A New Model of Thermal Propagation in Human Tissue by Using HIFU   Application
  In outside the body HIFU treatment that focused ultrasound beams hit severely with cancer tissue layer especially the soft one, at the time of passage of the body different layers as long as they want to reach tumor, put their own way components under mechanical and even thermal influence and they can cause skin lesions. To reduce this effect a specific mechanical model can be used that means body tissue is considered as a mechanical model, it is affected when passing sound mechanical waves through it and each layer has an average heat. Gradually sound intensity decreases through every layer passage, finally in one direction a decreased intensity sound reach tumor tissue. If sound propagated directions increase, countless waves with decreased intensity are gathered upon the tumor tissue that causes a lot of heat focus on tumor tissue. Depending on the kind and mechanical properties of the tissue, intensity of each sound wave when it passes through tissue can be controlled to reduce damages outside the tumor tissue. 
Saeed Reza Hajian, Ali Abbaspour Tehrani Fard, Majid Pouladian, Gholam   Reza Hemmasi
physics.med-ph