Transcript Diapositiva 1

Image Guided
Radiation Therapy
(IGRT) in prostate
cancer
MªCarmen Pujades
Hospital Universitario La Fe
Fundación Instituto Valenciano de Oncología (FIVO)
Treatment planification in
radiotherapy
Patient
simulation:
CT, RM…
Planning treatment
-Determination of
interest volumes:
GTV, CTV, PTV, OR
-Conformation-beams
Differences in
target position
Treatment
Treatment planification in
radiotherapy
POSITION IN THE CT SCAN
Determines the reference
position of the prostate
throughout the treatment.
POSITION IN THE TREATMENT
In the treatment the prostate
position changes with
respect to the reference
position.
Why may the target be
elsewhere?
■ Mispositioning (interfraction)
■ Organ motion (intrafraction)
■ Shape change (interfraction)
Sources of
uncertainties
May result in absorbed dose in the
volumes of interest and organs at
risk that do not correspond to the
theoretical dose planned.
Immobilization systems
In many cases it is
not enough.
Vacuum cushions
Personalized cushions
Image Guided Radiotherapy
■ How can we know the position of the
target?
IGRT
■ What is IGRT?
IGRT is the use of the image in the actual
treatment room as a tool for tracing and
verification of the tumour volume immediately
before or during treatment.
Image Guided Radiotherapy
■ IGRT Systems:
■Portal Imaging
2D Images
Data volumes
Portal Imaging
CBCT
Exac Trac X-Ray 6D
■CBCT
CT Scanner
Ultrasounds (US)
■CT Scanner
■Exac Trac X-Ray 6D
■Ultrasounds
What has been done until now
in radiotherapy by us?
Prostate
■ Treatment +
verification
■ Oncor
Siemens
Expression:
- aSi portal
imaging
system
Optivue RID
AG9 1000
- MV-CBCT
4 gold seeds implanted
transrectally in the
prostate guided by US
What has been done until now
in radiotherapy by us?
MV-CBCT
■ The fusion of the CBCT with the
planning CT provides the
displacement of the bone estructure.
Portal Imaging
■ EPID + seeds : provides
the displacement of the
prostate.
What has been done until now
in radiotherapy by us?
Prostate
■ EPID with gold seed markers
1 pair of portal images
(Not necessarily orthogonal, separated by more than 30 º)
Determination of the spatial position of
the seeds with a homemade program
What has been done until now
in radiotherapy by us?
Prostate
Before correction
After correction
OPTIMAL TRANSLATION CONNECT CENTERS OF
MASS OF THE SEEDS IN PLANNING AND TREATMENT
LEVEL OF ACTION: 3mm
What has been done until now
in radiotherapy by us?
Distance between seeds
Migration
Prostate volume changes
Prostate deformation
d12
d23
d13
d24
d14
d34
1,2
1,1
d/d TC
1,0
0,9
0,8
0,7
0,6
0,5
0
5
10
15
20
25
30
Fracción
Decrease in distance inter-seed due to organ
shrinkage.
35
What has been done until now
in radiotherapy by us?
■ Statistical analysis :
– 9 patients with prostate cancer
– 145 inter-fraction displacements
mm
MAX



LAT
9.7
-0.7
3.3
3.5
CC
18.1
2.1
6.5
4.6
AP
12.4
1.1
3.7
4.7
16
14
12
10
8
6
4
2
0
ANTERO-POSTERIOR
20
15
Nº
Nº
-1
,0
0
-0
,8
0
-0
,6
0
-0
,4
0
-0
,2
0
0,
00
0,
20
0,
40
0,
60
0,
80
1,
00
(cm)
Random positioning error
CRANEO-CAUDAL
10
5
0
-2
,0
0
-1
,6
0
-1
,2
0
-0
,8
0
-0
,4
0
0,
00
0,
40
0,
80
1,
20
1,
60
2,
00
16
14
12
10
8
6
4
2
0
Standard deviation of the
systematic error
(cm)
-2
,0
0
-1
,6
0
-1
,2
0
-0
,8
0
-0
,4
0
0,
00
0,
40
0,
80
1,
20
1,
60
2,
00
LATERAL
Nº
Systematic position error
(cm)
Conclusion
■ Whatever modality you choose to treat the
prostate:
The proper
treatment requires a
system of IGRT that
allows very accurate
localization.
Thanks!!
“No matter how good is the beam, if the target
is not where we thought”.