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Computed Tomography (CT) is commonly used to locate tumors for biopsy procedures. However, the process is vulnerable to human error. Consequently, robotic design has been implemented to eliminate said human error. Our client feels that the leading design in robotic image guided biopsy is flawed; needle insertion speeds are too slow. Our client believes that patient discomfort, and especially risk to the patient, can be decreased by reducing the amount of time required to execute each biopsy procedure. The goal of our project is to develop a device that is capable of rapidly inserting a biopsy needle, taking a tissue sample, and recovering the needle and sample in an automated sequence.
We developed several ideas within the constraints set that could feasibly drive the needle faster. Evaluation of these ideas allowed us to select a single design: the pneumatic driver. Prototypes have been constructed to test for possible needle deflection during operation; no visible deflection was observed when the needle was inserted into a porcine subject. A solenoid valve has been implemented in order to direct airflow of the pneumatic cylinder, and a spring is being used to eject the needle from the subject. Future work includes automating the system and attaching it to ImageGuide’s robotic arm.
Here is a photo of our design team. From left: Nate Gaeckle, Brian Frederick, Gordy Lawrence, Ryan Augustine
Following successful testing of the pneumatic needle injection phase with our third, and now fourth, prototypes, we have successfully designed a needle capture mechanism. This mechanism has been tested and successfully captured a tissue sample. We have also designed a mechanism within the fourth prototype that retracts the needle well. Additionally, our device is much closer to being fully automated, as we have integrated a solenoid valve to control needle insertion and retraction. As of now the valve is manually turned on and off, but in the future we will be adding a sensor that will automatically turn the solenoid valve off once the needle is fully inserted. A circuit has already been designed to control this sequence and is ready to be built and tested.
A few images and diagrams of our team and some of our work are seen below.
Here is a diagram depicting our Tissue Capture Mechanism at work:
The tissue capture mechanism shown above works as follows: As the piston and needle are fired forward inside the prototype, the pins at the front of the body of the capture mechanism are depressed upon impact with the front of the prototype cylinder. As the pins are depressed they in turn retract the stylet, or internal core of the biopsy needle, allowing a tissue sample to be captured in the hollow space now available in the needle. The mechanism remains like this, holding the tissue sample as the needle is retracted from the body.
Here is a picture of our most recent prototype completely disassembled to show all working parts:
In the image above, the screw, copper cap and hose, wing nut, and acrylic stop block in the top right hand corner are all part of the top assembly that holds the air connection and prototype together. Alongside the large copper cylinder is the real working part of our prototype; the tissue capture mechanism and biopsy needle, as well as the spring that retracts the needle once air pressure is released.
Here is a picture of the solenoid driver circuit that will fully automate our device in the future:
| Week | Reporting Period Beginning | Activities |
|---|---|---|
| 1 | January 21 | Meet with group members and advisor, contacted client, acquired patent application form. |
| 2 | January 28 | Worked on patent application form, new tissue capture mechanism for testing our fourth prototype. |
| 3 | February 4 | Continued work on our patent application, tissue capture mechanism almost complete. |
| 4 | February 11 | Completed tissue capture mechanism. |
| 5 | February 18 | Attempted prototype tests, but were not conducted successfully due to technical difficulties. |
| 6 | February 25 | Designed and built a new prototype cylinder, continued work towards patent application. |
| 7 | March 4 | Finished new prototype, tested it successfully, set up a meeting for next week with a WARF representative and our client. |
| 8 | March 11 | Discussing patent disclosure with Dr. Pozniak |
| 9 | March 18 | Sprink Break |
| 10 | March 25 | Meeting with WARF about patent application, met with Paul Victorey about circuit design to control solenoid coil. |
| 11 | April 1 | Worked on prototypes, began designing poster for BMES poster design competition. |
| 12 | April 8 | Completed poster for BMES poster design competition and Engineering Expo 2005, as well as attended Expo. |
| 13 | April 22 | We now have a rough idea of how the circuitry for automating the control of the solenoid coil will work. |
| 14 | April 29 | Final Presentations, preparing final design deliverables. |
| 15 | May 6 | Turn in final design deliverables and conduct final evaluative meeting with advisor. |
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Mid Semester Presentation - Spring 2005 (Mar 13 2005, 3546 kb) |
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Poster for Engineering Expo 2005 (Apr 28 2005, 2227 kb) |
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Spring 2005 Final Paper with PDS (May 4 2005, 523 kb) |
