The effective dose for a typical dental cone beam CT depends on the tube voltage, mAs, field of view and location of field of view with respect to radiosensitive organs.
Could you please let us know which dental cone beam CT machine (manufacturer and model) you are using?
Could you also let us know what are the typical b) fields of view c) tube voltage d) mAs and e) clinical protocols that you are using for a ten year old and an adolescent patient?
For the Scanora 3D, we used to scan all patients using the same protocol: 100x75mm, 85 kV, 30 mAs. This was the lowest dose protocol available (there is & 60x60mm FOV as well but this has higher mAs). Reinhilde repeatedly asked the manufacturer to implement a lower dose protocol for children, and this week it has been installed. The mA can now go down to 4, which would lead to 15 mAs for this 100x75mm FOV. We are still clinically evaluating the new protocols to find out which is the optimal setting for children.
For the Accuitomo 170, a FOV of 6x6cm is typically selected for children. Depending on the age, either a 180° or hi-speed scan or a combination of both is used. We do not (yet) lower the kV or mA for children, we keep them at the standard values of 90 kV, 5 mA.
For the Galileos, kV (85) and FOV (15x15cm) are fixed but the mAs can be selected based on patient size. For children, 10 or 14 mAs can be selected, for adolescents and adults it can be 21 or 28 mAs, depending on patient size.
Note that we usually don't consider adolescent to be much different from adults, especially 16-year old males usually have similar (or even greater) size and mass as adult women or even men.