E.A.O. guidelines for the use of diagnostic imaging in implant dentistry 2011. A consensus workshop organized by the European Association for Osseointegration at the Medical University of Warsaw.

Diagnostics imaging is an essential component of patient selection and treatment planning in oral rehabilitation by means of osseointegrated implants. In 2002, the EAO produced and published guidelines on the use of diagnostic imaging in implant dentistry. Since that time, there have been significant developments in both the application of cone beam computed tomography as well as in the range of surgical and prosthetic applications that can potentially benefit from its use. However, medical exposure to ionizing radiation must always be justified and result in a net benefit to the patient. The as low a dose as is reasonably achievable principle must also be applied taking into account any alternative techniques that might achieve the same objectives. This paper reports on current EAO recommendations arising from a consensus meeting held at the Medical University of Warsaw (2011) to update these guidelines. Radiological considerations are detailed, including justification and optimization, with a special emphasis on the obligations that arise for those who prescribe or undertake such investigations. The paper pays special attention to clinical indications and radiographic diagnostic considerations as well as to future developments and trends.

Methods for monitoring patient dose in dental radiology.

Different types of X-ray equipment are used in dental radiology, such as intra-oral, panoramic, cephalometric, cone-beam computed tomography (CBCT) and multi-slice computed tomography (MSCT) units. Digital receptors have replaced film and screen-film systems and other technical developments have been made. The radiation doses arising from different types of examination are sparsely documented and often expressed in different radiation quantities. In order to allow the comparison of radiation doses using conventional techniques, i.e. intra-oral, panoramic and cephalometric units, with those obtained using, CBCT or MSCT techniques, the same quantities and units of dose must be used. Dose determination should be straightforward and reproducible, and data should be stored for each image and clinical examination. It is shown here that air kerma-area product (P(KA)) values can be used to monitor the radiation doses used in all types of dental examinations including CBCT and MSCT. However, for the CBCT and MSCT techniques, the methods for the estimation of dose must be more thoroughly investigated. The values recorded can be used to determine the diagnostic standard doses and to set diagnostic reference levels for each type of clinical examination and equipment used. It should also be possible to use these values for the estimation and documentation of organ or effective doses.

Methods of determining the effective dose in dental radiology.

A wide variety of X-ray equipment is used today in dental radiology, including intra-oral, orthopantomographic, cephalometric, cone-beam computed tomography (CBCT) and computed tomography (CT). This raises the question of how the radiation risks resulting from different kinds of examinations should be compared. The risk to the patient is usually expressed in terms of effective dose. However, it is difficult to determine its reliability, and it is difficult to make comparisons, especially when different modalities are used. The classification of the new CBCT units is also problematic as they are sometimes classified as CT units. This will lead to problems in choosing the best dosimetric method, especially when the examination geometry resembles more on an ordinary orthopantomographic examination, as the axis of rotation is not at the centre of the patient, and small radiation field sizes are used. The purpose of this study was to present different methods for the estimation of the effective dose from the equipment currently used in dental radiology, and to discuss their limitations. The methods are compared based on commonly used measurable and computable dose quantities, and their reliability in the estimation of the effective dose.

Estimation of dose to the unborn child at diagnostic X-ray examinations based on data registered in RIS/PACS.

The aim of this work was to determine mean absorbed doses to the unborn child in common conventional X-ray and computed tomography (CT) examinations and to find an approach for estimating foetal dose based on data registered in the Radiological Information System/Picture Archive and Communication System (RIS/PACS). The kerma-area product (KAP) and CT dose index (CTDI(vol)) in common examinations were registered using a human-shaped female dosimetry phantom. Foetal doses, D(f), were measured using thermoluminescent dosimeters placed inside the phantom and compared with calculated values. Measured foetal doses were given in relation to the KAP and the CTDI(vol) values, respectively. Conversion factor D(f)/KAP varies between 0.01 and 3.8 mGy/Gycm(2), depending on primary beam position, foetus age and beam quality (tube voltage and filtration). Conversion factors D(f)/CTDI(vol) are in the range 0.02 - 1.2 mGy/mGy, in which the foetus is outside or within the primary beam. We conclude that dose conversion factors based on KAP or CTDI(vol) values automatically generated by the RIS/PACS system can be used for rapid estimations of foetal dose for common examination techniques.

Measurement of radiation dose in dental radiology.

Patient dose audit is an important tool for quality control and it is important to have a well-defined and easy to use method for dose measurements. In dental radiology, the most commonly used dose parameters for the setting of diagnostic reference levels (DRLs) are the entrance surface air kerma (ESAK) for intraoral examinations and dose width product (DWP) for panoramic examinations. DWP is the air kerma at the front side of the secondary collimator integrated over the collimator width and an exposure cycle. ESAK or DWP is usually measured in the absence of the patient but with the same settings of tube voltage (kV), tube current (mA) and exposure time as with the patient present. Neither of these methods is easy to use, and, in addition, DWP is not a risk related quantity. A better method of monitoring patient dose would be to use a dose area product (DAP) meter for all types of dental examinations. In this study, measurements with a DAP meter are reported for intraoral and panoramic examinations. The DWP is also measured with a pencil ionisation chamber and the product of DWP and the height H (DWP x H) of the secondary collimator (measured using film) was compared to DAP. The results show that it is feasible to measure DAP using a DAP meter for both intraoral and panoramic examinations. The DAP is therefore recommended for the setting of DRLs.

Dose and image quality in the comparison of analogue and digital techniques in paediatric urology examinations.

In paediatric radiology it has been recognised that children have a higher risk of developing cancer from the irradiation than adults (two to three times); therefore, increased attention has been directed towards the dose to the patient. In this study the effect on patient dose and image quality in replacing the exposure in micturating cystourethrography (MCUG) examinations with the stored fluoroscopy image has been investigated. In the intravenous urography (IVU) examination we compared analogue and digital image quality, but the dose measurements were performed on a phantom. Standard clinical X-ray equipment was used. Sixty-eight patients in each of two centres were studied for the MCUG. Doses were measured with a dose-area product (DAP) meter and the image quality was scored. A non-parametric statistical analysis was performed. For the IVU, a phantom was used in the dose measurements but clinical images were scored in the comparison between analogue and digital images. For the MCUG, replacing the exposure with stored fluoroscopy images lowered the DAP value from 0.77 to 0.50 Gy cm2. The image quality did not show any difference between the techniques; however, if reflux was to be graded, exposure was needed. For the IVU, the doses could be lowered by a factor of 3 using digital techniques. The image quality showed no statistical difference between the two techniques. There is a potential for a substantial dose reduction in both MUCG and IVU examinations using digital techniques.