MR Safety Flashcards
What guidance do you follow in NHST with regards to MR safety?
MHRA Safety Guidelines for MRI Equipment in Clinical Use
Provides general guidance on good practice. Following the guidance is not compulsory and other actions may be equally valid
Can you define the MR environment for me?
From MHRA Guidance:
‘The 3D volume of space surrounding the MR magnet that contains BOTH:
1. The farady shielded volume, &
2. The 0.5mT field contoir.
This volume is the region in which an item might pose a hazard from exposure to the electromagnetic fields produced by the MR equipment and accessories’
Can you define the MR controlled access area?
The MR controlled access area is a locally defined area of such a size to contain the MR ENVIRONMENT.
Access shall be restricted and suitable warning signs should be displayed at all entrances.
How is access to the MR controlled access area controlled?
Acess shall be controlled by suitable control methods.
This may include the provision of:
- Self locking doors
- Devices for operating the locks such as keys or plastic cards; these should be non-magnetic and should only be made available to MR authorised personnel.
- Free access should only be given to authorised personnel.
- Unauthorised staff and visitors must be appropriately screened and seek authority to enter the MR controlled access area
What is the MR Projectile zone?
A locally defined volume containing the full extent of the 3mT magnetic field contourm OR OTHER APPROPRIATE MEASURE, around the MRI scanner.
Convenient to include the whole MR environment for a control standpoint for materials that are ferromagnetic
Where do we turn to for standards of MR safety markings?
ASTM International standard F2503 for the marking of devices brought into the MR environment should be used. This has also been published by the IEC as an IEC standard
What are the three levels of MR safety marking, and can you briefly describe them?
- MR Safe:
‘An item that poses no KNOWN hazards resulting from exposire to any MR environment’: MR safe items are composed of materials that are electrically non-conductive, nonmetallic, and nonmagnetic. They are PROHIBITED from containing conductive, metalic and magnetic materials - MR Conditional:
‘An item whith demonstrated safety in the MR environment within defined conditions’: At a minimum, addresses the conditions of;
- The static field
- The swithced gradient magnetic field
- The radiofrequency fields
Additional conditions, including specific configurations of the item, may be required - MR Unsafe
‘An itm which posses UNACCEPTABLE risks to the patient, medical staff or other persons within the MR environment’
What is an MR unlabelled item? Are there conditions where you can bring this into the MR environment?
An MR unlabelled item is an item without an MR SAFE, MR CONDITIONAL or MR UNSAFE label.
Items which are not labelled (MR unlabelled) should be considered MR UNSAFE until determined to be otherwise
Describe the role of the MR Responsible Person, how are they appointed? What cant they do?
It is recomended that the chief executive or general manager deligate the day to day responsability for MR safety to a specified MR Responsible person who might most effectively be;
- the clinical director
- head of department
- CS
- MP
- or superintendant radiographer
The should be able to demonstrate compliance with the necassary competencies
The MR RP should not take on the role of the MRSE
Who is the MR safety expert? What is the role of the MRSE?
It is recommended that, in order to cover all the necassary aspects of safety, each MRRP should be in consultation with an MRSE
The MRSE should be a designated professional with adequate training, knowledge and experience of MRI equipment, its uses and associated requirement
The MRSE provides sientific advice to the MRRP
The MRSE will have advanced knowledge of MR techniques and an appropriate understanding of the clinical applications of MRI.
- Ideally a physicist with experience in MRI
They musy act according to recognised standards, i.e., HCPC registration
Are there any scenarios where you may need to scan ‘off-label?’
What guidance should be followed when scanning patients with implants where MRI may be contraindicated?
There may be a need to perform an MR examination in the following scenarious:
- Thepatient has a MR conditional device but the manufactureres guidance CANNOT BE MET
- The patient has an implanted device whose compatability is unknown (e.g, MR unlabelled)
- The patient is implanted with a device known to be MR Unsafe
If the BENEFIT to the patient OUTWEIGHS the POTENTIAL RISK of the procedure scanning should be undertaken provided the following are documented and available before the scan:
- RA undertaken with full MDT + MRRP & MRSE;
should consider:
- Alrernative modalities, scanning at lower field (maybe needing referal to other centre), advice from manufacturer, available recomendations from professional bodies, available device data and possible artefacts etc
- Identification and implementation of appropriate precausions to minimize the risk
- Appropriate programming of device
- Suitable monitoring (SAR, physiological signals) during scan
- SAR exposure including considerations of methods to reduce it
- Procedures for suitable clinitian to be present
- Procedures for post scan evaluation of the patient
PATIENT CONSENT MUST BE OBTAINED FOR THIS PROCEDURE
