Design and realization of a biopsy handtool

Keywords: Biomedical, FNAB (Fine Needle Aspiration Biopsy), Biopsy Handtool In this thesis study, a biopsy handtool was designed for use in fine needle aspiration biopsy. The designed device was supported by TÜBİTAK with the project number 2170269 and title of "Biyopsi El Cihazı Proje Geliştirmesi". Fine-needle aspiration biopsy (FNAB) is the most commonly performed biopsy method, because of the fact that it is necessary to repeat the procedure 10-15% [1] of time due to insufficient materials in current practice, automating the procedure with the help of a machine will be highly beneficial. As the name implies, the location of aspiration in fine needle aspiration biopsy is critical. One of the most important reasons for the differences between practitioners is related to how strong and continuous aspiration can be achieved. For example; there is a difference of effectivity in between a practitioner who can pull the piston through the process and creating negative pressure at the same time, and an applicator who performs aspiration and scraping separately. In FNAB, the main purpose is collecting cells. It is thought that the ability to perform tissue scraping at a constant negative pressure will allow more cell collection. In this case, the three main elements that determine the effectiveness of the FNAB are; sampling from the correct location, needle-punched movements for cell collection and aspiration efficiency. First factor, sampling from the correct locale, is a completely dependent on practitioner and is associated with the effective use of ultrasound image during processing. However, there is a significant difference between the manual procedure and automated FNAB thanks to the use of designed biopsy handtool. Second factor, needle movements, is again dependent on the manually operated movements of the operator and often involves back-and-forth manipulations. Usually practitioner can not perform the rotation movement with his hand. The designed biopsy handpiece is able to perform both forward and backward and rotational manipulations, making a significant difference from the manual method. Third factor, aspiration, is one of the most important step. The practitioner is usually doing this by applying intermittent negative pressures which leads to different applications among the people. For example, there is a significant difference in FNAB activity between a practitioner with greater hand strength and a strong aspiraton capability and a practitioner who can not adequately aspirate. The development of the device at this point to provide continuous aspiration and negative pressure will provide significant contributions to the effectiveness of the FNAB. This machine is basically aimed to ease the cell collection and increasing the cytopathological sufficiency of the sample taken. This machine, which will be used in fine needle aspiration biopsy (FNAB), will aspirate a sufficient number of cells and reduce the need for core needle biopsy (Core-biopsy), which is relatively damaging. With the designed machine, it is aimed to decrease the insufficiency of cell collection by increasing the frequency of tissue scraping while shortening the operation time and decreasing blood accumulation. In addition, when the biopsy handtool requires only for aspiration, the procedure will be more effective and practical. Standardization and control of a manually performed operation by the doctor will increase the feasibility of the operation with one hand. The use of a biopsy handtool device will reduce the amount of effort the doctor is spending, increasing the focus on a single point of concentration and minimizing the cell collection from wrong areas. To explain the working principle of the device, two different drive mechanisms are considered for scraping and aspiration. These drive mechanisms will be initially designed with electric motors and changes in the drive mechanism can be considered by evaluating the size and performance criteria of the device. In the first drive mechanism, circular motion will carry out the engraving process and the second drive mechanism will carry out the aspiration by converting circular motion into linear motion with the electric motor by worm gear. The motors will work with a drive circuit controlled by a control circuit and an adapter is considered as a supply source. Depending on the examination of size and assembly problems of the biopsy handtool after the prototype design, it can be considered to be mobilized with a rechargeable battery. The designed biopsy handtool prototype was composed of 3 units which are electronic unit, embedded system unit and mechanical unit. The electronic unit includes power unit, motor drive, potentiometer unit, buttons and stoppers. The mechanical unit is equipped with motors, impellers and worm and helical gears to help move the syringe. Other systems are controlled by the help of the embedded system unit. During the mechanical design phase; a special gear system, aspiration ring, syringe lid, syringe bed, endless shaft bed, aspirator, syringe stabilizer, lid 1, lid 2 and base were designed. A significant portion of design time is spent for a mechanical solution which can do vertical and horizontal movements altogether. The points that are considered in the assembly of the parts making up the mechanical design and in the efficient operation of the device are as follows; The syringe, which is locked by placing the special wheel system in the hub of the gear, is closed and the device is ready for operation. Diameter of the designed tooth was designed to include the standard 5cc syringe tabs. The gap in the gear is exactly equal to the syringe diameter so that the circular motion can be created without deflection. Syringe rotation from the motor specified for scraping and carving of the device is designed as a gear between the Syringe rotation gear and the rotary gear on one motor reducer for power transmission to the impeller. The single-gear transmission of the motor's power transmission is not achieved because the minimum cross-sectional area of the device is desired and a transferring ring is designed. To explain the electronic card design phase; Power transmission for mechanical movement in the biopsy handtool is provided by two 12V DC Gearmotors. A control and power card is designed on the device in order to control these two motors. In this context, a motor driver card connected to the control card is designed. Motor driver card is controlled by arduino control card. The circuit board on which the card and motor supply of the device are to be inserted contains signals generated by the control buttons on the remote control and circuit systems controling analog signals used for speed control. As a result, the card is made compact by mounting arduino, motor driver and all control connection equipment and power supply input. In this stage, a circuit board is designed to provide the connection between the Arduino and the power circuit (TB6612) and to provide the input of the control input signals and the supply adapter. Embedded System Design phase; the microcontroller selected for transmission of the designed command-to-engine signals to the motor control has been chosen to process both digital and analog signals and to occupy the minimum space within the device. Open source Arduino software and Arduino Pro Mini prototyping card are used. For engine control, the TB6612 motor driver card is preferred and the analog input information from the potentiometers used for determining motor speeds in the control circuit is transmitted through PWM (Pulse Width Modulation) as speed information to the motor board. The device was tested in Ex Vivo experiments. Performance (Ex-Vivo) Evaluation; It has been observed that there is no problem in the rotation and millimeter-scale back and forth movement of the device. Later, aspiration was tried, but no material was seen macroscopically on the needle tip. Even though the same procedure was repeated several times, the material could not be obtained. Then another liver was obtained and the procedure was tried again. However, any material could not be aspirated in the device aspiration. The appropriate material can not be selected besides the minimal blood product on the tip of the needle. During this time, in both liver specimens, the material was aspirated in a conventional manual procedure without a device. During the biopsy, the device was able to rotate and move back and forth properly, but the material could not be pulled during aspiration. This is thought to depend primarily on the fact that the rate of aspiration is very low. It was concluded that rapid and frequent repeated aspiration of the material could be achieved when a biopsy was performed with a 5 cc injector. The device performs rapid and millimetric forward and backward movements in conjunction with rotational movement which can not be done by hand in the manual method, but it can not perform sufficient aspiration. For this reason, it is considered that the next prototype should include especially improvements for aspiration. It was observed that the first prototype of the device could aspire 60 samples of different density liquids. In addition, 55 different experiments were performed on solid structures such as liver and kidney used in ex-vivo experiments; the device was found to be successful in rotation and back-and-forth motion but failed in aspiration. Evaluating the biopsy handtool as a result of the experiments; the device successfully completed aspiration in liquid biopsy. In short; it was concluded that the first prototype obtained in the experiments performed successfully from the above mentioned elements except aspiration and should be developed in the direction of aspiration continuity. As a result of the project, a successful prototype production has been designed.As a result, it is aimed to make the fine needle aspiration biopsy more comfortable for the patient and the doctor with the biopsy handtool that is designed to decrease the number of required fine needle aspiration biopsy procedures, to prevent labor and time losses and to reduce patient traumas due to process repetitions. It is envisaged that increasing multidisiplinary works by increasing the number of works in biomedical systems will significantly contribute high technology production in our country and such concept prototype designs should be supported by the Ministry of Health, where possible, in state hospitals.