A controller for determining a shape of an interventional medical device, comprising a memory that stores instructions; and a processor communicatively coupled to the memory storing the instructions, wherein, when executed by the processor, the instructions cause the controller to execute a process comprising: controlling an imaging probe to emit at least one tracking beam to an interventional medical device over a period of time comprising multiple different points of time; determining the shape of the interventional medical device, based on a response to the tracking beams received over the period of time from: a first sensor fixed at a position on a first portion of the interventional medical device that moves along the interventional medical device during the period of time relative to a fixed location on the interventional medical device for the period of time, and a second sensor fixed at the fixed location on a second portion of the interventional medical device; wherein the first sensor moves relative to the second sensor during the period of time, and characterized in that: a path of the movement of the first sensor relative to the second sensor during the period of time is determined by the controller, and wherein the path is used to determine the shape of the interventional medical device. a memory that stores instructions; and a processor communicatively coupled to the memory storing the instructions, wherein, when executed by the processor, the instructions cause the controller to execute a process comprising: controlling an imaging probe to emit at least one tracking beam to an interventional medical device over a period of time comprising multiple different points of time; determining the shape of the interventional medical device, based on a response to the tracking beams received over the period of time from: a first sensor fixed at a position on a first portion of the interventional medical device that moves along the interventional medical device during the period of time relative to a fixed location on the interventional medical device for the period of time, and a second sensor fixed at the fixed location on a second portion of the interventional medical device; wherein the first sensor moves relative to the second sensor during the period of time, and characterized in that: a path of the movement of the first sensor relative to the second sensor during the period of time is determined by the controller, and wherein the path is used to determine the shape of the interventional medical device. controlling an imaging probe to emit at least one tracking beam to an interventional medical device over a period of time comprising multiple different points of time; determining the shape of the interventional medical device, based on a response to the tracking beams received over the period of time from: a first sensor fixed at a position on a first portion of the interventional medical device that moves along the interventional medical device during the period of time relative to a fixed location on the interventional medical device for the period of time, and a second sensor fixed at the fixed location on a second portion of the interventional medical device; wherein the first sensor moves relative to the second sensor during the period of time, and characterized in that: a path of the movement of the first sensor relative to the second sensor during the period of time is determined by the controller, and wherein the path is used to determine the shape of the interventional medical device. a first sensor fixed at a position on a first portion of the interventional medical device that moves along the interventional medical device during the period of time relative to a fixed location on the interventional medical device for the period of time, and a second sensor fixed at the fixed location on a second portion of the interventional medical device; wherein the first sensor moves relative to the second sensor during the period of time, and characterized in that: a path of the movement of the first sensor relative to the second sensor during the period of time is determined by the controller, and wherein the path is used to determine the shape of the interventional medical device.