OPTIMISATION OF A PAEDIATRIC CT BRAIN PROTOCOL: A FIGURE-OF-MERIT APPROACH.

Paediatric head computed tomography (CT) dose optimisation was carried out using three figure-of-merits (FOMs), based on tube voltage, current, noise, volumetric computed tomography dose index (CTDIvol) and contrast-to-noise ratio (CNR). FOM1: spatial resolution and total minimum contrast level (N) against CTDIvol; FOM2: noise against CTDIvol; FOM3: CNR against CTDIvol. Stage 1: Application of FOM1 and FOM2 on a Catphan without current modulation. Stage 2: CTDIvol and noise assessed on an anthropomorphic phantom with current modulation. Stage 3: All FOMs applied to Catphan images acquired with current modulation. Results indicated no single test case outperformed the current protocol (100 kVp, 200 mA) in all FOMs. Some test cases offered a reduction in dose at the cost of higher noise. The 120-kVp, 100-mA combination offered good compromise between dose and noise. Further investigation is required to determine whether this protocol could be added for procedures where higher noise is acceptable (e.g. craniosynostosis).