Zap! Pfffft! Mind the Bubbles

A highlight of Mary and my recent trip to London was a visit to the Institute of Cancer Research where son-in-law Hugh Morris is looking for better ways to use ultrasound to kill tumors.  The Institute shares building with a cancer hospital so they are in no danger of having their work become too theoretical.  Cancer sucks and it’s good to be where people are doing something about it.

Ultrasound is both used diagnostically to locate tumors and surgically to attack them without invasive surgery.  To over-simplify, multiple beams of ultrasound converge on a tumor.  None of the individual beams has enough energy to damage the skin and other tissues it is passing through.  But, at the convergence point, pfffft!.  No need for an incision. Little collateral damage.  No general anesthesia.

But, in real life, nothing is quite this simple.  Bubbles form where the heat is high.  These bubbles can both scatter energy back to innocent tissue and block energy from reaching the cancerous cells.  So how to avoid the bubbles?  Avoid building up to critical temperatures.  What are critical temperatures?  How does heat travel through the tissue in the few seconds the beams are being applied?  How do you measure temperature since you don’t want a probe at the point of convergence which would also deflect energy?

These are the issues Hugh is working on with cow livers fresh from the butcher.  He thought we might be put off by the sight and smell of the experiments.  We were fascinated and proud.  BTW, experimenters still keep notebooks full of observations of each experiment even though they have plenty of computers around and in use.

Being around young scientists (I’m old; I’m allowed to age-discriminate) is fun.  One woman wants to know why the cells die when they get zapped.  Not enough to say “of course they die; they were zapped.”  Forensics are helpful in better targeting cancer cells and minimizing dangers to the rest of the body.  Turns out there is almost nothing known (yet) about the exact cause of cell death from this relatively minor heating.

Another scientist asks: “who says bubbles are bad?”  Maybe they can be used to BETTER focus the beam.  He’s experimenting with a second ultrasound source which induces bubbles before the zapper zaps.

As always the toolmakers are in great demand in a lab.  At tea, we met a woman from China who builds the custom hardware and software they need for their experiments.

Hugh set up a discussion with colleague Alex who’s working on ultrasound for treatment of prostate cancer – always interesting to us old guys.  One of the more interesting points was the social consequence of better diagnostic tools.  The more we see, the more scary stuff we see.  First reaction is to operate more often.  But, operations are also risky.  Turns out that a lot of that scary looking stuff is pretty prevalent and may never turn into anything really dangerous.  So what to do?

People don’t like being told “you have a pre-cancerous condition; we’re not going to do anything” even though doing nothing may well be the best course of action.  This course of non-treatment used to be called “watchful waiting” because follow-up surveillance is done.  Bad marketing name.  People hated it.

Now people are much happier with a course of treatment called “active monitoring”.  Same procedures as watchful waiting but it’s much more satisfying to being doing something “active”.  I agree.

And we’re glad Hugh is on the case.