DIMITRA paediatric skull phantoms: development of age-specific paediatric models for dentomaxillofacial radiology research.

OBJECTIVES: This report aims to describe the development of age-specific phantoms for use in paediatric dentomaxillofacial radiology research. These phantoms are denoted DIMITRA paediatric skull phantoms as these have been primarily developed and validated for the DIMITRA European research project (Dentomaxillofacial paediatric imaging: an investigation towards low-dose radiation induced risks).

METHODS: To create the DIMITRA paediatric phantoms, six human paediatric skulls with estimated ages ranging between 4 and 10 years- old were selected, protected with non-radiopaque tape and immersed in melted Mix-D soft tissue equivalent material, by means of a careful procedure (layer-by-layer). Mandibles were immersed separately and a Mix-D tongue model was also created. For validation purposes, the resulting paediatric phantoms were scanned using a cone-beam CT unit with different exposure parameter settings.

RESULTS: Preliminary images deriving from all scans were evaluated by two dentomaxillofacial radiologists, to check for air bubbles, artefacts and inhomogeneities of the Mix-D and a potential effect on the visualization of the jaw bone. Only skulls presenting perfect alignment of Mix-D surrounding the bone surfaces with adequate and realistic soft tissue thickness density were accepted.

CONCLUSIONS: The DIMITRA anthropomorphic phantoms can yield clinically equivalent images for optimization studies in dentomaxillofacial research. In addition, the layer-by-layer technique proved to be practical and reproducible, as long as recommendations are carefully followed.