CTOS 14.11.08CTOS 14.11.08
Soft Tissue Sarcoma of the Extremity
Comparison of Conformal Post-operative Comparison of Conformal Post-operative Radiotherapy (CRT) and Intensity Modulated Radiotherapy (CRT) and Intensity Modulated
Radiotherapy (IMRT)Radiotherapy (IMRT)
1Joint Department of Physics, Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK2St Luke’s Cancer Centre, Royal Surrey County Hospital, Guildford, Surrey, UK3Department of Radiotherapy, Royal Marsden NHS Foundation Trust, Sutton, Surrey, UK
Young K Lee1, Alexandra J Stewart2, Frank H Saran3
BackgroundBackground
Materials and MethodsMaterials and Methods
ResultsResults
SummarySummary
CRT and IMRT for extremity STSCRT and IMRT for extremity STS
BackgroundBackground
Materials and MethodsMaterials and Methods
ResultsResults
SummarySummary
CRT and IMRT for extremity STSCRT and IMRT for extremity STS
BackgroundBackground
Limb-sparing surgery in combination with focal Limb-sparing surgery in combination with focal radiotherapy - standard of care in patients with radiotherapy - standard of care in patients with intermediate and high grade limb and limb girdle intermediate and high grade limb and limb girdle soft tissue sarcomas (STS)soft tissue sarcomas (STS)
Normal tissue toxicity increases with escalating Normal tissue toxicity increases with escalating total and integral dosetotal and integral dose
Dose prescription limited by organs-at-risk (OAR) Dose prescription limited by organs-at-risk (OAR) surrounding the PTVsurrounding the PTV
AimsAims
To define a reproducible and comparable target To define a reproducible and comparable target volume definition for CT planningvolume definition for CT planning
To define reproducible prospective planning dose To define reproducible prospective planning dose volume constraintsvolume constraints
To assess the ability of inversely-planned IMRT To assess the ability of inversely-planned IMRT plans to minimise the dose to surrounding OARplans to minimise the dose to surrounding OAR
To assess efficacy of ‘simple’ IMRT compared to To assess efficacy of ‘simple’ IMRT compared to ‘complex’ IMRT planning‘complex’ IMRT planning
BackgroundBackground
Materials and MethodsMaterials and Methods
ResultsResults
SummarySummary
CRT and IMRT for extremity STSCRT and IMRT for extremity STS
Patient dataPatient data
TT22 and G and G2/32/3 STS of the thigh (n=10) STS of the thigh (n=10)
No tumours invading boneNo tumours invading bone
Entire surgical scar and all drain sites markedEntire surgical scar and all drain sites marked
Planning CT scan Planning CT scan (GE HiSpeed QX/i, Milwaukee, WI)(GE HiSpeed QX/i, Milwaukee, WI)
• pelvic brim to below kneepelvic brim to below knee
• customised immobilisation customised immobilisation
• slice thickness = 2.5mmslice thickness = 2.5mm
Target volume definitionTarget volume definition
Phase I volumePhase I volume
PTVPTV11 = tumour bed + 5cm SI and 3cm = tumour bed + 5cm SI and 3cm
circumferentially circumferentially
Phase II volumePhase II volume
PTVPTV22 = tumour bed + 2cm isotropically = tumour bed + 2cm isotropically
OAR defined as whole femur, neurovascular OAR defined as whole femur, neurovascular bundle, normal tissue corridor and normal tissue bundle, normal tissue corridor and normal tissue outside PTVoutside PTV11
Planning target volumesPlanning target volumes
PTVPTV11
PTVPTV22
normal tissue outside PTV1PTV1
whole femur
PTV2
tissue corridor
neurovascular bundle
Organ definitionOrgan definition
Radiotherapy planningRadiotherapy planning
Primary planning objective
• PTV dose PTV dose
• femur femur
• skin corridorskin corridor
Other planning objectives
• neurovascular bundle
• soft tissue outside PTV
Dose prescriptionDose prescription
PinnaclePinnacle33 v7.4f (Philips Radiation Oncology v7.4f (Philips Radiation Oncology Systems, Madison, WI)Systems, Madison, WI)
2-phase 3D-CRT2-phase 3D-CRT
• Ph I - 50 Gy/25# (5 weeks)Ph I - 50 Gy/25# (5 weeks)
• Ph II - 16 Gy/8# (1½ weeks)Ph II - 16 Gy/8# (1½ weeks)
IMRT with simultaneous integrated boost (SIB)IMRT with simultaneous integrated boost (SIB)
• Ph I - 50 Gy/25# (5 weeks)Ph I - 50 Gy/25# (5 weeks)
• Ph II - 62.5 Gy/25# (5 weeks) Ph II - 62.5 Gy/25# (5 weeks) ((// = 10 Gy) = 10 Gy)
AnalysisAnalysis
cumulative dose volume histograms (DVH) cumulative dose volume histograms (DVH)
DDmeanmean, D, Dmaxmax, D, Dminmin
Conformity Index (CI)Conformity Index (CI)
Heterogeneity Index (HI)Heterogeneity Index (HI)
BackgroundBackground
Materials and MethodsMaterials and Methods
ResultsResults
SummarySummary
CRT and IMRT for extremity STSCRT and IMRT for extremity STS
Conformal RadiotherapyConformal Radiotherapy2-3 field (simple) IMRT 2-3 field (simple) IMRT 4-5 field IMRT 4-5 field IMRT
conformalconformal 2-3f2-3f 4-5f IMRT4-5f IMRT
sagittal viewsagittal view
conformalconformal 2-3f IMRT2-3f IMRT 4-5f IMRT4-5f IMRT
coronal viewcoronal view
Conformity and HeterogeneityConformity and Heterogeneity
Mean Conformity
Index (range)p-value
Mean Heterogeneity Index (range)
p-value
3DCRT 1.76(1.48-2.47)
1.052 (1.031-1.065)
2/3f IMRT
1.59(1.15-2.67) 0.02
1.045(1.029-1.063) 0.06
4/5f IMRT
1.33(1.08-1.84) 0.0002
1.036(1.027-1.049) 0.001
DVH summaryDVH summary
‘‘Simple’ 2-3f IMRT?Simple’ 2-3f IMRT?
Median number of segmentsMedian number of segments
• 26 (range 13-37) for 2-3f IMRT26 (range 13-37) for 2-3f IMRT
• 36 (range 34-56) for 4-5f IMRT36 (range 34-56) for 4-5f IMRT
Both IMRT plans were more conformal and less Both IMRT plans were more conformal and less heterogeneous than 3D-CRTheterogeneous than 3D-CRT
Both IMRT delivered significantly lower femur VBoth IMRT delivered significantly lower femur V4545
compared to 3D-CRT planscompared to 3D-CRT plans
HOWEVER, 4/5f IMRT resulted in significantly HOWEVER, 4/5f IMRT resulted in significantly lower femur Vlower femur V4545 when compared directly to 2/3f when compared directly to 2/3f
IMRT (p=0.04)IMRT (p=0.04)
BackgroundBackground
Materials and MethodsMaterials and Methods
ResultsResults
SummarySummary
CRT and IMRT for extremity STSCRT and IMRT for extremity STS
SummarySummary
Reproducible, comprehensive planning guidelines Reproducible, comprehensive planning guidelines and dose-volume constraints for 3D planning for and dose-volume constraints for 3D planning for extremity sarcomas devised extremity sarcomas devised
4/5f IMRT plan - lowest clinically relevant doses to 4/5f IMRT plan - lowest clinically relevant doses to OAR whilst delivering conformal doses to PTVOAR whilst delivering conformal doses to PTV
Large primary tumour Large primary tumour
• 4/5f preferable to a 2/3f IMRT approach4/5f preferable to a 2/3f IMRT approach
Small, superficial diseaseSmall, superficial disease
• 3D-CRT may provide adequate treatment without 3D-CRT may provide adequate treatment without added cost and complexityadded cost and complexity
Results from this study may not be directly Results from this study may not be directly translated to all other primary locations of STS of translated to all other primary locations of STS of the extremitythe extremity
IMRT approach should be assessed prospectively IMRT approach should be assessed prospectively with respect to late toxicity within the confines of with respect to late toxicity within the confines of a prospective clinical triala prospective clinical trial
Further workFurther work
Radiotherapy DepartmentRoyal Marsden NHS Foundation Trust
AcknowledgmentAcknowledgment
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