MR-BASED SIMULATION + MR-GUIDED HIGH INTENSITY …chapter.aapm.org/pennohio/2012FallSymp... · •...
Transcript of MR-BASED SIMULATION + MR-GUIDED HIGH INTENSITY …chapter.aapm.org/pennohio/2012FallSymp... · •...
MR-BASED SIMULATION + MR-GUIDED HIGH INTENSITY FOCUSED ULTRASOUND FOR RADIATION ONCOLOGY
Melanie Traughber, D.Sc.
Conflicts of interest
• I am an employee of Philips Healthcare• I am an MR physicist
“The Role of the Physicist in State of the Art Radiation Therapy and Imaging Techniques”
MR
ˇ
The Radiation Oncology Learning CurveFrom the perspective of an MR physicist
MR can be used outside of Radiology.
“Oncology” is a general term. So is “Medical Physics”.
In RT, “simulation” does not involve MatLab or the Bloch equation.
RT has nothing to do with diagnosis or staging.
The existing MR technology will work for RT.
The existing MR workflow will notwork for RT.
MR should play a bigger role in RT.
MR-guided RTPotential Applications
• MR-only Simulation• Future workflow• Basic components• QA assessment tools
• Cortical bone imaging• Dose calculation• DRR generation
• MR-HIFU• Basic principles• Real-time monitoring • Volumetric heat deposition
• Clinical uses• Uterine Fibroids
• Bone metastases, Liver lesions• Hyperthermia
• Drug Delivery
Streamlined workflow for Therapy Planning with CTand MR
Localization/markingPatient positioning CT scanning
CT
Delineation
Patient positioning MR scanning
MR
TreatmentPatient positioning
Dosimetry DRR creationDelineationFusion
Localization/marking
Workflow for MR-only sim, without CT registration
Treatment
Patient positioning MR scanning
MR
Delineation/segmentation
DRR creationDose calculation
Patient positioning
Density assignment
Quality assurance for geometric deformation
Laser positioning system
Flat table top
Coil solutions for imaging in treatment position
RT software release•Dedicated ExamCards•Travel-to-Scan•QA analysis programs
Basic components of an MR SimulatorMR System dedicated for Radiation Therapy Planning
*Works-in-Progress
Quality Assurance for Radiation OncologyGeometric integrity and laser alignment
Phantom and analysis program• Provides geometric deformation
analysis of imaged phantom• Available on MR console• Dimensions 45 x 35 cm
Laser alignment• Guidance for the operator
throughout procedure • Calibration and alignment protocols
available on MR console
MR-only SimulationMR imaging in treatment position
Courtesy Henry Ford Health Systems, Detroit, USA
Bone imagingCalculation of bone-enhanced images
• Subtraction of IP from TE1
generates complete segemention of cortical bone.
• BE image is anatomically accurate in fine detail.
TE1
IP
BE
Slice 1 Slice 2
Clemente Anatomy, 4th Edition
Spongy bone
Inner table Outer table
Single acquisition UTE-mDIXONSequence specifics
• 3D isotropic acquisition with radial readout• Start FID acquisition on upslope of readout gradient (UTE)• Follow with 2-3 gradient echoes
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Rahmer, et. al. Merging UTE Imaging, Water-Fat Separation, and T2* Mapping in a Single 3D MSK Scan. Abstract #3224, ISMRM 2010.
MR-only SimulationDelineation and segmentation
Improved delineation on MR
Investigational use only
MR auto-segmentation
Courtesy Henry Ford, Detroit, USA
BE water IP OP fat
In collaboration with University Hospitals, Cleveland, USA
Dose calculated on MR images
MR-only SimulationDose calculation and DRR generation
DRRs generated from MR images
In collaboration with Henry Ford Health System, Detroit, USA In collaboration with University Hospitals, Cleveland, USA
MR-only SimulationHow close are we?
• All of the pieces seem to be available• What is still needed?
• Workflow• Proven benefits• Clinical outcomes Localization/mar
king
Workflow for MR-only simulation, without CT registration
Treatment
Patient positioning
MR scanning
MR
Delineation/segmentation DRR creation
Dose calculation
Patient positioning
Density assignment
High Intensity Focused Ultrasound (HIFU)Physical Interaction with tissue
Tissue Ablation/Hyperthermia@ the Focal Spot
Tissue Ablation/Hyperthermia@ the Focal Spot
Vibration of MoleculesVibration of Molecules
Energy AbsorptionEnergy Absorption
Temperature ElevationTemperature Elevation2 x 7 mm Focal spot
UltrasoundUltrasoundTransducer
Tissue
Non-invasive &Precise Treatment
1.2 -1.4 MHzGeometric Gain
Other Localizedeffects
Cavitationand/or
Mechanical Effects
MR-HIFU Paradigm
MR PlanningMR imaging for 3D planning and treatment simulation
HIFU Tissue Ablation or Hyperthermia
Focused ultrasound heats the target non-invasively
MR Therapy ControlSimultaneous MR is used
to guide, monitor, control, and assess HIFU therapy
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Image GuidedTherapy
Real-timeTemperature monitoring
ThermalAblation
Real-timecontrol
Ultrasound TransducerIn Therapy Tabletop
Therapy Console
HIFU Components1) Console2) Tabletop & Trolley3) Electronics Cabinet4) Cabling
Phased Array controlledby 5DOF Robot
MR with integrated HIFU
MR Multi-slice monitoring for Safety6 Simultaneous T monitoring planes
• 3 coronal + 1 sagittal• 1 skin + 1 sacral surface• 1 slice along the beam axis• Every 2.9 sec
Allows Optimal Target heating while monitoring critical Structures
x 6 speed
Courtesy Y. Kim, Samsung MC
Nearfield
Farfield
Focal Plane
Cavitation Detection
Early MR-HIFU Challenges
1) Slow Treatment Speed• Treating large tumors (2 – 20 cm) with
a small HIFU focal spot (mm)• Treatment Times 3-4 hours
2) Ablation Variability • Dependence on tissue properties• Unpredictable lesion sizes & shapes
3) Indication Expansion: Treatment around Scars, Bowel Loops & moving organs
4) Clinical Evidence: RCTs, Trials with Latest Technology
5) Healthcare System: Complex Regulatory, Turf Battles, Which Specialty?
Courtesy Nathan McDannold
Courtesy Y. Kim, Samsung MC, Korea
Volumetric HeatingIncreased Ablation Volume
Cell
Electronic beam steering:
Outwards-movingconcentric circles
4 – 16 mm ØFor details see:M. Köhler et al., Med.Phys. 36 (8),3521, August 2009
Diameter (mm)
Length (mm)
Volume (ml)
4 10 0.1
8 20 0.6
12 30 2.3
16 40 5.4
Real Time FeedbackReliable necrosis volume
Thermal map & Dose map
Real time visualization+ Feedback
T > 65°C* or Dose >240 EM
Stop heating
Reliable necrosis volume
Thermal map Dose map
Threshold
Non-perfused volumeJ. Enholm et al., IEEE Trans.Biomed.Eng. accepted
Reliable necrosis volumeNo a-priori knowledge needed
Simple and robust
* Applies to the border of the cell. Temperatures at the center are higher, especially for larger cells.
Beam Shaping to Avoid Scars & Bowel
Beam Shaping enables selective blocking of part of the ultrasound cone in user-specified region
� Organ Avoidance Region or OAR
Allows ultrasound delivery in the presence of :
� Scars� Umbilicus� Skin folds � Air bubbles on the
skin� Bowel
Umbilicus
OAR
Shaped Beam
MR-HIFU Applications
Ablation• Uterine fibroids (Phase III Trials)• Bone metastases (Phase II Trials)
• Prostate (Phase II starting 8/2012)• Breast tumors (Phase I enrolling)
• Liver & Kidney• Neurology & Cardiac
Conformal Hyperthermia (Translational)
• Radiation & Chemotherapy Sensitization
Local Drug Delivery (Translational)• Temperature or Mechanical Force induced
local drug release
• Partnerships with Pharma to develop novel drugs
Investigational Device in USA
Ablation Innovations in the Clinic: FibroidsAblation on or near a blood vessel
Courtesy: UMC Utrecht, The Netherlands
T1-w CE image post-treatment
T1-w CE image pre-treatment
= Non-Perfused Volume Post-treatment: Large fibroid 84% NPV Complete devascularization of four small fibroids
Ablated Area
T2-w image pre-treatment
Vessel & Perfusion Guided AblationNon-Contrast sequence
• Pre-Treatment perfusion and large vessel visualization (3-5 minute acquisition)
Delay = 1.5s Delay = 1.0s
Smaller Vessels Larger Vessels
Investigational Device in USA
First Oncology Application: Bone Mets Palliation
Palliation of Painful Bone Metastases•HIFU can be used to treat painful Bone Mets
• Pelvis, Sacrum, Scapula, Ribs, long bones• osteolytic & osteoblastic • RT failure or RT naïve
•HIFU is non-ionizing option potentially co-administered during RT of primary tumor
Bone & US/MR Physics•High US absorption in cortical bone
• Allows efficient & safe Tx at lower HIFU power• Potentially limits whole tumor treatment
•Low water content in Bone• Reduces MR SNR for traditional thermometry• T2,T1 approaches can be used to compensate
Pain Relief Mechanisms•Death of periosteal nerves•Tumor necrosis -> reduced mass effect
Courtesy: G. Czarnota, Sunnybrook Medical Center, Toronto, Canada
Planning: Scapula Met in 61F
Treatment: Pain VAS 8�2
Investigational Device in USA
Bone Pain PalliationFemur with Intact Cortical Bone
Low power (20 W)Excellent response: Pain score 8 � 0
Sunnybrook Health Sciences Center/Dr. G. Czarnota
Post TxT2 Imaging
AblationZone
Bone pain therapy – heating of bone surface, ablation of periosteal nerves
Large volume Hyperthermia in vivoMR-HIFU with Temperature Feedback and
Electrical & Robotic HIFU beam steerability allows precise conformal hyperthermia
Large Volume Hyperthermia is feasible• Vx2 tumor in rabbit hind muscle• 5 cm2 cross-sectional area (~ 50 cm3 ellipsoid)
Target Volume
Power/deflection limits
0 5 10 15 2036
37
38
39
40
41
42
43
Sonication Cooldown
Ttarget
Time (min)
Tem
per
atu
re (
°° °°C)
Max
T10
Mean
MinT90
Power and Temperature
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39
°C
30
W
0
MR-HIFU Drug Delivery With Low Temperature Sensitive Liposomes(LTSL) – Hyperthermia Release
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Drug circulates toTumor
Drug extravasates under HIFU Heat & Pressure
Drug released locally byHIFU Heat
Duke U
niversity
Key Benefits: Potentially high dose (10x) of Chemotherapy targeted at tumor sites with reduced systemic toxicity
AddHeat
Drug: ThermDox® (Celsion)
<39<39ooCC >39>39ooCC
Status•In 2008, Philips & Celsion initiated Partnership to develop MR-HIFU + ThermoDox•In July 2012, FDA IND for phase II Bone MR-HIFU + ThermoDox Study•Pre-clinical studies & Regulatory process underway for Pancreas
Towards an Integrated Workflow MR-HIFU+RT
MR with integrated HIFU transducer array
Integrated Planning &
Therapy RT Delivery System
Integrate the two therapies for simultaneous planni ng & time saving while offering inter-fraction imaging f or adaptive therapy as a “side benefit”.
30-60 minutes Hours to days
(CT,PET/CT, MR)
Simulation(CT,PET/CT, MR)
(CBCT, X-Ray)
60 - 90 minutes for Tx & plan adaptation
10 minutes 5-15 minutes
Focal Ablation and/or Hyperthermia
Thank you