Work package 3: Optimisation

This work package deals with “Optimisation” of X-ray exposures in CBCT. Under this heading, we can consider two aspects, dose limitation methods through adjustment of exposure parameters, including field volume, and quality assurance procedures.

It is extremely important that radiation exposure should be minimized in radiology, while maintaining diagnostic quality at acceptable levels. In CBCT, a key factor is volume size used. Different systems offer different volume sizes and some offer more options than others. For example the NewTom 9000 (Quantitative radiology, Verona, Italy) has only one volume size, while the NewTom 3G offers three volume size options. This is a key area where dose reduction is achievable, and selection should be matched to the particular clinical need. One area that has been studied, by a partner in this project, is the use of lead shielding on patients as a means of limiting radiation dose. These early results suggest that appropriate thyroid/ cervical lead shielding can offer significant dose reductions. Our research will build on this work and extend it to consider staff protection.

Dental CBCT artefacts have been reported, but there is no published literature dealing specifically with error rates and clinical quality problems of using CBCT units in dentistry. Quality assurance in dental imaging generally is a frequent problem, particularly in primary care away from the more organised quality-driven environment of hospitals. There needs to be clear guidance on quality assurance procedures for CBCT users and this research will develop such guidance. A key element of this is the development of a quality control phantom that can be used for routine testing of equipment by the dentist. A particular feature of this would be a phantom that is simple to use, economically realistic for users to buy and compatible with different CBCT systems. Our research consortium, involving a partner that specialises in the design and manufacture of radiological phantoms and having access to a range of CBCT units, is well placed to deliver such an outcome successfully.


To develop tools for Quality Assurance on CBCT in terms of image quality evaluation and use of dose reduction mechanisms.

  1. To develop, design and test a phantom for QA tests on dental CBCT equipment.
  2. To develop software tools for the evaluation of image quality and for routine QA testing.
  3. To form an Image Quality testing protocol and determine its implementation on CBCT units.
  4. To form and implement a routine QA protocol, for periodic QA tests in daily clinical practice.
  5. To investigate dose reduction techniques for patients and staff (thyroid shields; field of view limitation).