Principles of Radiation Protection and Legislation Flashcards
Who are the IRCP?
International Commission on Radiological Protection - It publishes recommendations (Fig 1) on radiation protection and liaises with all the other contributing international bodies.
How do the IRCP generate its recommendations and why?
Due to the sparse nature of the direct evidence of harm at or below levels of dose recommended by the Commission, its recommendations are developed via a scientific consensus, both from experts within its committee and Task Group structure and from experts outside ICRP. This consensus approach necessitates that the recommendations are both pragmatic and conservative in nature. They are also general in nature so as to apply to as wide a range of situations as possible.
What are the three tenets for radiation protection?
All practices involving ionising radiation should be ‘justified’, All practices involving ionising radiation should be ‘optimised’, Notwithstanding points 1 and 2 above, there are limits to the exposure of individuals above which one cannot go
How does the IRCP explain ‘justification’?
No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individuals or to society to offset the radiation detriment it causes.
Who is responsible for generic justification of a procedure in the uk?
In the UK, the Royal College of Radiologists (RCR) has published many guidelines indicating both preferred and acceptable imaging procedures for defined patient conditions. The RCR guidelines are now available online as i-Refer
Who is responsible on a patient level for justifying procedures and who is this regulated by?
The process of individual patient justification checks that the condition of the patient matches the procedure being proposed. This process is controlled by the Ionising Radiation (Medical Exposure) Regulations (IR(ME)R) 2017. The person carrying out such justification is called the ‘practitioner’.
What is the concept of optimisation?
Optimisation is concerned with gaining the maximum benefit from the radiation activity whilst ensuring the harm caused is minimised, e.g. ensuring staff doses for nuclear medicine are as low as reasonably achievable.
Optimisation also concerns the balancing of radiation dose and image quality for the imaging task under consideration. For optimal imaging, both patient dose and image quality must be considered as a pair, not in isolation.
How is optimisation of exposure often described?
ensuring that exposure is ‘as low as reasonably achievable’ (ALARA).
What is optimisation in relation to radioactive waste removal?
We are obliged to undertake a Best Available Techniques (BAT) assessment to ensure that our radioactive waste is disposed of in a manner that has the least effect on the population. The application of BAT ensures that we consider the route of disposal (e.g. incineration, land-fill) and whether we store the waste prior to disposal to allow radioactive decay to take place. It also demands that we minimise the activity and volume of waste.
What is the limit per year for a member of the public from occupational sources of radiation?
0.3 mSv per annum
What aspects of interventional radiology practice may affect the amount of Pb required in the apron?
Scattered radiation dose-rate from the equipment
Workload
Types of examination
Where you stand
Wearer comfort (size) in relation to operator
What is the occupational whole body effective dose limit?
20 mSv
What is the public whole body effective dose limit?
1mSv
What are the equivalent dose limits for the public to eye, skin and hands?
15, 50, 50 mSv
What are the equivalent dose limits for occupational exposure to eye, skin and hands?
20, 500, 500 mSv
If you double your distance from a radiation source how much will the dose you receive go down by?
factor of 4
T or F
A. The photoelectric effect involves loosely bound electrons
B. The Compton effect involves loosely bound electrons
C. Charge is measured in coulombs
D. Charge is the product of current and time
E. Alpha radiation is electromagnetic
F. A beta particle is a low energy electron
G. An alpha particle consists of two protons and two neutrons
H. The greater the kV, the higher the penetrating power of diagnostic x-rays
I. Fluence is the number of photons per unit area
A. False.
B. True.
C. True.
D. True.
E. False.
F. False.
G. True.
H. True.
I. True.
Are alpha and beta radiation EM radiation?
No - alpha and beta radiation, which are particles that have an associated charge and are consequently not part of the EM spectrum.
Are alpha and beta radiation ionising radiation?
Yes
What is exposure a measurement of with x-rays/gamma?
When x- or gamma radiation passes through air there is a consequent production of electrons (charge). Exposure is a measure of the amount of ionisation produced and is defined as being the charge liberated per kilogram of air. exposure is measured as the charge produced (dQ) by the electrons liberated in a small mass (dm) when all the electrons have been completely stopped.
What is the unit for exposure?
Exposure does not have its own specific unit, but is given the symbol X, where X = dQ/dm. Exposure is measured in coulombs per kilogram (Ckg-1) but is not a quantity generally used in medical radiation dosimetry or protection. Kerma tends to be used as a surrogate for exposure and has the advantage of being applicable to all media.
What is Kerma?
Kerma is a quantity that measures the kinetic energy released per unit mass (KERMa). It describes the energy (dE) of the charged ionising particles liberated by the passage of x- or gamma radiation (or neutrons) through a unit mass (dm) of material
What are the units for kerma?
joules per kilogram. The special unit for kerma is the gray (Gy).
How is air kerma related to energy fluence?
via a quantity called the mass energy transfer coefficient