Novák Petr, Moros Eduardo G, Straube William L, Myerson Robert J
Department of Radiation Oncology, Washington University School of Medicine, St Louis, Missouri 63108, USA.
Med Phys. 2005 Jan;32(1):230-40. doi: 10.1118/1.1835572.
A new ultrasound applicator with three-dimensional power distribution control was developed for simultaneous thermoradiotherapy. The system was named SURLAS for Scanning Ultrasound Reflector Linear Arrays System. In this paper, the hardware of the first clinical grade SURLAS applicator is described with emphasis on clinically important static acoustic characteristics and on construction aspects not reported before. Functionally, the SURLAS applicator consists of two parallel opposed ultrasound linear arrays aiming their acoustic beams to a V-shape scanning ultrasound reflector, which deflects the beams coming from opposite directions toward the treatment area. The reciprocating motion of the reflector in-between the arrays spreads the ultrasonic energy over the target area scanned. Control of power deposition over the 16 cm by 16 cm treatment window area is achieved by adjusting the power input into the transducer elements of the arrays as a function of the position of the scanning reflector. Furthermore, the arrays operate at significantly different frequencies (1.9 and 4.9 MHz) so that intensity modulation of beams of different frequencies can be exploited to adjust the depth of energy penetration. With this design, external electron or photon beams can be concurrently delivered with hyperthermia by irradiating through the applicator's body. Safety features were implemented into the applicator's design to monitor its performance during operation. A detailed description of the applicator including impedance matching circuits/filters, radiation force balance power measurements, hydrophone pressure field distribution measurements, as well as safety test results are reported.
为实现同步热放疗，研发了一种具有三维功率分布控制功能的新型超声换能器。该系统被命名为SURLAS，即扫描超声反射器线性阵列系统。本文介绍了首个临床级SURLAS换能器的硬件，重点阐述了临床上重要的静态声学特性以及此前未报道的结构方面。从功能上讲，SURLAS换能器由两个平行相对的超声线性阵列组成，它们将声束对准一个V形扫描超声反射器，该反射器将来自相反方向的声束偏转到治疗区域。反射器在阵列之间的往复运动将超声能量散布在扫描的目标区域上。通过根据扫描反射器的位置调整输入到阵列换能器元件中的功率，可实现对16厘米×16厘米治疗窗口区域内功率沉积的控制。此外，阵列以显著不同的频率（1.9和4.9兆赫）运行，因此可以利用不同频率声束的强度调制来调整能量穿透深度。通过这种设计，外部电子束或光子束可以通过照射换能器主体与热疗同时进行。在换能器设计中加入了安全特性，以监测其运行期间的性能。报告了换能器的详细描述，包括阻抗匹配电路/滤波器、辐射力平衡功率测量、水听器压力场分布测量以及安全测试结果。
