When is an 'industrial radiography walk-in enclosure' not an industrial radiography enclosure (and therefore does not require an HSE consent)?

Museum x-ray imaging of a painting

Imagine you work for a museum that curates precious artwork. Money has been spent and you have been given an x-ray imaging room that will be used to x-ray paintings. The aim is to look for hidden canvas and other artifacts below the top (visible) canvas without making cuts, or otherwise damaging the artwork.

The x-ray imaging room you have been given is identical to the room described in the previous section in every detail.

You are NOT testing the item (artwork) for a defect, you are not performing NDT. You are not performing industrial radiography (see definitions in the previous section). You are merely using x-rays to see beneath the top layer, you are investigating the art history which may be contained within. You are researching, experimenting, increasing knowledge and adding value to the art specimen under assessment. You may write a research paper of your findings, or use the x-ray images in teaching of undergraduate art history students. If you are involved in the academic side of the museum you might have a MSc or PhD student lined up to use the x-ray facility, under your direction, to help with their own research and dissertation etc.

We have chosen a painting as an example, but this could easily be a natural history specimens such as an ancient fish or perhaps a dinosaur bone. Or, you could be a science museum, seeking information about the inner workings of an enigma machine without disturbing its delicate inner workings. You are not 'testing' the item (NDT), you are investigating it for research purposes.

This is not NDT, it is not industrial radiography and you do NOT need a consent from HSE. What you need in place is a registration for use of an x-ray generator (or more precisely a radiation generator). Industrial radiography is a specified practice, whereas x-ray imaging in its various forms is a certain practice (i.e. work with x-ray generators).

Hope you are still with us so far? Perhaps you feel some unease, or perhaps even an element of disquiet about this. Perhaps you think comparing the various definitions is just semantics? We have sympathy. What we can state is that the safe operation of the facility noted in this section is identical to the safe operation of the industrial radiography room featured earlier.

[Ionactive post article submission - additional content. Often we sleep on an article submitted - and something else pops up - here is one of them. Suppose, for whatever reason, a consent was desired (or advised) for our museum x-ray room (wrong decision but let's go with it). This means that the work being carried out is industrial radiography (NDT) as noted in the previous section. It does not matter what is being radiographed (e.g. painting or other museum specimen), a decision has been made that it is a specified practice. Therefore, it would be expected that those working in the x-ray room were trained in NDT - this would be a requirement of compliance with the consent (suitable and sufficient training of personnel conducting NDT industrial radiography). Pointing out that you know how to x-ray a painting or other museum specimen will not rub, the expectation now is that you are trained in the radiographic procedures of NDT. So you would need to be in touch with the British Institute of Non-Destructive Testing (BINDT) and seek advice on training in radiographic NDT (specifically RT – Radiographic testing). This would lead to you undertaking training for your PCN (Personnel certification in non-destructive testing). In order to obtain a Level 1 PCN in RT you would need to take a Basic Radiation Safety (BRS) course before being allowed anywhere near a radiography bay (yes, you will be undertaking practical work as part of your Level 1 training and for this you need your BRS first). During your Level 1 training you will learn all about welding processes and weld defects, properties of X- and gamma-rays, film selection, film processing and much more! <-- all in order to carry out NDT (industrial radiography) on your painting or other museum specimen.

So, don't get a consent for your museum x-ray room - you need a registration. NDT is a highly specialised set of techniques, conducted by experienced personnel who have undergone months / years of training under the eye of trained NDT specialists and training institutes.]

Other uses of x-ray generators that require a registration

The latest (October 2023) HSE guidance for registrations states the following:

Work with radiation generators

A radiation generator is a device capable of generating ionising radiation such as X-rays, neutrons, electrons or other charged particles.

This includes the following work:

• X-ray devices used by dentists, vets, chiropractors and NHS trusts
• X-ray devices used by
  • an airport to scan baggage
  • a post room in an office building to scan incoming packages
  • a port or dock to scan incoming or outgoing cargo
• a handheld X-ray Fluorescence (XRF) device used to determine the metallurgic content of metal
• using X-rays in a cabinet that cannot be entered to examine products

Ionactive comment: We do not think that the above description goes far enough. Where is the screening / imaging of objects (other than to suggest security screening or cargo)? Also the last line ' using X-rays in a cabinet that cannot be entered to examine products'. What does 'examine products' mean, and how does that fit with the definition of industrial radiography (see earlier)? Does this mean that using x-rays to examine a product in a room, rather than an enclosure that cannot be entered, imply that this is a specified practice (i.e. industrial radiography)? If that were the case (or intention of HSE), then the legal definition of industrial radiography in IRR17 (noted earlier) needs amending, since this definition uses NDT (non destructive testing), and we have already stated that x-raying a painting or museum specimen is not 'testing'. Furthermore, where do you draw the distinction between examining a 'product' in a room, and a piece of cargo in a large x-ray machine (that can be entered on foot through a flappy shielded curtain, rather than through an interlocked shielding door in our x-ray room described earlier)?

Let us now examine some specific examples given above.

X-ray devices used by airport baggage screening/ post rooms / port or docks screening cargo

This is a huge area of ionising radiation use. We will put aside the smaller x-ray units (such as those screening carry on baggage at an airport or units used in postal rooms), since these are generally too small to be entered (deliberately or by accident). These units will require a registration from HSE.

We will concentrate on the much larger machines and installations - these will include:

• Cargo screening systems at cargo / freight forwarding companies - typically 160 - 300 kV x-ray systems.
• Screening systems at ports and docks (some of these will use accelerators which is outside the scope of this article and would require a consent). Most will use kV x-ray generators, and hence require a registration.

Generally the type of equipment featured above will have the following attributes:

• Large enough to take whole pallets / containers (normally loaded by forklift trucks).
• Large enough to be entered by a person (not desirable or permitted when x-ray generation is underway, but reasonably foreseeable).
• Many of the larger cabinet x-ray systems have the interior space of a small room (nearing the area space of our x-ray room described earlier).
• The infeed and outfeed of the systems are generally protected by leaded curtains - not interlocked doors.
• Systems will contain x-ray "on" warning lights and feature e-stops etc.

The systems described above will require an HSE registration and not a consent.

Compare the above features to our x-ray room for imaging the painting and museum specimens. Our room contains LPO buttons, search and lock up, active signage which fails safe, and an interlocked door which if opened will terminate x-rays. In theory, you could just walk into a cargo screening unit, or ride on the conveyor and receive an exposure. Typical in-beam dose rates of such systems will be several mSv/h (and many will contain two or three x-ray generators and hence higher compounded dose rates). The latest CT security screening machines will have internal dose rates in the 100's of mSv/h.

Shielding from scattered x-rays relies on leaded curtains which need to be inspected - parts of them can literally drop off due to wear and tear. Reliance is also placed on human factors; it has been known for shielding curtains to be folded back over the stop of the unit to allow 'light' objects to be screened - completely prohibited in the local rules.

Whether such bad practice is reasonably foreseeable is for employer / RPA judgement, but at least with our x-ray room (with a single lower energy x-ray generator) you are protected by an interlocked door.

If someone made a case that the above systems did require a consent (they do not), it would not make sense to insist the lower exposure risk x-ray room (for screening our painting / museum specimen) would also need a consent (notwithstanding the fact that we are not conducting NDT in the room). If you like numbers and calculations you might argue that the dose rate in the x-ray room is higher than the dose rate in the cargo screening systems. But remember, the x-ray room door is protected - you cannot just walk in and receive an exposure.

Other portable x-ray devices (not XRF or veterinary imaging systems)

We noted earlier that the list of x-ray uses (for a registration) could be expanded. Here is an example of where the 'use' can determine whether a registration or consent is required. In this example the actual radiation exposure risks appear to have little influence on the decision making process.

Imagine you have a portable battery operated x-ray unit (about the size of a suitcase). Some of the features might be as follows:

• The device can operate at up to 90kV and 1 mA.
• The device is used in pulse mode (i.e. several pulses a second rather than a continuous x-ray beam).
• Dose per pulse at 1m might be 10 micro Sv (unshielded, directly inline with the collimator).
• The device has a control box with a 3m lead, connected to the back of the unit. The user must stand 3m behind the unit when x-rays are to be generated.
• The device contains a prewarn amber lamp mounted on top. When x-rays are switched on a buzzer will sound and the amber lamp will be illuminated for about 5 seconds, the buzzer then ceases and a red flashing lamp denotes that x-rays are being generated (you will usually hear an audible click with each pulse).

If the above setup seems unusual then recall that portable x-ray systems are used in hospitals everyday (i.e. move the x-ray system to the patient). These hospital systems require a registration but since they are diagnostic radiology we will say no more (since we know this is a special case as mentioned earlier in this article).

Consider how this portable x-ray system might be used, and how this will influence the requirement for a registration or consent.

• The device is used by GCHQ (or equivalent) to screen an embassy partition wall for listening devices (bugs). This will require a robust set of local rules, the area the other side of the wall will need to have access restricted. There is no reliance on PPE, interlocked doors and similar, much of the radiation safety relies on human factors (doing the right thing). This x-ray screening requires a registration (it is not NDT).
• The device is used by an industrial radiographer to undertake NDT of thin bore pipework on a new boiler house installation. In practical terms the use of the device, and the protective procedures followed, is no different to the embassy screening example. It could be argued that the boiler house is a better controlled environment, with a permit-to-work (PTW) system and daily work briefings and similar, as compared to the embassy where employees the other side of the wall to be screened are told to pop off for 30 minutes and have a coffee. Nevertheless, this work requires a consent from HSE (since it is industrial radiography, performing NDT).

The above examples do not use our robust x-ray room as described earlier in this article. The use of the portable x-ray unit in the above examples is procedurally identical. They are both performed in open space (a work area), but require a registration / consent based on their use and not on the radiation risk they present. Considering radiation exposure risk alone, some might argue that there is a stronger case for a consent applying to the embassy screening work, when compared to the boiler house NDT. But overall, this example does show that how you use an x-ray device influences how you choose a registration or a consent for the work being undertaken.

Ionactive comment: Let us finish this section with an extreme scenario - but not an impossible situation! Suppose our museum x-ray room operator is paranoid that there is a listening device behind the wooden panelling which covers the radiation shielding walls internally. So the x-ray facility is locked off and the door opened wide. A security technician is invited in by the museum management and asked to x-ray image the wooden panelling around the room (using the pulsed x-ray source noted above). The company conducting this work in your x-ray room only needs a registration (it is not NDT), despite the fact that they are not using any of the engineered protective features that you would rely on if you were x-ray imaging your painting or other specimen. Think about that.