pre-requisites for volume definition - accuray exchange · 2020. 1. 31. · van elmpt, r&0 2016...
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Pre-requisites for volume definition
Prof Anne Laprie MD PhD
Radiation Oncologist
@anne_laprie
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Disclosure
• Speaker Honoraria : Accuray & Varian
• An honorarium is provided by Accuray for this presentation
• The views expressed in this presentation are those of the presenters and do not necessarily reflect the views or policies of Accuray Incorporated or its subsidiaries. No official endorsement by Accuray Incorporated or any of its subsidiaries of any vendor, products or services contained in this presentation is intended or should be inferred.
Volume definition on imaging
MRI
PET
CBCT
MVCT
CT
4Inspired by Thorwarth PhiRO2019
Tumordelineation
Dose painting
Adaptive radiotherapy
Dose calculation
Motion assessment MRI
PET
CBCT
MVCT
CT
CTImpact of reconstruction for contouring
Large FOV to encompass shoulders in head&neck planification Reconstruction ↘FOV ↗ Definition
CT
MRI
In Treatment position If mask : no standard dedicated head coil
Flexible coils : lower SNR
2D or 3D MRI ?
REGISTRATION CT slices acquired in orthogonal plan2D brain: Bi-commisural→ more uncertainties3D → Voxel by voxel
DISTORSION2D : slice by slice correction
3D : whole volume correction CONTRAST
Better in 2D
MRI geometric fidelityDistorsion linked with the gradients applied
Van der Heide, ctRO 2019
MRI geometric fidelityDistorsion linked with the gradients applied
Van der Heide, ctRO 2019
MRI geometric fidelity
Van der Heide, ctRO 2019
Liney, seminars RO 2014
Choose anatomy or diagnostic ?
Integrated Body coil and flat table top
Better Signal to noise ratio but different position
Diagnostic posterior and anterior coil
Recommendations
Paulson et al, Radiother Oncol 2016
Type of tumor MRI sequences Slices Position Maxdistorsion
Brain T1 gado & FLAIR 3D No consensus 1 mm SBRT2 mm
Head and Neck
Axial T1 gado Fat-Sat
1 mm Treatmentposition
2 mm
Prostate Axial & sag T2 1 mm No consensus 2 mm
Cervix Axial & sag T2 1 mm No consensus 2 mm
MRI
Van der Heide, ctRO 2019
Interest of MRI : seeing structures that you don’t see on CT
More difficult to performRegistration
MRI only workflow ?
PET in treatment for Hodgkin’s diseaseirradiation of involved sites (after response to chemo)
15Metwally et al, IJROBP 2009
Without diagnostic PET coregistration
PET in treatment for Hodgkin’s diseaseirradiation of involved sites (after response to chemo)
16Metwally et al, IJROBP 2009
Without diagnostic PET coregistration
coregistrationWith « in treatmentposition » diagnostic PET
PET in treatment for Hodgkin’s diseaseirradiation of involved sites (after response to chemo)
17Metwally et al, IJROBP 2009
Without diagnostic PET coregistration
coregistrationWith « in treatmentposition » diagnostic PET20 patients
5 experienced radiation oncologists
Significant Diminution of interobserver variations
Significant modification of CTV volumes size
Standard Rigid Registration
• Linked series
• Variable quality of tools
• Checking and modifying the registration
– PET
– rotation : around the cross
Elastic registration
AT PLANNING
• Organ delineation using atlas-based segmentation,
• Deformation-based planning target volume definition,
• Depends on tumor site
• Recent use on most TPS
Rigaud et al, acta oncologica 2019 Esteyrie et al, CTRO 2019
IGRT
• Contour propagation
• Dose calculation on per-treatment imaging.
• Accumulated dose from fraction to fraction in external beam RT both for dose reporting and adaptive RT
Delineation
• Optimal software use – Segmentation tools
– Interpolation tools
Aselmaa et al, J Biomed Inform. 2017
Functional and Metabolic Imaging
• Diffusion MRI
• Perfusion MRI
• MR Spectroscopic imaging
• Geometric and quantification robustness =challenge
• Value for
– esophageal tumors
– pancreatic cancer
– glioblastoma
– High risk regions in Cervical cancer,
– Differentiation of tumor vs non-tumor in prostate
22Liebfarth et al, ctRO 2019
Diffusion MRI
Diffusion MRI
• FLAME phase III randomized trial• Prostate 77 Gy• Tumor 95B Gy • T2 + DCE MRI + DWMRI
23Van Schie et al, R&0 2018
3D MR spectroscopicimaging
• SPECTRO GLIO trial
• Phase III randomized
• 180 Newly diagnosed GBM
• Stupp vs 72 Gy SIB guided by MR spectroscopy
• Clinical data upcoming
• Radiomics study ongoing
Laprie et al, IJROBP 2008, Khalifa et al, Eur J Radiol 2016, Laprie et al, BMC cancer 2019; Tensaouti et al, ESTRO 2019 & 2020
High field MRI ?
• Signal on noise ratio ↗↗↗
• But inhomogeneity ↗↗↗
• better small Field of view FOV →neurooncology
• Sodium and oxygen 17 imaging,
• P31 and C13 Spectroscopy
Knowles et al ctRO 2019Knowles et al, CTRO 2019
DUAL ENERGY CT or DECT
26Van Elmpt, R&0 2016
Metal Artefact Reduction
• MVCT • CT MAR sequences• Dual-Energy CT
Kovacs et al, R&0 2018
• DUAL CT vs. MAR • Both improve
delineation• optimal reconstruction
technique depends on the type of metalimplant
Inspired by Thorwarth PhiRO2019
Tumordelineation
Dose painting
Adaptive radiotherapy
Dose calculation
Motion assessment MRI
PET
CBCT
MVCT
CT
Pre-requisites for volume definition
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Prof Anne Laprie MD PhD
Radiation Oncologist
@anne_laprie