IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY L13.2: Occupational exposure Radioprotection measures IAEA International Atomic.
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IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology RADIATION PROTECTION IN DIAGNOSTIC AND INTERVENTIONAL RADIOLOGY L13.2: Occupational exposure Radioprotection measures IAEA International Atomic Energy Agency Introduction • Subject matter: occupational exposure and regulatory aspects • The monitoring procedures • Investigation and follow up protocols IAEA 13.2: Occupational exposure - Radioprotection measures 2 Topics Personal protective equipment Individual monitoring and exposure assessment Investigation and follow up Health surveillance Records IAEA 13.2: Occupational exposure - Radioprotection measures 3 Overview • To become familiar with the BSS detailed requirement for radiation protection of workers in diagnostic radiology. IAEA 13.2: Occupational exposure - Radioprotection measures 4 IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology Part 13.2: Occupational exposure Topic 1: Personal protective equipment IAEA International Atomic Energy Agency 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 3.76). • Protective equipment includes lead aprons, thyroid protectors, protective eye-wear and gloves. The need for these protective devices should be established by the RPO IAEA 13.2: Occupational exposure - Radioprotection measures 6 Protective clothing: • Gowns, aprons and thyroid protectors made of a material (such as vinyl) which contains lead or other high Z material • 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 • Heavy, leaded gloves have limited value because they are difficult to use IAEA 13.2: Occupational exposure - Radioprotection measures 7 Protective devices SCREEN AND GOGGLES IAEA CURTAIN 13.2: Occupational exposure - Radioprotection measures 8 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 IAEA 13.2: Occupational exposure - Radioprotection measures 9 IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology Part 13.2: Occupational exposure Topic 2: Individual monitoring and exposure assessment IAEA International Atomic Energy Agency 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 work in controlled areas, shall also be monitored. IAEA 13.2: Occupational exposure - Radioprotection measures 11 Individual monitoring and exposure assessment (II) • Individual external doses should be determined by using individual monitoring devices: • Thermoluminescent or optically stimulated luminescence • 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 IAEA 13.2: Occupational exposure - Radioprotection measures 12 Personal dosimetry Several personal dosimeters are recommended From: Avoidance of radiation injuries from interventional procedures. ICRP Publication 85 IAEA 13.2: Occupational exposure - Radioprotection measures 13 Different types of personal dosimeters… film termoluminescence (TLD) and optically stimulated luminescence (OSL) dosimeters ”electronic” dosimeters IAEA 13.2: Occupational exposure - Radioprotection measures 14 Film badge plastic filter metal filters open windows open window detects beta, gamma, X Ray IAEA 13.2: Occupational exposure - Radioprotection measures 15 TLD IAEA 13.2: Occupational exposure - Radioprotection measures 16 TLDs whole body IAEA extremity 13.2: Occupational exposure - Radioprotection measures 17 OSL 1 cm IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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 3.76) IAEA 13.2: Occupational exposure - Radioprotection measures 25 IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology Part 13.2: Occupational exposure Topic 3: Investigation and follow up IAEA International Atomic Energy Agency 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. IAEA 13.2: Occupational exposure - Radioprotection measures 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. IAEA 13.2: Occupational exposure - Radioprotection measures 28 Investigation levels (III) • Monthly values higher than 0.5 mSv (for the dosimeter worn under the lead apron) should be investigated. • Values higher than 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. IAEA 13.2: Occupational exposure - Radioprotection measures 29 Investigation levels (IV) • The licensee shall conduct formal investigations, as required by the Regulatory Authority, whenever (BSS 3.46): • 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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) IAEA 13.2: Occupational exposure - Radioprotection measures 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. IAEA 13.2: Occupational exposure - Radioprotection measures 32 IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology Part 13.2: Occupational exposure Topic 4: Health surveillance IAEA International Atomic Energy Agency 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. IAEA 13.2: Occupational exposure - Radioprotection measures 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. IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 36 IAEA Training Material on Radiation Protection in Diagnostic and Interventional Radiology Part 13.2: Occupational exposure Topic 5: Records IAEA International Atomic Energy Agency Records (I) • The registrant or licensee should maintain: • exposure records • medical records for each worker • results from workplace monitoring IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 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 IAEA 13.2: Occupational exposure - Radioprotection measures 41 Where to Get More Information • Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, Revision of IAEA Safety Series No. 115, IAEA, Vienna Austria, 2011 • The 2007 Recommendations of the International Commission on Radiological Protection, ICRP 103, Annals of the ICRP 37(2-4):1-332 (2007) • 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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