Transcript Radiation Protection for Assistant Practitioners in

Radiation Protection
for Assistant
Practitioners in
Mammography
Lecture 4
John Saunderson
Radiation Protection Adviser
(TPRH ext. 6690)
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“IRMER Syllabus”
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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
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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” won’t 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 .
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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X-ray tube
Primary beam
Scattered radiation
Patient
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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
1/ th dose.
•Triple
distance
=
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Shielding
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Shielding
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Typical Mammo. Doses
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Primary = 5 mGy @ 1 m from tube per shot
Through breast to film = 7 uGy
Max. scatter @ 1 m = 7.6 uGy (at 163o)
@ 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
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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 employer’s procedures
• Must follow employer’s 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 employer’s 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
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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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fin
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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
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