Session 3 Flashcards
What are the 5 main duty holders under IRMER?
Employer
Referrer
Practitioner
Operator
Medical Physics Expert
What does IRMER stand for?
Ionising Radiation (Medical Exposure) Regulations (IR(ME)R) 2017
What do IRMER regulations say?
Ensure patient and staff doses are kept ALARP.
Protect patients
Requires medical employers to ensure that medical exposures are optimised
Encourages diagnostic reference levels to be used to aid in the optimisation of diagnostic radiological practices
Requires procedures in place to check for pregnancy in persons of childbearing potential (12 – 55 yoa)
Employers are required to establish procedures, protocols and quality assurance programmes locally to ensure all exposures are justified and optimised.
What is the role of the referrer?
Provide sufficient relevant medical data - allow Practitioners to justify exposure.
Ensure they are clearly identified on the referral and that it is signed physically or electronically.
Provide accurate identification information for the patient and the procedure - allow Operators to correctly identify the individual and perform correct medical exposure.
> third, of all errors reported annually are due to Referrer errors, e.g., wrong patient being referred.
What are Ionising radiation sources?
IR all around us e.g.
Food (bananas contain radioactive potassium)
Air we breathe
Ground we stand on
Outer space
85% of background IR come from
natural sources while the rest are
man-made
What are the different photon interactions?
Type 1 Interaction: photon entering the human
body may change direction without losing energy
Type 2: photon loses some of its energy and
changes direction
Type 3: photon energy is completely absorbed)
Resulting in an electron being ejected from the atom
with significant energy. This electron then interacts
in the patient’s body causing many more ionisations.
2 and 3 are of interest to us = Radiation Dose
Note: These interactions occur when x-rays hit any type of material.
Therefore
When considering the radiation dose received by the patient, we MUST consider x-rays interacting with the human body tissues.
What are the risks vs benefits in patient exposure?
IRMER Core Principles: Justification + Optimisation
ALARP = how to optimise dose
All exposures must be justified by a practitioner to ensure the benefits outweigh the harm
All diagnostic exposures must be optimised to keep doses as low as reasonably practicable - ALARP
What are the uses of medical exposures in special circumstances?
Pregnancy:
- Foetuses have much higher risk factors as their cells are rapidly dividing
- The threshold for deterministic effects is also lower
- Referrers must include if the patient is pregnant in their referral as this will impact the risk-benefit analysis
- Breast-feeding status is also relevant for nuclear medicine procedures
- Consideration may be given to delay the examination or use special procedures
Children:
Children have higher risk factors than adults
They are more radiosensitive
They have a longer lifetime for cancer to express
This will impact the risk-benefit analysis made by practitioner
Special procedures may be used to optimise dose
Medical research and health screening:
Special circumstances where medical exposures may be used on healthy individuals (e.g. mammograms, chest xrays) must be approved by National Bodies
What is the justification of patient exposure?
It is appropriate to use x-rays or other ionising radiations for a specific purpose
Provided by the Practitioner based on weighing up the benefits and risks of the medical exposure
Any referrer should check if there are any previous x-rays.
Using alternative examination e.g. US or MRI scans
A medical exposure should affect the clinical outcome for the patient
It is not justified to use a medical exposure to obtain information you already have
