Rezaei Mohammad, Khoshgard Karim, Mousavi Mehdi
Sleep Disorders Research Center, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
Department of Medical Physics, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
J Med Signals Sens. 2017 Jul-Sep;7(3):178-184.
Nowadays, high-intensity focused ultrasound (HIFU) as nonionizing radiation is used for cancer treatment. Basically, the function of HIFU is similar to conventional ultrasound. Ultrasound beams are perverted when crossing the border of different environments. This decreases the beam's focus within the tumor and may induce damage to the normal tissues. In this study, we aim to develop appropriate algorithms for correcting the focal point displacement duced by the beam's refraction. First, the level of displacement due to difference in two specific tissues was calculated for one element of the transducer and, then, it extended to all of the elements. Finally, a new focal point was calculated, which is considered as a desired focal point of the transducer in which the maximum temperature occurs. Designed algorithms were implemented in MATLAB software. A HIFU simulator (by the Food and Drug Administration of US) was used to simulate HIFU therapy. The proposed algorithm was tested on four models with two layers of tissue. Results illustrated the use of proposed algorithm results for 78% correction in the focal point displacement. In addition, it was noted that a part of this displacement was caused by the absorption of the beam in the tissues. The proposed algorithm can significantly correct the focal point displacement in HIFU therapy and consequently prevent damage to the normal tissues.
如今，高强度聚焦超声（HIFU）作为一种非电离辐射被用于癌症治疗。基本上，HIFU的功能与传统超声相似。超声束在穿过不同环境边界时会发生畸变。这会降低束在肿瘤内的聚焦程度，并可能对正常组织造成损伤。在本研究中，我们旨在开发合适的算法来校正由束折射引起的焦点位移。首先，针对换能器的一个元件计算由于两种特定组织差异导致的位移水平，然后将其扩展到所有元件。最后，计算出一个新的焦点，该焦点被视为换能器的期望焦点，在该焦点处会出现最高温度。所设计的算法在MATLAB软件中实现。使用一个HIFU模拟器（由美国食品药品监督管理局提供）来模拟HIFU治疗。所提出的算法在具有两层组织的四个模型上进行了测试。结果表明，所提出的算法可使焦点位移校正达78%。此外，还注意到这种位移的一部分是由束在组织中的吸收引起的。所提出的算法能够显著校正HIFU治疗中的焦点位移，从而防止对正常组织的损伤。
