Principles of Radiation Protection and Legislation

Question 1

Who are the IRCP?

Answer 1

International Commission on Radiological Protection - It publishes recommendations (Fig 1) on radiation protection and liaises with all the other contributing international bodies.

Question 2

How do the IRCP generate its recommendations and why?

Answer 2

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.

Question 3

What are the three tenets for radiation protection?

Answer 3

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

Question 4

How does the IRCP explain ‘justification’?

Answer 4

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.

Question 5

Who is responsible for generic justification of a procedure in the uk?

Answer 5

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

Question 6

Who is responsible on a patient level for justifying procedures and who is this regulated by?

Answer 6

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’.

Question 7

What is the concept of optimisation?

Answer 7

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.

Question 8

How is optimisation of exposure often described?

Answer 8

ensuring that exposure is ‘as low as reasonably achievable’ (ALARA).

Question 9

What is optimisation in relation to radioactive waste removal?

Answer 9

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.

Question 10

What is the limit per year for a member of the public from occupational sources of radiation?

Answer 10

0.3 mSv per annum

Question 11

What aspects of interventional radiology practice may affect the amount of Pb required in the apron?

Answer 11

Scattered radiation dose-rate from the equipment
Workload
Types of examination
Where you stand
Wearer comfort (size) in relation to operator

Question 12

What is the occupational whole body effective dose limit?

Answer 12

20 mSv

Question 13

What is the public whole body effective dose limit?

Answer 13

1mSv

Question 14

What are the equivalent dose limits for the public to eye, skin and hands?

Answer 14

15, 50, 50 mSv

Question 15

What are the equivalent dose limits for occupational exposure to eye, skin and hands?

Answer 15

20, 500, 500 mSv

Question 16

If you double your distance from a radiation source how much will the dose you receive go down by?

Answer 16

factor of 4

Question 17

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

Answer 17

A. False.

B. True.

C. True.

D. True.

E. False.

F. False.

G. True.

H. True.

I. True.

Question 18

Are alpha and beta radiation EM radiation?

Answer 18

No - alpha and beta radiation, which are particles that have an associated charge and are consequently not part of the EM spectrum.

Question 19

Are alpha and beta radiation ionising radiation?

Answer 19

Yes

Question 20

What is exposure a measurement of with x-rays/gamma?

Answer 20

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.

Question 21

What is the unit for exposure?

Answer 21

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.

Question 22

What is Kerma?

Answer 22

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

Question 23

What are the units for kerma?

Answer 23

joules per kilogram. The special unit for kerma is the gray (Gy).

Question 24

How is air kerma related to energy fluence?

Answer 24

via a quantity called the mass energy transfer coefficient

Question 25

What is absorbed dose?

Answer 25

Absorbed dose is the fundamental dosimetric quantity used in radiation protection. Absorbed dose (D) describes the transfer of energy from the liberated charged particles to whichever matter they are travelling in (air or tissue). It too is described in terms of energy per unit mass or joules per kilogram and so it too has the special unit of gray (Gy)

Question 26

What is the difference between absorbed dose and absorbed dose to tissue and when do we use each?

Answer 26

when we are thinking in terms of radiation protection and the assessment of damage to tissue or organs which will result in a stochastic risk (e.g. cancer induction), then it is better to think of the absorbed dose being averaged over the organ or tissue under consideration. When we do this, we use the term absorbed dose to tissue, which is given the symbol DT.

If we are thinking about deterministic effects such as skin ulceration then the quantity we are concerned with is the absorbed dose at a point D.

Question 27

Is air kerma and absorbed dose different?

Answer 27

Yes - but only by 0.4% at diagnostic energies.

Question 28

How do you get from absorbed dose to equivalent dose?

Answer 28

multiplied by a radiation weighting factor which allows for the relative biological effectiveness (RBE) of the different radiations to be taken into account

Question 29

What are the units for equivalent dose?

Answer 29

The unit of equivalent dose is the sievert (Sv).

Question 30

When do we use effective dose?

Answer 30

to be able to estimate the stochastic risk resulting from any radiological investigation.

Question 31

How is effective dose calculated?

Answer 31

the dose to each organ is multiplied by a weighting factor which is proportional to its own radiosensitivity and the resulting weighted doses are added together. The result is the effective dose. The unit of effective dose (E) is also the sievert (Sv).

Question 32

How do weighting factors for effective dose calculation differ in paeds and geris populations?

Answer 32

You need to multiply the cancer coefficient by 3 for paediatric patients and divide by 3 for geriatrics.

Question 33

What are operational quantities?

Answer 33

it is of obvious benefit to be able to (a) obtain an approximate measurement of the effective dose rate using a monitor and (b) wear a personal dosimeter that is calibrated in some quantity which approximates effective or equivalent dose.

This is achieved via the application of what we call operational quantities. The most important of these are ambient dose equivalent and personal dose equivalent, although there are others, for example directional dose equivalent. The operational quantities are defined in such a way that they provide a measure of E, or at least a realistic overestimate of effective dose.

Question 34

How is ambient dose equivalent measured?

Answer 34

Ambient dose equivalent is measured in Sv and is given the symbol H*(d) where d is the depth in mm at which the dose is estimated:

H(10) is the quantity used for what is called strongly penetrating radiation (e.g. x- or gamma radiation)
H(0.07) is the quantity used for weakly penetrating radiation (e.g. beta particles).

Question 35

What is personal dose equivalent?

Answer 35

what your personal dosimeter measures
expressed in Sv and is given the symbol Hp(d). It is defined as the dose equivalent at an appropriate depth d, again in mm. A depth of 10 mm is usually used for monitoring effective dose (Hp(10)). A depth of 0.07 mm is used for monitoring finger doses.

Question 36

T or F -
A. Exposure is measured in terms of charge per unit time
B. A film badge estimates ambient dose
C. Whole body dose limits are expressed in terms of effective dose
D. Effective dose can be related to radiation risk
E. Dose limits to extremities are expressed in terms of equivalent dose
F. Absorbed dose describes the energy deposited in tissue
G. Air kerma is used to measure the output of an x-ray set

Answer 36

A. False.

B. False.

C. True.

D. True.

E. True.

G. True.

H. True.

Question 37

What does IRR stand for?

Answer 37

The Ionising Radiations Regulations

Question 38

Who does IRR 2017 relate to?

Answer 38

designed to minimise the radiation exposure to employees and members of the public.

Question 39

What does the Approved Code Of Practice do?

Answer 39

gives practical advice on how to comply with the law set out in IRR

Question 40

Who is the main duty holder under IRR 2017?

Answer 40

The employer is the main duty holder under IRR 2017

Question 41

What is the employer responsible for in IRR?

Answer 41

charged with ensuring that the requirements of the regulations are carried out. However, the duties do not rest with the employer alone and the regulations place duties on employees also.

Question 42

What is the role of an RPA?

Answer 42

The radiation protection adviser (RPA) is a qualified radiation expert who holds a certificate of competence issued by an approved body. The employer must appoint, in writing, an RPA who has the required knowledge and experience for the employer’s type of work. In a large hospital with many different uses of ionising radiation there may be more than one RPA. The employer must consult them for RPA advice on how to comply with IRR 2017.

Question 43

What is the role of an RPS?

Answer 43

Employers have to appoint one or more suitable radiation protection supervisors (RPSs). Work carried out in a designated area is subject to local rules and it is the responsibility of the RPS to ensure that those rules are complied with.

The role of the RPS is crucial when it comes to ensuring compliance with the regulations. The main function of the RPS is to supervise (in a hands-on way) the arrangements set out in the local rules.

Question 44

Does an RPA have responsibility for radiation safety?

Answer 44

RPA does not technically have any responsibility for radiation safety, although you will find that in your hospital the RPA is usually also the person with responsibility for providing the radiation protection service and consequently, does have a significant responsibility for radiation safety. However, consider the situation where an external consultant, such as Public Health England (PHE), is acting as RPA. In that case, they would have no responsibility for radiation safety since they would only provide advice to the employer.

Question 45

Who is responsible for what in regards to breastfeeding employees?

Answer 45

Responsibility of the employer
The employer is responsible for ensuring that female employees know about the possible risk arising from ionising radiation to the foetus or to a nursing infant.

Responsibility of the female employee
Female employees should be urged to notify their employer in writing as soon as the pregnancy is confirmed or if they are breastfeeding so that any particular precautions required can be put in to place.

Question 46

What are the responsibilities of manufacturers?

Answer 46

Manufacturers have a responsibility to ensure that equipment is designed and constructed in such a way that the extent to which employees and other persons are likely to be exposed to ionising radiation is restricted so far as is reasonably practicable.

Question 47

What are the responsibilities of installers?

Answer 47

Installers have a responsibility for undertaking a critical examination of the way that the equipment is installed to ensure that the safety features and warning devices operate correctly and that there is sufficient protection for persons exposed to ionising radiation. This critical examination will be done in conjunction with the RPA.

The installer is also responsible for providing adequate information about the proper use, testing and maintenance of the equipment.

Question 48

What are the responsibilites for employees?

Answer 48

Not knowingly expose themselves or others to ionising radiation to a degree that is greater than necessary
Exercise reasonable care
Make full and proper use of personal protective equipment (PPE) and report any defects in it
Return PPE to whence it came
Inform the employer about suspected incidents
Wear personal dosemeters when required

Question 49

What needs to happen before a new activity involving work with ionising radiation can start?

Answer 49

a risk assessment
The risk assessment:

Enables the employer to decide what measures are necessary to restrict exposure
Identifies hazards which may cause a radiation accident and evaluate the risks associated with these hazards
Enables the employer to determine whether access to areas needs to be restricted

Question 50

What are the 5 steps of a risk assessment?

Answer 50

Step 1: Identify the hazards
Step 2: Decide who may be harmed and how
Step 3: Evaluate the risks and decide on the precautions
Step 4: Record your findings and implement them
Step 5: Review your assessment and update if necessary

Question 51

What should be included in a risk assessment of radiation?

Answer 51

The nature of the source of ionising radiation
Estimated radiation dose rates
Likelihood of contamination
Results of previous monitoring
Advice from manufacturers
Engineering control measures in place or planned
Any planned systems of work
Suitability of PPE
Access arrangements
Accident scenarios
Failure of control measures
Steps to limit accidents

Question 52

Following on from the risk assessment what things should/may result from it?

Answer 52

Action to keep exposures ALARP
Steps required to do this, i.e. design features, safety devices, warning devices, and systems of work
Personal protective equipment required
Dose constraints for planning
A need to alter conditions for pregnant or breast-feeding staff
Investigation levels to check that exposures are restricted to ALARP
Maintenance and testing schedules
Contingency plans
Identification of training needs

Question 53

What is the employer responsible for regarding restricting exposure?

Answer 53

Employers are responsible for restricting exposures to employees and other persons to a degree which is considered to be ALARP. The regulations require that exposure is restricted using a hierarchy of control measures:

First and foremost, doses should be controlled using engineering controls and design features and also by the provision and use of safety features and warning devices
After these have been applied, consideration should be given to the use of supporting systems of work
The employer is also required to provide personal protective equipment to further restrict exposure when this is reasonably practicable

Employers must also:
Use dose constraints to restrict exposure to ionising radiation at the planning stage
Take special steps in the case of pregnant and breastfeeding women
Establish dose investigation levels to trigger a review of working conditions when exceeded

Question 54

What is the legal limit for investigation levels?

Answer 54

Investigation levels must be used to trigger a review of working conditions when an employee records an annual dose exceeding the investigation level. Legally, an investigation must be carried out when an employee exceeds 15 mSv for the first time in any year. However, it is far more likely that the investigation level will be set at a fraction of 15 mSv.

Investigation levels:

Will be determined locally and will be appropriate to the employee’s work
Must be specified in the local rules
Will normally be set following advice from the RPA

Question 55

What is the legal limit for foetal exposure?

Answer 55

The employer is required to make sure that, once informed that an employee is pregnant, the equivalent dose to the foetus does not exceed 1 mSv during the remainder of the pregnancy.

Question 56

What is the legal limit for infant exposure in breastfeeding?

Answer 56

The baby is subject to the same dose limit as a member of the public. The employer may well decide to apply a dose constraint to the dose on the baby.

The employer should carry out a risk assessment to determine whether there are any working areas where an employee may receive significant bodily contamination which could pose a risk to her infant. When deciding whether or not the contamination is significant, it is necessary to take in to account the fact that some radionuclides are likely to become concentrated in breast-milk and that the dose to the infant might be of much greater concern than the dose to the woman.

Question 57

In Employees of 18 years of age or above the limit on effective dose for any employee or trainee, being of 18 years of age or above, is…?

Answer 57

20 mSv in any calendar year

Question 58

In Employees of 18 years of age or above The limit on equivalent dose for the lens of the eye is…?

Answer 58

20 mSv in a calendar year; or 100 mSv in any period of five consecutive calendar years subject to a maximum equivalent dose of 50 mSv in any single calendar year

Question 59

In In Employees of 18 years of age or above The limit on equivalent dose for the skin + extremities is…?

Answer 59

500 mSv in a calendar year as applied to the dose averaged over any area of 1 cm2 regardless of the area exposed
The limit on equivalent dose for the extremities is 500 mSv in a calendar year

Question 60

In Trainees aged under 18 years the limit on effective dose in any calendar year is…?

Answer 60

6 mSv

Question 61

In Trainees aged under 18 years The limit on equivalent dose for the lens of the eye is…?

Answer 61

15 mSv in a calendar year

Question 62

In Trainees aged under 18 years The limit on equivalent dose for the skin is…?

Answer 62

150 mSv in a calendar year as applied to the dose averaged over any area of 1 cm2 regardless of the area exposed

Question 63

In Trainees aged under 18 years The limit on equivalent dose for the extremities is…?

Answer 63

150 mSv in a calendar year

Question 64

When is an employee classified?

Answer 64

If an employee is likely to receive an effective dose greater than 6 mSv per year or an equivalent dose greater than 15 mSv per year for the lens of the eye or greater than 150 mSv per year for the skin or the extremities, then the employer must designate that employee as a classified person.

Question 65

What must classified employees do?

Answer 65

Are subject to medical surveillance by a relevant doctor and must have a medical examination before first being designated as a classified person. They must also have a periodic review of their health by a relevant doctor at least once a year

Must have their dose records kept by an approved dosimetry service for at least 30 years

Question 66

When are controlled areas required?

Answer 66

Controlled areas are required if:
It is necessary for any person who enters or works in the area to follow special procedures designed to restrict significant exposure to ionising radiation in that area or prevent or limit the probability and magnitude of radiation accidents or their effects or

Any person working in the area is likely to receive an effective dose greater than 6 mSv a year or an equivalent dose greater than 15 mSv a year for the lens of the eye or greater than 150 mSv a year for the skin or the extremities

The external dose rate in the area exceeds 7.5 μSv per hour averaged over the working day

The dose rate exceeds 7.5 μSv per hour averaged over 1 minute and staff untrained in radiation protection are likely to enter the area (unless the source of radiation is a patient)

There is a significant risk of spreading radioactive contamination outside of the working area

Question 67

When are supervised areas required?

Answer 67

Supervised areas are required where any person is likely to receive an effective dose greater than 1 mSv a year or an equivalent dose greater than 5 mSv a year for the lens of the eye or greater than 50 mSv a year for the skin or the extremities.

Question 68

What should be on a designated area warning sign?

Answer 68

should be indicated by suitable warning signs stating whether the area is controlled or supervised. Signs should also give sufficient information to alert employees to the particular risk involved - e.g. x-rays or radioactive contamination, and should be positioned at each entrance to the area.

Question 69

What do Controlled and supervised areas need to be monitored for?

Answer 69

Ensure that levels of ionising radiation are appropriate
Indicate whether there have been breakdowns in controls or systems
Detect changes in radiation or contamination levels

Question 70

What need to be in the local rules for managing designated areas?

Answer 70

Essential content of local rules includes:

A description of the area covered by the local rules with details of its designation i.e. whether it is controlled or supervised
The name of the appointed radiation protection supervisor
Details of any contingency arrangements
Dose investigation levels
A summary of the working instructions for people entering or working in controlled areas
Other content of local rules includes:

Procedure for contacting the RPA
Arrangements for management and supervision of the work
Arrangements for radiation and contamination monitoring
Arrangements for personal dosimetry
Arrangements for pregnant and breastfeeding staff

Question 71

T or F
A. The limit on effective dose for an employee of 18 years or over is 20 mSv in any calendar year
B. The limit on the equivalent dose for the lens of an eye is 150 mSv in any calendar year
C. The limit on the equivalent dose for the skin is 500 mSv in a calendar year
D. The limit on the equivalent dose for the extremities is 500 mSv in a calendar year
E. If an employee is not a classified person they should not receive an effective dose of more than 1 mSv per year
F. The limit on effective dose for a patient is 100 mSv in a calendar year
G. The limit on effective dose for a member of the public is 0.3 mSv in a calendar year

Answer 71

A. True.

B. False. The limit on the equivalent dose for the lens of an eye is 20 mSv in a calendar year. In the previous regulations, the limit was 150 mSv. This was decreased to 20 mSv in IRR 2017, taking into account new evidence about the risk of radiation-induced cataracts.

C. True. Note that this limit applies to the equivalent dose averaged over any 1 cm2 area regardless of the area exposed.

D. True. Note that the term extremities refers to the hands, forearms, feet and ankles.

E. False. If an employee is not a classified person they should not receive an effective dose of more than 6 mSv per year. Note that this applies to staff working with radiation. There will be other employees who are not normally be exposed to ionising radiation in the course of their work (for example, administrative staff). Employers should make it unlikely that such people receive an effective dose greater than 1 mSv per year.

F. False. The dose limits in IRR 2017 do not apply to patients undergoing medical exposures. However, note that patients not undergoing medical exposures are subject to the dose limit for members of the public (1 mSv per year).

G. False. The limit on effective dose for any other person is 1 mSv in a calendar year. However, to build in an additional safety margin it is usual to plan x-ray facilities to ensure that an adjacent member of the public will not receive more than 0.3 mSv in any one year.

Question 72

What legislation relates to ionising radiation exposures of patients?

Answer 72

IRMER

Question 73

What do the The Ionising Radiation (Medical Exposure) Regulations 2017 relate to?

Answer 73

Medical diagnostic and therapeutic exposures
Exposures as part of health screening programmes
Medical research exposures
Exposures of carers and comforters
Exposures of asymptomatic individuals
Non-medical exposures using medical radiological equipment

Question 74

What are the responsibilities of the employer under IRMER?

Answer 74

The IR(ME)R employer has a duty to implement IR(ME)R and has the right to decide which employees are permitted to fill each or any of the roles.

There are additional duties placed on the employer to:

Provide written procedures and protocols
Ensure that staff are appropriately trained
Respond where an incident has, or may have occurred
Keep an inventory of equipment that delivers or controls medical exposures

Question 75

What are the responsibilities of the referrer under IRMER?

Answer 75

The referrer is ‘a registered healthcare professional who is entitled in accordance with the employers procedures’ to request and refer individuals for medical exposures. The referrer is commonly a doctor or dentist; however, other registered healthcare professionals can also act as referrers (e.g. physiotherapists or nurses).

The referrer is required to supply the practitioner with sufficient relevant medical information to allow the practitioner to decide if the net benefit to the patient is great enough to permit the exposure.

Question 76

What are the responsibilities of the practitioner under IRMER?

Answer 76

A practitioner is required to justify all medical exposures.

In order to justify an exposure a practitioner must have a full knowledge of both the benefits and the hazards associated with the procedure.

Special consideration is required by both the practitioner and operators when considering:

Exposures to pregnant females, specifically considering both the mother and the unborn child
Medico-legal and health screening exposures
Radionuclide administrations to a breastfeeding mother
High dose exposures
Paediatric exposures

Question 77

What are the responsibilities of the operator under IRMER?

Answer 77

Operators can be directly and indirectly involved in medical exposures.

A radiographer pressing the exposure button is acting as an operator, as is a technician performing annual quality assurance tests. In either case, by correctly or incorrectly carrying out their job the individual can affect exposures to patients.

Operators have responsibility for practical aspects they carry out. They can also have responsibility for authorising exposures under written guidance from a practitioner.

The operator also has responsibility for optimisation.

Question 78

What are the responsibilities of the medical physics expert under IRMER?

Answer 78

IR(ME)R 2017 require that “a suitable medical physics expert is appointed and involved” in every medical exposure. The degree of involvement required depends on the type of exposure:

For exposures in nuclear medicine, high dose interventional radiology and high dose computed tomography: a medical physics expert must be involved
For other diagnostic radiology exposures: a medical physics expert must be involved as appropriate for consultation on optimisation
A medical physics expert must also give advice on a range of matters including:

Dosimetry
Equipment selection and testing
Accidental or unintended exposures
Training
Compliance with IR(ME)R 2017
There is a formal certification scheme to recognise an individual having the knowledge, training and experience to act as a medical physics expert (MPE).

Question 79

What must the written procedures for medical exposures include (14)?

Answer 79

(a) Identification of patients
(b) Identifying staff roles
(c) Pregnancy and breastfeeding
(d) Quality assurance
(e) Patient dose assessment
(f) Use of diagnostic reference levels (DRLs)
(g) Research exposures
(h) Patient instructions and information
(i) Provision of information about benefits and risks
(j) Evaluation of exposures
(k) Minimisation of unintended exposures
(l) Clinically significant unintended or accidental exposures
(m) Non-medical imaging exposures
(n) Exposure of carers and comforters

Question 80

What are the 2 sections for training requirements under IRMER?

Answer 80

Section A consists of the fundamental theory background of radiation, radiation effects and specific cases where radiation hazards are increased or potentially disproportionate. It also includes patient selection and management criteria as well as radiation protection and statutory considerations.

Section B is the material relating to specific techniques and fields of medical exposures such as radiographic equipment, computed tomography (CT) equipment or radionuclide equipment and techniques. Practitioner and operators are expected to have efficient training within their areas of practice. However, there is no requirement for understanding of areas that are not relevant to their practice.

Question 81

What needs to be done to audit patient dose?

Answer 81

For general radiographic, fluoroscopic and CT examinations, a 3-yearly frequency of patient dose assessment is required (with 1-3 yearly for mammography)
Dose-monitoring equipment (including DAP meters) should be adequately calibrated
Results should be compared to either specific levels or current national reference doses

Question 82

What is a DRL?

Answer 82

Diagnostic reference level - Dose levels in medical radiodiagnostic or interventional radiology practices, or, in the case of radio-pharmaceuticals, levels of activity, for typical examinations for groups of standard-sized individuals or standard phantoms for broadly-defined types of equipment.

Question 83

What is a ’Non-medical imaging exposure’?

Answer 83

any deliberate exposure of humans for imaging purposes where the primary intention of the exposure is not to bring a health benefit to the individual being exposed.

e.g. Health assessment for employment purposes
Health assessment for immigration purposes
Health assessment for insurance purposes
Radiological age assessment
Identification of concealed objects within the body

Question 84

Under what circumstances is radiation allowed for research?

Answer 84

employers must ensure that individuals participate voluntarily in the research programme and are informed in advance about the risks of the exposure. Dose constraints must be set and adhered to. In addition to the usual requirement for justification, exposures can only take place as part of a research programme that has been approved by an ethics committee.

Question 85

What is the most common cause of IRMER incidents?

Answer 85

The most common cause of IR(ME)R incidents is mis-identification of patients.

Question 86

What is the difference between accidental and unintended exposure?

Answer 86

an accidental exposure where an individual has received an exposure in error when no exposure of any kind was intended
Unintended exposures occur when although the exposure of an individual was intended, it was significantly greater or different to that intended.h

Question 87

What is the IRMER definition if a carer/comforter?

Answer 87

‘individuals who knowingly and willingly incur an exposure to ionising radiation by helping, other than as part of their occupation, in the support and comfort of individuals undergoing or having undergone an exposure’

Question 88

T or F
A. Carers and comforters are subject to an annual effective dose limit of 1 mSv
B. A carer or comforter will normally be a relative or friend of a patient
C. A carer or comforter can be a healthcare employee
D. A carer or comforter might be someone who offers support for a patient at home after discharge from hospital

Answer 88

A. False. Carers and comforters are not subject to the dose limit for members of the public. They receive a medical exposure that has been justified by a practitioner as having sufficient net benefit.

B. True. A carer or comforter will normally be a relative or friend of a patient. However, a relative or friend does not automatically become a comforter or carer. He or she must first be given sufficient information about the risks and must knowingly and willingly agree to incur the exposure.

C. False. Employees cannot be carers or comforters under IR(ME)R 2017. If they need to support a patient as part of their work, they will have to meet the requirements of The Ionising Radiations Regulations 2017.

D. True. A carer or comforter might be someone who offers support for a patient at home after discharge from hospital following a particular nuclear medicine procedure.

Question 89

Who are ARSAC?

Answer 89

Administration of Radioactive Substances Advisory Committee - expert advisory committee regards the administration of radiopharmaceuticals and sealed radioactive substances

Question 90

What is required before radioactive substances may be administered to patients or research subjects?

Answer 90

ARSAC licence

Question 91

How can you help reduce dose in NM scans?

Answer 91

dose reduction techniques such as fluid-drinking and bladder-emptying and the use of thyroid blocking agents. Strategies such as increasing scan acquisition time and using resolution recovery software may permit reduced activity and hence reduced radiation dose.

Question 92

What do the Radioactive Substances Regulation govern?

Answer 92

controls the impact of radioactive substances on members of the public and the environment

Question 93

How is solid radioactive waste disposed?

Answer 93

Such items may be accumulated and stored in suitable containers for a period of time. If their activity has decayed to a negligible value, they may be disposed with non-radioactive waste. Otherwise, they may be removed for incineration (or possibly burial in a land-fill site)

Question 94

how is liquid radioactive waste disposed?

Answer 94

in the majority of cases, a direct disposal route via sewers is used; the radioactivity is eventually dispersed and diluted to low concentration in sea water. In some instances, it may be necessary for the excreted waste to be held in tanks to allow radioactive decay to take place before disposal to sewers.

Question 95

how is gaseous radioactive waste disposed?

Answer 95

dispersed and diluted in the atmosphere.

Question 96

what is very low level waste?

Answer 96

Radioactive waste that may be disposed with non-radioactive refuse is called very low level waste. It mostly comprises solid waste containing short-lived radionuclides (such as 99mTc) whose activity has decayed considerably during its period of accumulation, but it may also include old sealed sources that are no longer usable because of their low activity. For classification as VLLW, each 0.1 m3 of waste must contain a total activity of less than 400 kBq and each single item must have an activity of less than 40 kBq