A method of reducing grating lobes associated with an ultrasound linear phased array intended for transrectal thermotherapy

Some practical aspects of planar linear ultrasound phased arrays for transrectal thermotherapy of prostate diseases are discussed. Several regimens for driving the array are investigated and spatial distributions of ultrasound intensities are measured in water and compared with computer simulations. Practical recommendations for suppressing grating lobes based on the use of subsets of elements and de-activation of several elements in the array are given. Treatment safety could be increased by adopting these measures since the relative intensities and power in grating lobes and other secondary intensity peaks are decreased, as is the overall ultrasound energy introduced into the body without significant reduction in the maximum power at the focus.