Bone sonometry, densitometry and imaging

A bone sonometer or densitometer or small C-arm having a card reader that requires a charge to a card in order to carry out a patient examination but not procedures that may be similar or even identical to a patient examination from the machine's point of view, such as calibration procedures involving the use of phantoms. The card can be rejuvenated locally or from a remote location, via a communication link. Instead of a card, remote per-use authorization can be provided upon making a charge. In the case of a small C-arm, the card can keep track of radiation dosage to a user associated therewith.