Radiation Protection in Radiotherapy

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Radiation Protection inRadiotherapy
IAEA Training Material on Radiation Protection in
Radiotherapy

• Part 10
• Good Practice in EBT
• Lecture 1 (cont.) Equipment design

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3. Operational Considerations

• General Considerations include the following
  requirements
• Operation of a radiotherapy facility must be
  authorized by the relevant regulatory authority
• Suitably trained staff must be available
• All changes to equipment, purchases and
  decommissioning must be reported to the relevant
  regulatory authority
• Some guidance on equipment specifications is
  given in part 5 of the course - part 18 will
  provide more information on regulatory
  requirements

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Operation of equipment

• radiation generators and irradiation
  installations include provisions for selection,
  reliable indication and confirmation of
  operational parameters such as
• type of radiation
• indication of energy
• beam modifiers (such as filters)
• treatment distance
• field size
• beam orientation
• either treatment time or preset dose

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Most of this information is provided by computer
interface
type of radiation indication of energy beam
modifiers treatment distance field size beam
orientation treatment time preset dose
Varian
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Most of this information is provided by computer
interface
type of radiation indication of energy beam
modifiers treatment distance field size beam
orientation treatment time preset dose
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Acceptance Testing and Commissioning

• Acceptance testing verifying that the machine
  fulfils all the specifications given by the
  manufacturer and the ones agreed on as
  requirements for purchase. In addition to this
  the unit should fulfil ALL safety requirements as
  documented by national and international
  standards (e.g. IEC documents)
• Commissioning ensuring that the unit is suitable
  for patient treatment within a certain
  department. This includes preparation of planning
  data and verification thereof.

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Operational Considerations

• Comprehensive acceptance testing and
  commissioning tests shall be carried out by
  appropriately qualified experts prior to initial
  treatment
• A comprehensive quality assurance programme with
  the participation of appropriate qualified
  experts in the relevant fields shall be
  established

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Commissioning

• Commissioning of radiotherapy equipment is a very
  important and complex process
• Only qualified experts should perform the
  commissioning and certify that a treatment unit
  is fit for use on patients
• One needs to know all specs of the equipment AND
  have the appropriate tools (water phantom, ion
  chamber, )

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Commissioning

• The commissioning process is not only informed by
  the equipment itself but also by its intended use
  and its role within the department.
• e.g. a linac which shall be used primarily for
  stereotactic radiotherapy will require a
  different set of tests than a unit which will be
  used for prostate patients...

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Commissioning

• Protocols exist which provide guidance through
  the commissioning process (see reference list)
• A subset of the commissioning process can serve
  as protocol for ongoing quality assurance
• Commissioning of new equipment leads to
  requirements for training of staff

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Qualification and Training

• Accreditation or certification schemes exist from
  many professional organisations or boards
• The skills required are practical and theoretical
• Experience essential
• More on this in part 18 of the course

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Safety first...

• Once the equipment has been installed, the first
  commissioning tests should be
• preliminary radiation survey as soon as the
  equipment is powered to ensure that it is safe to
  proceed
• once the equipment has been fully set up and
  tuned, carry out a full survey outside the
  treatment room
• survey the shielding attached to the equipment

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Records are essential
They must be complete, easily accessible and
understandable
They serve both as baseline for future evaluation
of the equipment and QA and as data which may be
required for legal purposes...
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Summary

• Good design of equipment provides the best
  safeguard against accidents
• Design criteria should follow the defense in
  depth principle
• Understanding radiotherapy equipment and its
  operation is essential for the commissioning
  process

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Where to Get More Information

• Parts 5, 7 and 18

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IEC reference list

• International Electrotechnical Commission.
  Particular requirements for medical electron
  accelerators in the range of 1MeV to 50MeV,
  Section Two Radiation safety for equipment,
  International Standard 601-2-1, part 2 Geneva
  Bureau Central de la Commission Electrotechnique
  Internationale 1981
• International Electrotechnical Commission.
  Particular requirements for the safety of
  remote-controlled automatically-driven gamma-ray
  afterloading equipment, International Standard
  601-2-17. Geneva Bureau Central de la Commission
  Electrotechnique Internationale 1989
• International Electrotechnical Commission.
  Medical electron accelerators functional
  performance characteristics, International
  Standard 976. Geneva Bureau Central de la
  Commission Electrotechnique Internationale 1989
• International Electrotechnical Commission.
  Medical electron accelerators in the range 1 to
  50MeV guidelines for functional performance
  characteristics, International Standard 977.
  Geneva Bureau Central de la Commission
  Electrotechnique Internationale 1989
• International Electrotechnical Commission.
  Radiotherapy simulators - functional performance
  characteristics, International Standard 1168.
  Geneva Bureau Central de la Commission
  Electrotechnique Internationale 1993
• International Electrotechnical Commission.
  Electromedical Equipment Particular
  requirements for the safety of radiotherapy
  treatment planning systems, International
  Standard 62083. Geneva Bureau Central de la
  Commission Electrotechnique Internationale 1998.

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Any questions?
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Question

• Please explain how the defense in depth
  principle can be (and has been) applied to
  ensuring that a linear accelerator is turned off
  after the correct dose is given to the patient.

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Acknowledgment

• Malcolm Millar, Alfred Hospital, Melbourne,
  Australia