1. Radiological Sciences Department Ph.D., Paris-Sud 11 University
Radiotherapy Physics and Equipment
RAD 481
Lecture’s Title: Beam Directed Radiotherapy: Principles and practice
Dr. Mohammed EMAM
Ph.D., Paris-Sud 11 University
Vision :IMC aspires to be a leader in applied medical sciences, health care education and research.

2. Beam directed radiotherapy Beam Directing devices
Definition
Beam directed radiotherapy
Advance Planning
Beam Directing devices
Exact Calculations

3. Need for Beam direction
Homogenous Tumor Dose
Low normal tissue dose
Best therapeutic ratio

4. Steps Positioning Verification Immobilization Execution Calculations
Localization
Calculations
Field Selection
Dose distribution

5. 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.

6. Examples

7. Standard Positions Best for treating posterior structures like spine
In some obese patients setup improved as the back is flat and less mobile.
Supine
most comfortable.
Best and quickest for setup.
Minimizes errors due to miscommunication.
Prone

8. Positioning aids Help 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.

9. Positioning aids…
Prone Support
Pituitary Board
3 way support

10. Breast boards… Indexed wrist support Indexed Arm supports Head rest
Carbon fiber tilt board
Modern Breast Board
Wedge to prevent sliding

11. Arm Support Also known as the T bar.
Allows the arm to be positioned laterally when treating the thorax using lateral beams.

12. Belly boards & leg immobilizer

13. Mould making

14. Mould making : Contd..

15. Mould making : Contd..

16. Thermoplastics Thermoplastics are long polymers with few cross links.
They also possess a “plastic memory” - tendency to revert to normal flat shape when reheated

17. Thermoplastics : Principle

18. Foam systems Made of polyurethane Advantages: Disadvantages:
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

19. Vacuum bags
Consist of polystyrene beads that are locked in position with vacuum.
Can be reused.

20. 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 3 numbers. 20

21. SRS devices Stereotactic frames. Gill Thomas Cosman System.
TALON® Systems – NOMOS corp.

22. 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

23. Floor is open for Questions and Discussion
Thank you