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Effect of system parameters on target motion

Vos, Peter-Jan (2013) Effect of system parameters on target motion.

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Abstract:Breast cancer is the most common cancer, comprising 22.9% of all cancer cases in women. Early detection is of key importance for effective treatment. Small breast lesions are increasingly detected by medical imaging modalities. A biopsy of lesions is required to make a definitive diagnosis. During the biopsy, displacement of the target (lesion) occurs as the needle indents and punctures the skin layer and penetrates further into the breast soft tissue. The target motion makes it harder to reach the target. In this study, the effect of system parameters on target motion during flexible needle insertion is investigated in chicken breast. Target motion is measured using a target tracking algorithm when a bevel-tipped needle is inserted into chicken breast tissue. Then the effects of different parameters on target motion in chicken breast are tested. The tested parameters include skin thickness, insertion velocity, insertion depth, bevel angle, target size and needle diameter. These will be investigated to improve the accuracy of the steering process. The conducted experiments show that increasing target distance or insertion speed decreases the displacement of the target, while increasing the needle diameter or skin thickness increases the target displacement. Increasing the insertion speed from 1 mm/s by 400% decreases target movement by 37%, while increasing the speed a tenfold will decrease target movement by 86%. Doubling the needle diameter from 0.5 mm increases target movement four times. Adding a 0.6 mm skin layer will double target movement, while adding two skin layers will quadruple it. Increasing the target distance will slightly decrease target movement and doubling the target distance will lower the target movement by 10%. Increasing the distance by four times from 1 cm to 4 cm will halve the target displacement. Target displacement is unaffected by target size and bevel angle in the tested range. The main cause of errors in the experimental data is the inhomogeneous nature of the chicken breast. Another factor is the difference in elasticity between chicken breast samples. These effects account for the differences in magnitude of the displacement between the experiments, but do not influence the trends. The study also shows that it is possible to steer towards a virtual target inside a biological tissue if the tissue is submerged in gelatine. The gelatine is required to allow a bevel-tipped needle to be steered. The results of this study can be used to improve target motion models and consequently needle steering accuracy.
Item Type:Essay (Bachelor)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering BSc (56953)
Link to this item:http://purl.utwente.nl/essays/62653
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