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IGRT 3D/4D

Vera Fernandes

Radiographer Senior II

Vera.Fernandes@rmh.nhs.uk

27 Jan 2011

Royal Marsden NHS Foundation Trust Sutton

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CONTENTS

PROBLEMS WITH MOTION

SOLUTIONS

IGRT & ABC LUNG

FUTURE

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3D/4D

THREE-DIMENSIONAL FOUR-DIMENSIONAL

(3D)CT-based

VOLUME

(4D)

MOTION

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3D RT

o Treatment volume is defined on static CT image

Does not precisely define tumour in motion due to respiration

Traditionally:

o Target may move in and out of treatment field

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3D RT

o CT scan time: gratter compared with the time scale of many organ motions

o Patients move and breath

o ear ea s

o Intestine movements

o

Gas

o Variable filling of the rectum and bladder

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o Uncertainties occurring during treatment preparation (Systematic errors)

o Setup error & organ motion on the CT scan

GEOMETRIC UNCERTAINTIES

PROBLEMS

o Equipment calibration errors

o Uncertainties occurring during treatment execution (Random variations)

o Interfraction variations

o Intrafraction variations4D

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PROBLEMS

o Increase PTV to include the target in motion

Expand the PTV to cover the maximum ranges of target motions along all three directions

Treatment planning and dose delivery

Large volume of normal tissue is exposed unnecessarily to high

radiation dose

Limiting total dose and dose / #

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HOW TO MANAGE THE

4th DIMENSION?

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PROBLEMS WITH MOTION

SOLUTIONS

IGRT & ABC LUNG

FUTURE

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SOLUTIONS

o Breath-hold technique

Radiation is delivered with breath-hold

o Tracking technique

Radiation is delivered by tracking the motion of the target

Dynamic Tracking

Real time Tracking

o Gating technique

Gated radiation delivery is based on the selected phase of breathing cycle

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SOLUTIONS

o Breath-hold technique

Radiation is delivered with breath-hold

o Tracking technique

Radiation is delivered by tracking the motion of the target

Dynamic Tracking

Real time Tracking

o Gating technique

Gated radiation delivery is based on the selected phase of breathing cycle

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ACTIVE BREATHINGCOORDINATOR

(ABC)Mouthpiece &

Filter Kit

Single Useonly

Balloon

valve

Transducer balloon Balloon valve cableTransducer turbine

Courtesy of Helen McNair

Breathhold time

Breath holdvolume(Threshold Vol)

Tidal

volume

Trolleyattachment

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TREATMENT

Switch Linac on

Balloon valve closes

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SOLUTIONS

o Breath-hold technique our experience

Radiation is delivered with breath-hold

o Tracking technique

Radiation is delivered by tracking the motion of the target

Dynamic Tracking - e.g. Cyberknife

Real time Tracking e.g. Calypso System

o Gating technique

Gated radiation delivery is based on the selected phase of breathing cycle

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SOLUTIONS

o Breath-hold technique our experience

Radiation is delivered with breath-hold

o Tracking technique

Radiation is delivered by tracking the motion of the target

Dynamic Tracking - e.g. Cyberknife

Real time Tracking e.g. Calypso System

o Gating technique

Gated radiation delivery is based on the selected phase of breathing cycle

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PROBLEMS WITH MOTION

SOLUTIONS

IGRT & ABC LUNG

FUTURE

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INDICATIONS - ABC

Lung

Breast

Liver/Gallbladder

Pancreas

....

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ABC RMH

Developed1997John Wong 2011

October 07

USE OF ABC

CLINICAL PRACTICE

AND

CLINICAL TRIALS

Feb 02

Recruitment

for 2 Studies

Clinical trials

2002Commercial product 2004

Confidence

period

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The reduction in PTV size with ABC resulted in an 1825% relative reduction in

physical lung parameters.

PTV margin reduction has the potential to spare normal lung and allow dose-

escalation if coupled with image-guided RT.

Patient immobilisation is as important as attempts to control tumour motion.

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ABC device can be used throughout radical RT for NSCLC with reproducible intrafractiontumour position

Tumour position shift over time (interfraction variation), and patient setup errors, a

reduction in the size of the PTV margin is nevertheless not possible without

IMAGE GUIDANCE OR IMPROVED SETUP

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HOW TO MANAGE THE

4th DIMENSION?

CONTROL THE TARGET

ELIMINATE INTRAFRACTION MOTION

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CT SCAN

WITH ABCEXPORT IMAGES TPS PLANNING

TRAINING

Prior CT scan

EXPORT IMAGES TO XVIREGISTRATION AND

DEFINITION OF

CLIPBOX

PATIENT SETUP

CONE BEAM

AQCUISITIONMATCHING CORRECTION

TREATMENT

DELIVERY

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WHATS THE ADVANTAGE

OFUSING ABC & CBCT?

IGRT TO REDUCE

INTERFRACTION ERRORS

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SETUP CORRECTIONS

Protocol offline

Day 1

Offlinereview

Week 3 Week 5

Greymatching

Week 2

S + I

Gross error

CorrectionSystematic

error

Week 4 Week 6

TREATMENT

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Figure 2 Comparison of residual errors for different imageFigure 2 Comparison of residual errors for different imageFigure 2 Comparison of residual errors for different imageFigure 2 Comparison of residual errors for different image----guidedguidedguidedguided

correction techniques in treatment of lung tumors.

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VERIFICATION

CBCT & ABC

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VERIFICATIONCBCT & ABC

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VERIFICATION

CBCT

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VERIFICATIONCBCT

CTSCAN

CBCT

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LUNG COLAPSE

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OAR

DAY 1 DAY X

AUTOMATIC MATCHTUMOUR

NEW CENTRE

h l d

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PROBLEMS WITH MOTION

SOLUTIONS

IGRT & ABC LUNG

FUTURE

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FUTURE

Critical structure avoidance

Courtesy of Elekta

The Royal Marsden

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CONCLUSION

o ABC to manage motion reduce intrafraction motion

o IGRT - reduce interfraction motion

o Combined (CBCT & ABC) improve level of confidence and allow more

ambitious trials better clinical outcomes

o Professionals have to update skills to be able to respond to the future

o Dose needed for CBCT is considerable smaller than for EPID

o Future integration of technology (ABC, XVI and LINAC)

The Royal Marsden

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Thank you for listening!

AcknowledgementsHelen McNairSarah Armstrong

All other staff