HEALTH PROTECTION AGENCY

Working Party

with the

British Society of Dental and Maxillofacial Radiology (BSDMFR)

 

 

 

 

 

 

 

CORE CURRICULUM IN CONE BEAM COMPUTED TOMOGRAPHY (CBCT) FOR DENTISTS AND DENTAL CARE PROFESSIONALS

 

 

December 2009

INTRODUCTION

 

This document is designed to give guidance on the appropriate training of people in the dental team who take a role in the radiological exposure of a patient using Cone Beam Computed Tomography (CBCT).

Their roles are defined under the Ionising Radiation (Medical Exposure) Regulations 2000 (IR(ME)R 2000) and in the amendments of 20061,2 as; ‘IR(ME)R practitioner’, ‘referrer’ and ‘operator’ but, as will be evident, a dentist may find they fulfil a number of these roles.

 

Definitions of roles under IR(ME)R 2000/2006

An ‘IR(ME)R practitioner’ is a registered healthcare professional such as a dentist or doctor who is responsible for the ‘justification’ of a medical x-ray exposure. This is normally a dentist within a dental practice setting, and a radiologist or radiographer within a hospital setting. The justification of a radiological exposure is to weigh the benefits of a radiation exposure against the detriment, and to consider alternative methods for gaining the same diagnostic information with less or no exposure of the patient to ionising radiation.

 

A ‘referrer’ under IR(ME)R 2000/2006 is a registered healthcare professional such as a dentist or doctor who refers a patient to an IR(ME)R practitioner for a radiographic examination. Their request for a radiograph must be accompanied by sufficient clinical information to allow the IR(ME)R practitioner to justify and authorise and operator to authorise the radiograph and direct the most appropriate examination. Thus these duty-holders must be familiar with the strengths, limitations, selection criteria for CBCT investigations.

 

An ‘operator’ for the purposes of dental radiography may be a dentist, dental nurse, radiographer  or other health care professional who is entitled to carry out, in accordance with their employer’s procedures, all or part of the practical aspects associated with a radiographic exposure. The role of the operator in dental radiography can be separated into a number of parts. The first is positioning and imaging the patient. The others follow after the exposure, as the image is processed or manipulated, by the dentist or radiologist  in evaluating and reporting on the radiological examination, and handling/archiving the image and report.

 

Interpreting the legislation – duties and responsibilities

Here are some scenarios that may help explain the duties and responsibilities of members of the dental team who become involved in CBCT imaging of a dental patient:

 

1. A dentist who refers a patient to another dental practice or hospital for CBCT imaging, and interprets the resultant images him/herself:

The dentist who requests the CBCT scan acts a the ‘referrer’ and must supply sufficient clinical and radiological information to allow the receiving clinician (IR(ME)R practitioner) to ‘justify’ the examination. To do this the ‘referrer’ must be familiar with selection criteria for CBCT imaging and should follow referral guidelines provided by the owner of the CBCT equipment. If the request does not fit with referral guidelines then consultation should take place with the IR(ME)R practitioner and additional information be provided.

The referring dentist acts as an ‘operator’ (in a reporting capacity) when the images are returned to them for clinical evaluation and reporting, and they must be ‘adequately trained’ in this task. Most dentists in this position will almost certainly need additional training in CBCT interpretation.

 

2. A dentist who owns a practice with a CBCT facility, and receives requests from other dentists to perform CBCT investigations on their patients:

The dentist who receives a referral will consider the request and decide if the imaging is ‘justified’ – this is the role of the IR(ME)R practitioner. This duty-holder ultimately protects the patient from unnecessary or inappropriate x-ray exposure, and will need further training to enable them to make these judgements.

The dentist may also be the owner of the practice and the CBCT device (the ‘employer’ or ‘legal person’), and as such is responsible for providing the overall safety and radiation protection framework and for ensuring that staff and procedures comply with the Ionising Radiation Regulations (IRR) 1999 and IR(ME)R 2000.

 

3. A dental nurse with a Dental Radiography qualification who normally performs dental radiography and is asked to perform CBCT examinations:

Undertaking a CBCT examination (preparing and positioning the patient, choosing exposure factors, assessing the quality and suitability of the resultant CBCT images) is one of the roles of the ‘operator’ – the ‘imaging operator’ - and a person must be ‘adequately trained’ to do this. The Dental Radiography qualification does not provide this training, and so further specialised training will be needed.

 

Further examples and scenarios may be found in the section ‘IR(ME)R requirements for dental cone beam CT’.

 

 

Training

Regulation 11 paragraph 1 of the Ionising Radiation (Medical Exposure) Regulations 2000 states that no IR(ME)R practitioner or operator shall carry out a medical (or dental) x-ray exposure or any practical aspect without having been adequately trained.  The requirements for adequate theoretical training are set out in Schedule 2 of these Regulations.  The Schedule states that practitioners and operators shall have completed training, including theoretical knowledge and practical experience in; radiation production, radiation protection and statutory obligations relating to ionising radiations, as are relevant to their functions as practitioner or operator; and diagnostic radiology as relevant to their specific area of practice. Whilst IR(ME)R makes no explicit requirement for the training of referrers, the employer will need to be confident that anyone acting as a referrer for CBCT is capable of making appropriate referrals and of providing adequate clinical information. Evidence of formal training would help this decision.

 

The advent of CBCT has introduced a new field of dental and maxillofacial radiological practice which has only recently been introduced into the dental undergraduate curriculum (as defined by the BSDMFR core curriculum for Dental Radiology3) and is beyond the remit of current IR(ME)R radiation update courses. It is also not covered in Dental Radiography courses for dental nurses, hygienists, therapists or other dental care professionals (DCPs), nor examined for in the National Examining Board for Dental Nurses (NEBDN) Certificate in Dental Radiography.

 

The aim of this document is, therefore, to provide a curriculum that will prepare individuals to be adequately trained in a specific area of radiological practice, ie; the use of Cone Beam Computed Tomography (CBCT) in dental and maxillofacial imaging and to meet the requirement for adequate training in the use of dental and maxillofacial CBCT as required by IR(ME)R 2000/2006.

 

 

THEORETICAL INSTRUCTION IN THE USE OF CBCT EQUIPMENT

 

Radiation protection and radiological principles relevant to CBCT

General principles of radiation protection and radiography would normally be covered during undergraduate training and updated during regular Radiation Protection updating courses, as required by the General Dental Council (GDC) for registered dental professionals. These form the background to, and underpin, CBCT training.

It is recommended that items on this list should specifically be covered in CBCT training:

 

 

Radiation Physics in relation to CBCT equipment:

Referrer

IR(ME)R

Practitioner

Operator (imaging)

Operator (reporting)

·        Biological effects of radiation at doses relevant to CBCT

x

x

x

x

·        Risks/benefits of radiation at doses relevant to CBCT

x

x

x

x

·        Dosimetry- absorbed dose, equivalent dose, effective dose and their units

 

x

x

x

·        Factors affecting radiation dose including variables on CBCT units such as exposure factors (kV, mA  exposure time, pulsed/constant beam), field size, voxel size, region of interest

 

x

x

x

·        CBCT Image quality versus radiation dose

 

x

x

x

·        Dose optimisation for CBCT examinations

 

x

x

x

·        Comparative doses for CBCT and other dental examinations

x

x

x

x

Radiation Protection in relation to CBCT examinations:

Referrer

IR(ME)R

Practitioner

Operator (imaging)

Operator (reporting)

·        Use of radiation protection devices during CBCT

 

 

 

 

·         For the patient

 

x

x

 

·         For personal & staff protection

 

x

x

 

·        Definition and procedures for untoward incidents involving overexposure to ionising radiation during CBCT examinations

 

x

x

x

·        Pregnancy and potential pregnancy

x

x

x

x

·        Medical research and health screening

x

x

x

x

·        Infants and children

x

x

x

x

·        Justification of the individual exposure and application of appropriate selection criteria

x

x

x

x

·        Patient identification and consent

x

x

x

x

·        Use of existing appropriate radiological information

x

x

x

x

·        Alternative techniques

x

x

x

x

·        Clinical evaluation of outcome and duties in relation to the reporting of CBCT images

x

x

x

x

·        Medico-legal issues relevant to CBCT

x

x

x

x

·        Local Rules and Working Procedures specific to CBCT

 

x

x

x

·        Routine inspection and testing of equipment

 

x

x

x

Apparatus and equipment:

Referrer

IRMER

Practitioner

Operator (imaging)

Operator (reporting)

·        Applied potential (kV), tube current (mA) and exposure setting (mAs) - how change affects x-ray quality and quantity and CBCT image quality

 

x

x

x

·        Selection of other image parameters that may influence patient dose

 

x

x

x

·         Relationship of image quality to patient dose

 

x

x

x

CBCT image acquisition and processing:

Referrer

IRMER

Practitioner

Operator (imaging)

Operator (reporting)

·   Principles of CBCT image production

x

x

x

x

·   Imaging detectors for CBCT

 

x

x

x

·  Care of imaging receptors

 

x

x

 

·         CBCT image faults and Quality Assurance

 

x

x

x

·         Data storage and retrieval, and data protection

x

x

x

x

·         Information exchange

x

x

x

x

Principles of CBCT imaging:

Referrer

IRMER

Practitioner

Operator (imaging)

Operator (reporting)

·         Importance of image quality

x

x

x

x

·         Optimisation of viewing conditions

x

x

x

x

·         Use and limitation of CBCT as a diagnostic aid

x

x

x

x

·         Viewing, manipulation and diagnostic pitfalls in 3D imaging

x

x

x

x

·         Knowledge of multiplanar reconstruction and applications

x

x

x

x

 

 

PRACTICAL INSTRUCTION

 

Operators should obtain practical experience in the safe use of CBCT equipment and optimise the exposure by making best use of dose reduction features. An applications specialist from the CBCT manufacturer may best deliver much of this aspect of machine-specific training. Practical instruction will help develop accurate radiography.

IR(ME)R practitioners should ensure they are aware of patient doses arising from the imaging techniques which are available.

 

Techniques

Operators should know the fundamentals of CBCT radiological techniques relevant to dental and maxillofacial imaging and be able to;

  • Advise the patient regarding the practical aspects of the procedure
  • Position the patient and equipment accurately
  • Select and use the most appropriate imaging programmes and correct exposure factors
  • Store and transmit the image data appropriately and in keeping with current legislation
  • Manipulate the 3D image data to allow suitable clinical interpretation of the image

 

Quality assurance for CBCT imaging systems

·      Quality assurance and quality control relevant to CBCT

·      The use of a two-point quality scale with a reject rate target of less than 5%

 

Quality Rating

Target

Diagnostically acceptable

Not less than 95%

Diagnostically unacceptable

Not greater than 5%

 

 

Understand care of patients

·        Children

·        Special care patients

·        Infection control

  • Communication of risks to patients

 

 

 

 

RADIOLOGICAL INTERPRETATION IN THE DENTO-ALVEOLAR REGION

 

Radiological anatomy and an understanding of the image should form part of the updating for any healthcare professional who takes on a role in interpreting and evaluating the CBCT image dataset. Thus referrers, IR(ME)R practitioners and operators (including those who undertake clinical evaluation and report the images) should be familiar with the anatomy of the dento-alveolar region as seen on CBCT images, in order to properly target and evaluate the quality of the examination.

Those making a radiological diagnosis from CBCT images act in an operator (reporting) role - this curriculum is intended to guide the further training of those dentists, doctors and radiologists undertaking this radiological reporting of CBCT images of the dento-alveolar region. It builds on knowledge gained during their undergraduate training, on anatomy and disorders affecting this region.

Note that this curriculum does not include radiological interpretation in areas such as base of skull, temporal bones, neck and spine. If your scans incorporate these regions the European and SEDENTEX Guidelines recommend that these are reported by a radiologist unless the reporting operator has appropriate experience.5,6

 

 

Principles and practice of interpretation of dento-alveolar 3D CBCT images:

Referrer

IR(ME)R

Practitioner

Operator (imaging)

Operator (reporting)

·  Principles of radiological differential diagnosis

 

x

 

x

·  Reporting on cross sectional imaging of the dento-alveolar region - methods and conventions

 

x

 

x

·  Recommendation that reporting of larger volume images covering structures beyond the immediate dento-alveolar region is undertaken by a trained maxillofacial or head and neck radiologist.

x

x

 

x

An update on radiological anatomy of teeth and jaws relevant to CBCT:

 

 

 

 

·  An update on fundamentals of radiological anatomy

x

x

x

x

·  Teeth, periodontium and jaws, including TMJ

x

x

x

x

·  Facial bones and sinuses

x

x

x

x

·  Soft tissue structures and air spaces

x

x

x

x

·  Normal development of teeth and jaws

x

x

x

x

An update on dental and maxillofacial pathology that may include:

Referrer

IRMER

Practitioner

Operator (imaging)

Operator (reporting)

·  Definition of fundamental terms

x

x

x

x

·  Methods of describing radiological lesions

 

x

 

x

·  Understanding the appearances on CBCT imaging of;

 

 

 

 
    • Developmental abnormalities

 

x

 

x
    • Disorders of teeth and periodontium

 

x

 

x
    • Infective disorders, caries and periapical infection within the dento-alveolar region

 

x

 

x

·  Radiological interpretation may also cover;

Referrer

IRMER

Practitioner

Operator (imaging)

Operator (reporting)

·  Localised and spreading infection in the jaws

 

x

 

x

·  Cysts of jaws

 

x

 

x

·  Tumours and tumour-like lesions of the jaws

 

x

 

x

·  Fibro-osseous lesions

 

x

 

x

·  Metabolic disorders of significance in dental practice

 

x

 

x

·  Trauma including fractures     - teeth & facial bones

 

x

 

x

·  Disorders of the maxillary sinuses on dento-alveolar scans

 

x

 

x

·  Disorders of the temporomandibular joints

 

x

 

x

 

 

Both theoretical training and practical instruction are required in order that duty-holders are ‘adequately trained’. The working group recommends that this be undertaken commensurate with the purchase of the CBCT device.

 

Time required

This course could be covered using lectures, practical radiography workshops and/or seminars.  In addition, other teaching styles may also be used such as computer-aided learning, supervised case reporting, and mentoring. The main objective of the course is that the dental personnel should be competent to undertake CBCT radiography, and radiology of the dento-alveolar structures, to a level and standard required for general practice. 

 

 

Theoretical Training:

Radiological Physics, Protection, and Principles of CBCT Imaging

It is suggested that a minimum of 3 hours is sufficient to cover the theoretical knowledge of radiation protection and imaging for the referrer, IR(ME)R practitioner and operator, as outlined in this document.

 

Radiological Interpretation of the dento-alveolar region

A further minimum of 2 hours should be allocated to coverage of interpretation, anatomy and pathology of the teeth and their supporting structures for the IR(ME)R practitioner and operator (reporting). Further supervised reporting of cases is recommended.

 

IR(ME)R Updating and Refresher Courses

It is suggested that at least a further 1 hour of CBCT-related training is required to cover the radiological updating for the referrer, IR(ME)R practitioner and operator as part of their 5 year re-accreditation cycle with the GDC, once initial CBCT training has been completed.

 

Practical Instruction:

It is suggested that staff undertake a minimum of 6 hours in practical training in the use of the specific CBCT machine and in its software. This would be ideally delivered by a trained applications specialist.

 

Tuition

Training of personnel to undertake CBCT radiography should draw on the combined expertise of;

·        A dental & maxillofacial radiologist +/- specialist dental radiographer

·        An applications specialist from the manufacturer of the equipment and

·        A Medical Physics Expert

 

 

 

REFERENCES

1.      The Ionising Radiation (Medical Exposure) Regulations 2000. SI 2000 Number 1059 London: The Stationery Office 2000.

2.      The Ionising Radiation (Medical Exposure) (Amendment) Regulations 2006. Number 2523 London: The Stationery Office Limited.

3.      Core Curriculum in Dental Radiography and Radiology for Undergraduate Dental Students. British Society of Dental & Maxillofacial Radiology (BSDMFR) 2008.

4.      National Radiological Protection Board/Department of Health. Guidance Notes for Dental Practitioners on the Safe Use of X-ray Equipment. Chilton: NRPB 2001. Web link: http://www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1194947310610

5.      Horner K, Islam M, Flygare L, Tsiklakis K, Whaites E. Basic principles for use of dental cone beam computed tomography: consensus guidelines of the European Academy of Dental and Maxillofacial Radiology. Dentomaxillofac Radiol. 2009 May;38(4):187-95.

6.      Radiation Protection: Cone Beam CT for Dental and Maxillofacial Radiology. Provisional guidelines 2009. V1.1 May 2009 SEDENTEXCT Project for the European Commission; www.sedentexct.eu

 

 

 

ACKNOWLEDGEMENTS

This document is based upon the ‘Core Curriculum in Dental Radiography and Radiology for Undergraduate Dental Students’ published by the British Society of Dental and Maxillofacial Radiology (BSDMFR) in 1993 and updated in 2008.