Recent developments in simulation technology have expanded clinical use of hyperthermia treatment planning (HTP). HTP involves simulation of 1) the induced power absorption and 2) the induced temperature elevation distribution. Specifically the electromagnetic (EM) simulators have evolved into reliable tools providing accurate predictions of the absorbed power distributions applied during radiofrequency (RF) hyperthermia (HT). Such simulation tools are imperative for optimizing the energy delivery by phased array applicators with over four independent antennas. Consequently, HTP is currently being utilized in the clinic before, and during, deep-regional HT. For deep-local HT this strategy has even stronger potential but, due to steep thermal gradients, also more stringent quality requirements. In this paper, we exemplify the clinical implementation process for planning guided HT using phased-Array HT applicators by reporting the steps taken for the HYPERcollar, a head and neck HT applicator. Besides treatment guidance, HTP allows applicator development, investigations into improved heating strategies and detailed assessment of confounding influences. In this way, treatment quality can been assessed and improved offline making HTP an inevitible tool in the improvement of deep-local HT when aiming at target conformal heat delivery.