X-Ray Safety | Environmental, Health and Safety Services | Virginia Tech
Environmental, Health and Safety Services

X-Ray Safety Miscellaneous Equipment

8.0 Miscellaneous X-ray Equipment

The rules in this section apply to the following miscellaneous X-ray producing equipment: electron microscopes, electron microphones, luminoscopes, and cold-cathode gas discharge tubes. These requirements are in conformity with title 21 of the Code of federal Regulations, Part 1020, and the Rules and Regulations for the use of Ionizing Radiation in the Commonwealth of Virginia.

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8.1 Posting

No area posting is required for miscellaneous X-ray equipment.

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8.2 Warnings and labels

A clearly legible and visible label bearing the statement: "CAUTION: THIS EQUIPMENT PRODUCES X-RAYS INCIDENTAL TO ITS PRIMARY FUNCTION - TO BE OPERATED BY QUALIFIED PERSONNEL ONLY" shall be posted on all miscellaneous X-ray producing equipment.

In addition to the above requirement, cold-cathode gas discharge tubes shall bear the following labels:

    1. A label stating the maximum safe operating voltage.
    2. A label that identifies the correct polarity of the terminals.

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8.3 Training

Individuals who wish to operate miscellaneous equipment are not required to complete documented radiation safety training. However, all individuals should receive hands-on instruction and training (e.g. working with experienced users, reading the manufacturer's operation manual) before independently using a miscellaneous system.

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8.4 Operating Procedures

Operating procedures shall be written and available to all users.

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8.5 Radiation Limits

Radiation emitted from electron microscopes, electron microprobes, and luminoscopes shall not exceed an exposure rate of 0.5 mrem/hr at 5 cm from the external surface.

Radiation exposure from cold-cathode gas discharge tubes shall not exceed 10 mrem/hr at 30 cm from the external surface averaged over 100 square centimeters.

All miscellaneous X-ray producing equipment shall contain sufficient shielding, and be located and operated so exposure rates in unrestricted areas do not exceed 2 mrem/hr or 100 mrem/yr.

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8.6 Personnel Monitoring

Personnel monitoring is not required for users of miscellaneous X-ray producing equipment.

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8.7 Potential X-ray Exposure From Magnetic-Effect Tubes

Magnetic-effect tubes demonstrate that cathode rays carry an electrical charge that can be deflected by a magnetic field. These tubes may produce X-rays incidental to their intended use and should be used with caution. Where there is a source of electrons, a target, sufficiently high voltage, and tube gas pressure within the proper range, X-ray production will occur. X-ray output from magnetic-effect tubes, however, is unpredictable and intermittent. Under identical operating conditions it may vary from one tube to another; one tube may be an X-ray producer while another may not. X-ray production may vary during a given period of operation or from day to day for the same tube.

Since the educational benefits derived from these tubes are gained by visual observation of their operation, unshielded operation of these tubes is required; with the subsequent potential for student and operator exposure. To keep exposures to a minimum, requirements for the safe use of these tubes are as follows:

    1. Magnetic-effect tubes must be used only for demonstrations conducted by the instructor.
    2. The instructor should stand as far as practical from the tube during the demonstration.
    3. Only the instructor shall operate a magnetic-effect tube.
    4. Bystanders should stand at least 8 feet from an operating tube.
    5. Tubes must always be operated with the correct polarity and the lowest practical current and voltage.
    6. Operating time is to be kept to a minimum.

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8.8 Surveys

Radiation surveys shall be performed and documented by the Radiation Safety Office:

  • When installed and at least once every five years thereafter to monitor leakage and area radiation levels.
  • After system relocation or maintenance.

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8.9 Administrative Checks

The Radiation Safety Office will conduct administrative checks once each year to verify conditions such as locations and operability of units.

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