Safety Requirements And Guidance For Analytical X-ray Equipment - Safety Code 32

3. Radiation Safety Requirements and Responsibilities

Within the scope of the 1990 ICRP objectives, analytical x-ray equipment must conform with applicable regulatory standards and facility requirements, and persons associated with the equipment ownership, use and maintenance must strictly adhere to their respective responsibilities.

3.1 Regulatory Standards and New Equipment

All new analytical x-ray equipment sold in Canada must conform to the Radiation Emitting Devices (RED) Regulations⁽⁶⁾ at the time of sale. Depending on the analytical x-ray equipment design, Part XIV or Part XV of Schedule II of the RED Regulations may apply. These regulations are promulgated under the RED Act,⁽⁴⁾ and it is the responsibility of the manufacturer or distributor to ensure that the equipment conforms to the applicable regulations. Since the regulations are subject to amendments in order to reflect changes in technology, information on their current applicability may be obtained by contacting the X-Ray Section, Radiation Protection Bureau, 775 Brookfield Road, Ottawa, Ontario, K1A 1C1.

When selecting or procuring analytical x-ray equipment, the equipment owner is well advised to obtain a copy of the most recent regulations to familiarize oneself with the requirements, and to enquire of the intended manufacturer or importer if the product complies with those current regulations. (These actions may eliminate or minimize the need for modifications to the equipment. Such modifications may be costly and cause considerable inconvenience because of disruption in service.)

3.2 Requirements for Used Equipment^*

Equipment manufactured prior to the advent of design guidelines presents a number of safety deficiencies when compared to current standards,⁽⁷⁾ and some equipment has been decommissioned as a result. Although equipment presented with fewer deficiencies is in general less costly and often practical to upgrade, absolute safety cannot be assured; however, a reasonable level of safety can be achieved by following the operational instructions specified in the equipment manual and the safe working procedures and guidelines outlined in this Code. In addition, operationally used equipment must be equipped with the following minimum requirements:

1. Control panel
   
   
   1. A keylock control switch or an alternate device must be installed to prevent unauthorized use.
   2. A power ON/OFF switch must be installed to energize the equipment.
   3. A warning sign that reads "Caution x rays. This equipment produces high intensity x rays when energized. To be used and serviced by qualified personnel only." and where appropriate, its French equivalent: " Attention Rayons X. Cet équipement émet un rayonnement X de haute intensité. II ne doit être utilisé que par du personnel qualifié." The sign(s) should be placed, preferably, next to the power ON/OFF switch and must be clearly legible at a distance of 2 metres and be clearly visible at any time.
   4. An x-ray ON/OFF switch must be installed.
   5. All lights, meters, controls and other indicators must be properly labelled and marked as to function.
   6. Separate fail-safe light indicators must be present to indicate when the x-ray tube is energized and when x rays are being produced. For equipment designed with a single control panel that operates more than one x-ray tube, each tube must be equipped with its separate fail-safe light indicators (of the type just described) to show when it is energized and producing x rays. Tubes not in use must be disconnected to prevent them from becoming energized or be removed from the equipment.
      
      
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2. Shutters and beam ports
   
   
   1. Warning indicators must be installed to indicate the open/shut status of shutters. Shutter mechanisms must be interlocked with x-ray production. Shutters should normally be in the closed position and positive action required to open them, and unused shutters must be secured to prevent casual opening. Unused beam ports should be permanently blocked-off with lead.
      
      
3. Shields
   
   
   1. Primary beams transmitted beyond the detector must be attenuated by a beam stop or trap or other permanent shield that is positioned closest to the equipment to confine the beam, and that does not permit radiation levels to exceed 0.5 mR [~ 4.39 µGy air kerma] per hour at 5.0 centimetres from its external surface.
   2. For any equipment operating under open beam configurations (i.e., where the primary beam may be incident on the extremities or organs in the upper chest and facial regions, and where stray radiation fields are in excess of permissible limits) access to such radiation fields must be restricted. In addition to the facility safeguard requirements in section 3.3, such equipment may need to be placed in a physical enclosure that contains:
      
      1. lead-glass or equivalent material (e.g., lead-acrylic copolymer) of sufficient thickness to attenuate existing radiation levels to 0.5 mR [~ 4.39 µGy air kerma] per hour at 5.0 centimetres from all externally accessible surfaces of the enclosure, when the equipment is operated at its maximum ratings;
      2. sliding door(s) or similar access openings to facilitate safe set-up procedures;
      3. an automatic shut-off or appropriate audible alarm to alert personnel of intrusion into a high radiation zone when any sliding door(s) or similar access opening is not in the closed position; and
      4. a warning sign of the type described in section 3.2.(1)(iii), that is clearly visible at any time on a part of the sliding door(s) or similar access opening.
4. Interlocks
   1. Where appropriate and feasible, fail-safe interlocks should be installed on accessories or components for which their removal would cause direct access to the primary beam or to high radiation areas on the equipment.

3.3 Facility Safeguards Requirements

Potential sources of stray radiation have been identified through surveys to be defective parts, poorly fitting accessories causing unshielded gaps, and tube rectifiers on x-ray diffraction devices, especially amongst equipment manufactured before regulatory control was imposed; often the levels are orders of magnitude higher than permissible limits. In a number of cases equipment presented with such problems was improperly secured and/or identified, and this potentially increases the risk of unnecessary radiation exposure.

In order to a chieve an acceptable standard of protection, facilities must include the following safeguards:

1. Proper isolation and designation of analytical x-ray equipment
   
   
   1. Allocate a room, or portion thereof, for the equipment.
   2. Permanently affix on the outside of the room, on the door that provides access to the equipment, the appropriate x-ray warning sign shown below. The sign must be clearly legible and visible at a distance of 2 metres to personnel approaching the room door.
      
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• 2.  Restricted access

Access to rooms in which analytical x-ray equipment is in use must be restricted strictly to the equipment users and other authorized personnel.

3.3.1 Pre-operational and Maintenance Measures

The reliability and safety of any physical system decreases with age and use because of component wear or corrosion effects.^(8,9) In order to ensure safe and reliable operation of analytical x-ray equipment in every facility, the user must routinely conduct certain pre-operational safety checks on components critical to x-ray safety, and the equipment owner or designee must establish and implement a suitable preventive maintenance program. These measures should account for the age and frequency of use of the specific equipment.

3.3.1.1 Pre-operational Safety Checks

When analytical x-ray equipment is installed and whenever maintenance functions are performed on it or on its accessory components, the user must consult section 3.4.2 of this Code, and conduct examinations or tests that ensure:

1. the proper functioning of all protective and safety devices;
2. the proper assembly and functioning of all radiation shields, beam ports, accessories and fittings;
3. the ambient radiation levels are within the permissible regulatory limit (0.5 mR [~ 4.39 µGy air kerma] per hour at 5.0 centimetres from all the external surfaces of the equipment) by using an appropriate survey meter (see Appendix II for guidance) provided by the equipment owner or the designee; and
4. any safety by-pass procedures are of the one time actuation and revert back to a fail-safe situation at start-up time of the x-ray generator.
   
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3.3.1.2 Maintenance Measures

Hazardous x-ray exposures can be significantly reduced or eliminated when maintenance procedures are in accordance with the manufacturer's guidelines specified in the service manual. Maintenance personnel must observe the following procedures while ensuring that unauthorized individuals are not near the x-ray equipment during servicing:

1. test all protective and safety devices and ensure their proper functioning. If by-passing a safety device is deemed essential to facilitate a specific maintenance task, the following requirements are mandatory:
   
   
   1. install a flashing red light or intermittent sound signal that is clearly visible or audible to a person with normal or corrected vision and hearing proximal to that part of the equipment where the safety device was altered,
   2. attach, near the flashing red light or intermittent sound signal, a written notice that indicates explicitly what safety device was altered,
   3. use an appropriate survey meter if radiation emissions are potentially associated with the intended task, and ensure that the permissible limits are not exceeded (see section 3.4.3 for guidance reference levels for body organs), and
   4. ensure that the safety device is re-established and any shielding removed or modified to facilitate the intended task is replaced after the task is completed;
      
      
2. examine all radiation shields, beam ports, shutters, accessories and fittings for proper installation and function; and
3. monitor the radiation levels nearest that part of the equipment where
   maintenance functions will be carried out, before and after the maintenance function(s). Use an appropriate survey meter (either provided by the equipment owner or oneself), and observe the guidance reference limits suggested in section 3.4.3 for body organs and the permissible levels established for the performance of the equipment (see section 3.3.1.1(iii)).

3.4 Human Considerations

If radiation risks are to remain low in conformity with the ICRP objectives, personnel in every facility at which analytical x-ray equipment is installed for use must strictly adhere to the responsibilities charged to them. The respective responsibilities affecting equipment ownership, use and maintenance are indicated below.

3.4.1 Equipment Owner Responsibilities

The ultimate responsibility for the radiation safety of analytical x-ray equipment rests with the equipment owner. The equipment owner is defined as a person, organization, or institution having title to or administrative control over one or more facilities having source(s) of ionizing radiation. The equipment owner must ensure that the analytical x-ray equipment meets all applicable radiation safety standards. For some applications, this responsibility may be delegated to staff (e.g., a senior user or the facility health and safety officer, henceforth, called the equipment owner designee). In every facility where analytical x-ray equipment is in use, the equipment owner or designee is responsible for:

1. ensuring that the equipment is installed in accordance with the requirements set out in section 3.3 of this Safety Code;
2. ensuring that all users have received training on the proper operation and x-ray hazards appropriate to the analytical x-ray equipment installed;
3. prescribing and posting prominently near the x-ray equipment radiation safety rules, and safe operating and emergency procedures which shall include address information and contact details of a hospital or clinic where medical treatment can be administered;
4. making readily available a copy of this Safety Code for reference by users and maintenance personnel;
5. implementing a system of verification, supervision and periodic review to ensure that all users and maintenance personnel have received adequate training, and have read and understood the relevant parts of this Safety Code, the applicable radiation safety rules, safe operating and emergency procedures before using and servicing the analytical x-ray equipment;
6. establishing a maintenance program, taking into account the age and frequency of use, that ensures all safety devices and components critical to both x-ray production and shielding, are routinely checked and defective parts replaced or repaired;
   
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7. providing an appropriate survey meter, and ensuring that it is in a working and functional condition at all times for use by users and maintenance personnel;
8. conducting prompt investigations of all radiation overexposures and accidents, and submitting appropriate reports to the equipment owner or designee and to the appropriate radiation protection regulatory authority within 5 calendar days;
9. ensuring that victims of radiation overexposures receive specialized medical attention (e.g., consultation with a radiation oncologist or physician knowledgeable in human biological effects of ionizing radiation);
10. determining the appropriate corrective measures following radiation overexposures, unsafe events and accidents, and ensuring that such measures are implemented effectively; and
11. ensuring that, during a radiation protection survey, a copy of the most recent survey report including summaries of corrective measures recommended and instituted on the equipment, is readily available to the rad iation inspector.

3.4.2 User Responsibilities

All users of analytical x-ray equipment must:

1. receive training, authorized or approved by the equipment owner or designee, on the operation and x-ray hazards relevant to the particular analytical x-ray equipment intended for use;
2. have read, understood and follow all applicable radiation safety rules and emergency procedures that are prescribed by the equipment owner or designee and by the appropriate radiation protection regulatory authority, before operating the analytical x-ray equipment;
3. wear personal radiation monitors consistent with the equipment design and operation (see section 3.7 of this Code) and as recommended by the regulatory radiation protection authority;
4. perform regular reviews of their own personal dosimetry data and identify unexpected radiation exposures, investigate them as to root cause(s) and implement appropriate corrective action(s);
5. use an appropriate survey meter to identify and monitor radiation levels at critical areas (tube housing, beam ports, shutters, analysis accessories, etc.) of the equipment during set up and beam alignment procedures, and following modifications and alterations to the device or its accessories, and to ensure that compliance with the regulatory limit (0.5 mR [~ 4.39 µGy air kerma] per hour at 5.0 cm from any external surface of the equipment) is maintained, and that the guidance levels (indicated in section 3.6) including the permissible dose limits (Appendix I) would not be exceeded under routine operational conditions of the equipment;
6. conduct the pre-operational safety checks indicated in section 3.3.1.1 of this Code; and
7. stop the operation of the analytical x-ray equipment if any unsafe operational conditions arise, and immediately notify the equipment owner or designee of such conditions.

3.4.3 Maintenance Personnel Responsibilities

All personnel responsible for the maintenance of analytical x-ray equipment must:

1. be adequately trained in the proper maintenance and repair of the various analytical x-ray equipment for which they are responsible, with emphasis on maintenance operations that may require x-ray production;
2. have read, understood and follow all radiation safety rules, requirements and emergency procedures applicable to the analytical x-ray equipment and the facility, including sections 3.6 and 3.7 of this Code;
3. wear personal radiation dosimeters to monitor separately whole body and extremity doses as deemed appropriate for the opera-tion(s) being undertaken;
4. use a properly functioning radiation survey meter (supplied by the equipment owner or oneself) to identify and monitor the radiation levels at critical areas (tube housing, beam ports, shutters, analysis accessories, etc.) of the equipment during set up, beam alignment and maintenance procedures, and following modifications and alterations to the device or its accessories;
5. undertake precautionary measures to eliminate or reduce radiation levels (measured according to clause 3.4.3.4) to ensure that the regulatory limit (0.5 mR [~ 4.39 µGy air kerma] per hour at 5.0 cm from any external surface of the equipment) is met, and that the guidance levels (indicated in section 3.6) including the permissible dose limits (Appendix I) would not be exceeded during routine operational conditions of the equipment;
6. perform regular reviews of their own personal dosimetry data and identify unexpected radiation exposures, investigate them as to root cause(s) and implement appropriate corrective action(s) as may be necessary;
7. provide the user and the equipment owner or designee with a written report that specifies explicitly any user procedure or action that could lead to an x-ray safety hazard, as soon as such a procedure or action is identified;
8. consult and adhere to the maintenance procedures indicated in section 3.3.1.2 of this Code;
   
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9. supervise the work of maintenance personnel in training; and
10. prevent the operation of the analytical x-ray equipment if any unsafe operational conditions arise, and immediately notify the equipment owner or designee of such conditions.

3.5 Radiation Protection Surveys

A radiation protection survey of analytical x-ray equipment is intended to determine whether the equipment functions according to applicable design and performance standards and is used and maintained in a way that provides maximum x-ray safety to all persons. In order to achieve these objectives, the following requirements apply to all facilities:

1. Analytical x-ray equipment must be surveyed when it is initially installed, and when maintenance, modification, damage and overexposure accidents have occurred on it.
2. Surveys must be performed by the appropriate radiation protection regulatory agency. However, authorized equivalents may be permitted provided that prior approval has been obtained from the appropriate regulatory authority.
3. Routine surveys of analytical x-ray equipment should be conducted at a frequency that depends on the particular equipment design, conditions of use, and performance history. The survey frequency may be based on consultation with the appropriate radiation protection regulatory authority.
4. Surveys of analytical x-ray equipment must include:
   
   
   1. a thorough inspection of all safety devices and radiation shields;
   2. stray radiation measurements carried out under worst-case (if feasible) user conditions around the system;
   3. proper quantification of stray radiation levels above the regulatory limit and their exact distance specification of the area or location on the x-ray equipment where they were found;
   4. an assessment of occupational and public exposures when radiation levels have exceeded the regulatory limit;
   5. audits on:
      
      
      • the availability of a copy of this Safety code, applicable radiation safety rules, safe operating and emergency procedures at or near the analytical x-ray equipment,
      • the maintenance program established and followed by the equipment owner or designee,
      • reports of unsafe operational conditions, overexposure incidents and accidents; and
        
        
   6. review and assessment of personal dosimetry records.
      
      
5. Survey reports must state the following:
   
   
   1. an identification of the analytical x-ray equipment that sets out the manufacturer, brand name, model number, serial number and the date of manufacture;
   2. an assessment of the safety devices, radiation shields, occupational exposures, and personal dosimetry records and the deficiencies observed;
   3. specific corrective actions necessary for compliance with this Safety Code and RED Regulations, including the completion deadlines; and
   4. safety recommendations (if any).
      
      
6. After analytical x-ray equipment has been decommissioned, all survey reports pertaining to that equipment must be retained for a period of five years by the last responsible user.
   
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3.6 Guidance on Operational Safety

Unattended x-ray equipment is not considered a potential hazard unless there is human intervention. In order to reduce the probability and severity of radiation accidents and overexposures, strict adherence to operating and maintenance procedures recommended by the analytical x-ray equipment manufacturer must be observed in addition to those indicated in this Code. The following general guidance should also be observed and incorporated where feasible:

For operations not requiring constant user supervision or surveillance, the analytical x-ray equipment must be adequately secured to prevent access by unauthorized individuals.

1. For operations not requiring constant user supervision or surveillance, the analytical x-ray equipment must be adequately secured to prevent access by unauthorized individuals.
   
2. Personnel must not expose any part of the body in the primary beam. If and when alignment of analysis accessories requires the use of an open x-ray beam, specific precautions must be exercised to reduce or eliminate radiation exposures to the extremities and other parts of the body. Long-handle forceps or remote handling devices, low x-ray tube current, and fluorescent beam-definers of higher radiation sensitivity should be employed.
3. While it may be necessary, under some circumstances, for maintenance operations to be performed with stray radiation fields above the regulatory limit (0.5 mR [~ 4.39 µGy air kerma] per hour), every effort must be made to minimize exposures to organs or parts of the body that could be affected, so as to minimize the likelihood of long-term risks. The ICRP recommended maximum permissible dose equivalent limits (Appendix I) must not be exceeded by any maintenance personnel.

   A practical guide, based on a busy maintenance worker performing, on average, one job per week under such conditions, would be to assume 1/50th of the annual permissible dose limit for each individual maintenance worker per week. This translates to a weekly working reference level of 10 mSv(1000 mrem) for the hands and other organs in the chest and upper facial regions, except the lens of the eye for which the limit would be 3 mSv (300 mrem). Nonetheless, all efforts must be made to reduce radiation exposure.

• 4.  All protective apparel and safeguards, including the radiation survey meter(s), must be tested regularly to ensure that they are in proper working and functional condition and are not defective; and proper documentation that such tests were carried out should be maintained.

3.7 Personal Exposure Monitoring

Personal dosimeters are intended to monitor occupational doses thereby providing a mechanism for restricting future radiation exposures to an individual, so that the recommended maximum permissible limits indicated in Appendix I are not exceeded. For the general application of this Safety Code, users and maintenance personnel are considered radiation workers and the applicable limits are indicated in column 2, Appendix I.

Depending on the analytical x-ray system design, monitoring the extremity doses as well as the whole body doses may be required. For extremity measurements, which typically would be the case for alignment procedures that involve open x-ray beams and systems potentially capable of irradiating the extremities, at least two finger monitors should be worn on the hand nearest the beam; one monitor should be worn on the dorsal surface of the finger and the other on the palmar surface, so as to detect exposures from narrow beams. For whole body monitoring, the monitor should be worn at chest level for work situations above bench height, enabling estimates of the dose to the breast and possibly facial organs; otherwise, wearing the monitor at waist level is satisfactory. Dosimetry records must reflect separate
extremity and whole-body cumulative doses, where applicable, in order to facilitate better control on doses approaching the respective permissible limits.

The need for personal dosimeters should be determined by the appropriate radiation protection regulatory authority on the basis of survey results and the particular analytical x-ray equipment in use. Given the historic injuries, effective lines of defense against radiation exposure to the body are the application of shielding and the proper use of a survey meter in the work area of the equipment, during beam alignment and set up procedures, as well as following modifications and alterations to the equipment or its accessories; personal monitoring should be used as confirmation rather than control.

Dosimetry records should be maintained at the facility for at least 5 years after a user has terminated working with such equipment.