The detection of the acoustic contact between the ultrasound transducer and the external load, is a main issue to consider in the design of the therapeutic ultrasound generating system. It has been reported that it can be obtained a substantial increment in the bandwidth where the detection of the acoustic contact can be implemented, by a method that uses the phase variations of the transducer electric impedance produced by variations of the value of the external acoustic load. This article focuses on the losses that can occur in the therapeutic ultrasound transducer in normal operation or with a deficient acoustic contact with the external load. It was found that the mentioned phase approach can imply in addition to the extended bandwidth, a substantial reduction of the losses that can arise in the transducer. Quantitatively, it was computed that for the phase approach regarding the classic design, the losses are reduced up to 20% and 65% for specific emissions in water and air respectively, for 25 mm diameter PZT-4 transducers working at frequency of 1 MHz.