A METHOD OF REDUCING GRATING LOBES ASSOCIATED WITH AN ULTRASOUND LINEAR-PHASE ARRAY INTENDED FOR TRANSRECTAL THERMOTHERAPY

Some practical aspects of planar linear ultrasound phased arrays for t ransrectal thermotherapy of prostate diseases are discussed. Several r egimens for driving the array are investigated and spatial distributio ns of ultrasound intensities are measured in water and compared with c omputer simulations. Practical recommendations for suppressing grating lobes based on the use of subsets of elements and de-activation of se veral elements in the army are given, Treatment safety could be increa sed by adopting these measures since the relative intensities and powe r in grating lobes and other secondary intensity peaks are decreased, as is the overall ultrasound energy introduced into the body without s ignificant reduction in the maximum power at the focus.