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Image Guided Image Guided Radiation TherapyRadiation Therapy (IGRT) in prostate (IGRT) in prostate
cancercancer
MªCarmen PujadesHospital Universitario La Fe
Fundación Instituto Valenciano de Oncología (FIVO)
Treatment planification in Treatment planification in radiotherapyradiotherapy
Patient simulation: CT, RM…
Planning treatment -Determination of interest volumes: GTV, CTV, PTV, OR
-Conformation-beams
Treatment
Differences in target position
Treatment planification in Treatment planification in radiotherapyradiotherapy
POSITION IN THE CT SCAN POSITION IN THE TREATMENT
In the treatment the prostate position changes with respect to the reference position.
Determines the reference position of the prostate throughout the treatment.
Why may the target be Why may the target be elsewhere?elsewhere?
■ Mispositioning (interfraction)Mispositioning (interfraction)
■ Organ motion (intrafraction)Organ motion (intrafraction)
■ Shape change (interfraction)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 systemsImmobilization systems
In many cases it is not enough.
Personalized cushionsPersonalized cushions
Vacuum cushions
Image Guided RadiotherapyImage Guided Radiotherapy
■ How can we know the position of the target?
IGRT is the use of the image in the actual IGRT is the use of the image in the actual treatment room as a tool for tracing and treatment room as a tool for tracing and verification of the tumour volume immediately verification of the tumour volume immediately before or during treatment.before or during treatment.
■ What is IGRT?
IGRT
Image Guided RadiotherapyImage Guided Radiotherapy
■Portal Imaging
■Exac Trac X-Ray 6D
■CBCT
■CT Scanner
2D Images Data volumesPortal Imaging CBCT
Exac Trac X-Ray 6DCT Scanner
Ultrasounds (US)
■Ultrasounds
■ IGRT Systems:
What has been done until nowWhat has been done until now in radiotherapy by us? in radiotherapy by us?
Prostate
4 gold seeds implanted transrectally in the prostate guided by US
■ Treatment + verification
■ Oncor Siemens Expression:- aSi portal
imaging system Optivue RID AG9 1000
- MV-CBCT
What has been done until nowWhat has been done until now in radiotherapy by us? in radiotherapy by us?
■ The fusion of the CBCT with the planning CT provides the displacement of the bone estructure.
MV-CBCT Portal Imaging
■ EPID + seeds : provides the displacement of the prostate.
What has been done until nowWhat has been done until now in radiotherapy by us? in radiotherapy by us?
■ EPID with gold seed markersEPID with gold seed markersProstate
Determination of the spatial position of the seeds with a homemade program
1 pair of portal images(Not necessarily orthogonal, separated by more than 30 º)
What has been done until nowWhat has been done until now in radiotherapy by us? in radiotherapy by us?
LEVEL OF ACTION: 3mm
Prostate
OPTIMAL TRANSLATION CONNECT CENTERS OF MASS OF THE SEEDS IN PLANNING AND TREATMENT
Before correction After correction
What has been done until nowWhat has been done until now in radiotherapy by us? in radiotherapy by us?
Migration Prostate volume changes Prostate deformation
Distance between seeds
0,5
0,6
0,7
0,8
0,9
1,0
1,1
1,2
0 5 10 15 20 25 30 35
Fracción
d/d
TC
d12 d13 d14d23 d24 d34
Decrease in distance inter-seed due to organ shrinkage.
What has been done until nowWhat has been done until now in radiotherapy by us? in radiotherapy by us?
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
LATERAL
0246810121416
(cm)
Nº
CRANEO-CAUDAL
0246810121416
(cm)
Nº
ANTERO-POSTERIOR
0
5
10
15
20
(cm)
Nº
■ Statistical analysis :– 9 patients with prostate cancer– 145 inter-fraction displacements
Systematic position error
Standard deviation of the systematic error
Random positioning error
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”.