曲線陣列探頭掃描之超音波影像橫向解析度及精確度：假體模型檢測研究

Identifying Lateral Resolution and Accuracy of Ultrasonography with a Curvilinear Array Transducer: A Phantom Study

蔡世瑩(Shih-Ying Tsai) ； 朱美滿(Mai-Mang Chu) ； 柴惠敏(Huei-Ming Chai) ； 王淑芬(Shwu-Fen Wang)

《物理治療》 41卷4期 (2016/12) Pp. 264-270

https://doi.org/10.6215/FJPT.PTS1450148152

摘要

背景：不同頻率的超音波探頭之解析度不同，曲線陣列探頭可吻合枕骨下緣至頸部的弧度，有潛力用於測量枕骨與頸椎之距離。因此筆者欲探討腹部超音波常用之2～5 MHz曲線陣列探頭掃瞄影像之橫向解析度，作為進一步使用此工具的基礎。目的：檢測2～5 MHz曲線型探頭於自製假體模型之解析度。並以此探頭及游標卡尺測量一標準長方體塑膠物，比較測量結果之差異。實驗方法：自製的假體系統，以7根石墨棒(直徑為0.5 mm)兩兩相隔不同之距離(0.5, 1, 2, 3, 4, 5mm)，測試探頭在深度1 cm與3 cm之橫向解析度，再使用超音波測量一塑膠立方體在探頭下6個不同位置時的長度，比較超音波測量結果與游標卡尺測量結果之差異。結果：當假體模型置於1 cm及3 cm深處時，兩根石墨棒距離相距1 mm及以上時，才可以肉眼清楚辨識超音波影像中有兩根石墨棒。使用超音波量得之假體模型長度與游標卡尺量得長度差異小於0.65 mm，量測誤差小於2%。結論：可採用2～5 MHz曲線型探頭來測量大於1 mm之距離。生物體的距離大於此解析度，將可運用超音波影像量測。

關鍵字

超音波影像 ； 橫向解析度 ； 超音波

並列摘要

Background: The curvilinear probe with lower frequency (2 ~ 5 MHz) provides much poor resolution than the linear probe with higher frequency (7 ~ 12 MHz). A 2 ~ 5 MHz curvilinear array transducer which commonly used in abdominal scanning is relatively suitable for measuring the distance of an object with a curvy surface. Its shape fits the curvature of the spine, and has potential to measure the segmental distance between occipital bone and vertebrae. Before adapting this new measurement method for segmental bony distance, the lateral resolution and accuracy of a curvilinear array transducer need to be tested. Purposes: To evaluate the lateral resolution and accuracy of the ultrasonography with a 2 ~ 5 MHz curvilinear array transducer using a designed phantom system. Methods: Seven fine graphite sticks (diameter: 0.5 mm) were placed in a row at a difference distance of 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm at bottom of a tank filled with water. The graphite phantom system was placed 1 cm and 3 cm below a 2 ~ 5 MHz curvilinear array transducer to study the lateral resolution. A plastic phantom was placed in 6 different positions under the probe. The lengths of this plastic phantom those measured by curvilinear probe. The measurements from ultrasonography and Vernier calliper were compared. Results: Using the ultrasound scanning images obtained from 2 ~ 5 MHz curvilinear array transducer, it is unable to identify two objects with interval of 0.5mm at the depth of 1 or 3 cm. While the interval was larger than 1 mm, the ultrasound image of two graphite sticks could be identified. The difference of phantom lengths obtained from 2 ~ 5 MHz curvilinear array transducer and Vernier caliper is less than 0.65 mm, the measurement tolerance is less than 2%. Conclusions: Distance larger than 1mm can be identified by using the ultrasound scanning images obtained from 2 ~ 5 MHz curvilinear array transducer. Ultrasound image could be a potential tool for measurement of the segmental bony distance.

並列關鍵字

Ultrasound imaging ； Lateral resolution ； Ultrasound transducer