頁籤選單縮合
題名 | Control of Scanned, Focused Ultrasound Hyperthermia Treatments |
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作者 | Lin,Win-li; Wang,C. Y.; Shieh,M. J.; | 書刊名 | 醫學工程 |
卷期 | 4:6 1992.12[民81.12] |
頁次 | 頁30-37 |
分類號 | 410.1644 |
關鍵詞 | Ultrasound; Hyperthermia; Control; Optimization; |
語文 | 英文(English) |
英文摘要 | Maintenance of the treatment temperature at their target levels in the face of disturbances, a uniform temperature distribution within the treatment region, an acceptable temperature rise outside that volume and stability are desirable characteristics of an optimal hyperthermia treatment control system. Since scanned, focused ultrasound systems (SFUS) have a great deal of flexibility it is necessary to use an optimization and control system in shaping the power filed during hyperthermia treatments. For best use of such a system many complicated, interacting decisions must be made to obtain an optimal hyperthermia treatment. This paper studies this optimization problem using a simulation program which searches for the optimal scan parameters, and presents a PID plus bang-bang feedback control system which gives a suitable power distribution to meet the above requirement for this ultrasound hyperthermia system. A comprehensive study of the optimal temperature distribution attainable with single and multiple circular scans of a tumor was done based on a given objective function. The results show that the optimal scan parameter configuration will allow this SFUS to produce a close to ideal treatment temperature distribution for a wide variety of clinically relevant conditions. To further study the variation of the temporal and spatial blood perfusion, a controller was used to obtain a more suitable power to meet the treatment needs. Both the simulation results and in vivo dog thigh experiments show that the controller works well in practice, and verify that it can compensate for spatial and temporal blood perfusion variations. As shown in both these experiments and in simulations, the controller can be sued for controlling a single temperature or multiple temperature points simultaneously, thus allowing relatively uniform temperature fields to be created. |
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