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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Institut für Radiotherapie

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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Institut für Radiotherapie

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)