Thick-film planar resistive heating elements by IRC (TT Electronics), Corpus Christi, TX, enable “instant on/instant off” temperature control for sensitive medical applications. The elements are integrated onto a rugged ceramic dielectric glaze, which is directly applied to a stainless steel substrate, resulting in robust heating elements with excellent thermal transfer characteristics. The elements can be designed directly into the medical equipment. Fuses and thermistors can be integrated directly into the heating elements to provide additional over-temperature protection as well as closed-loop feedback control. The thick film-on-steel technology can also be used as an ultra-high power surge resistor. Medical applications include use as a low-pass filter in MRI and CT scanners to improve image definition by suppressing EMI, and as a line load control to reduce power to surgical lasers during idle periods before powering down.