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RADIATION PROTECTION IN RADIOTHERAPY

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Typical film. Marked with pen - shows thin white lines where ... Important to label film directly after developing it. Part 12, Practical 2. 12. Radiotherapy ... – PowerPoint PPT presentation

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Title: RADIATION PROTECTION IN RADIOTHERAPY


1
RADIATION PROTECTION IN RADIOTHERAPY
IAEA Training Material on Radiation Protection in
Radiotherapy
  • Part 12 Quality Assurance
  • PRACTICAL EXERCISE

IAEA Post Graduate Educational Course Radiation
Protection and Safe Use of Radiation Sources
2
Objectives
  • To be familiar with the concepts of Quality
    Assurance as a multidisciplinary activity and its
    interrelation with radiation protection in
    radiotherapy.
  • To be familiar with Quality Assurance procedures
    as a tool for reviewing and assessing the overall
    effectiveness of a radiation protection program.
  • To be able to understand the need for and role of
    specific tests in the context of quality control
    and be able to identify appropriate national and
    international protocols for this task
  • To be aware of the need for involvement of
    professionals in a quality assurance program and
    for radiation protection

3
Part 12 Quality Assurance
IAEA Training Material on Radiation Protection in
Radiotherapy
  • Practical 2 Check X Ray light field coincidence
    for a megavoltage treatment unit

IAEA Post Graduate Educational Course Radiation
Protection and Safe Use of Radiation Sources
4
Geometry
  • Must work for
  • all collimators
  • different field sizes
  • different SSDs
  • gantry and collimator angles
  • blocks

5
X Ray light field co-incidence
  • Also applicable to 60-Co gamma rays
  • Also applicable to some diagnostic equipment
  • If treatment set-ups are mostly fixed distance
    and aligned to marks on the skin, this is one of
    the most important factors for successful
    treatment.

6
Contents Objective
  • Appreciate the importance of X Ray/ /light field
    coincidence checks
  • Use a simple test based on film to check
    coincidence

7
What Minimum Equipment is Needed?
  • Radiographic film
  • Pen, ruler

8
Set-up
  • Place slab phantom at desired distance
  • Place pre-packaged film on top and secure with
    tape
  • Mark the light field outline using
  • pressure and a pen
  • radio-opaque objects
  • Use appropriate build up to remove electron
    contamination

9
Film with marks
Tape to secure the film
Mark beam geometry
Marks for light field
Package labeled
Slab phantom
10
Comments
  • If no pre-packaged film is available, one can use
    a film cassette from the X Ray department
  • Suitable radio opaque objects are screws,
    washers, .

11
Typical film
  • Marked with pen - shows thin white lines where
    emulsion has been squeezed
  • Test two fields at the same time
  • Arrow marks Gun/Target direction
  • Can verify field collimator readouts
  • Important to label film directly after
    developing it

12
Technique using pin pricks
13
Repeat as necessary for
  • Different SSDs
  • Different field sizes
  • Different gantry angles
  • Blocks
  • MLC

Courtesy Elekta
14
Questions?
  • Lets get started...
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