day 3 breast dosimetry - fisica.edu.uymedica.fisica.edu.uy/docs/is/day 3 breast dosimetry.pdf ·...

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Dosimetría en imagenologíade la mamaIoannis 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

OutlineMotivationMotivationCurrent dosimetry modelTomo vs. mammo doseLimitationsLimitations

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LimitationsLimitations Future dosimetry

Why studyWhy study dosimetry in breast imaging?

Tx

breast imaging?

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Tx Tx

Breast Dosimetry

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Average Glandular Dose

Energy deposited by x‐rays in glandular tissueMass of glandular tissue

Tx

What can we measure?

Tx


D Ai K (K) *D = Air Kerma (K) * g c s

Obtained with M t C l

Tx

Monte Carlo simulations

Monte Carlo SimulationsX‐Ray Source Emitted

X RayX‐Ray

Adipose Tissue

s At

tenu

atio

n C

oeffi

cien

t (cm

2 /g)

10-1

100

101

102

103

104

Photoelectric EffectCompton ScatterRayleigh Scatter

Compton Scatter

4e+0

6e+0

8e+0

30

60

90

120

150

Tx

Repeat 1 million times!

X-Ray Energy (keV)

0 20 40 60 80 100

Mas

s

10-3

10-2

0 2e+0 4e+0 6e+0 8e+00

2e+0

02e+04e+06e+08e+00

2e+0

4e+0

6e+0

8e+0

0180

210

240

270

300

330

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Need to define the breast model

Breasts vary in shape

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Breast Shape ‐ CC View

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Standard Breast Shape ‐ CC View

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Boone, Med Phys, 2002; 29(5): 869‐875Dance, PMB, 1980; 25(1): 25‐37

Wu et al, Radiology, 1991; 179: 143‐148

Breast Shape – MLO View

Tx

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Standard Breast Shape ‐MLO View

1.9 * CN

DCND

Tx Sechopoulos et al, Med Phys, 2007; 3(1): 221‐232Sechopoulos et al, JACMP, 2008; 9(4): 161‐171

Glandular Tissue Varies

Tx

Dose variation with vertical positionDose variation with vertical position of glandular tissue:

68‐84%

Tx Boone JM, Radiology, Response to eLetter, 25 October 2000 TxHammerstein et al, Radiology, 1979; 130, 485–491.

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Standard Breast Model ‐ CC View

Tx Dance, PMB, 1990; 35(9): 1211‐1219

Conversion factors ‐ g

Tx Dance (1990 and 2000)

Glandular Density90

100

30

40

50

60

70

80

90

Gla

ndul

arity

(%)

Tx

0

10

20

10 20 30 40 50 60 70 80 90 100 110 120

Compressed breast thickness (mm)

40-4950-64

Dance, PMB, 2000, Vol 45, 3225.

Conversion factors ‐ c


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Conversion factors ‐ s


Mammography:g p y

Tomosynthesis:

MAMMOD Kgcs

Tx

TOMOD Kgcst

Tx Sechopoulos et al, Med Phys, 2007; 3(1): 221‐232 Tx Sechopoulos et al, Med Phys, 2007; 3(1): 221‐232

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Tx Sechopoulos et al, Med Phys, 2007; 3(1): 221‐232 Tx Sechopoulos et al, Med Phys, 2007; 3(1): 221‐232

Conversion factors ‐ t

Tx Dance (2011)

Conversion factors ‐ T

Tx Dance (2011)

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Different model in the USA

Tx Wu et al, Radiology, 1991; 179, 143‐148.

….for both viewsThickness Spectrum MLO View CC View

Glandularity (%) Glandularity (%)1 25 50 75 100 1 25 50 75 100

2 Mo/Mo 25 2.33 2.19 2.05 1.92 1.80 2.59 2.43 2.28 2.13 2.00Mo/Mo 26 2.44 2.29 2.14 2.01 1.89 2.70 2.54 2.38 2.23 2.09Mo/Mo 27 2.53 2.38 2.23 2.10 1.97 2.81 2.64 2.48 2.33 2.18Mo/Rh 27 3.03 2.86 2.69 2.54 2.40 3.34 3.16 2.98 2.81 2.65Mo/Rh 29 3.19 3.02 2.85 2.69 2.54 3.52 3.34 3.15 2.97 2.81Rh/Rh 29 3.24 3.07 2.91 2.76 2.61 3.57 3.39 3.21 3.04 2.88

(cm)p

(Target/Filter/kVp) Glandularity (%) Glandularity (%)

Tx Sechopoulos et al, Med Phys, 2007; 3(1): 221‐232

Rh/Rh 31 3.45 3.28 3.11 2.95 2.80 3.79 3.61 3.42 3.25 3.09Rh/Rh 33 3.62 3.45 3.28 3.12 2.97 3.98 3.80 3.61 3.43 3.27Rh/Rh 35 3.78 3.60 3.43 3.26 3.11 4.15 3.96 3.77 3.59 3.42

3 Mo/Mo 25 1.81 1.65 1.50 1.37 1.25 2.01 1.83 1.66 1.51 1.38Mo/Mo 26 1.90 1.73 1.58 1.44 1.32 2.11 1.92 1.75 1.59 1.46

Tx AAPM TG 223 Report, Med Phys, 2014; 41(9): 091501

Philips MicroDose – Slot Scan

Tx AAPM TG 223 Report, Med Phys, 2014; 41(9): 091501

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Conversion factors ‐ TS

Tx Dance (2011)


D Ai K (K) * tD = Air Kerma (K) * g c s t

Obtained with M t C l

Tx


PhantomPhantom (Prospective)Dosimetry

Tx

y

Cheap phantoms

Tx Feng and Sechopoulos, Radiology, 2012, 263(1): 35‐42

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Dose vs. Breast Thickness


MammographyMean Glandular Dose (mGy)Breast Thickness 14 3% Density 50% DensityBreast Thickness

(cm)14.3% Density 50% Density

2 0.313 0.3765 0.775 1.208 1.66 2.28


TomosynthesisMean Glandular Dose (mGy)Breast Thickness 14 3% Density 50% DensityBreast Thickness


2 0.735 0.6705 1.48 1.308 3.07 2.64


Tomosynthesis / MammoMGD RatioBreast Thickness 14 3% Density 50% DensityBreast Thickness


2 2.34 1.785 1.90 1.088 1.85 1.16


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PMMA

Tx EUREF Guidelines, 4th edition

PMMA to model breast conversionPMMA thickness

(mm)Equivalent breast thickness (mm)

Glandularity of equivalent breast (%)

20 21 97

30 32 67

40 45 41

45 53 29

50 60 20

Tx

50 60 20

60 75 9

70 90 4

80 103 3

EUREF Guidelines, 4th edition

Air Kerma

Tx EUREF Guidelines, 4th edition

Apply the conversion…Mammography:Mammography:

Tomosynthesis:

MAMMOD Kgcs

D K t

Tx

TOMOD Kgcst

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Tx EUREF Guidelines, 4th edition Tx

PatientPatient (Retrospective)Dosimetry

Tx

os et y

DICOM Header

Tx

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System I Ratio DBT/DM:Mean = 1.08 (0.54 – 1.81)

Tx Bouwman et al, Phys. Med. Biol. 60 (2015) 7893Hendrick et al, AJR. 194 (2010) 362

System I Ratio DBT/DM:Mean = 1.08 (0.54 – 1.81)

Tx Bouwman et al, Phys. Med. Biol. 60 (2015) 7893

System II (DBT CC only)7

8

clinical DM

Ratio DBT / DM:Mean = 1.62 (unpaired)

2

3

4

5

6

AGD (m

Gy)

clinical DM

clinical DBT


0

1

0 20 40 60 80 100Breast thickness (mm)

System IV Ratio DBT‐ST / DM:Mean = 1.48 (unpaired)


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System V Ratio DBT / DM:Mean = 0.90 (!) (unpaired)


Mean AGD [mGy]GE SenoClaire EssentialBreast Thickness N Mammo Tomo

All 236 1.62 1.49<40 mm 28 1.13 1.1441‐50 mm 46 1.34 1.3351‐60 mm 74 1.48 1.4161‐70 mm 55 1.82 1.62>70 mm 33 2.39 1.98

Tx 58Paulis et al, Investigative Radiology, online ahead of print

Are these final?

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System III Ratio DBT / DM:Mean = 2.00 (!)

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System III Ratio DBT / DM:Mean = 2.00 (!)

Tx

After software upgrade…

Tx

System III Ratio DBT / DM:Mean = 1.90 (1.51 – 2.74)

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System III Ratio DBT / DM:Mean = 1.90 (1.51 – 2.74)

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AEC settings…

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In addition…

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What is a tomo exam?

Tx

Ratios Dose DBT/DM from Clinical Studies

1‐view DBT vs DM = 0.34 – 1.02‐view DBT vs DM = 0.68 – 1.17

1‐view DBT + DM vs DM = 1.03 – 1.50

Tx

2‐view DBT + DM vs DM = 2.0 – 2.23

Svahn et al, The Breast, 24 (2015) 93‐99

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Synthetic (?)

1‐view DBT vs DM = 0.34 – 1.02‐view DBT vs DM = 0.68 – 1.17

Tx Svahn et al, The Breast, 24 (2015) 93‐99

DBT implementation is still in flux

Tx

DBT + DM ≥ 2*dose of DMDBT + DM ≥ 2*dose of DM(minus reduced recalls!)

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1 DBT alone co ld1v DBT alone could be lower dose

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Developing Technology

Tx

X i f DBTX‐views of DBT + Y‐views of DM

Tx

S th tiSynthetic

Tx

Ratios Dose DBT/DM from Clinical Studies

1‐view DBT (+ Synth) vs DM = 0.34 – 1.02‐view DBT (+ Synth) vs DM = 0.68 – 1.17

1‐view DBT + DM vs DM = 1.03 – 1.502 i DBT DM DM 2 0 2 23

Tx

2‐view DBT + DM vs DM = 2.0 – 2.23

Svahn et al, The Breast, 24 (2015) 93‐99

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Tx

Let’s be happy, dose is/will be low!

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Wait, that’s not it…

Let’s celebrate for the correct reason!

Tx Tx

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Tx Tx

Dance or Wu or Boone?Dance or Wu or Boone?

Tx

Air kerma?Air kerma?

Tx

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Breast density???Breast density???

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Low dose is easyLow dose is easy…

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Phantom Patients?

Tx

Patient to phantom MGD ratio

Tx Bouwman et al, PMB, 60 (2015) 7893

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Not good enough anymore…

Tx Bouwman et al, PMB, 60 (2015) 7893

bCan we be more objective?

Tx

Tx

Standard Breast Shape ‐ CC View

Tx

Boone, Med Phys, 2002; 29(5): 869‐875Dance, PMB, 1980; 25(1): 25‐37

Wu et al, Radiology, 1991; 179: 143‐148

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Standard Breast Shape ‐MLO View

1.9 * CN

DCND

Tx Sechopoulos et al, Med Phys, 2007; 3(1): 221‐232Sechopoulos et al, JACMP, 2008; 9(4): 161‐171 Tx Rodriguez‐Ruiz et al, Medical Physics, in press

Examples…

Tx Rodriguez‐Ruiz et al, Medical Physics, in press

Principal Component Analysis

Tx

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Average distance error


191 ‐> 210 cm2

144 ‐> 155 cm2

Boone 2000: 157 cm2


Tx Rodriguez‐Ruiz et al, Medical Physics, in press Tx Rodriguez‐Ruiz et al, Medical Physics, in press

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How about the 3rd dimension?

Can we

Tx

Can we characterize this?

Acquisition of 3‐D breast shapeCompression

Projector

Camera3‐D scanner

Compression paddle

Tx

Support paddle

Agasthya et al, AAPM 2015

3‐D scanner

Tx Agasthya et al, AAPM 2015

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Tx http://www.david‐3d.com/?section=Gallery Tx Agasthya et al, AAPM 2015

Tx Rodriguez‐Ruiz et al, Radiology, under review Tx Rodriguez‐Ruiz et al, Radiology, under review

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Tx Rodriguez‐Ruiz et al, Radiology, under review Tx Rodriguez‐Ruiz et al, Radiology, under review

Tx Rodriguez‐Ruiz et al, Radiology, under review

3D Model


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3D Model

Tx

Principal component analysis again

Rodriguez‐Ruiz et al, Radiology, under review Tx Rodriguez‐Ruiz et al, Radiology, under review


Breast model


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How about the interior?

Tx

Glandular Density

90

100

30

40

50

60

70

80

90

Gla

ndul

arity

(%)

Tx

0

10

20

10 20 30 40 50 60 70 80 90 100 110 120

Compressed breast thickness (mm)

40-49

50-64

Dance, PMB, 2000, Vol 45, 3225.

Glandular Density

= 14.3 %

Tx Yaffe et al, Med Phys, 2009, Vol 36, 5437

Skin Thickness

= 1.45 mm

Tx Huang et al, Med Phys, 2008, Vol 35, 1199

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The (near) future in breast dosimetry…

Tx

Improved Dosimetry Model

Universal (!)Universal (!)MammographyTomosynthesisContrast enhanced mammo

Tx


CC and MLO viewsCC and MLO viewsSpot and magnification views

Tx


QA/QC – Phantom dosimetryQA/QC Phantom dosimetryPatient model dosimetry

Tx

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Improved Dosimetry ModelAppropriate phantom for AECAppropriate phantom for AECMore accurate breast model No biasSoftware (!)

Tx

Joint AAPM/EFOMP Task

But what do absolute values of AGD mean?

Tx

TxHammerstein et al, Radiology, 1979; 130, 485–491.

Tx

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So…“detailed information will have to be obtained on the amount and distribution of gland tissue in many individual cases” before individual risk estimates can be made.

Hammerstein et al, Radiology, 1979

Tx

Homogeneous breast dose modelGood for relative comparisons of doseTechnique optimizationSystem comparisonModality comparison (?)Quality control

Tx

But of course…A. Berrington de Gonzalez and G. Reeves, “Mammographic screening before age 50 years in the UK: Comparison of the radiation risks with be o e age 50 yea s t e U Co pa so o t e ad at o s s tthe mortality benefits,” Br. J. Cancer 93, 590–596 (2005).A. Berrington de Gonzalez, C. D. Berg, K. Visvanathan, and M. Robson, “Estimated risk of radiation‐induced breast cancer from mammographic screening for young BRCA mutation carriers,” J. Natl. Cancer Inst. 101, 205–209 (2009).R. E. Hendrick, “Radiation doses and cancer risks from breast imaging studies,” Radiology 257, 246–253 (2010).

Tx

M. J. Yaffe and J. G. Mainprize, “Risk of radiation‐induced breast cancer from mammographic screening,” Radiology 258, 98–105 (2011).E. Warner, “Breast‐cancer screening,” N. Engl. J. Med. 365, 1025–1032 (2011).

Tx

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What is the error introduced by the homogeneous tissue approximation in breast

Tx

approximation in breast dosimetry?

Heterogeneous Mammography DgN

Heterogeneous BCT DgN

Patient BCT Tissue Simulated

Monte Carlo Simulation Monte Carlo

Simulation

HomogenizationHomogenization

Imaging Classification Compression

Tx

Homogeneous Mammography

DgNHomogeneous BCT DgN

Monte Carlo Simulation

Monte Carlo Simulation

19 patients

Breast CT

300 projections300 projections10 seconds49 kVp, 16 – 200 mA8 ms0.273 mm voxel size20 patients

Tx

p

Courtesy of Koning Corp.

Automated Tissue Classification

Tx Yang et al, Medical Physics, 2012, 39(10), 6397‐6406.

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Breast CT image

Manual

Automated

Manual

TxDifference

Accuracy of Classification1

0.84

0.88

0.92

0.96

Percen

tage

Gland

Fat

Skin

Tx

0.81 2 3 4 5 6 7 8

Subject

34.4% 12.5% 8.5% 10.7% 11.1% 6.4% 8.9% 31.6%Gland tissue

Mechanical Breast Compression

Tx Zyganitidis et al, Med. Biol. Eng. Comput. 2007, 45, 661‐669.


Tx

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mG

y)

0.3

0.4(a) Mammography

ogen

eous

DgN

(mG

y/m

0.1

0.2

TxHeterogeneous DgN (mGy / mGy)

0.0 0.1 0.2 0.3 0.4

Hom

o

0.0

Sechopoulos et al, Medical Physics, 2012, 39(8), 5050‐5059

gene

ous

DgN

1.8

2.0

2.290th percentile

75th percentilemean

median25th percentile

neou

s D

gN /

Het

erog

1.2

1.4

1.610th percentile

Tx

Mammography BCT 49 kVp BCT 80 kVp

Hom

ogen

0.8

1.0


Model‐based Confirmation (N=219)

Mo anode: −35.3% (SD = 4.1)W anode: −24.2% (SD = 3.0)

Tx Hernandez et al, Medical Physics, 2015, 42(11), 6337

10.3

Tx0.0


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Internal Dose Distribution ‐Mammo

Tx Sechopoulos et al, Medical Physics, 2010; 37(8), 4110.

Internal Dose Distribution ‐ BCT

Tx Sechopoulos et al, Medical Physics, 2010; 37(8), 4110.

Tx

Homogeneous tissue gmixture approximation good enough for QA/QC.

Tx

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Patient‐Specific Breast Dosimetry

Tx


Need a tomosynthesis image classification algorithm

Tx

Representative Classification ‐ Fuji

Tx

Tomography ClassificationGold Standard

Representative Classification ‐ Phillips

Tx

Tomography ClassificationGold Standard

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Classification Validation – Physical phantoms

0 9

1.0 Philips Data Set (n=10)

Fuji Data Set (n=11)

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Performance

Fuji Data Set (n 11)

Siemens Data (n=10)

Tx

0.0

0.1

0.2

DSC Sensitivity Specificity

Evaluations for Glandular Tissue


Tx


Tx


4 j4‐year project funded by the Susan G. Komen Foundation for

Tx

the Cure

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In short…

Tx

Patient dose DBTPatient dose DBT~ 0.9 – 1.8 * DM

Tx

DBT + DM > 2*dose of DMDBT + DM > 2*dose of DM

(minus reduced work‐up dose!)

Tx

But…

Tx

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D l i t h lDeveloping technology

Tx

S th tiSynthetic

Tx

X i DBTX‐view DBT + Y‐view DM

Tx

Current breast dosimetryCurrent breast dosimetry has limitations

Tx

(the future one will too!)

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Remove biasRemove bias

Tx

We don’t estimateWe don t estimate patient dose!!

Tx

(should we?)

Clinical performance!Clinical performance!

Tx

Questions?

Tx

day 3 breast dosimetry - fisica.edu.uymedica.fisica.edu.uy/docs/is/day 3 breast dosimetry.pdf ·...

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