Is it permissible for a doctor to interrupt his prayer if he becomes aware of an emergency that requires his immediate intervention, given that he is the only doctor on call?

If a doctor begins to pray and is then informed of an emergency requiring his intervention, and there is no one else available, he must interrupt his prayer to save the patient. This is because the patient's life cannot be recovered once lost, whereas the prayer can be made up later. That which would be lost irrevocably is given precedence over that which would not. It is obligatory to interrupt prayer to save an innocent life, just as it is in the case of rescuing a drowning person or averting danger.