X-Ray Safety



June 2004




Applicable Documents


X-Ray Machine Classification

General Operational Safety Requirements

Warning Signs and Labels

Exposure Limits

Personnel Monitoring Equipment




To establish the policies and practices of the Missouri University of Science and Technology (Missouri S&T) pertaining to the safe use of x-ray emitting equipment.


  1. Controlled area - a specified area to which access is managed in order to protect personnel from radiation.
  2. Occupational exposure - dose received by an individual in the course of employment in which the individual's assigned duties involved exposure to radiation or radioactive material. 
  3. Shall - used for a provision that is intended to be a requirement. 
  4. Should - used for a provision which is not required, but which is recommended as good practice.
  5. X-rays - a form of electromagnetic radiation with a wavelength in the range of 1E-11 to 1E-7 cm. 
  6. X-ray machines - equipment that produces X-rays. At Missouri S&T only X-ray diffraction machines designed for routine analytical work are allowed.


The policy of Missouri S&T is to protect personnel from harmful exposure to radiation. The X-ray Machine Safety Program described herein is established to implement this policy consistent with the requirements of federal and state regulations, the regulations of the Missouri University of Science and Technology Radiation Safety Committee, and the guidelines contained in national standards applicable to the control of ionizing radiation.

Applicable Documents  

A. Federal Regulations 

B. Missouri State Regulations 

  • Missouri Statutes Section 192.400 Radiation Control, Department of Health and Senior Services 
  • Missouri Code of State Regulations (CSR) 19 CSR 20-10, "Protection Against Ionizing Radiation"

C. Missouri University of Science and Technology 

  • Handbook of Radiological Operations

D. National Standards

  • American National Standard Institute (ANSI) / Health Physics Society (HPS) N43.2-2001, "Radiation Safety for X-Ray Diffraction and Fluorescence Analysis Equipment"


A. The implementation of the X-ray Machine Safety Program is a function of the Missouri S&T Radiation Safety Officer (RSO).

Program elements shall include:

  1.  Advising administrators regarding safety requirements for personnel, equipment and facilities, as a result of the use of x-ray producing equipment.
  2. Maintaining surveillance over x-ray sources, by periodic health physics surveys including determination of the levels of exposure, and the inspection of shielding, interlocks, warning lights, signs, labels, and survey instruments.
  3. Providing personnel monitoring devices, when required, and maintaining personnel exposure records.
  4. Maintaining records regarding x-ray source data including State registration information and survey results.

B. Department chair or research center directors utilizing x-ray producing equipment shall comply with the requirements of this standard practice within their area of responsibility.

C. Researchers, faculty members, staff members, and students shall use x-ray producing equipment in accordance with their departments' established procedures and the requirements of this standard practice.

X-ray Machine Classification

All X-ray producing equipment is regulated under this standard practice; however, for administrative convenience all equipment is divided into three broad classes: 

Class 1: Analytical X-ray Equipment

Class 2: Radiographic Equipment and Particle Accelerators

Class 3: Electron Microscopes

Designation into a class, in the cases where there is doubt, will be determined by the RSO.

General Operational Safety Requirements

A. Requirements For All Classes

  1. The Department Chair Research Director shall name a specific researcher, faculty member, or staff member as the responsible person for each X-ray producing device in his or her area of administration.
  2. The responsible person shall supply the RSO with the following information (for each X-ray producing unit or tube) to comply with Missouri State registration requirements:
    - manufacturer model number
    - maximum kvp serial number
    - maximum amperage
  3. The responsible person should supply the RSO with written operating procedures for each X-ray machine. In addition to general start-up, shut-down and alignment procedures, the procedures should include any routine precautionary actions, such as routine shielding placement, testing for shield effectiveness, operation of survey meters, and placement of warning signs required by the operator to maintain exposures as-low-as-reasonably achievable.
  4. When not in use, each operable machine shall be left in a secure state such that start up of the machine is restricted to authorized operators. This may be accomplished by restricting access to a machine key or to the room where the machine is located. 

B. Requirements For Class 1: Analytical X-Ray Equipment

This class of equipment includes x-ray diffraction and fluorescence analysis equipment.

  1. Each machine shall have a functioning fail-safe light located in a conspicuous position near the radiation source housing interlocked to the x-ray energizing mechanism which indicates when the x-ray tube is on.
  2. Normal operating procedures and alignment procedures shall be such that a qualified operator, following instructions, will not receive in any one hour a dose in excess of 25 mrem to the hands and forearms, or 2.5 mrem to the whole body, gonads, blood forming organs or lens of the eye.
  3. On multiple port tube housings, shutters at unused ports shall be secured to prevent casual opening.
  4. All interlocks, warning lights or other safety apparatus installed at the time of manufacture, shall be maintained in operable condition and shall not be defeated except by qualified repair personnel during repair. Variances to this condition must be approved by the Missouri S&T Radiation Safety Committee.
  5. Each machine which is to be left operating unattended shall be left as follows:

    a)  in a secure area to which access is available only to authorized operators and Missouri S&T Security, Maintenance, and Administrative personnel authorized general access to all building locations.
    b)  with the primary beam stopped by secured shielding which cannot be inadvertently displaced.
    c)  all scattered radiation detectable by a thin-window GM Survey meter shall be shielded so as to be stopped at the perimeter of the tube console.

  6. An operable thin-window GM Survey meter shall be immediately accessible to the machine operator to insure the effectiveness of in-place shielding.
  7. A logbook should be kept for each machine noting the time and date of operation and the signature of the qualified operator. 

C. Requirements For Class 2: Radiographic Equipment and Particle Accelerators

This class of equipment includes radiographic X-ray tubes, experimental equipment utilizing an X-ray tube and particle accelerators from which X-rays may be emitted.

  1. Each machine shall have a fail-safe light visible to the operator indicating that X-rays are being produced.
  2. When the X-ray source cannot be seen by the operator at the control console interlocks, barriers and/or positive administrative procedures shall be used to insure that no person is in the area of the primary beam or intense scatter or could enter the area during operation.
  3. Each machine which is to be left operating unattended shall be left as follows:

    a)  in a secure area to which access is available only to authorized operators and Missouri S&T Security, Maintenance, and Administrative personnel authorized general access to all building locations.
    b)  with the primary beam stopped by secured shielding which cannot be inadvertently displaced.

D. Requirements For Class 3: Electron Microscopes

This class of equipment includes electron microscopes and other equipment which normally do not require additional external shielding due to the inherent shielding of the structure. External leakage of radiation is unlikely and probably low level. The general requirements, including a periodic health physics survey, are sufficient for safe operation.

Warning Signs and Labels

A. Each x-ray machine shall be clearly labeled as follows: 

"Caution: Radiation. This equipment produces radiation when energized."

Labels should be placed on the control panel near the switch which energizes the X-ray circuit.

B. Any area in which an individual could receive to a major portion of the body 5 mrem within one hour, or 100 mrem in any seven consecutive days, shall be conspicuously posted with a sign bearing the conventional radiation symbol and the words "Caution: Radiation Area."

C. Any area where a radiation level exists in excess of 100 mrem per hour shall be conspicuously posted with signs bearing the conventional radiation symbol and words "Caution: High Radiation Area."

D. Each High Radiation Area shall be equipped with an internal control circuit which shall either cause the radiation exposure rate to be reduced to below 100 mrem per hour upon entry of an individual into the area or shall energize a conspicuous visible or audible signal in a manner that the individual entering and the supervisor of the activity are made aware of the entry. In the case of a temporary High Radiation Area (30 days or less), a control circuit is not required if a barricade, such as a fence or rope is erected and the required caution signs are posted.

E. All radiation hazard labels posted shall be removed when the source of the radiation is no longer present or not capable of producing X-rays.

Exposure Limits

No X-ray machine shall be used in such a manner as to cause any individual to receive more than the limits indicated in Table 1 from that X-ray machine and any other campus radiation source.

The problem of correctly evaluating doses due to intense small-area beams of low-energy X-ray photons is not trivial. Exposures must be evaluated by the RSO.


Radiation exposures to individuals in a controlled area



Per Calendar Quarter

Whole body, head and trunk, active blood-forming organs; lens of eyes; or gonads

1250 mrem

Hands and forearms; feet and ankles

18,750 mrem

Skin of whole body

7,500 mrem

in vivo fetus

500 mrem in 9 month term

Radiation exposure of individuals in a non-controlled area

Whole body 2 mrem in one hour,
100 mrem in any seven
consecutive days,
500 mrem in a year


Personnel Monitoring Equipment

X-ray users should submit a Request for Film Badge Service to the RSO. The RSO will determine if personnel monitoring in the form of Lapel monitoring badges or ring TLD's are required by personnel. If necessary, these devices will be supplied by the RSO and must be worn when personnel are exposed to any campus source of radiation. Exposure summaries will be given to individuals upon request.


A. Operator Instructions and Qualifications

  1. The RSO shall make available a presentation on the basic biological effects of exposure to radiation and the practical procedures for reducing personnel exposure.
  2. The person named responsible for each X-ray machine shall instruct operators in the hazards of excessive radiation exposure and the proper procedures for safely using the machine. The person named responsible shall determine if the machine operators are qualified to operate the machine safely and know the associated hazards. The person named responsible shall also see that the operators review the Radiation Safety Presentation made available by the RSO.

B. Emergency Instructions

Persons receiving or suspected of having received a harmful dose of radiation must report such fact or suspicion immediately to the person responsible for the X-ray machine and the RSO. The RSO can be reached during normal hours at 341-4305. For all emergencies call the University Police at 341-4300.