TU Darmstadt / ULB / TUbiblio

Positioning a Hollow Needle in Soft Tissue

Riad, Matteo :
Positioning a Hollow Needle in Soft Tissue.
TU Darmstadt
[Bachelorarbeit], (2016)

Kurzbeschreibung (Abstract)

This thesis discusses automating a part of a medical procedure called brachytherapy. Brachytherapy is a type of radiation therapy, in which radioactive “seeds” are planted inside the prostate, that destroy the tumour through radiation from the inside. For this procedure, the amount and exact positions of the seeds are firstly calculated using an ultrasonic image of the organ. The operating doctor then positions a hollow needle in each position to then push the seed through it. The designed system will only be used for research purposes in the near future, along with the product of another bachelor thesis, that involves designing a force sensor that can fit on the tip of the needle. The constructed actuator in this thesis has the task of automatically placing the hollow needle with a minimum accuracy of 0.25mm. It is capable of applying a given force, which can be read from an external input signal, or read using an integrated force sensor, that detects the applied force on a haptic control handle. The main problem in this thesis is finding an appropriate method to provide translational motion onto the used needle. Different principles were examined thoroughly, and evaluated individually. Between the finalists, the rack and pinion method and a lead screw drive, the lead screw had advantages and was chosen for this construction. Two guiding shafts assure limiting movement to a single degree of freedom. The used spindle nut is pressed into a moving plate, on which a needle mount is screwed on top. The needle mount holds the needle with a frictional connection. The actuator uses a DC-motor to drive the spindle in the needed direction. An attached incremental encoder measures position of the moving body continuously to give an overview of both speed and position during a whole operation, and facilitates controlling both. The controller of this system is programmed on a microcontroller called an Arduino. The code for the position controller is structured in a cascade control system, in which the outer loop handles the position error and determines the setpoint for the inner velocity controller. The arrangement described above was tested using a built prototype of the concept design, and is indeed capable of achieving the required accuracy in positioning as well as applying the required amount of force onto the needle. This design requires 5V and about 1.5A to function, making it possible to run the whole system off of most USB charging bricks (that provide 2A).

Typ des Eintrags: Bachelorarbeit
Erschienen: 2016
Autor(en): Riad, Matteo
Titel: Positioning a Hollow Needle in Soft Tissue
Sprache: Englisch
Kurzbeschreibung (Abstract):

This thesis discusses automating a part of a medical procedure called brachytherapy. Brachytherapy is a type of radiation therapy, in which radioactive “seeds” are planted inside the prostate, that destroy the tumour through radiation from the inside. For this procedure, the amount and exact positions of the seeds are firstly calculated using an ultrasonic image of the organ. The operating doctor then positions a hollow needle in each position to then push the seed through it. The designed system will only be used for research purposes in the near future, along with the product of another bachelor thesis, that involves designing a force sensor that can fit on the tip of the needle. The constructed actuator in this thesis has the task of automatically placing the hollow needle with a minimum accuracy of 0.25mm. It is capable of applying a given force, which can be read from an external input signal, or read using an integrated force sensor, that detects the applied force on a haptic control handle. The main problem in this thesis is finding an appropriate method to provide translational motion onto the used needle. Different principles were examined thoroughly, and evaluated individually. Between the finalists, the rack and pinion method and a lead screw drive, the lead screw had advantages and was chosen for this construction. Two guiding shafts assure limiting movement to a single degree of freedom. The used spindle nut is pressed into a moving plate, on which a needle mount is screwed on top. The needle mount holds the needle with a frictional connection. The actuator uses a DC-motor to drive the spindle in the needed direction. An attached incremental encoder measures position of the moving body continuously to give an overview of both speed and position during a whole operation, and facilitates controlling both. The controller of this system is programmed on a microcontroller called an Arduino. The code for the position controller is structured in a cascade control system, in which the outer loop handles the position error and determines the setpoint for the inner velocity controller. The arrangement described above was tested using a built prototype of the concept design, and is indeed capable of achieving the required accuracy in positioning as well as applying the required amount of force onto the needle. This design requires 5V and about 1.5A to function, making it possible to run the whole system off of most USB charging bricks (that provide 2A).

Fachbereich(e)/-gebiet(e): 18 Fachbereich Elektrotechnik und Informationstechnik > Institut für Elektromechanische Konstruktionen
18 Fachbereich Elektrotechnik und Informationstechnik > Institut für Elektromechanische Konstruktionen > Mess- und Sensortechnik
Hinterlegungsdatum: 24 Apr 2017 15:10
Gutachter / Prüfer: Kupnik, Prof. Mario ; Hatzfeld, Dr.-Ing. Christian
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