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RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY

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Title: RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY


1
RADIATION PROTECTION INDIAGNOSTIC
ANDINTERVENTIONAL RADIOLOGY
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology
  • L13.2 Occupational exposure - Radioprotection
    measures

2
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

4
Overview
  • To become familiar with the BSS detailed
    requirement for radiation protection of workers
    in diagnostic radiology.

5
Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology
  • Topic 1 Personal protective equipment

6
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

7
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

8
Protective devices
SCREEN AND GOGGLES
CURTAIN
9
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

10
Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology
  • Topic 2 Individual monitoring and exposure
    assessment

11
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.

12
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

13
Personal dosimetry
  • Several personal dosimeters are recommended

From Avoidance of radiation injuries from
interventional procedures. ICRP draft 2000
14
Different types of personal dosimeters
15
Film badge
detects beta, gamma, X Ray
16
TLD
17
TLDs
extremity
whole body
18
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

19
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

20
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

21
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

22
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

23
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

24
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)

25
Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology
  • Topic 3 Investigation and follow up

26
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.

27
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.

28
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.

29
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

30
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)

31
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.

32
Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology
  • Topic 4 Health surveillance

33
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.

34
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.

35
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

36
Part 13.2 Occupational exposure
IAEA Training Material on Radiation Protection in
Diagnostic and Interventional Radiology
  • Topic 5 Records

37
Records (I)
  • The registrant or licensee should maintain
  • exposure records
  • medical records for each worker
  • results from workplace monitoring

38
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

39
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

40
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

41
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).
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