radiotherapy physics and equipment · 2017. 10. 8. · radiotherapy physics and equipment...
TRANSCRIPT
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Vision :IMC aspires to be a leader in applied medical sciences, health care education and research.
Dr. Mohammed EMAMPh.D., Paris-Sud 11 University
RAD 481
Radiotherapy Physics and Equipment
Lecture’s Title: Beam Directed Radiotherapy: Principles and practice
Radiological Sciences Department
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DEFINITION
Beam directed
radiotherapy
Advance Planning
Beam Directing
devices
Exact
Calculations
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NEED FOR BEAM DIRECTION
Homogenous Tumor Dose Low normal tissue dose
Best therapeutic ratio
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STEPSPositioning
Immobilization
Localization
Field SelectionDose distribution
Calculations
Verification
Execution
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POSITIONING
Patient positioning is the most vital and often the most NEGLECTED part of beam direction:
Good patient position is ALWAYS: Stable.
Comfortable.
Minimizes movements.
Reproducible.
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EXAMPLES
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STANDARD POSITIONS
most comfortable.
Best and quickest for setup.
Minimizes errors due to miscommunication.
Best for treating posterior structures like spine
In some obese patients setup improved as the back is flat and less mobile.
Supine
Prone
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POSITIONING AIDSHelp to maintain patients in non standard positions.
These positions necessary to maximize therapeutic ratio.
Accessories allow manipulation of the non rigid human body to allow a comfortable, reproducible and stable position.
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POSITIONING AIDS…
Pituitary
Board
Prone
Support3 way
support
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BREAST BOARDS…
Modern Breast
Board
Indexed Arm
supports
Indexed wrist
support
Head rest
Carbon fiber
tilt board
Wedge to prevent
sliding
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ARM SUPPORT
Also known as the T bar.
Allows the arm to be positioned laterally when treating the thorax using lateral beams.
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BELLY BOARDS & LEG IMMOBILIZER
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MOULD MAKING
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MOULD MAKING : CONTD..
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MOULD MAKING : CONTD..
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THERMOPLASTICS
Thermoplastics are long polymers with few cross links.
They also possess a “plastic memory” - tendency to revert to normal flat shape when reheated
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THERMOPLASTICS : PRINCIPLE
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FOAM SYSTEMS
Made of polyurethane
Advantages: Ability to cut treatment portals into foam.
Mark treatment fields on the foam.
Rigid and holds shape.
Disadvantages: Chance of spillage
Environmental hazard during disposal
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VACUUM BAGS
Consist of polystyrene beads that are locked in position with vacuum.
Can be reused.
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BITE BLOCKS
A simple yet elegant design to immobilize the head.
A dental impression mouthpiece used.
The impression is attached to the base plate and is indexed.
Head position recorded with 3numbers.
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SRS DEVICESStereotactic frames.
Gill Thomas Cosman System.
TALON® Systems – NOMOS corp.
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LOCALIZATION
The target volume and critical normal tissues are delineated with respect to patient’s external surface contour.
What to localize? Tumor
Organ
Methods? Clinical examination
Imaging
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Thank you
Floor is open for Questions and Discussion