The field of view (FOV) in a radiological examination is the volume of the image dataset. In some CBCT machines, this is fixed and there is no scope for matching the FOV to the clinical problem. This means that either the FOV is not large enough to cover the area of interest or that it is too large, leading to unnecessary exposure of areas of the patient that have no relevance to the clinical problem. Many CBCT machines offer a choice of FOV. This is to be preferred as it avoids these problems. There is no uniformity amongst manufacturers in the volume options, so anyone planning to buy a CBCT machine should check to ensure that the available FOV choices suit their practice. For example, in a specialist endodontic practice, it would be sensible to choose a machine that offers small volumes suitable for single tooth imaging. In a hospital department, where maxillofacial procedures (e.g. orthognathic surgery) is performed, a large volume option is worth considering.
FOV may be linked to the resolution options for a CBCT machine. Thus larger FOVs may use a default lower resolution.
The European Academy of Dental and Maxillofacial Radiology established a set of "Basic Principles of dental Cone Beam CT use in 2009. One of these states that: "CBCT equipment should offer a choice of volume sizes and examinations must use the smallest that is compatible with the clinical situation if this provides less radiation dose to the patient" . 1
- 1. 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.
