John Saunderson

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Radiation Protection for Assistant Practitioners
in MammographyLecture 4

• John Saunderson
• Radiation Protection Adviser
• (TPRH ext. 6690)

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IRMER Syllabus

• Production of X-rays
• Absorption and scatter
• Radiation hazards and dosimetry
• Special attention areas
• Radiation Protection
• Laws Guidelines
• Equipment .

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2. Management and Radiation Protection of Patient
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2.1 Patient Selection

• Justification of the individual exposure
• Patient identification and consent
• Use of appropriate radiological information
• Alternative techniques
• Clinical evaluation of outcome
• Medico-legal issues .

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Justification of the individual exposure

• By law, all exposures must be justified
• For breast screening
• Women invited within NHSBSP invitation protocol
• Women not invited, but fit NHSBSP protocol
• For other, practitioner must decide (e.g.
  radiologist)
• A written record must be made of who authorised
  each X-ray.

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Patient identification and consent

• (covered elsewhere)
• By law, the Trust must have a patient ID
  procedure
• ID should be positive (Yes, dear wont do!) .

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General Points

• Use of appropriate radiological information
• (covered elsewhere)
• Alternative techniques
• Always use lowest dose technique, that will
  achieve the clinical result
• Clinical evaluation of outcome
• By law, all films must be reported
• Medico-legal issues
• e.g. X-rays for insurance purposes
• Special procedures must be in place to ensure
  that exposures are justified .

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2.2 Radiation Protection

• General radiation protection
• Use of radiation protection devices
• patient
• personal
• Procedures for untoward incidents involving
  overexposure to ionising radiation .

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• Justification
• Optimisation
• Limitation

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(No Transcript)
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All doses should be kept

• As
• Low
• As
• Reasonably
• Achievable
• The ALARA Principle .

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Basic Principles

• Time
• Distance
• Shielding

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Distance

• Double distance 1/4 dose
• Triple distance 1/9th dose.

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Shielding
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Shielding
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Typical Mammo. Doses

• Primary 5 mGy _at_ 1 m from tube per shot
• Through breast to film 7 uGy
• Max. scatter _at_ 1 m 7.6 uGy (at 163o)
• _at_ 30 kV 0.3 mm Pb transmits 0.00006 (i.e. less
  than a millionth)

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Organising radiation safety

• Controlled Areas
• Local Rules
• Radiation Protection Supervisor
• Radiation Protection Adviser
• Radiographer
• Assistant Practitioner .

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Use of radiation protection devices

• patient
• personal

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Untoward Incidents

• Overexposure of patient
• Overexposure of staff
• ?.

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Incidents

• Any untoward occurrence which may result in
  excess radiation to staff or patients must be
  referred to the Radiation Protection Supervisor
  and the Radiation Protection Adviser, who will
  estimate the dose and liase with management, HSE,
  DoH, HMIP, etc. as appropriate
• Suspect equipment must be withdrawn from service
  and labelled according .

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Patient Doses Much Greater Than Intended

• x 20 - extremities, skull, chest, etc.
• x 10 - lumbar spine, abdomen, pelvis, mammography
  and other examinations not referred to elsewhere,
  
• x 3 - fluoroscopy, digital radiography, C.T.

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Investigation

• establishing what happened
• identifying the failure
• deciding on remedial action to minimise the
  chance of a similar failure
• estimating the doses involved
• decide whether patient informed (usually yes).

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3. Statutory Requirements and Advisory Aspects
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3.1 Statutory Requirements and Non-Statutory
Recommendations

• Regulations
• Local rules and procedures
• Individual responsibilities relating to medical
  exposures
• Responsibility for radiation safety
• Routine inspection and testing of equipment
• Notification of faults and Health Department
  hazard warnings
• Clinical Audit .

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UK Regulations

• Ionising Radiations Regulations 1999
• IRR99
• inspected by Health Safety Executive
• Mostly relate to staff and public safety (not
  patients)
• Covers equipment
• Ionising Radiation (Medical Exposures)
  Regulations 2000
• IRMER
• Relate to patient safety .

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IRR99

• Justification, optimisation, limitation
• Optimisation
• ALARP,
• controlled areas,
• local rules,
• RPS,
• RPA,
• risk assessments,
• equipment QA.

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IRMER

• Justification, optimisation, constaints
• Procedures and protocols
• Roles and responsibilities
• Audit and adequate training.

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Employer's Procedures to ...

• (a) identify patient correctly
• (b) identify referrers, practitioners and
  operator
• (c) for medico-legal exposures
• (d) for making enquiries of females of
  childbearing age to establish whether the
  individual is or may be pregnant or
  breastfeeding
• (e) ensure that QA programmes are followed
• (f) for the assessment of patient dose
• (g) diagnostic reference levels

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Employer's Procedures to ...
(a) identify patient correctly (b) identify
referrers, practitioners and operator (c) for
medico-legal exposures (d) for making enquiries
of females of childbearing age to establish
whether the individual is or may be pregnant or
breastfeeding (e) ensure that QA programmes are
followed (f) for the assessment of patient
dose (g) diagnostic reference levels (h)
(biomedical research)

• (i) (nuclear medicine)
• (j) recording result and exposure factors
• (k) minimise accidents.

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Roles and Responsibilities

• Employer
• Referrer
• Practitioner
• Operator
• Medical Physics Expert.

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Referrer

• Must provide sufficient info. for the
  practitioner to justify exposure
• X-ray department must provide referral criteria.

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Practitioner

• Justifies X-ray - decides net benefit
• Can delegate authorisation to an operator in
  written procedures
• Usually a radiologist, but does not have to be -
  define in employers procedures
• Must follow employers procedures .

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Operator

• Anyone who performs practical aspects, e.g.
• radiographer
• radiologist
• assistant practitioner
• medical physics
• engineer
• If procedures allow, can authorise exposure
• Must follow employers procedures .

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Training

• Practitioners and operators must have adequate
  training
• Schedule 2 lists theory, also do practical
• Records must be available.

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4. Diagnostic Radiology
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4.1 General

• Fundamentals of radiological anatomy
• Fundamentals of radiological technique
• Production of X-rays
• Equipment selection and use
• Factors effecting radiation dose
• Dosimetry
• Quality assurance and quality control .

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4.3 Fundamentals of Image Acquisition, etc.

• Image quality v. radiation dose
• Conventional film processing
• Additional image formats, acquisitions, storage
  and display .

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f i n
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Trash next
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Attenuation, Scattering and Absorption

• 0.34 mm Al at 28 kV Mo/Mo
• For average breast
• 0.2 of x-ray energy reaches film
• 99.8 absorbed in breast