Kaoru Natsume

Active induction of bubble liposome at the bifurcation of in vivo blood vessel with optical measurement and robotic positioning

For active induction of microbubbles to apply for drug delivery, we have reported active control of microbubbles using acoustic radiation force. However, since there was no evidence that in vivo bubbles act as similar as in vitro experiments, we have examined an experiment with in vivo conditions. However, since the position determination to adjust the focal point of ultrasound was in manual, the effect of the active induction of microbubbles was unreliable. Thus we have updated the experimental setup by introducing an optical position sensor and a robotic positioning for active control of in vivo microbubbles. We have prepared and examined the property of bubble liposomes (BLs) to estimate the concentration using brightness variation on an echogram. First we have measured the destruction property of BLs using the experimental setup including a circulation path before applying an in vivo experiment. From the result we are able to estimate the amount of BLs destructed by continuous ultrasound exposure according to maximum sound pressure. Also, we have prepared the parallel link robot, which can hold an ultrasound transducer, with an optical position sensor to enhance the position accuracy. Since the maximum error using the system was 1.19 mm, which is less than the beam width of sound pressure distribution, we regarded the position accuracy using the system is satisfied with the determination of the focal point. In the experiment using a rabbit ear, we have indirectly confirmed the active induction of BLs, where a significant difference in brightness between two paths and the difference of concentration in the induced path was several times higher than that in the other path. We enhanced the accuracy of active induction of in vivo BLs using the robotic system with optical position tracking.

Development of robotic system with optical position sensing for ultrasound theranostics

Ultrasound is widely applied to clinical purpose of not only diagnosis but also therapy. To enhance the accuracy for ultrasound theranostics, precise position control of therapeutic ultrasound source is necessary. Therefore, we propose a robotic system to control a position of an ultrasound therapeutic device based on the therapy plan on echogram. The system consists of ultrasound probe, a robot with the therapeutic device, an optical tracking sensor to integrate the coordinates and positioning software. The system enables the therapeutic device follows to an imaging probe based on a therapeutic plan. In this study, positioning and following control accuracies were evaluated. The results demonstrate the system has a potential for targeting the therapeutic device based on intra-operative planning.

Positioning System of an Ultrasound Therapeutic Device with Consideration with Body Surface Contact

原稿受付 2013 年 12 月 9 日 ∗東京農工大学大学院生物システム応用科学府 ∗Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology ■ 本論文は有用性で評価されました. ■ J-STAGE では本論文の電子付録として動画が閲覧できます. しくは術中に把握した上で,超音波の照射領域を空間的に複数 回制御する必要があるため,治療用超音波トランスデューサ(以 下トランスデューサ)の位置・姿勢を精確に保証することが不 可欠である.治療中の画像モニタリング手法として MRI を用 いたシステム [7] などが研究・臨床段階にあるが,必要とする スペースやコストの問題から導入可能な医療機関は限定される. そのため,超音波治療の優位性を確保するためには,モニタリ ングにも超音波を用いることが望まれる. 超音波画像を用いたナビゲーションとしては,トランスデュー サとプローブの相対的位置関係を三次元グラフィックとして可 視化するシステムが提案されている [8] [9].これらは拡張現実 感(Augmented Reality)を用いてビデオ画像上に断層面位置 などの情報を可視化するシステムであり,前者は穿刺ナビゲー ション,後者は微小気泡誘導のための超音波照射ナビゲーショ ンを目的としている.一方,両者とも手動でナビゲーションに 合わせる必要があるため,位置決め精度は数mmが限界である. また,診断用プローブと HIFUトランスデューサを一体化した 前立腺がんの治療システムも開発・評価されている [10].これ は,標的部位の深度が 30 [mm]程度以下に収まる前立腺ガン治