Designing an anal probe

December 24, 2008

If someone offered to pay you to design an anal probe, would you do it? I once made the decision to, and my life was never the same again. It turned out to be a very interesting project with a lot of mechanical challenges, and by the time my prostate turns 50, hopefully that work will have meant something. “How about some details?”, you ask. Just a second.

Since I design a lot of medical devices at Key Tech, there are definitely going to be projects coming across my desk that might make some people squirm. It certainly made me, at first, but this was not to be my last work in anal probes. I have since worked on the design of an endoscopic tool to treat hemmorhoids and other lesions using infrared coagulation, and I even got to see a couple of relevant procedures performed. I don’t mind designing a device to be inserted into the rectum, stick needles into the brain, or palpate an eyeball, and I always appreciate the chance to observe a real medical procedure. Maybe I have a little bit of morbid curiosity. Yes, I do, but I am also happy to work on cool stuff.

Now, without getting too graphic, a few project details.

Fabricated prototype of the helical transrectal needle insertion device

Fabricated prototype of the helical transrectal needle insertion device for prostate brachytherapy

In grad school, I designed a device that, using trans-rectal ultrasound imaging, could insert a needle through the rectum and into the prostate for the purpose of implanting radioactive “seeds” that kill the cancerous tissue. This procedure, known as brachytherapy, is normally done through the perineum. It’s painful because of a dense cluster of nerves at the site and not very accurate because of the much longer distance between the controlled insertion point and the target location. Our (myself and my advisors) hypothesis was that entering through the rectum would avoid those nerves and decrease the distance to the target, improving patient comfort and procedural accuracy. Preliminary testing on simulated tissue was inconclusive, meaning it wasn’t more accurate than the transperineal approach, but it should decrease pain and healing time. My work never made it to clinical trials, that I know of, so it’s impossible to quantify pain or healing time. That’s the 5-second summary, but if you want to see some calculations and read the details – there are absolutely NO pictures of anyone’s rectum, it’s all completely safe for work – then you can read my paper on the subject, which I also published and presented at ICRA 2004.


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