Abstract: A method of assisting transducer placements on a subject's body for applying tumor treating fields includes: determining, based on one or more images associated with a portion of a subject's body, a first image data, wherein the first image data comprises one or more recommended transducer placement positions; determining, based on the one or more images, a second image data, wherein the second image data comprises one or more transducer placement positions; registering the second image data to the first image data; and generating a composite data comprising the one or more transducer placement positions and the one or more recommended transducer array placement positions.