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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