| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 106 === One of the most common complications in the needle biopsy is the hematoma, which is believed to be related to tissue fragmentation. Previous studies suggested that different designs of needle tip geometry used in the biopsy procedure can cause different levels of tissue damage (fragmentation), which is believed to be highly related to tissue bleeding. The purpose of this study is to understand the effect of biopsy needle geometry on tissue damage.
In this study, two major needle tip designs, the lancet and back bevel, are evaluated. The parameter configurations of the lancet tip needle are φ of 15°, 20°, 25° and β of 15°, 30°, 45°. As for back bevel tip, the φ are 15°, 20°, 25°and the β are 105°, 120°, 135°. The rake angles of these needles are calculated to assess the cutting ability. The tissue damage is quantified by measuring the radial stress during the needle insertion. Furthermore, the optimal parameter configurations for minimal radial stresses are investigated, and the relationship between the rake angle and the radial stress is discussed.
We found that the lancet tip needle of φ=25°and β=15°and the back bevel tip needle of φ=25°and β=135°would produce the highest radial stress. For lancet tip needles, a design with a higher rake angle would cause a greater radial stress during the needle insertion. As for back bevel tip needles, a higher transition angle results in a larger rake angle near the needle tip, which would cause greater radial stresses.
In conclusion, the rake angle of a needle can be used to determine the radial stress that would occur in the needle insertion. For the lancet tip needle, the design strategy is to choose a larger rake angle around the needle. As for the back bevel tip needle, it is suggested to choose a higher transition angle.
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