Preparation for the procedure

1. Justification of the examination

There are many steps which are needed in order to successful undertake and complete a mobile X-ray examination. Before attending a ward or department it is important to ensure that the requested examination is justified. Justification is two-fold in that there needs to be an appropriate clinical reason for the requested examination but also a reason to justify that the examination should be undertaken outside of the radiology department (mobile).  Referral criteria are available but are not specifically focused for mobile examinations, for example the Royal College of Radiologists iRefer criteria and the American College of Radiology Appropriateness Criteria. Specific criteria for mobile examinations are likely to be governed by local protocols and also discussion with the referrer. Radiographer / RTs should understand local protocols for promptly identifying mobile radiography referrals and ascertaining the appropriateness of such referrals.  Some of these steps may need to involve reporting radiographer / RTs or radiologists. It is also important that the examination remains justified when the radiographer / RT attends the patient’s bedside. By way of an example, when radiography is requested following an intervention (line insertion, drain removal, etc) it is important that the radiographer / RT ensures that these procedures have been completed. It is not unheard of for a radiographer / RT to be requested to perform a mobile chest X-ray on a patient for nasogastric tube position when this has not yet been sited or the patient has removed it.  Justification should also consider repeat referrals, acutely unwell patients are often transported between departments and wards (i.e. A&E, theatre and ITU) and as such referrers may be unaware of previous examinations.  Radiographer / RTs should, where appropriate, make referrers aware of previous examinations as part of the justification process.  It is also good practice for the radiographer / RT to review any prior imaging.  This will provide the opportunity to assess the size of a patient’s chest and whether a portrait or landscape image receptor orientation would be most appropriate.  Review of prior imaging also provides the opportunity to consider exposure factor selection and how the presence of pathology may have an impact on dose optimisation.  Severe cases of COVID-19 may present with a viral pneumonia, as a result there may be significant opacification of the lung fields and an increase in exposure factors may be warranted.  This is important when attempting to demonstrate the exact locations of central venous catheters, endotracheal tubes, chest drains and other medical devices. Additionally, severe cases of COVID-19 have been associated with the presence of existing comorbidities (cardiovascular disease, diabetes, chronic respiratory disease, hypertension and cancer) and being aware of these issues may also help planning radiography¹⁰.   

2. Mobile X-ray equipment & Image detector

Prior to undertaking the mobile X-ray examination, the radiographer / RT must select an appropriate mobile X-ray unit and image receptor.  Most radiology departments will utilise either digital radiography (DR) or computed radiography (CR) systems.  In some jurisdictions mobile radiography may still be undertaken using film-screen based systems but these are likely to be a relatively limited number of decreasing cases.  Selection of the most appropriate X-ray unit and image receptor will depend on several factors.  These will include equipment availability, location, infection control issues and local protocols. Where available mobile radiography should ideally be undertaken using a DR unit, this will allow review of the resultant image at the patient’s bedside and the opportunity for immediate repeat imaging.  Such repeats could be due to technical reasons or the relocation of medical devices, for example endotracheal or nasogastric tubes (Figure 3).  Prior to undertaking a mobile X-ray examination, it is important to ensure that the mobile machine is adequately charged, fully functioning, contains the necessary ancillary items and has been cleaned to locally accepted standards.  A full list of items required for undertaking mobile examinations can be found in Table 3.  As a result of the COVID-19 pandemic it is likely that mobile X-ray units will be segregated for COVID-19 and non-COVID-19 cases.  This may require relocation of units to different parts of the hospital.  In such circumstances it is important to minimise the movement of X-ray equipment between segregated areas.

3. PPE

Personal protective equipment (PPE) required for the examination will be governed by local and national guidelines and will be specific to each individual imaging referral (Figure 4).  All X-ray examinations should commence with a correct hand-washing procedure (see Youtube video).  Healthcare associated infections can often be prevented through correct infection control practices and these should be part of formal radiography training curricula and part of regular mandatory training for qualified radiographer / RTs.  Hand hygiene guidelines can be useful to guide practice.  Correct PPE should be worn by all staff members involved in patient handling and imaging and should follow accepted standards (Figure 5).  In cases of suspected or proven COVID-19 the guidance is available and is constantly being updated¹¹. Not only should the correct PPE be worn but the correct protocol should be followed for donning and doffing.

With regards to the image receptor, generally good practice would recommend that this is placed within a waterproof protective barrier (Figure 6).  In many instances it is advantageous if two radiographer / RTs can perform the examination with one ‘clean’ and one ‘dirty’ in terms of infection control.  The radiographer / RT designated ‘clean’ would be responsible for the operation and positioning of the mobile X-ray unit and the initiation of the X-ray exposure.  The radiographer / RT designated ‘dirty’ would be responsible for direct contact with the patient and the positioning of the image receptor. Such systems would also be common for other transmittable infections, for example MRSA, C.Diff and Norovirus.