Nadobny Jacek, Wlodarczyk Waldemar, Westhoff Lothar, Gellermann Johanna, Rau Beate, Mönich Gerhard, Wust Peter
Center of Radiation Medicine, Campus Virchow-Klinikum, Charité Medical Center, Humboldt University at Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
Med Phys. 2003 Aug;30(8):2052-64. doi: 10.1118/1.1589611.
A novel twelve-channel three-dimensional (3-D) hyperthermia applicator has been developed and evaluated, which consists of twelve separate WAter COated Antenna (WACOA) modules. The modules are arranged in three transversal antenna rings (sub-arrays) and are placed into an acrylic applicator frame as cartridge-like elements in a staggered arrangement. The operating frequency is 100 MHz. For the design of the applicator, the finite-difference time-domain (FDTD) method was used. The applicator's dimensions allow its placement into the gantry of a magnetic resonance (MR) tomograph. The WACOA modules are designed as MR-compatible specially shaped metallic cylindrical dipole structures that are placed into hermetically closed water-filled cassettes. Due to the design of the dipole structures, only a conventional coaxial feed circuitry is needed, and no external impedance matching networks are necessary. Instead, fine on-line impedance matching is realized using adjustable tuning rods and matching rings, both elements being parts of the radiating antenna structure. Experimental and numerical evaluations demonstrate a good stability of impedance matching, a low inter-channel coupling of less than -20 dB, and a good ability of field pattern steering.
一种新型的十二通道三维（3-D）热疗施加器已被开发并评估，它由十二个独立的水涂覆天线（WACOA）模块组成。这些模块排列成三个横向天线环（子阵列），并作为类似盒式的元件以交错排列的方式放置在丙烯酸施加器框架中。工作频率为100 MHz。在施加器的设计中，使用了时域有限差分（FDTD）方法。施加器的尺寸使其能够放置在磁共振（MR）断层扫描仪的机架中。WACOA模块被设计为与MR兼容的特殊形状的金属圆柱形偶极结构，放置在密封的充满水的盒中。由于偶极结构的设计，仅需要传统的同轴馈电电路，不需要外部阻抗匹配网络。相反，使用可调节的调谐棒和匹配环实现精细的在线阻抗匹配，这两个元件都是辐射天线结构的一部分。实验和数值评估表明阻抗匹配具有良好的稳定性，通道间耦合低于-20 dB，并且具有良好的场型控制能力。
