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1 AAPM’07 New Developments in Radiation Therapy Targeting D.A. Jaffray, Ph.D. Radiation Therapy Physics Princess Margaret Hospital/Ontario Cancer Institute Associate Professor Departments of Radiation Oncology and Medical Biophysics University of Toronto AAPM’07 Learning Objectives • Understand the presence and variety of inter- fraction motion present in radiation therapy. • Develop awareness of novel approaches being proposed to address these issues. AAPM’07 Targeting Uncertainty in RT • Setup Variation – Patient position/geometry differs planning – Commonly inferred by radiography, from skeletal anatomy – Not necessarily indicative of target location • Internal Organ Displacement – Tumor and/or normal tissues are positioned differently relative to the skeleton than they were during planning and simulation • Volume Change and Deformation – Geometry of the tumor and/or normal tissues is different from simulation/planning conditions AAPM’07 Respiration-Induced Motion Normal Breathing Deep Breathing Breath-hold Exhale Breath-hold Inhale
Transcript of Learning Objectives New Developments in … › meetings › amos2 › pdf › 29-7959-51777...1...
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AAPM’07
New Developmentsin RadiationTherapyTargeting
D.A. Jaffray, Ph.D.
RadiationTherapyPhysicsPrincessMargaret Hospital/OntarioCancerInstituteAssociateProfessorDepartmentsof Radiation Oncologyand Medical BiophysicsUniversity of Toronto
AAPM’07
LearningObjectives
• Understandthepresenceandvarietyof inter-fractionmotion presentin radiationtherapy.
• Develop awarenessof novelapproaches beingproposedto address theseissues.
AAPM’07
Targeting Uncertainty in RT• SetupVariation
– Patientposition/geometrydiffersplanning
– Commonly inferredbyradiography,from skeletalanatomy
– Not necessarily indicative oftarget location
• InternalOrgan Displacement
– Tumorand/or normaltissuesarepositioneddifferently relative to theskeletonthan theywere during planning andsimulation
• VolumeChangeandDeformation
– Geometryof thetumorand/or normal tissuesis differentfromsimulation/planningconditions
AAPM’07
Respiration-InducedMotion
NormalBreathing
DeepBreathing
Breath-holdExhale
Breath-holdInhale
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Variability in Respiratory Motion
Courtesy of Sonke, vanHerk et al, NKI
11 CBCT scanswith
retrospective4D CBCTsorting and
reconstruction
AAPM’07
“ Full” Rectum “ Empty” Rectum
Prostate Anatomy: PatientSpecificMobility
AAPM’07
Motion tracessuperimposedon a commonexampleimagefor easeof intercomparison.
“ Full” Rectum “ Empty” Rectum
ProstateAnatomy: PatientSpecific Mobility
AAPM’07
Pro
babi
lity
ofE
xcur
sion
(%)
Time Interval (min)
Excursion > 1 mm
2 mm
4 mm
3 mm
5 mm
7 mm
10 mm
POI= Posterior-Mid Prostate
“ Full” Rectum “ Empty” Rectum
Prostate:Probability of Excursionvs.ElapsedTime
Time Interval (min)
3
AAPM’07
BladderFilling
1 hr cineMR (sagittal, TRUFISP sequence) AAPM’07
BladderWall Velocity
TruFISP Sequence,Siemens1.5T
AAPM’07
Therapy-inducedChanges:Head andNeck
7 weeksof therapywith weekly MR
imaging
Shrinking TargetandNormalStructures
Cancerof the
Cervix:Therapy-inducedChanges
Week1
Week3
Week 2
Week4
SagittalImages
Chan, Dinniwellet al., PMH
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SerialMRI imagesof a 54 year old woman with a FIGO IBadenosquamouscarcinomaof thecervix.
8 Gy 20 Gy
28 Gy 38 Gy
48 Gy
Pre-Tx
Chan, Dinniwell et al., PMH
Dose-dependant VolumeChangesinCancerof theCervix
AAPM’07
4D IGRT andTemporalScalesof Intervention
On-line
Off -lineRe-planningor Adaptation
• Definitely not exclusiveprocesses
• Efficiencyandtechnology wil l drive therelative useof thesescales.
• Needsufficientinformation in theon-lineimagingto indicatetheneedfor off-line re-planning.
• Off-line planningmayrequire additional anddifferentinformation.
Real-time ?
AAPM’07
Sensitive,FrequentImaging
• GreaterContrast to Noise
• HigherSampling Rates
• LessAmbiguousSignals– e.g.Volumetric vs. radiographic vs. fiducials
• Lower AcquisitionPenalty– Time,Dose
AAPM’07
Precise,ResponsiveDelivery
• FasterResponseTimes
• SteeperDoseGradients
• Higher Dose Rates
• Lower Body Doses
• MoreDegreesof Freedom
• Robustness
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AAPM’07
IGRT Technologies
Cyberknife
kV RadiographicUltrasound Portal Imaging Markers
Varian OBI™Elekta Synergy™
TomoTherapyHi-Art™
SiemensPRIMATOM™
kV and MV Cone-beam CTMV CTkV CTAAPM’07
ImplantableSensors• Wireless AC electromagnetic
resonant circuit– No externalleadwires– No internalpowersupply
• Designedfor permanentimplantation
• Implant prior to therapy• Positionedin soft tissuein or near
treatment target• Remainsinactiveuntil energized
by system console• 1.85 mm x 8 mm for initial
prostateapplication
AAPM’07
ImplantableSensors
Beacon ® transp onders are excitedby a pulse of electromagnetic energy
The transpond ers respond with anidentifiable signature allowing the clinicianto determine tumor location and motion –
GPS for the Body ®
AAPM’07
ImplantableSensors:Localization System
Components1. Wireless Transponders
2. Arra y
3. Console
4. Infrared Cameras
5. Tracking Station
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AAPM’07
Examplesof behaviorsobservedin thecontinuoustrackingdata: (a) continuoustarget drift; (b) transient excursion; (c) stabletargetatbaseline;(d) persistentexcursion; (e) high-frequencyexcursions; (f) erratic behavior.Red:vertical,green:longitudinal,blue: lateral,black: vector length.
From Kupelian etal. Int. J. Radiation Oncology Biol. Phys., Vol. 67, No. 4, pp. 1088–1098, AAPM’07
Commentson ImplantableSensors
• Raisesinteresting feedback/interventionquestionsfor thetherapistat theunit.– Beaminterruption
• Are theseexcursionsrelevantinconventionalfractionation? Hypo-fractionation?
• Is therea sub-group of patientsthatsignificantly benefit? E.g.Continuousdrift?
AAPM’07
Exterior view of thesystem.TheO-ring is skewedin thecounterclockwisedirection.
AAPM’07
(a) Thebasicstructureis the O-ring with diameterof about330cm.(b) ThestructurearoundtheX-ray headis shown.The X-rayhead is hiddenbehindthesupportstructure andonly themultileafcollimator (MLC) canbeseen. ThekV X-ray tubesare installed on theboth sidesof theMLC.
(a) Cone beamcomputedtomographyimageof thepelvis for a prostate case.TheX-rayparameterswere120kVp, 200mA, 10 ms,and800mAs. Thetotal monitoring dosewas19.4 mGy. (b) TheconventionalX-raycomputed tomographyimageofthesameareaof thesamepatient.
Kamino et al. IJORBP,2006
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AAPM’07
Commentson MHI Unit
• Imagingfor respiratory motionandadjustablecollimation for compensating.
• Volumetric andfluoroscopicfunctionality.
• Maintained non-coplanarfeatures.
• Largeat 3.3m in diameter
AAPM’07 Courtesy of J. Lagendijk, Utrecht, Netherlands
AAPM’07 Courtesy of J. Lagendijk, Utrecht, Netherlands AAPM’07 Courtesy of J. Lagendijk, Utrecht, Netherlands
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AAPM’07 Courtesy of J. Lagendijk, Utrecht, Netherlands AAPM’07
Commentson UtrechtMR Unit
• LeveragesexistingMR design.• Why choose thehigh (1.5T) field strength?• How do you achieverepair andmaintenancein
1.5T context.• GeneralMR questions:
– Geometric DistortionCorrections(B, chemicalshift ,susceptibility)
– Pre-clearanceof patientsfor MR– Throughput issues– Dosimetrychallenges
AAPM’07 Courtesy of G. Fallone, CrossCancerInstitute,Edmonton, Canada AAPM’07 Courtesy of G. Fallone, CrossCancer Institute, Edmonton, Canada
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AAPM’07 Courtesy of G. Fallone, CrossCancerInstitute,Edmonton, Canada AAPM’07 Courtesy of G. Fallone, CrossCancer Institute, Edmonton, Canada
AAPM’07 Courtesy of G. Fallone, CrossCancerInstitute,Edmonton, Canada AAPM’07
Commentson Edmonton MR-guidedAccelerator
• Sufficient field strengthwith 0.2T?
• Significant SAD in HumanScale:ISL->1/3Drate
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AAPM’07 Courtesyof J. Dempsey AAPM’07 Courtesyof J. Dempsey
AAPM’07
Commentson Viewray Proposal
• Feasibil ity of MR imagingduring RT delivery?– Cobaltis quite.
• How well does 60Co perform?– Doserate,conformality
AAPM’07
Summary• Preciseandaccurateradiationdelivery
continuesto bea challenging task.• Significantadvancesin IGRT havebeen
made in thepast5 years.• Increasedactivi ty in developmentof new
image-guided megavoltagephoton therapysystems.
• Interplaybetweenreal-time,adaptive,andresponseassessmentfeedbackon thesesystemspromises anexcitingfuturefor RT.
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AAPM’07
Acknowledgements
Jim Dempsey,Viewray, Florida
Michel Ghilezan, Wil liamBeaumont Hospital,Michigan
MarcelvanHerk , NKI, Amsterdam
JanJacobSonke, NKI, Amsterdam
B. GinoFallone– CrossCancer Institute,Edmonton
JanLagendijk – UMC, Utrecht
MichaelSharpe– PrincessMargaret Hospital,Toronto
P. Chan- PrincessMargaret Hospital, Toronto
AAPM’07
Copyright ©2005 by theNationalAcademyof Sciences
Moff at, Bradford A. et al. (2005)Proc. Natl. Acad. Sci. USA 102, 5524-5529
ClusterAnalysis:
100%sensitivi ty anda specificity of100%for distinguishingPR patients
from SDandPD patients
Thepredictive values and overallaccuracyfor discriminating PR,SD,andPD patientsat3 weekspost-treatment
initiationwere foundto be 100% for all20 patients.
20 PatientsRT, Chemoor both
Pre-Tx andIntra-Tx CourseMRDiffusion (ApparentDiffusion
Coefficient, ADC)
Persistent Disease StableDisease PartialResponse
Moffat, Bradford A. et al. (2005)Proc. Natl. Acad. Sci. USA 102, 5524-5529
