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Design of a Catheter Measuring Device for Brachytherapy
Welcome to the Home Page for Team 20!
For more details on our Catheter Measuring Device, read "Story Time" below and check out our Final Design page.
Meet the Team!
05/04/17: Check out our Proof of Concept Presentation for initial prototypes and results of the Wire Storage and Friction Drive! (Presented 05/04/17)
04/16/17: Stay tuned for a CAD model of our proposed design! For now, refer to our Design Proposal Presentation to get an idea of what our design could look like. (Presented on 04/13/17)
03/21/17: Check out our Risk Reduction Presentation in which we address potential risks and introduce a possible design solution! (Presented on 03/21/17)
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Demonstration of Catheter Measuring Device
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Story Time
Figure 1: Varian Measurement Ruler, nitinol wire, and clip for manually measuring catheter
length in the brachytherapy procedure
Davey G., a medical physicist, is part of a team that treats cancer using an advanced treatment called brachytherapy. Brachytherapy requires the use of up to 30 thin tubes called catheters, all of which must be measured for length. Davey is presented with 15 catheters which he must measure-- one by one. He begins the procedure of measuring catheter length by inserting a long wire into the catheter until it hits the end. He then places a clip on the wire at the entrance to the catheter, pulls the wire out, and inserts it into a special ruler (Fig. 1). Davey squints at the markings on the ruler and reads off the measurement. Taking the wire out of the special ruler to proceed to the next catheter, Davey thinks to himself, "Did I do that whole thing right?" Doubting himself, Davey repeats the measurement of that same catheter.
Figure 2: Annotated Catheter Measuring Device
On the other hand, with a Catheter Measuring Device...
Step 1: Young S., a medical physicist like Davey G., plugs the catheter into the device and presses the blue lock onto the catheter. (Fig. 2, #1)
Step 2: He then runs the Arduino program using Arduino software and a PC. (In the future, this will be replaced with a button, so no PC is required.)
Young is done for now. Now it's the Catheter Measuring Device's turn!
Step 3: The same wire that was used for the manual measurement of catheters has been stored in a Spool (Fig. 2, #4). A Friction Drive (Fig. 2, #3) drives the wire toward the catheter until it is detected by a sensor which is mounted at the hole in the cylindrical catheter holder (Fig. 2, #2).
Step 4: Once the wire is detected by the sensor, the Friction Drive continues moving the wire forward and the controller starts counting every 0.075 centimeters.
Step 5: The wire continues down the catheter. Once the controller detects that the wire has run into the end of the catheter, it stops counting and displays the sum as the Final Catheter Length measurement (cm) on an LCD.
Step 6: Young reads the measurement off the LCD screen on the device and records it with pen and paper. In the meantime, the wire is retracted into the device and the Friction Drive runs in reverse simultaneously with the running Retraction Motor (Figure 2, #4).
Step 7: The wire passes the sensor signaling to the controller that the wire is now in the device. In response, all motors stop.
Step 8: Young exclaims, "That was easy!", and unplugs the catheter. He then confidently plugs another catheter into the device and repeats.
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What is Brachytherapy?
Brachytherapy (pronounced "bray-kee therapy") is an advanced cancer treatment commonly used to treat prostate and breast cancer. A key component to the treatment is the use of catheters, or tubing widely used in the medical field. During the treatment, multiple catheters are connected to a cancerous tumor region inside the patient. The opposite end of the catheters are connected to a machine called an HDR (High-Dose Radiation) afterloader. By a computer control system, the HDR afterloader sends a wire with a radioactive iridium pellet drilled into the end of it down a number of catheters, one at a time. The radioactive material is successfully transferred through a catheter to the tumor, and the tumor receives a high dose of radiation.
Figure 3: The brachytherapy procedure. The HDR afterloader which carries out the treatment
process is shown at the bottom left. An oncologist is shown connecting the catheters from the
HDR (High-Dose Radiation) afterloader to the patient.
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Why do we need a Catheter Measuring Device?
Accurately measured catheter length is a key parameter in successful brachytherapy, because the computer system of the HDR afterloader, which transfers the radioactive pellet through the catheter to the human body, needs to know where to position the radioactive pellet in the catheter. The desired positions for treatment are determined by the catheter length. Therefore, doctors must measure the length of every catheter and input the measured length value into the HDR afterloader computer.
By the current catheter measuring process, a doctor must manually measure up to 30 catheters-- one at a time! This manual measuring process is time-consuming and could potentially lead to inaccurate measurements resulting in unsuccessful treatment. Doctors, including our sponsors (see Team), want a device that can replace the current manual measuring process with a semi-automated or even fully-automated process. With a device that automates the catheter length measuring process, doctors can save time and further ensure the successful treatment of cancer patients.
Figure 4: Both ends of one "transfer guide tube". The transfer guide tube is one part of what
is considered the catheter. The other part which is connected to the transfer guide tube is
called the "applicator" (not shown).