An apparatus for imposing electric fields through a target region in a body of a patient, the apparatus comprising: at least one transducer array having a plurality of electrode elements configured for placement on the body of the patient, the plurality of electrode elements being configured to provide tumor treating fields (TTFields) via an alternating current waveform; a plurality of first conductors (30; 30a-c; 30a-d; 30a-e; 30a, b); and a plurality of second conductors (30; 30d-f; 30e-h; 30f-i; 30c, d); characterized by: a sensor array (90; 90a; 90b; 90c; 90d) having a plurality of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h) positioned within proximity to the plurality of electrode elements, the pluralities of first and second conductors (30; 30a-f; 30a-h; 30a-i; 30a-d) each having a plurality of temperature sensors connected thereto, and the plurality of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h) comprising a first plurality of temperature sensors connected to the first conductors (30; 30a-c; 30a-d; 30a-e; 30a, b) and a second plurality of temperature sensors connected to the second conductors (30; 30d-f; 30e-h; 30f-i; 30c, d); a circuit configured to provide a known amount of electricity via a selected conductor of the first conductors (30; 30a-c; 30a-d; 30a-e; 30a, b) and a selected conductor of the second conductors (30; 30d-f; 30e-h; 30f-i; 30c, d) to one temperature sensor within the first and second pluralities of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h), and obtain an electrical reading corresponding to a temperature reading of the one temperature sensor; and a controller configured to adjust the alternating current waveform based on the electrical reading. at least one transducer array having a plurality of electrode elements configured for placement on the body of the patient, the plurality of electrode elements being configured to provide tumor treating fields (TTFields) via an alternating current waveform; a plurality of first conductors (30; 30a-c; 30a-d; 30a-e; 30a, b); and a plurality of second conductors (30; 30d-f; 30e-h; 30f-i; 30c, d); characterized by: a sensor array (90; 90a; 90b; 90c; 90d) having a plurality of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h) positioned within proximity to the plurality of electrode elements, the pluralities of first and second conductors (30; 30a-f; 30a-h; 30a-i; 30a-d) each having a plurality of temperature sensors connected thereto, and the plurality of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h) comprising a first plurality of temperature sensors connected to the first conductors (30; 30a-c; 30a-d; 30a-e; 30a, b) and a second plurality of temperature sensors connected to the second conductors (30; 30d-f; 30e-h; 30f-i; 30c, d); a circuit configured to provide a known amount of electricity via a selected conductor of the first conductors (30; 30a-c; 30a-d; 30a-e; 30a, b) and a selected conductor of the second conductors (30; 30d-f; 30e-h; 30f-i; 30c, d) to one temperature sensor within the first and second pluralities of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h), and obtain an electrical reading corresponding to a temperature reading of the one temperature sensor; and a controller configured to adjust the alternating current waveform based on the electrical reading. a sensor array (90; 90a; 90b; 90c; 90d) having a plurality of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h) positioned within proximity to the plurality of electrode elements, the pluralities of first and second conductors (30; 30a-f; 30a-h; 30a-i; 30a-d) each having a plurality of temperature sensors connected thereto, and the plurality of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h) comprising a first plurality of temperature sensors connected to the first conductors (30; 30a-c; 30a-d; 30a-e; 30a, b) and a second plurality of temperature sensors connected to the second conductors (30; 30d-f; 30e-h; 30f-i; 30c, d); a circuit configured to provide a known amount of electricity via a selected conductor of the first conductors (30; 30a-c; 30a-d; 30a-e; 30a, b) and a selected conductor of the second conductors (30; 30d-f; 30e-h; 30f-i; 30c, d) to one temperature sensor within the first and second pluralities of temperature sensors (16; 16a-i; 16a-m; 16a-t; 16a-h), and obtain an electrical reading corresponding to a temperature reading of the one temperature sensor; and a controller configured to adjust the alternating current waveform based on the electrical reading.