Delivery and verification - SASRO
Transcript of Delivery and verification - SASRO
Institut für Radiotherapie
Delivery and verification
Peter Cossmann, PhDHead of Medical PhysicsInstitute for RadiotherapyRadiotherapy Hirslanden AGAarau&Zürich/Switzerland
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Contents
� Historical milestones
� Delivery systems
� LINAC – the workhorse
� Respiration controlled delivery
� Verification approaches
� The use in clinical routine
� Current IGRT approaches
� Clinical Examples
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1895 Discovery of x-rays - called Röntgen-Rays - by W. C. Röntgen
1896 First treatment of a bathing trunk nevus by Prof Freund, Wien
1898 First application of x-rays for the treatment of sk intumors
1914 First full-rotation treatment
1930 Development of the first linear accelerator by R. Wideröe in Zurich
1948 First clinical use of a Betatron (Electron cyclot ron)
1949 First clinical use of a linear accelerator
1952 First use of a cobalt unit
Historical milestones
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1. X-ray unit
2. Cobalt unit
3. Linear accelerator
4. Intraoperative unit
5. Brachytherapy unit
6. Radioactive implants
Delivery approaches
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Siemens Stabilivolt, 1919
Siemens Dermopan, 1967
Philips RT 250, 1953
X-ray units I: First systems
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X-ray units II: Modern systems
Gulmay XStrahl 100 & 300
WoMed T300
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Cobalt unit
MDS NordionTheratronPhoenix(1980)
MDS Nordion TheratronEquinox(2006)
UJP Teragam K01(2003)
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Ring accelerator/CyclotronSiemens Betatron (1956)
BBC Asklepitron (1962)
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Siemens Mevatron, 1974
Varian Clinac, 1978
Linear accelerator
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A modern linear accelerator (LINAC)
Varian Clinac EX
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Intraoperative unit I
Zeiss Intrabeam
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Intraoperative unit II
Accent Xoft
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Bebig Multisource Ir,Co (1991)
Bebig Curietron Cs (1983)
Sauerwein Gammamed Ir (1989)
HDR Afterloading
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A modern HDR afterloading unit
Varian Gammamed Plus
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Radioactive implants
Ruthenium-106
Iodine-125 for Prostate LDR
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4Ergonomic
40.7 Sek. min beam activation time
4High dose rate: up to 1000/Min
4Fast & acurate beam steering
4Optimized movement controls
4Beam/dose stability
4Integrated system
Precision and stability of a LINAC
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Gantryaccelerating section
Modulator standElectronics, Klystron
Analog indicator for collimator rotationcollimator position 0-360E°
Accessory trayElectron appl., blocks and
compensatorCollimator
variable positioning of jaws and MLC
Digital position indicationsshowing gantry parameters/visual control
PVI armRemotely retractable arm
PortalVision KassetteDigital cassette for digital port films
Manual table controlDirect
Patient couch4 axes (3 translation, 1 rotation)
Visible parts of a LINAC
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Table rotation (360°E)IEC scale
Longitudinal (Y)
Lateral (X)
Isozentrum
Gantry rotation (360°E)IEC scale
collimator rotation (360°E)IEC scale
Vertical (Z)
Possible movements of a LINAC
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Components of a LINAC
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Monitor chambers
Energyswitch
Caroussel Electron gun
Beam/Bending Magnet
Real time Beam steering
Standing wave accelerating section
Target
Flattening filters andscatter foils
Asymmetricblades
A look into more detail
Multileaf collimator
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4Digital dose rate control4Highly precise: electrons are injected puls controlled, i.e. only when HF wave is stable.
4Energy switch4Selection between two photon energies.
4Standing wave accelerating section4Electrons are linearly accelerated on a HF wave.4Hollow wave guide, ultra high vacuum. Series of hollow cylinders = cavities.
4Target4Electrons hit target: production of Bremsstrahlung radiation (photons)
4Real-time beam steering4Symmetry and intensity are stabilized.
4Beam/Bending Magnet4Beam bending, energy control.
4Caroussel4Holds flattening filter and scatter foils
4Flattening filter and scatter foils4Broadening of the beam.
4Unvented monitor chambers4Energy-, dose- and symmetry control
4Asymmetric jaws4Field size definition, EDW
Components
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Accelerating section
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Accelerating section with gun and target
Magnetron
Standard head
HF-Generator
Clinac 600 (Single energy-CLINAC)
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Positiv
NegativE Maximum
λ
Time
t1
t3
t2
Vorwärts
Vorwärts
Vorwärts
Rückwärts
Rückwärts
Rückwärts
Standing wave acceleration
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Beam Flatness und Symmetry control
Beam stability control - Underdose- Overdose- Energy per puls
MLC Position control.Beam off, if leaf deviation 1mm from defined position
≈Beam monitoring
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ElektronenQuelle
Elektronen
Photonen
TransversalKorrektur
Target
1.) Energie Detector
2.) Vertikal Abweichung
3.) Transversal Abweichung
4.) Dosis Anzeige am Monitor
5.) Dosis Anzeige am Monitor
<
<
<
<
VerticalKorrektur
1
3
5
4
2
Dose and symmetry control I
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E
B
A
F
G
C
D
H
e
Target
Transversal rechts
Transversal links
Im Strahlengang nach vornegerichtet
Im Strahlengang nach hintengerichtet
Dose and symmetry control II
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41.5cm/sec leaf speed for dynamic treatments
41 cm leaf width at isocenter
42 x 40 leafs = 40 x 40 cm field size
4Add-on completely integrated and verified
Multileaf collimator (MLC)
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Dose distributionMultileaf field
Dose distributionCerrobend block
TransmissionMultileaf field
Transmission Cerrobend block
MLC vs. block
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45 mm leaf width around isocenter for 20 cm
440x40 field, 120 leafs, 80 @ 5 mm & 40 @ 10 mm
4All leafs are additionally backupped by the primary collimator
4All leafs can be moved over the field center (for IRMT).
120-leaf MLC
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Monitor chamber
Collimator bladesY1,Y2
Collimator bladesX1,X2
MLC
Linac with MLC
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2300CD, 5cm, Low ResLINAC: 2300 CDPhoton energy: 6 MVTarget film distance: 100 cmWater depth: 5.0 cmLeaf width: 1.0 cm x 1.0 cm
5.0 mm
9.5 mm
MLC-80 measurements
lower collimator
Multi-Leaf collimator
uppe
r co
llim
ator
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5.0 mm
MLC-120 measurements
LINAC: 2300 EXPhoton energy: 6 MVTarget film distance: 100 cmWater depth: 5.0 cmLeaf width: 0.5 cm x 0.5 cm
uppe
r co
llim
ator
6.0 mm
lower collimator
Multi-Leaf collimator
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4only possible with upper jaws
4same functionality as conventional hard wedges
4integrated and verified
4Similar approach: Siemens Virtual Wedge
Enhanced dynamic wedge (EDW)