An ultrasound linear array for use in intracavitary applicators for thermotherapy of prostatic diseases

Ultrasound intracavitary applicators for hyperthermal treatment may offer significant advantages over electromagnetic devices. The authors present specific absorption rate (SAR) distributions produced in a homogeneous medium (attenuation 10Np/m/MHz) by a linear array of 25 planar elements, each 3×15 mm, driven at 500 kHz. Using the pseudo-inverse method to synthesize intensity patterns with a single focus or multiple foci, the authors show that this array has the potential to treat at distances of approximately 20-60 mm and over ±30 mm with respect to the centre-line of the array. Optimisation of array efficiency and intensity distribution and effects of practical details such as inter-element spacing and phase quantization have also been investigated