new developments in proton treatment planning systems daniel … · 2009-05-12 · beam profile...
TRANSCRIPT
New Developments in New Developments in Proton Treatment Planning Systems
Daniel Yeung
Statement of Disclosure
Funded Research & Development:
Philips Medical Systems
IBA
Proton Planning Systemsg y
C i l S t A d i S tCommercial Systems Academic SystemsAnalytical/Semi-Analytical CMS - Xio MGH, HCL
Varian – Eclipse Proton PSIVarian – EyePlan ClatterbridgeOptivus - Odyssey Loma LindaDosigray OrsayDosigray Orsay
Others… Others…* Under Development Philips – Pinnacle* UF*Monte Carlo CMS*, Varian*,… MGH, DKFZ,…
Proton Pencil Beam Algorithmsg
Hong et al, MGH 1996
Szymanowski et al, Institut Curie 2001
Beam Model dosimetry in water inhomogeneity correction g y
• water equivalent thickness (wet) • HU stopping power
Proton Pencil Beam Algorithmg
Beam Model
CAX Depth Dose (DD) broad beam pristine peak sobp
Radial Spread (RS) multi coloumb scatter
• beamline: degrader, nozzle elements (wet only)• compensator: material dependent scattering powerp p g p• patient: wet only
gaussian kernelσ2
total = σ2line + σ2
comp + σ2patientσ total σ line σ comp σ patient
Proton Pencil Beam Algorithmg
Dose CalculationDose Calculation
Dose from a pencil beam
Convolve DD with RS for each pencil Sum dose from all pencils
Bortfeld Model of Pristine Peak
Analytical model of proton BP (up to ~ 200 MeV)• accounts for energy spread • empirical model of nuclear fragmentation (data fitting)empirical model of nuclear fragmentation (data fitting)• numeric depth dose calculation of fitted BP• assumption – range straggling ‘constant’ with depth
Pristine Peak - Analytical Model y
R=9 0 g/cm2R=5 86 g/cm2
R=21.86 g/cm2
R 9.0 g/cmR 5.86 g/cmV 8.0
V 8.1R=19.8 g/cm2
For R > 15 g/cm2,
Range straggling depth
E i B tf ld d l
Eclipse Model Bortfeld Model
Error in Bortfeld model
Pristine Peak – Bortfeld Model
R=19.8 g/cm2
R=28.4 g/cm2
Bortfeld Model Bortfeld - Enhanced
SOBP Calc vs MeasurementCalc vs Measurement
Courtesy R. Slopsema
Beam Profile Calc vs MeasurementCalc vs Measurement
R=15.1 M=10.4
d=5 mm
d=10 cm
Option B5 - R=15.1 g/cm^2, M=10.4 g/cm^2, Air gap = 11.7cm, SSD=220.1, aperture: 15cmx15cm
1
1.11.2
1.3
umbr
a [c
m]
Eclipse convolved - @9.9 cm Measurement (av) - @9.9 cmEclipse convolved - @0.5 cm Measurement (av) - @0.5 cmEclipse convolved - @14.1 cm Measurement (av) - @14.1 cm
0.5
0.6
0.70.80.9
180
% L
ater
al P
enu
d=15 cm 0.3
0.4
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00Air Gap [cm]
20%
-8
Courtesy R. Slopsema
Proton Dose Calc in water is generally accurate!
…ok, what about Clinical Issues?
Physics Clinical
Match & Patch Fields
used to avoid OARs adjacent to target used to avoid OARs adjacent to target partition target into segments (sub-targets)
• sub-targets treated with ‘sub-beams’ • angle sub-beams to avoid OARs
combined with other fields for dose uniformity
Match Fields match fields abutting each other penumbra matching penumbra penumbra matching penumbra
Inf - LAT Sup - RAO
matchline
Patch Fields
th b t t ti l t t thru beam txt partial target residual txt with patch lateral penumbra (t beam) ‘matched’ with distal lateral penumbra (t-beam) matched with distal
falloff (p-beam) LPO beam (inferior) patched with SPO (superior) LPO beam (inferior) patched with SPO (superior)
Lacrimal Gland CarcinomaPTV 50 4PTV 50.4
partition into sup + inf targetsb i t
sup
inf
brainstem
inf
PTV50 4 5 fi ld ith t h & t h
LPO-Inf (spare optics & BS)SPO-patch
PTV50.4: 5 fields with match & patch Target FieldsPTV LAO LPO50%
PTV(Inf) LPO-InfPTV(Sup) LAO-match SPO-patch
Lacrimal Gland CarcinomaPTV50 4 – 5 FieldsPTV50.4 5 Fields
Inf - LPO Sup – LAO match Sup – SPO patch
LPO LAOLPO LAO
Patch Field Selection
Patch Field Angle Selection optimal geometric coverage (G = 230 ) avoid inhomogeneity along path (G = 205 )
Patch line Patch line
Gantry 230 Gantry 205
Patch Field – Beam Angle Selectiong
Gantry 230° Gantry 205°
G=205°
G 230°G=230°
Distal Blockingg
selective pullback of range to spare OARs pullback achieved with added compensator potential pitfalls setup error or motion may nullify sparing ‘simple’ distal blocking may compromise
target coverage b t f h assess robustness of approach
Distal Blockinggadded compensator
distal blockTarget
p
OAR
range pullback
Distal Blockingg
underdose
Whole BS Partial BS
PTV
Whole BS Partial BS
BS
RPO FieldPartial BS
Clinical Tools
I t t Cli i l kflIntegrate Clinical workflow clinical database web-based applications mu model physics qa plan evaluation
quality assurance clinical efficiency & efficacy
Plan/Dvh Evaluation/
Dvh statistics for CTV, PTV, OARs
Courtesy R. Malyapa, C.McKenzie, Z. Li
, ,are extracted manually from plots
RT PACSTPS
Treatment Plans Plan, Dose , ROI Information
Clinical RT-PACSTPS Information Server
Active Forms
SharePointServerPhysics
• Plan• Contouring • DVH
Q/A Forms
Clinicians
• Prescription
Tx Delivery
Electronic Q/A Process:Electronic Q/A Process:Upon export of Upon export of txtx plan to RTplan to RT--PACS, clinical Q/A forms are generated. PACS, clinical Q/A forms are generated. Tx. DeliveryActive forms are sent via email to the personnel on the list . Active forms are sent via email to the personnel on the list . Contents of active forms is stored in a Clinical Information Database.Contents of active forms is stored in a Clinical Information Database.
Courtesy V. Frouhar
Electronic Q/A Process:Electronic Q/A Process:U f l RTU f l RT PACS i li i l Q/APACS i li i l Q/AUpon expert of treatment plan to RTUpon expert of treatment plan to RT--PACS, appropriate clinical Q/A PACS, appropriate clinical Q/A forms are generated. Active forms are sent via email to the personnel forms are generated. Active forms are sent via email to the personnel on the list . Contents of active forms is stored in a Clinical on the list . Contents of active forms is stored in a Clinical Information Database.Information Database.
Integration of Clinical Workflow
Patient Information
R&VHIS
External Connectivity
IGRT LinacTPSPhysics Calc. Clinical
D t M t Machine Data
TPSCT SimPET/MRQuality
Assurance
RXDelivery Setup
Data Management&
Workflow
Clinical I f ti
PhysicianPhysicist
Information DosimetristTherapist
Golden Beam Data
TPS commissioning time consuming share beam data among gantries (institutions)?s a e bea data a o g ga t es ( st tut o s)? golden beam data set accuracy requirements on modeling parameters accuracy requirements on modeling parameters
• pristine depth dose & sobp• effective source size• virtual sad• effective sad
Golden Beam Data
max error in penumbra of ±0.5mm in air, at isocenter
Courtesy R. Slopsema
Golden Beam Data
Summaryy
Analytical Proton Algorithms provide accurate dose Analytical Proton Algorithms provide accurate dose model
Proton specific clinical planning issues requires p p g qvigilance
Dose plan is a snap shot of dose distribution Dose delivered depends on uncertainties in range, setup, organ motion, etc.
Select beams and parameters to minimi e ncertainties Select beams and parameters to minimize uncertainties Tools to integrate clinical workflow are essential Golden beam data looks feasible Golden beam data looks feasible
Thanks!