This package focuses upon “Dosimetry” of CBCT. It is fundamental to radiation protection that the benefits of a procedure using ionizing radiation outweigh the risks; this is incorporated into the relevant European Directive 97/43/Euratom. The limited studies in the literature indicate that the radiation dose achievable with CBCT units is substantially less than conventional CT, but that it varies according to the particular manufacturer's system being assessed. For example, one system may give a dose ten times another for the same examination. Doses are many times greater than those for conventional ‘dental’ examinations. Dose depends upon the size of the volume of the patient imaged and the other selected technique factors.
These studies suffer because they are individually limited to reports related to one or two CBCT systems. More work is needed to verify this limited literature on a greater range of current CBCT systems and without the inter-study variation in measurement methodologies; the planned research will achieve this. Importantly, however, our research will specifically deal with paediatric dosimetry, an area that has not been previously assessed using anatomically appropriate paediatric phantoms. Our research will also develop a robust system of Monte-Carlo dose simulation for CBCT that will facilitate optimisation of exposures.
The overall aim of this work package is to determine the level of (1) patient dose in dental CBCT, paying special attention to paediatric dosimetry, and (2) personnel dose.
These goals correspond to the following sub-objectives:
- To develop a method to readily characterise the dose distribution for different scanners, using measurements simply performed in the field, to allow simple conversion to effective dose.
- To determine the scatter dose distribution around scanners and explore the consequences for operator dose.