Triangulation of item in patient body

A method of locating an object during a surgery, comprising:

• receiving a model of a portion of a patient's anatomy;
• receiving a surgical plan comprising information about a planned position of an implant within the portion of the patient's anatomy;
• calculating, based on the planned position of the implant and the model, a predicted speed of sound along at least one path that extends at least partially through the portion of the patient's anatomy, the predicted speed of sound being calculated by:
• determining, using the model, which materials lie along the at least one path;
• measuring, within the model, a thickness of each material that lies along the at least one path;
• determining a speed of sound through each material that lies along the at least one path;
• and
• calculating the predicted speed of sound based on the thickness of each material and the speed of sound of each material that lies along the at least one path;
• receiving, from at least three microphones, detection information about a detected sound generated by a speaker secured to the implant;
• and
• determining, based on the predicted speed of sound and the detection information, a position of the implant.

A surgical triangulation system comprising:

• a plurality of microphones configured to be installed in fixed locations about an operating room;
• an emitter configured to be secured to an internal anatomical feature of a patient or an implant, the emitter comprising:
• a speaker;
• and
• a power source;
• at least one processor;
• and
• a memory storing instructions for execution by the at least one processor that, when executed, cause the at least one processor to:
• receive a surgical plan comprising information about a portion of the patient's anatomy;
• receive a model of the portion of the patient's anatomy, the model being generated from one or more preoperative images that include the portion of the patient's anatomy;
• calculate, based on the model, a predicted speed of sound through at least a segment of the portion of the patient's anatomy by:
• determining, using the model, which materials lie along the segment;
• measuring, within the model, a thickness of each material that lies along the segment;
• determining a speed of sound through each material that lies along the segment;
• and
• calculating the predicted speed of sound based on the thickness of each material and the speed of sound of each material that lies along the segment;
• receive, from the plurality of microphones, sound information about a sound detected by the plurality of microphones and generated by the speaker;
• and
• calculate, based on the surgical plan, the predicted speed of sound, the sound information, and information about the fixed locations of the plurality of microphones, a position of the emitter.