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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Image guided Adaptive Brachytherapy
for Cervical Cancer
Christian Kirisits
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Acknowledgements
The financial support by the Federal Ministry of Economy, Family
and Youth and the National Foundation for Research, Technology
and Development is gratefully acknowledged.
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
The Department of Radiotherapy at the Medical University of
Vienna received/receives financial and/or equipment support for
research and educational purposes from Nucletron, an Elekta
Company and Varian Medical Systems, Inc.
Christian Kirisits is a consultant to Nucletron, an Elekta Company.
This research was supported by the Austrian Science Fund FWF
grant No L562.
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Point A
2cm2cm
2cm 2cm
2
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Point A / target dose
84 Gy
84 Gy
60 Gy
D90 = 65 Gy EQD2
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
84 Gy
93 Gy
D90 = 75 Gy EQD2
Point A / target dose
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Point A / target dose
84 Gy
84 Gy
84 Gy
D90 = 90 Gy EQD2
~ 500 Gy
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Point A / target dose
79 Gy
84 Gy
84 Gy
D90 = 85 Gy EQD2
~ 500 Gy
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Recommendations
• GYN GEC ESTRO recommendations I (Haie-Meder et al.) - contouring
• GYN GEC ESTRO recommendations II (Pötter et al.) - dose parameters
• GYN GEC ESTRO recommendations III (Hellebust et al.) - reconstruction
• GYN GEC ESTRO recommendations IV (Dimopoulos et al.) - imaging
• ABS recommendations on GYN general (Viswanathan and Thomadsen, ABS
Cervical Cancer Recommendations Committee) -general
• ABS recommendations on GYN HDR (Viswanathan et al.)
• ABS recommendations on GYN PDR (Lee et al.)
• ICRU 38 revision (coordinators: R. Pötter and C. Kirisits,
committee members: B. Erickson, C. Haie-Meder, J. Lindegaard, E. van
Limbergen, J. Rownd, K. Tanderup, B. Thomadsen)
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
DOSE AND VOLUME PARAMETERS FOR
PRESCRIBING, RECORDING, AND REPORTING
TARGET VOLUMES AND ORGANS AT RISK
Target parameters
TRAK, point A
D98, D90, D50 for HR CTV, IR CTV* (*if used for prescription)
D98, D90 for GTV
D98, D90 for PTV (if applicable, only for research!!)
D98?, D50?, D90? for pathological lymph nodes
(state of the art parameters in bold)
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
DVH for target volumes
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
DOSE AND VOLUME PARAMETERS FOR
PRESCRIBING, RECORDING, AND REPORTING
TARGET VOLUMES AND ORGANS AT RISK
OAR parameters
D2cm³, D0.1cm³ for high doses to bladder, rectum,
sigmoid and bowel (if applicable)
Vaginal points at level of vaginal sources
Intermediate dose by e.g. V50Gy, D50, and points and lengths
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits 12
DVH for OAR
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Dose
V
Typical DVH curve for OAR from intracavitary BT
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Dose
V
An increase of TRAK will result in an increase of the dose to the OAR. The shape of the new curve is strechted, the ratio of the two upper points on the DVH curve becomes larger. The impact on the low dose regions is smaller. The same ratio applies. The blue symbols are from the previous figure with lower dose to the OAR. The third point in the low dose region is not needed necessarily to describe the shape.
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Dose
V
The orange curve could be the result of different external beam component or other treatment technique. The shape of the curve is completely changed. All three points on the DVH curve are needed to describe the difference to the two curves shown before.
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Rectum:D2cc 63%
D0.1cc 80%
Typical dose distribution
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Rectum:D2cc 63%
D0.1cc 100%
Optimized only based on limited parameter set
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Standard loading
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Inverse optimizationwithout thinking
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
0.1 cm³
2 cm³
> 5 cm³
Reference Points
Bladder
Rectum
Va
gin
a
Small Bowel
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits 21
upper
mid
lower
ventral
dorsal
right
center
x c
m
Vag
inal le
ng
th
cm
cm
Vaginal dose –
DVH, Dose surface histogram, points, dimensions
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
FROM PLANNING AIMS TO PRESCRIPTION
Traditional concepts:
“when prescribing to a target, the prescription
dose is the planned dose to cover this target as
completely as possible.”
or
prescription to a 100% isodose which is “to
cover” the target volume”
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Need for common terminology according to ICRU
reports on proton treatment and IMRT
• Planning aim dose
� Set of dose and dose/volume constraints for a treatment
• Prescribed dose
� Finally accepted treatment plan (which is assumed to be delivered
to an individual patient)
• Delivered dose
� Actually delivered dose to the individual patient
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Need for common terminology according to ICRU
reports on proton treatment and IMRT
Example:
Previously: 4x7 Gy ~ 84 Gy EQD2 prescribed, D90 was mean 93 Gy
Planning aim was to deliver 4 x 7 Gy ~ 84 Gy, D2cm³ for rectum,
sigmoid < 70 Gy EQD2, bladder < 90 Gy EQD2
Prescribed dose was mean 93 Gy ± 13 Gy (1SD) EQD2 to D90 HR CTV
Delivered dose ? Depending on variations and uncertainties – on
average no systematic deviation from prescribed dose
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
LINKING DVH PARAMETERS TO CLINICAL OUTCOME
for TARGET/TUMOUR
1
Pro
bab
ilit
y o
f lo
ca
l co
ntr
ol
0 10 20 30 5040 90 1007060 80 110 120 130 140
0
0.1
0.2
0.3
0.5
0.4
0.9
0.7
0.6
0.8
D90 (HR CTV)
Entire population (n=141)
Tumours > 5cm (n=76)
Dimopoulos et al. IJROBP 2009, Strahlentherapie 2009
141 patientsFIGO: IB-IVA, median follow-up:51 monthsD90 for the HR-CTV and probability of local control
20% less D90 per fraction ~ 10 Gy less for total dose
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Incid
ence V
RS
> 3
0
10
20
30
40
50
60
70
80
90
100
Dose [Gy]
30 40 50 60 70 80 90 100 110 120 130 140
Incid
en
ce L
EN
T/S
OM
A >
2
0
10
20
30
40
50
60
70
80
90
100
D2ccD1ccD0.1ccDICRU
P. Georg IJROBP 2010
Koom et al. IJROBP 2007
Rectum dose
N=141Clinical
Symptoms
0,00
0,10
0,20
0,30
0,40
0,50
0,60
0,70
0,80
0,90
1,00
1,10
30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
D2cc (Gy)
p
21
N=35Changes visible
with rectoscopy
Georg et al. 2009
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
www.embracestudy.dk
> 650 patients enrolled!
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
82
Mean Values
93 81 85 89 94 90 81 89 91 92 81 94 86
HR CTV D90 by Center Preliminary - 3D QA pending!
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
HR-CTV dose and technique
Median HR CTV volume: 30cc HR CTV >30cc Mean ± SD
HRCTV D90IC 81.9 ± 9.5 Gy
IC/IS 88.2 ± 7.7 Gy
Bladder D2ccIC 79.1 ± 10.3 Gy
IC/IS 78.7 ± 13.4 Gy
Rectum D2ccIC 65.6 ± 8.2 Gy
IC/IS 64.6 ± 6.1 Gy
Sigmoid D2ccIC 64.4 ± 6.4 Gy
IC/IS 63.7 ± 7.6 Gy
Large tumours (>30cc): � IC/IS increases target dose by 6Gy
� OAR doses not increased
Small tumours (≤30cc)� No difference for target or OARs
IC/IS Combination of intracavitaryand interstitial application
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Application technique and
patterns of tumor regression
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
IIIB, 8 cm width, insufficient response (11/99)
no adaptation of application technique
intracavitary approach only
Brachytherapyrecurrence
9 months after treatment
DiagnosisOptimization with
Tandem/ringonly
HR CTVD90: 69 Gy
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Improvement of local control
MRI based brachytherapy Vienna 98-03
Late side effects at 3 years
Total G3/4: 98-03: 7/145; 98-00: 6/73;
[93-97: 14/189] 01-03: 1/72Pötter et al. Radiother Oncol 2007
Depending on treatment period(experience, modification of application)
D90: 81 Gy (98-00) – 90 Gy (01-03)
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Pötter et al. 2011
Current local control rates (Vienna experience)
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Uncertainties?
Where to improve?
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits 35
Example for HDR intracavitary Cervix brachytherapy – per fraction
Category Optimum level Assumptions
Source strength 2% PSDL traceable calibrations
Treatment planning 3% Reference data with the appropriate bin width is used
Medium dosimetric Applicator without shielding and CTVcorrections 1% inside pelvis (concerning for scatter)
Dose delivery including Accurate QA concept for commissioning and registration of applicator constancy checks, especially for sourcegeometry to anatomy 4% positioning and applicator/source path
geometry, appropriate imaging techniques, applicator libraries
Interfraction/Intrafraction For one treatment plan per applicatorchanges 12% insertion but several subsequent fractions –
check for major deviations in subsequent
fractions
Total dosimetric uncertainty 13%
for one single fraction
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits 36
Example for HDR intracavitary Cervix brachytherapy – total dose 4 fractions
Category Optimum level Assumptions
Source strength 2% PSDL traceable calibrations
Treatment planning 3% Reference data with the appropriate bin width is used
Medium dosimetric Applicator without shielding and CTVcorrections 1% inside pelvis (concerning for scatter)
Dose delivery including Accurate QA concept for commissioning and registration of applicator constancy checks, especially for sourcegeometry to anatomy 4% 2% positioning and applicator/source path
geometry, appropriate imaging techniques, applicator libraries
Interfraction/Intrafraction For one treatment plan per applicatorchanges 12% 6% insertion but several subsequent fractions –
Total dosimetric uncertainty 7%for entire BT
1 / √N
1 / √N
We would need interfraction value < 3% to have total uncertainy < 5 %
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Visualization of the “real” source positions in relation to the
outer dimensions and holes of the Vienna ring applicator
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Applicator surface
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Source path
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Applicator + Source path
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Reconstruction
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Reconstruction
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Reconstruction
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Reconstruction
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Reconstruction
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Reconstruction
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Reconstruction
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
MRI for each fraction?
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
3D applicator reconstruction
2nd application: CT
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
2nd application: CT3D applicator reconstruction
Target transfer
Targets from first application MRI
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Target transfer from MRI to CT with applicator as reference system
2nd application: CT
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
2nd application: CT
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
2nd application: CTContouring OAR on CT
Target contours from
1st appliction MRI
OAR contours from
2nd application CT
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
2nd application: CTDose planning and optimization based on copied target and individual OAR
contours. All dose constraints for targets and OAR have to be achieved.
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AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Levels
• X-ray
• CT-based for one application
• CT-based for all applications
• MRI for first, CT for subsequent applications
• MRI for each application
• MRI for each fraction
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Ultrasoundtechnology
AAPM 2012– IGABT for Cervical Carcinoma – C Kirisits
Outlook
• ICRU 38 revision
• EMBRACE studies to increase insight into dose-effect
relationships
• New cost effective methods keeping accuracy reasonable