Radiation protection - X-ray equipment

These guidelines describe different areas of responsibility, and who is responsible when buying, using and maintaining x-ray equipment.

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X-rays are high-energy electromagnetic waves (rays) that can penetrate various materials. The rays stop immediately when the power is cut on a piece of X-ray equipment.

Use the glossary if you don't understand the meaning of a word.

Areas of responsibility

Line leader

The line leader is responsible for appropriate radiation protection in the unit. Responsibility and tasks related to radiation protection are described in the guidelines Radiation protection - responsibility and task delegation

The line leader is also to make sure that all authorized users of the X-ray equipment complete the introductory course in radiation protection and the user course in sealed radioactive sources and X-ray equipment. See expertise development at NTNU (login required) for course date announcements. Users should also have specific training in the use of the X-ray apparatus.

Academic supervisors

The academic supervisor for the X-ray equipment has responsibilities described in Radiation protection - responsibility and task delegation

The academic coordinator should also consider the following:

Before the unit purchases X-ray equipment:

  • Consider whether someone should be appointed instrument coordinator. If the academic supervisor doesn't appoint a coordinator when the equipment is purchased, the supervisor him or herself is responsible for the points detailed in the instrument coordinator section.
  • Inform the local radiation protection coordinator. Local and central radiation protection coordinators should be aware of all new purchases, relocations and disposal of X-ray equipment.

Before the installation and use of the X-ray equipment:

  • Perform a risk assessment as described in the guidelines Radiation protection - responsibility and task delegation.
  • Consider whether a separate operator room might be necessary.
  • Make sure that all X-ray machines are correctly marked, locked and have warning lights.
  • Inform other employees (cleaning personnel, maintenance staff) of the X-ray machine's characteristics and dangers, cleaning routines, the meaning of warning signs and/or lights, and contact information.
  • Create and document technical measures that prevent exposure to ionizing radiation above the safety limit. For example, open radiation channels should be shielded with plexiglass, lead screens or lead curtains.
  • Protect the X-ray machine and the X-ray source from theft, sabotage, fire and water damage.

When the X-ray machine is in use, the academic coordinator should:

  • Perform regular test measurements
  • Discuss with the local radiation protection coordinator whether individual dosimeters for users are necessary.
  • Minimise individual's time near the radiation source.
  • Appoint authorized users of the radiation source. This should be documented with a form or list in the X-ray apparatus's log book. At the end of the year, this list as well as documentation of the last year's use of the X-ray machine should be sent to the local radiation protection coordinator.
  • Make sure that everyone observing experiments or demonstrations of the machine has understood the dangers of X-rays and behaves accordingly. During demonstrations for special groups, such as children, such safety measures are especially important. If possible, such demonstrations should be done with the X-ray machine turned off.

Local radiation protection coordinator

Local radiation protection coordinators are to perform the tasks described in the guidelines Radiation protection - responsibility and task delegation.

Local radiation protection coordinators should also keep backup copies of the form or list of authorized users and documentation of the use of the X-ray equipment. Backup copies should be saved by the unit for 10 years.

Instrument coordinator

The instrument coordinator is responsible for the equipment, radiation protection and user training for a specific X-ray apparatus. Technical staff and operators can also give user training, run the X-ray machine and service the machine if approved by the instrument coordinator. People who aren't authorized users can perform measurements under the supervision of the instrument coordinator.

The instrument coordinator should:

  • Inform of purchases, relocations and disposal of the X-ray equipment to the academic coordinator and local and central radiation protection coordinator
  • Perform necessary maintenance of the X-ray equipment. If authorized by the instrument coordinator, operators and technical staff can perform service.
  • Train users to use the X-ray equipment.
  • Keep a log book.
  • Create and maintain the information binder for the X-ray apparatus.
  • Make the operating instructions, equipment card and a list of the authorized users for each instrument.
  • Make sure that the X-ray equipment is correctly signed and marked.
  • Make sure the equipment is locked or has a passcode.
  • Assess the risk involved with different types of service work and small changes that a regularly made on the instrument, and create internal routines to control any leaked radiation.

Authorized users

Authorized users should be knowledgeable enough to be able to assess and use the X-ray equipment safely. This means that they should know start procedures, instrument settings, safety measures, shut down and emergency procedures, the contents of the information binder, and radiation test measurements.

Marking and signs

Set up standard warning signs with the symbol for ionizing radiation on all access doors to the room containing the X-ray apparatus, or to areas with X-ray equipment. A room card should also be made up. If the workplace is classified as a controlled area, this should be marked on the door, or near the entrance to the area containing the X-ray machine. There should also be an explanation of what this means.

Radiation sources in all types of X-ray apparatuses should be marked with the standard warning sign for ionizing radiation. The marking should be in Norwegian. The same information can be given in other languages if necessary.

Keys or electronic locks on the X-ray equipment

It shouldn't be possible to start the X-ray machine without a key or passcode. If the instrument has a key, take it out and hide it from unauthorized personnel when the equipment isn't in use. Electronic locks with usernames and passwords can also be used.

Access to laboratories

Limit the access to rooms with X-ray sources as much as possible. The rooms should only be open to individuals who need them. Keep the door locked when no one is there.

Instrument safety

Certain X-ray machines will always have the radiation source on. This might be because of a long warm-up time or to increase the radiation source's lifetime. At NTNU this applies to certain X-ray diffractometers. In this case, limiting the access to the rooms containing the X-ray sources is an appropriate safety measure. X-ray machines that are always turned on should be equipped with a system to turn off the machine if the user makes a mistake or if the cooling system is turned off.

Log book

Each X-ray machine should have a log book with:

  • The names of all the users, date, type of work and the duration of the work performed. This includes the list of authorized users, and for how long they have been authorized.
  • Maintenance and other significant changes in the set-up.
  • Results of radiation test measurements.

Information binder

Each X-ray machine should have an information folder that contains at least the following documents:

Equipment data, including:

  • make, model, age, owner, serial number
  • amperage (mA), peak voltage (kV)
  • regulation labelling
  • adjustment range (maximum, minimum) for output effect/power

General information

User instructions

Operating instructions for use, safety regulations, logging, locking, use of radiation monitors and more

Emergency procedures

  • Emergency procedures (fires, water leaks, radiation injuries and more).
  • The procedures should describe how to correctly turn off the equipment, how to make sure that there is no radiation when the equipment is turned off, measures in case of radiation injuries, contact information and reports.
  • Feel free to use images/figures in the emergency procedures.
  • Look up the emergency procedures if necessary, and distribute them locally or to others, e.g. the maintenance staff.
  • Consider making English copies of the documents.

Test measurements

The radiation dose around the equipment (not in the direct ray) should be measured at least yearly, after maintenance, and after any significant changes to instrument set-up. The results should be noted in the log book.

Use a radiation monitor that is adapted to the radiations characteristics. Contact the local or central radiation protection coordinator to have a test measurement performed.


Normally, X-ray apparatus users are required to carry personal dosimeters. Students who are performing practical work as a part of their studies (i.e. in a laboratory or in practice in an enterprise) are considered as employees, and must therefore carry personal dosimeters. NTNU administers personal dosimeters to students who are about to start a practice period.

The use of a personal dosimeter isn't necessary if:

  • The effective radiation dose for one person is estimated to less than 1mSv/year, based on dose measurements, a realistic user pattern and without significant risk of exposure to the direct ray.
  • There are yearly test measurements for leaked radiation, after maintenance work and after any significant changes in the instrument set-up.

Each X-ray equipment user should assess his or her work with the X-ray equipment. This includes an assessment of the necessity of a radiation dosimeter. The local radiation protection coordinator administers the dosimeter service.

The results of dosimeter measurements are registered in the Norwegian Occupational Dose Register, administered by the Norwegian Radiation and Nuclear Safety Authority (DSA). The purpose of this register is to keep an inventory on the doses from ionizing radiation to employees in Norway, with data from all employers that each employee has had. Both private persons, organizations/companies and DSA can access the register. NTNUs employees/students and radiation protection coordinators can access the register through the "ID-porten" system.

Exposure index

Working with ionizing radiation may imply registration in the Exposure index. Go to Exposure index to see what actions are necessary. To get into the index: Log into the substance index, click 'Administration' in the menu on the left side, and click 'Exposure'.


X-ray equipment with a open radiation path

X-ray equipment that radiates into open air. Accidents may cause direct exposure to X-rays.

X-ray equipment with a closed radiation path

The radiation path is built into the instrument. The maximum amount of radiation permitted outside the instrument is 5µSv/h. The machine should have a safety switch that turns off the source if any part of the instrument is opened.

Controlled area

The unit should characterized the workplace as controlled if the employees can be exposed to radiation doses larger than 6 mSv/year, or if the dose to the hands may exceed 150 mSv/year. Controlled areas should be physically enclosed, or clearly marked in some other way if closure is difficult.

Monitored area

The unit should classify a workplace as monitored if employees can be exposed to radiation doses greater than 1 mSv/year, or if the dose to the hands may exceed 50 mSv/year.


NTNU regulations




Approved by Director of HSE – February 3rd 2020 – HMSR36E