A method of administering subcutaneous treatment to a patient is provided. The method includes delivering, by a needle-free injection device, a first volume of a treatment at a first location on a surface of a body of the patient； detecting a movement of the needle-free injection device relative to the first location； determining, from the movement of the needle-free injection device relative to the first location, a second location of the needle-free injection device relative to the first location； determining a second volume of the treatment to deliver at the surface of the body of the patient at the second location； and delivering, by the needle-free injection device, the second volume of the treatment at the second location on the surface of the body of the patient.
