reconstructed volume but that contributes to
attenuation
Tx 211
Breast tissue outside wide projection FOV
Reconstructed volume
Sechopoulos, Medical Physics, Vol. 40, No. 1, 2013
“Mask” to reconstruct only inside the breastonly inside the breast
Faster reconstruction
Avoids artifacts outside breast
Tx 212Zhang et al, Med. Phys. 34(9), 3603–3613 (2007) Tx 213 Zhang et al, J. Comput. Assist. Tomogr. 33(3), 426–435 (2009).
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Uncorrected Previous Improved
Tx 214 Lu et al, Proceedings of the 11th IWDM 2012, pp. 745–752.
Improved estimation of x‐ray path length in tissue outside field of view
SYNTHETIC MAMMOGRAMS
Tx
SYNTHETIC MAMMOGRAMS
215
What is a iscreening
mammographic
Tx
exam?216
What is a iscreening
tomosynthesis
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exam?217
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Mammogram Orig. Synthetic Tomo Slice
Tx 218 Gur et al, Academic Radiology, Vol 19, No 2, 2012
Recall Rates
DBT + FFDM DBT + SyntheticNegativeor Benign
High Risk or Malignant
Negativeor Benign
High Risk or Malignant
Average 29.8 82.6 29.7 77.2
Tx 219Gur et al, Academic Radiology, Vol 19, No 2, 2012
DBT + Improved (current) synthetic (3Ds) vs. FFDM
Tx 220 Hologic Selenia Dimensions FDA Executive Summary September 2012
Recall RatesDBT + FFDM DBT + Synthetic
False Positive Rate
% Detected Cancers
False Positive Rate
% Detected Cancers
1st Generation 53.1 83.5 46.1 77.7
2nd Generation 45.6 87.3 45.2 85.5
Tx 221Skaane et al, Radiology, Vol 271(3), 2014
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Synthetic MammogramsCurrent synthetic 2D image can replaceCurrent synthetic 2D image can replace FFDM in combination with DBT
Included in various commercial systems
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systems
222
CLINICAL PERFORMANCE
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CLINICAL PERFORMANCE
(Some) Screening Trials
i l N C ll ∆Trial N Cancer DetRate ∆
Recall Rate ∆
STORM‐2 9,672 DM: +35%Synth: +40%
DM: +16%Synth: +30%
OSLO 25,547 +30% ‐13%
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MALMÖ 14,848 +30% +43%
Remaining questions in DBT
Patient throughput
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Remaining questions in DBT
Reconstruction time
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Remaining questions in DBT
Reading time
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Remaining questions in DBT
DM + DBT or DBT (+ synth) alone?
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Remaining questions in DBT
How many views?
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Remaining questions in DBT
Synthetic 2D or DM?
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Remaining questions in DBT
What after a tomo screen?
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Current ResearchCADe and CADx for tomosynthesisy
Need to lower reading timeContrast enhanced tomosynthesisPhase contrast tomosynthesisTomosynthesis elastography
Tx 232
Multimodality ImagingTomosynthesisTomosynthesis
+ US+ SPECT+ Electrical Impedance+ Optical
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+ Optical
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