Module 6

Question 1

What are the names of the Radiation Regulations we use?

Answer 1

The Ionising Radiations Regulations 1999 updated 1st January 2018 now IRR17

The Ionising Radiation (Medical Exposure) Regulations 2000 updated now called IRMER 2018

Question 2

Authorization for use of dental x-ray equipment

Answer 2

Use of dental X-ray equipment for research purposes should be in accordance with
a generic authorizations granted by the Health and Safety Executive (HSE)

Question 3

Notification

Answer 3

The HSE must be notified of the routine use of dental X-ray equipment and of any material changes to a notification including a change in ownership of the practice or a move to new premises.

Question 4

What is the Approach recommended by the HSE and how many steps are there?

Answer 4

A five-step approach is recommended by the HSE:

1. Identify the hazards (i.e. routine and accidental exposure to X-rays).
2. Decide who might be harmed and how they might be affected.
3. Evaluate the risks and decide whether existing precautions are adequate or whether more precautions need to be taken, Implement additional precautions, if needed.
4. Record the findings of the risk assessment.
5. Review the risk assessment and revise it, if necessary

Question 5

Radiation Protection Adviser

Answer 5

RPA must be suitably qualified
Must be certified by HSE approved body
- Employer must consult RPA on the following matters:
Implementation of Controlled and Supervised Areas (e.g. signage)
Prior examination of plans for installations and the acceptance into service of new or
modified sources of radiation in relation to safety and warning features
Regular calibration of equipment provided for monitoring levels of ionising radiation
Regular checking of systems of work provided to restrict exposure to ionising radiation
- In addition, Employer must consult RPA on the following matters:
Risk assessment
Designation of controlled areas
Conduct of investigations
Drawing up of contingency plans
Quality Assurance programs

Question 6

Radiation Protection Supervisor

Answer 6

Designated Person within the dental practice
• Must have a knowledge of regulations and Local Rules
• Understanding of precautions required and extent to which these will restrict
exposures
• Assess risks
• Supervises all aspects of radiography within the practice
• Ensures precautions for minimising
• Normally the dentist but could be
• Registered dental nurse
• Hygienist
• Therapist
Must have radiography certificate

Question 7

Legal Person

Answer 7

Ensures compliance with the legislation
Usually the dentist
Ensures that Local Rules are available at every x-ray machine in the dental practice

Question 8

All practices should have a written set of Local Rules relating to radiation protection measures in the practice which applies to all employees and should include:

Answer 8

• the name of the RPS
• identification and description of the controlled area
• summary of working instructions including the names of staff qualified to use the X-ray
• equipment and details of their training as well as instructions on the use of equipment
• contingency arrangement in the event of equipment malfunction and /or accidental
• exposure to radiation.
• name of the person with legal responsibility of compliance with the regulations.
• details and results of dose-investigation levels (A dose constraint of no higher than 1mSv
  per year is recommended as generally appropriate for practice staff from dental
  radiography)
• name and contact details of the RPA arrangements for pregnant staff
• reminder to employees of their legal responsibilities under IRR17

Question 9

Manufacturers

Answer 9

The installer is responsible for the critical examination and report of all new or
significantly modified X-ray equipment, which should include:
- a clear and unambiguous description of the equipment and its locations- an evaluation of the
acceptability of the equipment’s warning signals.

• an evaluation of the acceptability of the exposure controlconfirmation that the equipment’s safety features are in place and operating correctly (e.g. beam dimensions and alignment, beam filtration and timer operation)
• an overall conclusion as to whether or not the equipment’s safety features are operating correctly, the installation is providing sufficient protection for persons from exposure to X-rays and whether the user has been provided with ‘adequate information about proper use, testing and maintenance of equipment’.

Question 10

The acceptance test, in addition to the features covered in the
critical examination outlined should include:

Answer 10

•measurements to determine whether the equipment is
operating within agreed performance parameters (e.g.
operating potential (kV), X-ray output (mA) and timer accuracy
(s)
•an assessment of the typical patient dose for comparison
with national Diagnostic Reference Levels (DRLs)
•a review and record of film, film/screen combinations and
processing details and an evaluation of the adequacy of
processing
•a review and record of digital imaging systems.
•A permanent record should be made of the results and
conclusions of all tests and this should be retained as part of
the QA program and all deficiencies should be rectified

Question 11

Intraoral Radiography

Answer 11

• Tube voltage should not be lower than 50kV. New equipment should operate within the range
  60- 70kV.
• All equipment should operate within 10% of the stated or selected kV setting.
• Beam diameter should not exceed 60mm at the patient end of the spacer cone or beam
  indicating device.
• Rectangular collimation should be provided on new equipment and fitted to existing
  equipment to ensure the beam size does not exceed 40 by 50mm.
• Total beam filtration should be 1.5mm of aluminum for sets operating below 70kV
  2.5mm of aluminum for sets operating above 70kV
• The focal spot position should be marked on the outer casing of the tubehead, focal spot to
  skin distance (fsd) should be at least
  100mm for sets operating below 60kV
  200mm for sets operating above 60kV
• Film speed controls and finely adjustable exposure time settings should be provided. The fastest film available (E or F speed) should be used

Question 12

Panoramic Radiography

Answer 12

• Equipment should have a range of tube potential settings, preferably from 60 to 90kV.
• The beam height at the receiving slit of cassette holder should not be greater than the film in use (normally 125mm or 150mm). The width of the beam should not be greater
  than 5mm.
• Equipment should be provided with adequate patient positioning aids incorporating light beam markers.
• New equipment should provide facilities for field-limitation techniques.

Question 13

Cephalometric Radiography

Answer 13

Equipment must be able to ensure the precise alignment of X-ray beam, cassette and patient

The beam should be collimated to include only the diagnostically relevant area.

To facilitate the imaging of the soft tissues, an
aluminium wedge filter should be provided at
the X-ray tubehead, in preference to one at the cassette.

Question 14

All Equipment:

Answer 14

• Should have a light on the control panel to show that the mains supply is switched on.
• Should be fitted with a red light that gives a clear and visible indication to the operator
that an exposure is taking place and audible warnings should also provide the operator
with the same information.
• Exposure switches (timers) should only function while continuous pressure is
maintained on the switch and terminate if pressure is released.
• Exposure switches (timers) should be positioned so that the operator can remain
outside the controlled area and at least 2 m from the X-ray tube head and patient.
• Exposure times should be terminated automatically.

Question 15

Duties of Employees:

Answer 15

The person legally responsible, the legal person has over-riding responsibilities on
employees which include
• to not knowingly expose themselves or any other person to X- rays to an extent
greater than is reasonably necessary for the purposes of their work
• to exercise reasonable care when working on any aspect of dental radiology
• to immediately report to the legal person whenever they have reasonable cause
to believe that an incident or accident has occurred with the X-ray equipment
and that they or some other person have received an overexposure.

Question 16

The Legal Person
Must ensure the overall safety and that the practice is conforming to all regulations
There must be written procedures to include:

Answer 16

• Patient Identification
• Identification of referrers, practitioners and operators
• Authorisation and justification
• Justification of medico legal exposure
• Identification of pregnant patients
• Compliance with Quality Assurance
• Patient dose assessment
• Diagnostic reference levels (DRLs)
• Clinical evaluation of exposures
• ALARP – accidental/unintended dose
• Clinical audits
• Referral criteria
• Exposure setting protocols
• Excessive exposure procedures
• Copies of these should be in the radiation protection file

Question 17

IR(ME)R 2018 Requirements

Answer 17

• Ensures the safety of patients
• Replaced the Ionising Radiation Regulations 2000
• Clarifies the positions of responsibility
• The employer
• The referrer
• The practitioner
• The operator
Enforced in the UK by the Care Quality Commission (CQC)

Question 18

IRMER Referrer

Answer 18

• Registered Healthcare professional who is entitled in accordance with the with the employer’s procedures to refer individuals for medical exposure to an IRMER
Practitioner
• Must supply the IRMER practitioner with sufficient medical data to help him justify
exposure.

Question 19

IRMER Practitioner

Answer 19

• A registered dental professional who is entitled to take responsibility
for an individual medical exposure
• Must justify exposure
• Must authorise exposure
• Must be adequately trained
• May delegate the practical aspects to the operator
THEIR MAIN ROLE IS TO JUSTIFY THE MEDICAL EXPOSURE
BENEFITS vs RISKS

Question 20

IRMER Operator

Answer 20

Any person who is entitled, in accordance with employer’s procedures, to carry out
practical aspects of the exposure
• Must be adequately trained
• Functions and responsibilities of individual operators must be clearly defined in
employer’s procedures
• Practical aspects include:
• patient identification
• positioning the image receptor, patient or X- ray tube head, setting the
exposure parameters
• pressing the exposure switch to initiate the exposure processing films or
scanning of phosphor plates
• exposing test objects as part of the Quality Assurance prog

Question 21

Duties of Employer

Answer 21

Written procedures MUST be in place and adhered to by all IRMER Practitioners and
Operators
• Written exposure protocols MUST be in place to ensure consistent patient exposure and
must establish
• Referral criteria - these must be made available to the referrer QA programs
• Diagnostic reference levels
• Upper levels of dose for research exposures must be adhered to
• Ensure that every practitioner and operator undertakes continual education and training
• If there is an exposure ‘much greater than intended’ it must be reported
• To take corrective action whenever patient Diagnostic Reference Levels are consistently
exceeded
• Ensure that the upper levels of patient dose should not be exceeded

Question 22

IRMER Practitioner AND IRMER Operator

Answer 22

• Practitioner and operator to ensure all doses are kept ALARP
• Both are legally obliged to make sure that the above happens
This is possibly the most important aspect of the regulations

Question 23

Employees Do’s and Dont’s:

Answer 23

• Must not recklessly interfere with the x-ray machine or associated equipment
• Must not expose themselves unnecessarily
• Must report immediately to the RPS/Employer if an incident or accident occurs

Question 24

Notification of Accidents

Answer 24

• All accidents must be reported to an external source if the dose is greater than
intended
• If the machine is at fault it must be reported immediately to the HSE and the
machine must be switched off immediately and not used
• If it is an operator problem then the CQC must be informed

Question 25

Adequate Training

Answer 25

Adequate training for IR(ME)R operators involved in selecting exposure settings
and/or positioning the patient , image receptor or X-ray tube head
Dentists – practitioner training
Dental Nurses – should possess a recognised post qualification Certificate in Dental Radiography awarded by a reputable body
Dental hygienists and therapists– should have received an equivalent level of training to that for dental nurses
Dental nurses (or other staff), who simply ‘press the exposure button’ after the patient has been
prepared by another adequately trained operator, may only do so in the continued presence and
under the direct supervision of the operator

Question 26

Before Making The Exposure

Answer 26

Think is it clinically justifiable?
Previous radiographs
Objectives
Benefit v risks
Is there an alternative?
Optimisation
Ensure everything is ALARP
Is the equipment working correctly and has everyone had adequate training?

Question 27

Continuous Professional Development

Answer 27

It is recommended that IR(ME)R practitioners and operators attend a formal course (equivalent to 5 hours of verifiable continuing education) every 5 years covering all aspects of radiation protection.
Radiography is one of the core CPD topics as laid down by the GDC

Question 28

Lead Protection

Answer 28

• There is no justification for the routine use of lead aprons for patients in dental radiography
• Thyroid collars should be used when the thyroid may be in the primary beam
• Lead aprons do not protect against scattered radiation internally
• If an adult has to provide assistance for a patient that is having a dental x-ray then a protective apron having a lead equivalence of not less than 0.25mm should be worn
• The protective apron must be stored correctly, not folded and regularly checked
  for damage

Question 29

Film Badges

Answer 29

Blue frame normally containing a film
Worn outside of clothing - level with the reproductive organs
Worn for 1-3 months, then sent for processing
Simple, tough, inexpensive
Not immediately informative if there is a problem
Processing required and the badges are prone to filter loss

Question 30

Thermo luminescent dosimeters (TLDs)

Answer 30

• Whole body
• Lithium fluoride
• Emits light if exposed
• Light emitted proportional to absorbed dose
• Yellow/orange holder
• Reusable
• Easily automated
• Rapidly reproduced
• Variety of dose measurements
• Not permanent
• Not checked or reassessed
• Information limited
• Gradients undetectable
• Expensive

Question 31

Quality Assurance

Answer 31

It is a legal requirement to
Carry out a formal analysis of the film quality every 6 months this can be
done retrospectively or prospectively
Record the necessity for taking the radiograph in the patient records
Ensure diagnostically adequate film with minimum exposure time
Make sure all film processing is done correctly
Ensure all X-Ray films are easy to locate and stored so that the quality does
not depreciate
Ensure all staff are aware of the risks of Ionising Radiation

Question 32

Step Wedge Test

Answer 32

Use daily to ensure that chemicals and films do not need changing as you can see the image and compare it to a previous one
• Take a radiograph of the step wedge with the same exposure settings and develop the film
• Monitor the results against the previous images
• You can either buy a step wedge or make one with various thicknesses of lead
foil

Question 33

Coin Test

Answer 33

Tests the safelight in the darkroom or the seal on an automatic processing machine
Place 6 coins on the film and cover with a dark card
Put the film on a work surface with the lights out
Put on the safelight and pull the cover back to uncover the first coin
Leave for 1 minute then pull the dark card to uncover the second coin
Leave both coins uncovered for 1 minute
Repeat this until all 6 coins have been uncovered
If the safelight is working correctly you should only be able to see the first 1 -3 coins
If you can see an outline of the 6th coin then there is a problem with the safelight