RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY

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RADIATION PROTECTION INDIAGNOSTIC
ANDINTERVENTIONAL RADIOLOGY
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology

• L13.2 Occupational exposure - Radioprotection
  measures

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Introduction

• Subject matter occupational exposure and
  regulatory aspects
• The monitoring procedures
• Investigation and follow up protocols

3
Topics

• Personal protective equipment
• Individual monitoring and exposure assessment
• Investigation and follow up
• Health surveillance
• Records

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Overview

• To become familiar with the BSS detailed
  requirement for radiation protection of workers
  in diagnostic radiology.

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Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology

• Topic 1 Personal protective equipment

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Personal protective equipment

• Registrants and licensees shall ensure that
  workers are provided with suitable and adequate
  personal protective equipment which meets any
  relevant regulations or standards (BSS I.28).
• Protective equipment includes lead aprons,
  thyroid protectors, protective eye-wear and
  gloves. The need for these protective devices
  should be established by the RPO

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Protective clothing

• Gowns, aprons and thyroid protectors made of a
  material (such as vinyl) which contains lead
• Aprons should be equivalent to at least 0.25 mm
  Pb if the X Ray equipment operates up to 100 kV
  and 0.35 mm Pb if it operates above 100 kV
• Aprons may be of the style which is open, or
  contains less lead, at the back, due to the extra
  weight of lead required - this assumes, however,
  that the wearer is always facing the radiation
  source
• Gauntlets are heavy gloves. They have limited
  value because they are difficult to use and
  should therefore only be used where appropriate

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Protective devices
SCREEN AND GOGGLES
CURTAIN
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Personal protective equipment

• Additional protective devices should be available
  in fluoroscopy and interventional radiology rooms
  which include
• Ceiling suspended protective screens.
• Protective lead curtains mounted on the patient
  table.
• Protective lead curtains for the operator if
  the X Ray tube is placed in an over couch
  geometry and if the radiologist must stand near
  the patient

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Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology

• Topic 2 Individual monitoring and exposure
  assessment

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Individual monitoring and exposure assessment (I)

• Individual dose monitoring shall be undertaken
  for workers who are normally exposed to radiation
  in controlled areas
• radiologists, medical physicists, the RPO,
  radiographers and nurses
• Other frequent users of X Ray systems such as
  endoscopists, anaesthetists, cardiologists,
  surgeons etc., as well as ancillary workers who
  frequently work in controlled areas, shall also
  be monitored.

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Individual monitoring and exposure assessment (II)

• Individual external doses should be determined by
  using individual monitoring devices
• Thermoluminescent
• Film badges
• Electronic dosimeters
• Worn at breast level, between the shoulders and
  the waist
• The monitoring period should be one month, and
  shall not exceed three months.
• The exchange of dosimeters and report receipt
  should not exceed three months

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Personal dosimetry

• Several personal dosimeters are recommended

From Avoidance of radiation injuries from
interventional procedures. ICRP draft 2000
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Different types of personal dosimeters
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Film badge
metal filters
open windows
plastic filter
open window
detects beta, gamma, X Ray
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TLD
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TLDs
extremity
whole body
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Individual monitoring and exposure assessment
(III)

• Evaluation of dose is an important aspect of
  radiation protection
• It is important that workers return dosimeters on
  time for processing
• Delays in the evaluation of a dosimeter can
  result in the loss of the stored information
• Licensees should make every effort to recover any
  missing dosimeters

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Individual monitoring when a lead apron is used
(I)

• The dosimeter should be worn under the apron for
  estimating the effective dose
• The other body areas not protected by the apron
  will receive higher dose
• One dosimeter worn under the apron will yield a
  reasonable estimate of effective dose for most
  instances
• In case of high workload (interventional
  radiology) an additional dosimeter outside the
  apron should be considered by the RPO

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Individual monitoring when a lead apron is used
(II)

• When expected doses are high, two dosimeters are
  required
• 1 under the apron at waist level
• 1 over the apron at collar level
• The effective dose E is given by
• E 0.5 Hw 0.025 Hn
• where
• Hw dose at waist level under the apron
• Hn dose recorded by a dosimeter worn at neck
  level over the apron
• Note The thyroid shielding allows 50 reduction
  of the E
• The dosimeter worn over the apron at collar level
  gives also an estimation of thyroid and eye lens
  doses

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Individual monitoring and exposure assessment (IV)

• In some facilities and for some individuals with
  a low level of exposure (e.g. general dental
  practitioners), area dosimetry to estimate the
  level of dose per procedure can be an acceptable
  alternative.
• Some X Ray systems for dental radiography, or
  others used in surgical theatres which use X Rays
  on a limited number of occasions a month may not
  require individual dosimetry for all staff
  involved although fluoroscopy in surgical
  theatres may lead to high dose in short time if
  not properly conducted
• In these cases, area dosimetry or some other
  individual dose evaluation per procedure could
  allow the RPO to estimate the typical level of
  risk

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Special aspects of individual monitoring

• In case of loss of a dosimeter, the dose
  estimation may be carried out from
• recent dose history,
• co-workers dose
• or, workplace dosimetry
• Individual monitoring devices should be
  calibrated
• Laboratory performing personnel dosimetry should
  be approved by the regulatory authority

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Monitoring of the workplace (I)

• Registrant and licensees shall develop programmes
  for monitoring of the workplace
• All survey meters used for workplace monitoring
  shall be calibrated and this calibration shall be
  traceable to a standards dosimetry laboratory
• Initial monitoring should be conducted
  immediately after the installation of new
  radiology equipment and shall include
  measurements of radiation leakage from equipment,
  and area monitoring of useable space around
  radiology rooms

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Monitoring of the workplace (II)

• Annual area surveys should be performed
• All radiation monitors shall be calibrated, and
  their warning devices and operability should be
  checked prior to each day of use (BSS I.3739)

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Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology

• Topic 3 Investigation and follow up

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Investigation levels (I)

• Employers, registrants and licensees shall, in
  consultation with workers or through their
  representatives, include in the local rules and
  procedures the values of any relevant
  investigation level, and the procedure to be
  followed in the event that any such value is
  exceeded.

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Investigation levels (II)

• A suitable quantity for use as investigation
  level is the monthly individual effective dose.
• The dose measured outside the lead apron (at
  collar or shoulder level) and the dose to the
  hands can also be used as a quantity for an
  investigation level for staff in interventional
  radiology.

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Investigation levels (III)

• Monthly values higher than say 0.5 mSv (for the
  dosimeter worn under the lead apron) should be
  investigated.
• Values higher than say 5 mSv per month in the
  over apron dosimeter or in the hand or finger
  dosimeters should also be investigated with a
  view to optimization.

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Investigation levels (IV)

• The licensee shall conduct formal investigations,
  as required by the Regulatory Authority, whenever
  (BSS IV.1820)
• an individual effective dose exceeds
  investigation levels
• any of the operational parameters related to
  protection or safety are out of the normal range
  established for operational conditions

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Investigation levels (V)

• any equipment failure, severe accident or error
  takes place, which causes, or has the potential
  to cause, a dose in excess of annual dose limit
• any other event or unusual circumstance that
  causes, or has the potential to cause a dose in
  excess of the annual dose limits or the
  operational restrictions imposed on the
  installation (e.g., the significant change in
  workload or operating conditions of radiology
  equipment)

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Investigation levels (VI)

• The investigation shall be initiated as soon as
  possible following discovery of the event, and a
  written report shall be prepared concerning its
  cause (determination or verification of any doses
  received, corrective actions, and instructions or
  recommendations to avoid recurrence)
• The report shall be submitted to the Regulatory
  Authority and other concerned bodies as required,
  as soon as possible after the investigation, or
  as otherwise specified and kept for a specified
  period.

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Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology

• Topic 4 Health surveillance

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Health surveillance (I)

• Primary purpose is to assess the initial and
  continuing fitness of employees for their
  intended tasks
• Medical surveillance (medical examinations) to
  workers as specified by the Regulatory Authority.
• Counselling should be provided for women who are
  or may be pregnant
• This is especially relevant in interventional
  radiology.

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Health surveillance (II)

• Under normal working conditions, the doses
  incurred in a radiology department are lower than
  the dose limits.
• No specific radiation-related medical
  examinations are normally required for persons
  who are occupationally exposed to ionizing
  radiation, as there are no diagnostic tests which
  yield information relevant to exposures that are
  close to or below dose limits.

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Health surveillance (III)

• It is therefore rare for the radiation component
  of the working environment of a radiology
  department to significantly influence the
  decision about the fitness of a worker to
  undertake work with radiation or the influence
  the general conditions of service
• However in the case of accidental exposure to
  high doses (of the order of magnitude of 0.2-0.5
  Sv or higher), specific radiation-related medical
  investigation are necessary

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Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology

• Topic 5 Records

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Records (I)

• The registrant or licensee should maintain
• exposure records
• medical records for each worker
• results from workplace monitoring

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Record (II)

• Other records to be maintained
• The authorization or registration documents
• Training provided (initial and refresher)
• Name of the person who delivered the training
• Name of the person who received the training
• Date and length of the training
• List of the topics addressed
• Copy of the certificates of training

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Record (III)

• Other records to be maintained
• Results from acceptance and commissioning tests
  of radiology equipment
• Audits and reviews
• Installation, maintenance and repair work
• Facility modification
• Incident and accident investigation reports

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Summary

• Different technical approaches can be followed to
  monitor the occupational exposure as well as to
  optimize the radiation protection
• Several operating rules can be used to
  investigate the radiation dose level occurring at
  the different working area

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Where to Get More Information

• International Basic Safety Standards for
  Protection Against Ionizing Radiation and for the
  Safety of Radiation Sources. 115, Safety
  Standards. IAEA, February 1996.
• 1990 Recommendations of the International
  Commission on Radiological Protection, Pergamon,
  Oxford 1991 (ICRP 60).
• INTERNATIONAL ATOMIC ENERGY AGENCY, Safety Report
  on Methodology for Investigation of Accidents
  involving Sources of Ionizing Radiation, IAEA,
  Vienna (in press).