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4D Radiotherapy1
4D Radiotherapy4D Radiotherapy
Paul KeallPaul KeallVirginia Commonwealth UniversityVirginia Commonwealth University
4D Radiotherapy2
OutlineOutline
Medical rationale Basic science and technology State-of-the-art Future needs, directions and
opportunities Advice …
4D Radiotherapy3
Medical rationaleMedical rationale
What is the purpose of your research?
4D Radiotherapy4
What do we know?What do we know?
Where the ‘visible’ tumor is To within 1 cm (on day of imaging study)
Where the microscopic tumor extends to To within 1 cm
Where the patient’s skeleton is wrt the radiation beam To within 1 cm
What the shape of the tumor is To within 1 cm
Where the tumor is wrt the skeleton To within 2 cm
4D Radiotherapy5
What can we do about it?What can we do about it?
Reduce the uncertainties Improved/functional imaging Ongoing commitment to education Daily 2D/3D imaging Monte Carlo dose calculation/optimization Intrafraction motion
Develop methods to account for residual uncertainties Incorporate uncertainties into planning process Probabilistic planning Online planning
4D Radiotherapy6
Chem
o-response
GI motion
Inter-observer
differences
Tumor growth
Tu
mo
r sh
rin
kag
e
Tumor spread
ReoxygenationR
epair
Repopulation
RedistributionVascular growth
Weight loss
Cardiac motion
Hormone response
Diet
Bladder filling
Rectal fillin
g
Intra-observerdifferences
Skeletal motion
Respiratory motion
Weight gain
Respiratory motion
Why 4D?Why 4D?
4D Radiotherapy7
Respiratory motion affects:Respiratory motion affects:
All tumor sites in the thorax and abdomen
Lung cancer alone: 173 770 new cases in 2004 (ACS) 160 440 deaths (28% of cancer deaths) 15% five-year survival Evidence of tumor dose response 50%/30
month LPFS at 85 Gy (Martel et al) Strong evidence of lung dose response (many
100+ patient studies)
4D Radiotherapy8
Problems of Problems of respiratory motion respiratory motion
in radiotherapyin radiotherapy
4D Radiotherapy9
The tumor moves with time The tumor moves with time
4D Radiotherapy10
Conventional With gated imaging
Distorted images, incorrect Distorted images, incorrect anatomical positions, volumes or anatomical positions, volumes or
shapesshapes
Tumor
Keall et al Aust Phys Eng Sci Med 2002
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PTV
Treatment Planning: Large margins Treatment Planning: Large margins are added to the clinical target are added to the clinical target
volumevolume Increases normal tissue dose
and limits target dose
CTV
Conventional With gating
PTV
CTV
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IMRT Delivery: Interplay between IMRT Delivery: Interplay between anatomy and MLC leaf motion anatomy and MLC leaf motion
leads to motion artifactsleads to motion artifacts
Dos
e
Position
Planned doseDelivered dose
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Basic science and technologyBasic science and technology
What is the underlying scientific/technological basis of your research?
4D Radiotherapy14
“The explicit inclusion of the temporal changes in anatomy during the imaging, planning and delivery of radiotherapy”
4D Radiotherapy PanelASTRO 2003
What is 4D radiotherapy?What is 4D radiotherapy?
4D Radiotherapy15
4D Radiotherapy
4D CT Imaging
4D Treatment Planning
4D Treatment Delivery
Acquisition of a sequence of CT image sets over consecutive phases of a breathing cycle
The explicit inclusion of the temporal changes in
anatomy during the imaging, planning and
delivery of radiotherapy
Designing treatment plans on CT image sets obtained for each phase of the breathing cycle
Continuous delivery of the 4D treatment plans throughout the
breathing cycle
The 4D radiotherapy processThe 4D radiotherapy process
4D Radiotherapy16
4D Radiotherapy I:4D Radiotherapy I:
4D CT Imaging4D CT Imaging
4D Radiotherapy17
4D CT imaging4D CT imaging
4D Radiotherapy18
Vedam et al PMB 2003 48:45-62
8 respiratory phases Peak inhale Early inhale Mid inhale End inhale Peak exhale Early exhale Mid exhale Late exhale
4D CT images4D CT images
4D Radiotherapy19
4D Radiotherapy20
4D Radiotherapy II:4D Radiotherapy II:
4D Planning4D Planning
4D Radiotherapy21
Acquire 4D CT
Define anatomy
Create/adjust treatment plan
Evaluate dose distribution
1
4
3
2
Proceed to treatment6
…
Plan acceptable?No
Yes
Deformable registration …
Automatedplanning…
Deform
able
regis
tratio
n
5
4D Planning Flow Chart4D Planning Flow Chart
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4D PTVs4D PTVs
4D Radiotherapy23
3D BEV 4D BEV
BEVsBEVs
4D Radiotherapy24
3D (solid) vs 4D (dashed) DVHs3D (solid) vs 4D (dashed) DVHs
4D Radiotherapy25
4D Radiotherapy III:4D Radiotherapy III:
4D Delivery4D Delivery
4D Radiotherapy26
4D radiotherapy delivery4D radiotherapy delivery
Linac Controller MLC Workstation
MLC Controller4DC
Tracking Signal
Treatment parameters
Linac Controller MLC Workstation
MLC Controller4DC
Tracking Signal
Treatment parameters
4D Radiotherapy27
MLC leaf motion MLC leaf motion
3D 4D Keall et al PMB 2001 46:1-10
4D Radiotherapy28
MLC leaf motion MLC leaf motion
3D IMRT 4D IMRT
4D Radiotherapy29
Tracking motion perpendicular Tracking motion perpendicular and parallel to the MLC and parallel to the MLC
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Finite response time- Finite response time- need motion predictionneed motion prediction
Linac Controller MLC Workstation
MLC Controller4DC
Tracking Signal
Treatment parameters
Linac Controller MLC Workstation
MLC Controller4DC
Tracking Signal
Treatment parameters
4D Radiotherapy31
Respiratory motion causes problems during the imaging, planning and treatment stages of radiotherapy
Several methods have been proposed to address respiratory motion
4D radiotherapy has some advantages over existing methods
There are still many unanswered questions …
4D radiotherapy summary4D radiotherapy summary
4D Radiotherapy32
State-of-the-artState-of-the-art
How does your research fit into the overall scheme of
medical research?
4D Radiotherapy33
Respiratory motion solutionsRespiratory motion solutions Breath-hold techniques (ABC/DIBH)
Uncomfortable for patients, limited applicability (MSKCC: 7/13 patients)
Increases treatment time (MSKCC: 17 to 33 minutes for conventional RT)
Respiratory gating Residual motion within gating window Increases treatment time Baseline shift
4D Radiotherapy Hardware/Software complexity
4D Radiotherapy34
Future needs, directions and Future needs, directions and opportunitiesopportunities
What is currently limiting your research or what change in
direction do you anticipate in the future?
4D Radiotherapy35
LimitationsLimitations
Ethics/IRB Length of grant review cycles Industry support
We need them unless resource and time unlimited
Why isn’t my project the highest priority?
Distractions
4D Radiotherapy36
DirectionsDirections
Incorporate recent scientific and technical developments
Greater scope More general More scientifically rigorous Integrate with concurrent internal
and external programs
4D Radiotherapy37
OpportunitiesOpportunities
Many problems to solve Many different ways to solve
problems
4D Radiotherapy38
NCI RoadmapNCI Roadmap
A focus on the following initiatives will move the work of NCI through the process of discovery, development, and delivery toward the goal of eliminating suffering and death from cancer by 2015 …
4D Radiotherapy39
AdviceAdvice
4D Radiotherapy40
1999 $4500 VCU faculty grant-in-aid 2001 $20 000 ACS Inst. Research Grant 2002 $1.5 million NCI grant 2003 $400 000 industrial grant 2003 Co-I $1 million NCI grant 2004 Consultant $1 million NCI grant 2004 Co-I STTR …
How did you get started?How did you get started?
4D Radiotherapy41
Why get a grant?Why get a grant?
Promotion Tenure Independence Invitations Staff Resources Travel Intangibles
4D Radiotherapy42
What advice can you give?What advice can you give?
Write early Write often Work hard Work smart Think broadly Good luck
4D Radiotherapy43
And get a great team!And get a great team! Ted Chung Rohini George Sarang Joshi Vijay Kini Radhe Mohan Jeffrey Siebers Sastry Vedam Krishni
Wijesooriya Jeffrey Williamson
ACS NIH MDACC MGH Philips Medical
Systems Standard Imaging UNC Varian Medical Systems
4D Radiotherapy44
Another great team!Another great team!
