Ghidurile Europene pentru CBCT - partea I

RADIATION PROTECTION: CONE BEAM CT FOR DENTAL AND MAXILLOFACIAL RADIOLOGY
Evidence based guidelines , a report prepared by the SEDENTEXCT project 2011

www.sedentexct.eu

 

The SEDENTEXCT project (2008-2011) is supported by The Seventh Framework Programme of the European Atomic Energy Community (Euratom) for nuclear research and training activities (2007 to 2011) http://cordis.europa.eu/fp7/euratom/.

Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use that might be made of the following information. The views expressed in this publication/document/guidelines are the sole responsibility of the author and do not necessarily reflect the views of the European Commission.

PREFACE 

SEDENTEXCT was a collaborative project that aimed to acquire key information necessary for sound and scientifically based clinical use of Cone Beam Computed Tomography (CBCT) in dental and maxillofacial imaging. In order that safety and efficacy are assured and enhanced in the “real world”, a parallel aim was to use this information to develop evidence-based guidelines dealing with justification, optimisation and referral criteria for users of dental CBCT. The aim of this document is to provide such evidence-based guidelines to professional groups involved with CBCT in dental and maxillofacial imaging, including:

• Dental and Maxillofacial Radiologists
• Dentists working in primary care and their assistants
• Radiographers/ Imaging technicians
• Medical Physicists
• Equipment manufacturers and suppliers

The core guidance in preparing the document has been from the two relevant Council Directives of the European Union:

• Directive 96/29/Euratom, of 13 May 1996, laying down the basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionising radiation (Basic Safety Standards Directive)

• Directive 97/43/Euratom, of 3 June 1997, on health protection of individuals against the dangers of ionising radiation in relation to medical exposure (Medical Exposures Directive).

Beyond these sources, the detailed guidelines have been prepared by systematic review of the currently available literature. No exposure to X-rays can be regarded as completely free of risk, so the use of dental CBCT by practitioners implies a responsibility to ensure appropriate protection. 

This document supersedes the Provisional Guideline document published in May 2009, incorporating new research, including work carried out within the SEDENTEXT project itself. 

Guidelines are not a rigid constraint on clinical practice. Local variations will be required according to national legislation, healthcare provision and practice and the unique clinical circumstances of patients.

I hope that the document will be of help to professional groups and contribute to optimizing the use of ionizing radiation in dental imaging. 

K. HORNER

SEDENTEXCT project Co-ordinator

Ghidurile Europene pentru CBCT - partea a II - a

2: RADIATION DOSE AND RISK

2.1: X-rays

X-rays are a type of electromagnetic (EM) radiation. EM radiation also includes visible light, radio waves, microwaves, cosmic radiation, and several other varieties of “rays”. All can be considered as “packets” of energy, called photons, which have wave properties, most importantly a wavelength and frequency. EM radiation can vary in wavelength from 10-13 to 103 m with X-rays having a small wavelength of 10-9 to 10-13m. The importance of this is that small wavelengths mean high energy, deeper penetration though matter and high energy transfer to the matter. When X-rays hit atoms this energy can be transferred, producing ionisation of atoms. Other examples of ionising radiation are alpha, beta and gamma radiation, which are mostly associated with the decay of radioactive materials. All ionising radiations have the capability cause harm to the organs and tissues of the body of exposed persons.

2.2: Radiation damage

When patients undergo X-ray examinations, millions of photons pass through their bodies. These can damage any molecule by ionisation, but damage to the DNA in the chromosomes is of particular importance. Most DNA damage is repaired immediately, but rarely a portion of a chromosome may be permanently altered (a mutation). This may lead ultimately to the formation of a tumour. The latent period between exposure to X-rays and the clinical diagnosis of a tumour may be many years. The risk of a tumour being produced by a particular X-ray dose can be estimated; therefore, knowledge of the doses received by radiological techniques is important. While doses and risks for dental radiology are small, a number of epidemiological studies have provided some limited evidence of an increased risk of brain (Longstreth et al, 1993; Preston-Martin & White, 1990), salivary gland (Preston-Martin & White, 1990; Horn-Ross et al, 1997) and thyroid (Hallquist et al, 1994; Wingren et al, 1997; Memon et al, 2010) tumours for dental radiography.