Curvilinear transurethral ultrasound applicator for selective prostate thermal therapy
Curvilinear transurethral ultrasound applicator for selective prostate thermal therapy
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DOI：
10.1118/1.1924314
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发表时间：
2005-06-01
期刊：
影响因子：
3.8
通讯作者：
Bouley, DM
中科院分区：
文献类型：
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作者：
Ross, AB;Diederich, CJ;Bouley, DM
热疗为治疗良性前列腺增生（BPH）和局限性前列腺癌提供了一种微创选择。在这项研究中，我们研究了一种经尿道超声应用器设计，利用曲线或轻微聚焦的换能器来快速和可控地加热前列腺组织。涂抹器由两个独立供电的换能器组成，工作频率为6.5 MHz，测量时间为3.5 min X 10 min，短轴曲率半径为15 min。通过声效率测量、声束图、人体前列腺的生物热模拟、牛肝脏的体外加热试验和犬前列腺的体内加热试验（n=3）对该曲线应用器进行了表征。研究发现，每个换能器段都能发出窄声束（最大宽度< 3毫米），这延长了换能器的长度，比以前开发的平面或扇形管状经尿道超声应用器具有更深的穿透性。人体前列腺的声学和生物热模拟证明了曲线涂抹器的三种治疗方案：单次射击（10 W, 60 s）方案产生狭窄的消融区域（13 X 4 mm，病变边界52°C），增量旋转（10 W， 10度/45 s）产生更大的扇形消融区域（16分钟X 180度扇区），以及可变超声时间旋转（10 W， 10度/15-90 s）使消融区域符合预定义的边界（9 - 17 mm X 180度扇区，总治疗时间13分钟）。在犬前列腺实验中，在MR温度成像的引导下，单次超声（6 W/传感器，2-3分钟）与曲线涂抹器消融20度的组织切片至前列腺边界（9-15 mm）。多次相邻超声（“扫描”）消融前列腺大切片（180度），使用磁共振温度成像，每10度旋转调整功率（4-6.4 W/换能器）和超声时间（30-180秒），使前列腺周围在下一次旋转前达到52摄氏度。本研究的结论是，当与图像引导相结合时，曲线涂抹器产生窄而穿透的超声束，可以通过小步旋转同时动态调整每个位置的净施加功率和超声时间，为具有轮廓外边界的目标区域（如前列腺囊）提供精确的消融技术。(c) 2005年美国医学物理学家协会。
Thermal therapy offers a minimally invasive option for treating benign prostatic hyperplasia (BPH) and localized prostate cancer. In this study we investigated a transurethral ultrasound applicator design utilizing curvilinear, or slightly focused, transducers to heat prostatic tissue rapidly and controllably. The applicator was constructed with two independently powered transducer segments operating at 6.5 MHz and measuring 3.5 min X 10 min with a 15 min radius of curvature across the short axis. The curvilinear applicator was characterized by acoustic efficiency measurements, acoustic beam plots, biothermal simulations of human prostate, ex vivo heating trials in bovine liver, and in vivo heating trials in canine prostate (n=3). Each transducer segment was found to emit a narrow acoustic beam (max width < 3 mm), which extended the length of the transducer, with deeper penetration than previously developed planar or sectored tubular transurethral ultrasound applicators. Acoustic and biothermal simulations of human prostate demonstrated three treatment schemes for the curvilinear applicator: single shot (10 W, 60 s) schemes to generate narrow ablation zones (13 X 4 mm, 52 degrees C at the lesion boundary), incremental rotation (10 W, 10 degrees /45 s) to generate larger sector-shaped ablation zones (16 min X 180 degrees sector), and rotation with variable sonication times (10 W, 10 degrees/15-90 s) to conform the ablation zone to a predefined boundary (9 - 17 mm X 180 degrees sector, 13 min total treatment time). During in vivo canine prostate experiments, guided by MR temperature imaging, single shot sonications (6 W/transducer, 2-3 min) with the curvilinear applicator ablated 20 degrees sections of tissue to the prostate boundary (9-15 mm). Multiple adjacent sonications ("sweeping") ablated large sections of the prostate (180 degrees) by using the MR temperature imaging to adjust the power (4-6.4 W/transducer) and sonication time (30-180 s) at each 10 degrees rotation such that the periphery of the prostate reached 52 degrees C before the next rotation. The conclusion of this study was that the curvilinear applicator produces a narrow and penetrating ultrasound beam that, when combined with image guidance, can provide a precise technique for ablating target regions with a contoured outer boundary, such as the prostate capsule, by rotating in small steps while dynamically adjusting the net applied electrical power and sonication time at each position. (c) 2005 American Association of Physicists in Medicine.