Cancer is an important health problem all over the world. An important approach of fight against cancer is the discovery of novel techniques for treatment. Accurate treatment methods will empower the therapy for the patient. High Intensity Focused Ultrasound (HIFU) which is a noninvasive method in cancer therapy. No cut, no operation and no convalescence are needed. It can be coupled with other cancer therapy techniques as well. HIFU techniques in especially cancer treatment need to be supported by metrological tools in order to establish the safe use of ultrasound. This book clearly gives an idea of caracterisation of transducers traceable to national standards in HIFU system and its effects.