Features of Newly Installed Linac.“Trilogy” at Dr. Ziauddin Hospital

Dept. of Radiation oncology

Overview

Introduction Engineering Working principle Versatility

High Tech. using Trilogy 3DCRT, IMRT, VMAT, IGRT, SRS, Electrons Imaging Modalities

MV imaging KV imaging

Eclipse treatment planning system Planning algorithms

Treatment Delivery process RV mode Online treatment verification

Conclusion Take home message

Trilogy

Tri- means three Power, Precision, Versatility

Power High dose rate, Dose rate gain

Precision Repetition with accuracy Mechanical stability Tight is center alignments

Versatility 3DCRT, IMRT, VMAT, SRS Variety of electrons

All In One, Best In One

Beautiful Engineering

CompactRapid on-board imaging

KV ArmsMV Imaging EPID

ImagingPortal Dosimetry

Portal DosimetryWill discuss

120 MLC leavesVirtual wedges

Enhanced Dynamic WedgesCone Beam CT

Working principle

Same as the most of Linacs. Versatile dose rates

100-600MU/mint Treatment time reduction

1000MU/mint (SRS) Dose Rate stability Rapid Arc

Dose rate Gantry speed Dynamic MLCs

Versatility

In terms Energies Photons

6 and 16 MV, 6MV SRS Electrons

6, 9, 12, 15, 18 and 22 Mev

In terms of treatment Modalities Electrons Photons

IMRT, IGRT, VMAT,SRS Use of gating

3DCRT Forward planning Using asymmetric jaws MLC field shaping Enhanced dynamic wedges

High Tech. using Trilogy

IMRT

Intensity Modulated Radiation Therapy Varying beam intensity

Using dynamic MLCs Concept of inverse planning

DVH formation Dose constraints

Concave shape iso-dose lines Steep dose gradient near OAR

What is the Magic Dynamic MLCs

IMRT optimization window

IMRT pre treatment QA

why? How? MLC fluence Dose fluence Calculated dose matrix

Eclipse Measured Dose matrix

Using EPID Portal dosimetry

External Device 2- D Array Map check

Analysis

IMRT verification using EPID

Portal Dosimetry Creation of verification plan

Predicted dose (calculated dose) Predicted dose matrix

Irradiation at linac Measured dose Measures dose matrix

Comparison Pass or fail Why failure?

Why we are doing all this?

Rapid Arc (VMAT)

Volumetric Modulated Arc Therapy Dynamic Arc Therapy

Dynamic MLCs Variable dose rate Gantry speed variation

Inverse planning Benefits

Time efficient Better conformamity

Drawbacks Needs stringent quality assurance

Optimization is almost same as that of IMRT

Treatment planning system(TPS)

Brain of Radiotherapy Eclipse planning system

Treatment planning algorithms PBC, AAA

Best contouring tools Auto contouring

Insightful Plan Evaluation Plan Revision

Treatment delivery path

CT simulation BB’s placement

TPS Contouring Planning Evaluation Approval RT chart, treatment approval Time planner

Console RV mode up Set up verification Treatment delivery

Treatment console

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Treatment delivery

Treatment console 4DICT, OBI,

Patient mode up,Imaging modalities

KV Imaging, MV imaging cone beam CT

On Board Imaging Plan DRR Vs. Acquired Image

Auto matching Manual matching

Bony land marks External markings

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Cone beam using OBI

Planning CT Vs. Acquired CT images Auto matching Shifting Plan revision

Off line review Matching Shifting Modifications instructions

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OBI

KV source KV detector Set up fields Matching with planed DRRs

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Real-time Position Management (RPM) system

Respiratory gating External cameras Synchronization Threshold Stable dose rate gain

Take Home Message

“Any sufficiently advanced technology is indistinguishable from magic”

Technology Increases Therapeutic Ratio

Team work In union there is strength

Change is something which is permanent