WEBVTT
00:00:00.000 --> 00:00:15.640
Music
00:00:18.160 --> 00:00:24.940
Herald Angel: And now we come to the talk
entitled low-cost non-invasive biomedical
00:00:24.940 --> 00:00:32.000
imaging. Current medical imaging has
problems: it is expensive, it is large,
00:00:32.000 --> 00:00:39.940
rarely preventively used and maybe you've
heard of the story of a fMRI - this is the
00:00:39.940 --> 00:00:45.960
magnet resonance tomography - they put in
a dead Salmon and they can get a signal
00:00:45.960 --> 00:00:51.729
from brain activity from it. There's also
lots of problems in the software as well.
00:00:51.729 --> 00:00:59.450
A little story, maybe you look it up. And
how this whole mess can be solved with the
00:00:59.450 --> 00:01:06.769
technique called Open Electrical Impedance
Tomography - this will tell us Jean
00:01:06.769 --> 00:01:10.509
Rintoul. Give a big round of applause for
Jean.
00:01:10.509 --> 00:01:18.541
applause
Jean Rintoul: Thank you.
00:01:18.541 --> 00:01:20.939
Hello everyone. Today I
00:01:20.939 --> 00:01:28.159
will be talking about an open source route
for biomedical imaging using a technique
00:01:28.159 --> 00:01:34.090
that's in R&D called Electrical Impedance
Tomography. Not many people have heard of
00:01:34.090 --> 00:01:42.609
it, which is why it seems like it's
important to mention. First of all, I'll
00:01:42.609 --> 00:01:48.789
just give you the vision of what it would
be like if everybody had access to cheap
00:01:48.789 --> 00:01:56.210
biomedical imaging. Right now you only get
imaged when something's gone wrong. And,
00:01:56.210 --> 00:02:02.189
moreover, you only actually get to use
these tools when something has gone wrong
00:02:02.189 --> 00:02:08.780
in a first world country when you're lucky
enough to be close to a hospital and have
00:02:08.780 --> 00:02:15.030
access to these technologies. That's a
very limited number of people. What's even
00:02:15.030 --> 00:02:20.720
worse about it: is it's hard to hack! So,
if you wanted to improve this technology
00:02:20.720 --> 00:02:28.260
yourself - medical physics is an amazing
field - but it would be very hard to do so
00:02:28.260 --> 00:02:34.510
because you don't have a three million
dollar MRI scanner sitting in your garage.
00:02:34.510 --> 00:02:40.360
Maybe you do, that's good for you, just
not many of us do. If we did have cheap
00:02:40.360 --> 00:02:46.190
biomedical imaging we could do things like
do preventive scans so you would wake up
00:02:46.190 --> 00:02:51.520
in the morning you'd like, take a shower,
the device would be quietly imaging your
00:02:51.520 --> 00:02:55.750
body, would warn you if the slightest
little thing when went wrong. You'd do
00:02:55.750 --> 00:03:02.290
machine learning over it, it'd be
wonderful wonderful for health care. So,
00:03:02.290 --> 00:03:07.750
that's the vision of what biomedical
imaging could be. And the other point is
00:03:07.750 --> 00:03:13.310
sometimes we move forward faster when we
share the information. I worked in defense
00:03:13.310 --> 00:03:16.410
for a brief period and people didn't
really share information between each
00:03:16.410 --> 00:03:21.440
other, and I think that inhibited science
from moving forward. So, sharing is
00:03:21.440 --> 00:03:24.760
caring.
So today I'm going to go through a few
00:03:24.760 --> 00:03:28.020
different things. I'm going to go through
the current biomedical imaging
00:03:28.020 --> 00:03:31.020
technologies. I'll give you an
introduction to Electrical Impedance
00:03:31.020 --> 00:03:35.590
Tomography. I'll go through the open
source Electrical Impedance Tomography
00:03:35.590 --> 00:03:40.660
Project. Then I'll go through some
applications that we could apply it to.
00:03:40.660 --> 00:03:45.040
And then I'll suggest a few different next
steps that we can go into because by no
00:03:45.040 --> 00:03:52.980
means is it finished. Right now we have
four different main existing imaging
00:03:52.980 --> 00:04:00.910
modalities. Your MRI scanner, which is a
wonderful tool, it's huge, very expensive.
00:04:00.910 --> 00:04:06.320
The most commonly used imaging is actually
CAT scanner which sends our x-rays through
00:04:06.320 --> 00:04:11.070
your body which is ionizing radiation,
which is bad for you because it causes
00:04:11.070 --> 00:04:17.220
cancer in the long run if you get too many
of those scans and it's actually the first
00:04:17.220 --> 00:04:21.460
first scan that you'll get when you go
into the emergency room. It's the most
00:04:21.460 --> 00:04:24.650
commonly used. And as we all know we've
got those grainy images that come from the
00:04:24.650 --> 00:04:32.400
ultrasound of fetuses, wonderful tool
except for the scattering due to the sound
00:04:32.400 --> 00:04:36.299
gets scattered when you have different
density materials next to each other. And
00:04:36.299 --> 00:04:45.160
not exactly an imaging modality but a very
important diagnostic technique is EEG.
00:04:45.160 --> 00:04:50.980
So you might ask, how do we classify these
right now? we have 3 main types of
00:04:50.980 --> 00:04:58.850
resolution. Spatial, contrast, and time.
Spatial resolution is, basically, what
00:04:58.850 --> 00:05:04.010
space you can determine 2 different
objects from each other. Contrast
00:05:04.010 --> 00:05:09.000
resolution is soft tissue or subtle
differences in tissues. And time
00:05:09.000 --> 00:05:13.540
resolution, as it sounds, is how things
change over time and how quickly you can
00:05:13.540 --> 00:05:19.400
do these images together. Your CAT scan,
your basic machine in a hospital,
00:05:19.400 --> 00:05:24.210
costs 1 to 2.5 million dollars.
You probably didn't get one for Christmas
00:05:24.210 --> 00:05:30.020
to play around with. Oh well. It's also
got this ionizing radiation, you've got
00:05:30.020 --> 00:05:32.710
a lot of maintenance, and
dedicated technicians.
00:05:32.710 --> 00:05:35.240
An MRI, say, your average 3 Tesla magnet
00:05:35.240 --> 00:05:41.060
with its own helium quenching chamber
no less, as well as dedicated technicians
00:05:41.060 --> 00:05:50.710
and experts who can actually read
the images. Again $3,000,000. An amazing
00:05:50.710 --> 00:05:55.950
and beautiful technology, but really
expensive. Amazing spatial resolution, the
00:05:55.950 --> 00:06:01.010
best. When it does something at this very
high spatial resolution, it actually takes
00:06:01.010 --> 00:06:06.490
4 minutes and 16 seconds. Which is a
really long time to take to do this
00:06:06.490 --> 00:06:11.200
wonderful spatial resolution image.
Ultrasound, it's a bit grainy due to
00:06:11.200 --> 00:06:18.560
scattering. On average it costs about
1$115k, not too bad. It's a pretty minimal
00:06:18.560 --> 00:06:25.460
health risk. EEG. EEG doesn't do any image
reconstruction. In fact it does very
00:06:25.460 --> 00:06:33.040
little in many ways. But it is still very
useful. Your average medical grade by EEG
00:06:33.040 --> 00:06:37.920
system is $40k. You might also know of
some open source EEG projects which are
00:06:37.920 --> 00:06:45.070
pretty cool. So just a note on the
radiation of CAT-scans. It's actually the
00:06:45.070 --> 00:06:53.700
biggest contributing cause of radiation in
the United States. So here I just put
00:06:53.700 --> 00:06:58.550
those biomedical imaging modalities onto a
graph so that you can kind of think of
00:06:58.550 --> 00:07:03.120
them in terms of spatial resolution and
time resolution, and where they fall in
00:07:03.120 --> 00:07:09.240
the picture of common things that go wrong
with people. Like, X-rays or CAT scans are
00:07:09.240 --> 00:07:15.430
great for for looking at bone and bone
breaks; pulmonary edema, that's water on
00:07:15.430 --> 00:07:20.760
the lung ,tuberculosis, huge in third-
world countries, massive problem. You
00:07:20.760 --> 00:07:25.380
don't actually need super high spatial
resolution to be able to detect it. And
00:07:25.380 --> 00:07:29.610
it's important to sort of understand what
you can do at different spatial and time
00:07:29.610 --> 00:07:35.430
resolutions. Under like, the optimal goal
of all of this, I put non-invasive
00:07:35.430 --> 00:07:40.370
electrophysiology. What that is, is high
spatial resolution and high time
00:07:40.370 --> 00:07:46.820
resolution. That's where you can measure
ion activation, or basically what cells
00:07:46.820 --> 00:07:51.460
are doing when they communicate with each
other, which is right now only done in an
00:07:51.460 --> 00:07:55.850
invasive manner.
Today I'm gonna talk about this new
00:07:55.850 --> 00:08:00.870
technique called Electrical Impedance
Tomography and describe where it will fit
00:08:00.870 --> 00:08:09.650
in amongst what already exists. So what is
it. Okay yeah basically you send AC
00:08:09.650 --> 00:08:17.130
currents through the body, say a 50
kilohertz current. And that will take
00:08:17.130 --> 00:08:23.360
different routes based on what tissue
there is. So it might go around some cells
00:08:23.360 --> 00:08:29.620
and straight through others. And that's
really important because differentiating,
00:08:29.620 --> 00:08:34.869
say, fat from muscle is one thing that you
could do. But you can go further and
00:08:34.869 --> 00:08:41.969
differentiate, say, tumors from healthy
tissue. Because tumors have different
00:08:41.969 --> 00:08:47.960
impedance spectra to the healthy tissue.
So as you can see, that would be very
00:08:47.960 --> 00:08:53.470
useful to do. This set up here is a called
a phantom. What it is, it's like a
00:08:53.470 --> 00:08:58.650
simulated human body. You get some
saltwater - the body is 80% water as you
00:08:58.650 --> 00:09:03.369
might know -you get some meat or
vegetables. You put it inside and then you
00:09:03.369 --> 00:09:07.249
use that to image. So we have current
flowing through all these different
00:09:07.249 --> 00:09:13.120
directions and we recreate an image. Right
now it's used for lung volume
00:09:13.120 --> 00:09:18.399
measurements. This is a baby with an EIT
setup. Muscle and fat mass, there's a
00:09:18.399 --> 00:09:22.180
paper on gestural recognition that just
came out this year, you can look at
00:09:22.180 --> 00:09:27.260
bladder and stomach fullness. There's some
research papers on breast and kidney
00:09:27.260 --> 00:09:33.860
cancer detection. There's another research
paper on hemorrhage detection for stroke.
00:09:33.860 --> 00:09:39.110
You can also look at the ... there's more
R&D on the depth of anesthesia in in
00:09:39.110 --> 00:09:42.820
surgery as well, which would be another
interesting use for it. So all of these
00:09:42.820 --> 00:09:50.649
are sort of in the works and you might
ask, "Great, that sounds amazing, why
00:09:50.649 --> 00:09:55.589
isn't everybody using it already?" Well
yeah it's really an R&D technique right
00:09:55.589 --> 00:10:03.029
now and it has a big problem: its spatial
resolution seems pretty limited. So it's
00:10:03.029 --> 00:10:06.990
limited by the number of electrodes. But I
will discuss some potential ways to get
00:10:06.990 --> 00:10:12.929
around that. As we go, it might not ever
get to the spatial resolution of MRI.
00:10:12.929 --> 00:10:16.740
But maybe we don't need it to to be
useful. Because it's so compact. It's so
00:10:16.740 --> 00:10:23.810
cheap, nothing about it is expensive. It's
got better source localization than EEG.
00:10:23.810 --> 00:10:27.759
It does not ionize,
it's not harmful to human tissue. It's
00:10:27.759 --> 00:10:33.589
also got great time resolution, so it has
advantages and disadvantages. I'll just
00:10:33.589 --> 00:10:39.240
remind you of what the first MRI scan
looked like at this point in time. As you
00:10:39.240 --> 00:10:45.599
can see it looks pretty crappy in 1977.
And now it looks pretty awesome. That's a
00:10:45.599 --> 00:10:51.230
slice of my head by the way in a 3 Tesla
MRI scanner. This is what early EIT looks
00:10:51.230 --> 00:10:59.429
like. That's with 16 electrodes only. What
will it look like in a few years time I
00:10:59.429 --> 00:11:06.899
don't know. I hope that MRI gives you a
pathway that it will take take too.
00:11:06.899 --> 00:11:13.110
Now I'll introduce you to the OpenEIT
project. The OpenEIT project is obviously
00:11:13.110 --> 00:11:20.449
open source. It has a PCB design done in
Eagle CAD. It has firmware written in C.
00:11:20.449 --> 00:11:24.919
It has a Python dashboard that lets you
see the reconstruction in real time. It
00:11:24.919 --> 00:11:29.300
also has a reconstruction algorithm which
I'll go into. And you can get it from
00:11:29.300 --> 00:11:36.540
github right there. So how does it
reconstruct an image? OpenEIT right now
00:11:36.540 --> 00:11:43.059
has 8 electrodes and what you do is, you
send this 50 kHz current through every
00:11:43.059 --> 00:11:48.920
combination of those 8 electrodes and you
get a different impedance value for each
00:11:48.920 --> 00:11:55.519
of those measurements. On the left you can
see basically what you're doing. You know where the
00:11:55.519 --> 00:12:01.269
electrodes are positioned and you get one
value going horizontally. You add it to
00:12:01.269 --> 00:12:06.099
another value coming from another
direction. And again, you can sort of see
00:12:06.099 --> 00:12:11.240
it's getting a low resolution image as it
goes around adding those values together.
00:12:11.240 --> 00:12:18.370
If you use many, many views you bring the
image back. This is the radon transform,
00:12:18.370 --> 00:12:23.749
that's what it's called, and you
basically just send lots of current
00:12:23.749 --> 00:12:26.900
through these different slightly different
angles and you build up something called a
00:12:26.900 --> 00:12:33.580
sinogram which is over there. And then you
invert it to get the image back. I used
00:12:33.580 --> 00:12:37.209
OpenCV which is a really common image
processing library to do this. You can
00:12:37.209 --> 00:12:43.360
just do it with a regular image yourself
and try it out. But what I did is exactly
00:12:43.360 --> 00:12:49.069
the same as what you do with a regular
image, except I use current to be the
00:12:49.069 --> 00:12:57.810
input data. So this is the PCB design
in Eagle. Basically it has a
00:12:57.810 --> 00:13:02.830
few different features. A connector for
your 8 electrodes. It's running an ARM
00:13:02.830 --> 00:13:11.339
Cortex M3, which is quite nice. It has a
dedicated DFT engine for doing your direct
00:13:11.339 --> 00:13:16.829
Fourier transform in real, time which is
also quite nice. A JTAG debugger to easily
00:13:16.829 --> 00:13:22.619
reprogram it. It's got coin cell or
external battery options. It has UART to
00:13:22.619 --> 00:13:28.660
get the serial data off. And you can also
flip it to Bluetooth mode and get the data
00:13:28.660 --> 00:13:32.040
off by Bluetooth if you felt like going
Wireless.
00:13:32.040 --> 00:13:37.131
At this point you might be asking "Is this
safe for me to play around with?", which
00:13:37.131 --> 00:13:42.879
is a really great question because the
answer is actually "Yeah! it is". There's
00:13:42.879 --> 00:13:51.050
some guidelines called the IEC60601-1
guidelines for safer use in humans. And
00:13:51.050 --> 00:13:56.949
basically which says it should be, and
openEIT is less than 10 micro amps which
00:13:56.949 --> 00:14:02.959
is great because that's well within their
guidelines. If you want to compare it to
00:14:02.959 --> 00:14:06.220
other things that are completely legal,
say I don't know if you've seen there's
00:14:06.220 --> 00:14:10.629
like late-night TV ads for those abs
stimulators that stimulate your muscles,
00:14:10.629 --> 00:14:17.269
there are about 15 to 20 milliamps just
for reference and as a scale to look at
00:14:17.269 --> 00:14:23.749
the 10 micro amps. So some of you might
have used them already and that's hugely
00:14:23.749 --> 00:14:27.890
more current than what we're putting
through to image the body here. This is
00:14:27.890 --> 00:14:33.480
what the dashboard looks like. It does the
reconstruction. You can connect to serial
00:14:33.480 --> 00:14:37.850
at baseline. You can obviously adjust
sliders to look at the area that you want
00:14:37.850 --> 00:14:43.849
to look at. You can read from a file and
fiddle around however you would like to.
00:14:43.849 --> 00:14:49.169
This is what it looks like when you
reconstruct something. I have a phantom up
00:14:49.169 --> 00:14:54.079
there which is a part of water with a cup
in it. I moved the cup around anti-
00:14:54.079 --> 00:14:58.900
clockwise so you can see in each of the
pictures I move it around a little bit
00:14:58.900 --> 00:15:04.400
more. And you can see the reconstruction
there with me moving the cup around again.
00:15:04.400 --> 00:15:07.969
This might not be wow-ing you with the
resolution, with only 8 electrodes. It's a
00:15:07.969 --> 00:15:14.800
proof of concept but that's okay. Let's
see if we can make this I make this go.
00:15:14.800 --> 00:15:20.720
Here's a real-time video demonstration of
it. Here's me with a shot glass. I'm
00:15:20.720 --> 00:15:24.639
moving around anti-clockwise. Hopefully
you can see on the left the image being
00:15:24.639 --> 00:15:33.920
reconstructed in real time. And there we
go, move to the bottom. You can see it
00:15:33.920 --> 00:15:41.030
over there and again up to the top. you
can see it over there. So that's a basic
00:15:41.030 --> 00:15:44.739
proof of principle version of it running.
00:15:49.129 --> 00:15:55.079
So the first MRI scan of human
lungs wasn't that amazing.
00:15:55.079 --> 00:15:57.634
Early EIT scan wasn't either.
00:15:57.634 --> 00:16:02.824
applause
Something else that you can use it
00:16:02.824 --> 00:16:08.590
that for is differentiating objects.
Multi-frequency. This is what they're
00:16:08.590 --> 00:16:13.969
doing the breast cancer and kidney cancer
scans on. Basically you send different
00:16:13.969 --> 00:16:17.920
frequencies through these times, called
multi-frequency Electrical Impedance
00:16:17.920 --> 00:16:23.180
Tomography and you build up a spectrum.
Here I've got an apple, a pear oh no a
00:16:23.180 --> 00:16:27.660
sweet potato and and some water. And I've
sent through these different frequencies
00:16:27.660 --> 00:16:32.309
and I get these different spectrums.
They're different, you can see that
00:16:32.309 --> 00:16:35.829
they're different. They're quite obviously
different but yeah you can also just
00:16:35.829 --> 00:16:39.680
simply classify. And on the left you can
see where the water is, the apple is, the
00:16:39.680 --> 00:16:44.769
sweet potato is. Or, the sweet potato and
the apple a little bit harder that one.
00:16:44.769 --> 00:16:53.800
But that's basically what you do when you
detect cancer. So that's what I did. But
00:16:53.800 --> 00:16:57.760
maybe we should look at the other papers
and see what they did because they did
00:16:57.760 --> 00:17:04.589
better than me. So there's this guy called
Aristovich, 2014 he published spatial and
00:17:04.589 --> 00:17:07.569
temporal resolution, and using this
technique 200 micro meters less than 2
00:17:07.569 --> 00:17:14.230
milliseconds which covers most of the
applications that I listed on that graph
00:17:14.230 --> 00:17:19.260
at the start of the talk. The downside
here is that it was an intracranial array,
00:17:19.260 --> 00:17:24.190
so it was under the skull. So very dense
electrodes, a lot more electrodes. I only
00:17:24.190 --> 00:17:32.089
used 8 he used like 256 so you can see
that it can be, like, the potential is
00:17:32.089 --> 00:17:36.859
there.
So how should we use it first? what's a
00:17:36.859 --> 00:17:41.230
nice low hanging through fruit? What about
medical imaging in the developing world
00:17:41.230 --> 00:17:46.649
where I believe 4 billion people don't
have access to medical imaging. No MRI, no
00:17:46.649 --> 00:17:51.519
CAT scans. Why is the EIT good for that?
It's cheap to mass-produce, super
00:17:51.519 --> 00:17:58.089
portable, super low power. So that would
be a great place to start. What could we
00:17:58.089 --> 00:18:05.330
do first? I'm going to go back to this
image again and have a look. Tuberculosis
00:18:05.330 --> 00:18:09.110
affects a lot of people in the developing
world and you don't need amazing spatial
00:18:09.110 --> 00:18:14.901
resolution to detect it. That would be a
good one. Or what about a pulmonary edema?
00:18:14.901 --> 00:18:21.660
Pulmonary edema is water on the lung. It's
actually already used for that. You can
00:18:21.660 --> 00:18:26.640
quite easily see the different volume
present, or the different conductivity
00:18:26.640 --> 00:18:33.590
maps it's called, of a working lung and a
not so working lung right there.
00:18:33.590 --> 00:18:41.410
Next steps. So what should we do to make
this technique better? What should we do
00:18:41.410 --> 00:18:48.200
for OpenEIT to make it better? If you want
to innovate again, that's the github
00:18:48.200 --> 00:18:53.460
project. Just go ahead. Oh that's an
avocado, it has a seat in the middle. Who
00:18:53.460 --> 00:19:05.519
knew? I do. So I see the two main routes forward
as: One would be this low-cost biomedical
00:19:05.519 --> 00:19:10.690
imaging for the developing world. You
could just stick with the static imaging
00:19:10.690 --> 00:19:16.270
reconstruction because why not. you'd need
a few more electrodes than it currently
00:19:16.270 --> 00:19:22.240
has. One of the main problems with the
technique is how you stick it to the skin.
00:19:22.240 --> 00:19:25.730
So my suggestion for that is why don't you
just use a water bath and stick the body
00:19:25.730 --> 00:19:31.929
part of interest in a body of water,
because water gets rid of a lot of the,
00:19:31.929 --> 00:19:38.390
it's called the contact impedance problem.
Or, on the kind of exciting science front,
00:19:38.390 --> 00:19:47.230
you've got the advancing neuroscience
option. Which would be measuring both high
00:19:47.230 --> 00:19:50.340
spatial resolution and high time
resolution. So that's the non-invasive
00:19:50.340 --> 00:19:57.710
electrophysiology solution. Or, and that
would be super awesome, there's a couple
00:19:57.710 --> 00:20:03.629
of ways forward to do that and I'm going
to sort of discuss each of those.
00:20:03.629 --> 00:20:10.169
So roughly there's physical configuration
improvements that could be done. There's
00:20:10.169 --> 00:20:14.480
things that you can do to improve the
spatial resolution. There's things you can
00:20:14.480 --> 00:20:19.480
do to improve the time resolution. And
this is interesting tack on at the end
00:20:19.480 --> 00:20:25.210
that I thought I'd mentioned, which is
'write' functionality. So we're using very
00:20:25.210 --> 00:20:33.090
small currents to read an image. What if
we pumped the current up a little before
00:20:33.090 --> 00:20:38.939
you know it you're writing. I think not
invasive deep brain stimulation in a
00:20:38.939 --> 00:20:48.670
focused way, that would be very very cool.
So, contact impedance. Major problem right
00:20:48.670 --> 00:20:54.059
now, there is a well-known solution I
haven't done it yet you do this thing
00:20:54.059 --> 00:21:00.909
called differential referencing, common
mode rejection should be done I haven't
00:21:00.909 --> 00:21:05.069
done it that's the next step. That means
that it will work when you just attach it
00:21:05.069 --> 00:21:10.630
with electrodes on the body. What happens
is, electrodes have a like some
00:21:10.630 --> 00:21:16.620
capacitance and different amounts which
kind of interfere with the the measurement
00:21:16.620 --> 00:21:19.690
that you want to make which you want to be
very accurate and just of your body. You
00:21:19.690 --> 00:21:24.529
don't want to include the electrode
information in there that's changing.
00:21:24.529 --> 00:21:30.110
There's a way to remove that that's well
known already. Another physical
00:21:30.110 --> 00:21:34.870
configuration improvements: just increase
the number of electrodes. Wonderful, now
00:21:34.870 --> 00:21:41.640
you've just improved the resolution. Or
the placing the part in water. Another set
00:21:41.640 --> 00:21:46.700
of next steps would be on the mathematical
side. I mentioned that I use linear back
00:21:46.700 --> 00:21:55.759
projection which is a wonderful technique,
that's how they do CAT scans. With X-rays
00:21:55.759 --> 00:21:59.310
that's exactly what they do.
However, it makes some appalling
00:21:59.310 --> 00:22:06.649
assumptions, like parent moves and
straight lines. That is not true. What you
00:22:06.649 --> 00:22:11.209
should do is get a finite element model
and solve Maxwell's equations because
00:22:11.209 --> 00:22:18.630
current bends around objects. Actually it
works in three dimensions too which might
00:22:18.630 --> 00:22:23.639
not be all that surprising but it needs to
be solved for those three dimensions which
00:22:23.639 --> 00:22:26.810
is why you just need to solve
Maxwell's equations and
00:22:26.810 --> 00:22:30.899
create a finite element model.
And there's a quite a bit of work on
00:22:30.899 --> 00:22:34.610
mathematical solutions that get higher
resolution.
00:22:34.610 --> 00:22:42.189
That's another improvement area. And now
as I mentioned this awesome new technique.
00:22:42.189 --> 00:22:44.649
Which, actualy there's a paper on
this year called
00:22:44.649 --> 00:22:50.990
magneto-acoustic electical tomography.
You might remember
00:22:50.990 --> 00:22:55.580
the FBI rule from high school.
When you have a current flowing,
00:22:55.580 --> 00:23:02.429
perpendicular to that there will be a
force. Now that force, say it's vibrating
00:23:02.429 --> 00:23:07.309
with 50 kilohertz. that's the AC signal
that you're sending through. Now you have
00:23:07.309 --> 00:23:11.460
a vibrating compression wave. That's
sound. You can pick that up with a little
00:23:11.460 --> 00:23:19.580
piezoelectric element. And that's actually
a focus of work. From that you can get
00:23:19.580 --> 00:23:27.070
really good edge information, because as I
mentioned earlier, sound scatters at
00:23:27.070 --> 00:23:31.460
edges. So you would also get the
electrical impedance tomography
00:23:31.460 --> 00:23:38.549
information for the tissue sensitivity.
Why not combine those results together and
00:23:38.549 --> 00:23:43.259
you would have a better tool. It currently
gets lesser resolution in the middle
00:23:43.259 --> 00:23:50.180
simply from how you every combination of
electrodes just ends up having a less
00:23:50.180 --> 00:23:56.799
dense number in the middle. You can also
do something as simple as increasing the
00:23:56.799 --> 00:24:02.049
power that you send through if you're game
to do that. This is a kind of gory
00:24:02.049 --> 00:24:07.961
picture. Right now epileptics, if they're
really troubled by their problem, which
00:24:07.961 --> 00:24:13.460
they are often, they go into a hospital
have their brains opened up and they
00:24:13.460 --> 00:24:18.580
stick this array on their head through
their skull. And they leave it open
00:24:18.580 --> 00:24:24.340
for a week. And they try to induce
seizures through sleep deprivation.
00:24:24.340 --> 00:24:30.440
And then they measure the activation
potentials that way to locate the foci or
00:24:30.440 --> 00:24:36.200
where they going to do surgery to stop you
from having seizures. But it would be much
00:24:36.200 --> 00:24:40.260
better and nicer if you could do it not
invasively and you probably can if you
00:24:40.260 --> 00:24:43.600
improve the time resolution of EIT.
there's nothing stopping you from doing
00:24:43.600 --> 00:24:50.360
that by the way. You just have to, like,
it's just a next step really.
00:24:50.360 --> 00:24:56.919
And then I'll also mention write-
functionality. So there was a paper that
00:24:56.919 --> 00:25:02.700
came out halfway through this year by a
guy called Neil Grossman (?) and what he
00:25:02.700 --> 00:25:09.170
did is, he showed that you can stimulate
neurons by sending current through the
00:25:09.170 --> 00:25:18.739
skull and in a focused way. Now why that's
interesting is, you can non-invasively
00:25:18.739 --> 00:25:23.190
stimulate neurons. So that's the write-
functionality. It's unknown what
00:25:23.190 --> 00:25:27.950
resolution is or how well you could
control the the focal point here. But it
00:25:27.950 --> 00:25:34.220
works in the principle of beat frequencies
so he sent through two kilohertz and 2.05
00:25:34.220 --> 00:25:42.379
kilohertz and basically had a beat
frequency of 10 Hertz arise from that and
00:25:42.379 --> 00:25:50.279
basically stimulated neurons in this area
that he can control via an x- and y-axis
00:25:50.279 --> 00:25:59.940
which is very impressive. Leaves a lot of
questions open. Those are some possible
00:25:59.940 --> 00:26:06.309
next steps that it could go in. Obviously
I think this is interesting. I hope that
00:26:06.309 --> 00:26:11.340
you do too. I'd love it if you would want
to sign up to a mailing list I'll give a
00:26:11.340 --> 00:26:17.049
link on the next page. If you want to
collaborate email me. If you know any
00:26:17.049 --> 00:26:22.070
funding bodies that might be interested in
the developing medical imaging for
00:26:22.070 --> 00:26:26.330
the third world I'd love to be put in
contact. If you wanted a kit and, if there
00:26:26.330 --> 00:26:30.230
were enough people that wanted a kit,
probably of the next version which would
00:26:30.230 --> 00:26:36.200
have 32 electrodes sign up to the mailing
list, talk to me. Thanks.
00:26:36.200 --> 00:26:46.820
applause
Rintoul: Thank you
00:26:46.820 --> 00:26:49.690
applause Herald Angel: Thank you
very much. We have a little bit
00:26:49.690 --> 00:26:57.610
time for Q&A. And please if you have to
leave the room make it in a very quiet
00:26:57.610 --> 00:27:05.730
way. So is there ... there are some
questions I've seen microphone 4 first.
00:27:05.730 --> 00:27:08.970
Please go ahead.
Audience member: So, a great thing
00:27:08.970 --> 00:27:15.649
thinking about developing countries and
getting them medical tech. But at the very
00:27:15.649 --> 00:27:20.889
first beginning you said imagine a world
where this imaging would be all available
00:27:20.889 --> 00:27:26.610
like every day and it creeped me out a
little bit. Do you really think that it's
00:27:26.610 --> 00:27:33.740
a good idea to go in the shower in the
morning and have your I don't know your
00:27:33.740 --> 00:27:40.019
bathtub telling you that there is a small
mass inside your lungs.
00:27:40.019 --> 00:27:46.889
Rintoul: That's a good question. Basically
the question was: There's a privacy
00:27:46.889 --> 00:27:52.360
concern with looking inside your body. It
doesn't sound that great to some people.
00:27:52.360 --> 00:27:56.200
To those people I would say you should
turn off I know that sounds a little
00:27:56.200 --> 00:28:05.179
harsh. But please just turn it off, don't
use it. And with all scientific movements
00:28:05.179 --> 00:28:12.080
forward comes great risk, I also say. And
it can be used for good or evil and it's
00:28:12.080 --> 00:28:17.769
up to us as a society how we want to
choose to use it. And how we structure
00:28:17.769 --> 00:28:24.510
ourselves and potentially motivate and
incentivize corporations to use it in a
00:28:24.510 --> 00:28:31.919
responsible way. Part of making this open
is I hope that, basically if people have
00:28:31.919 --> 00:28:36.470
access to it you can choose for yourself
how you'd want to use it.
00:28:36.470 --> 00:28:40.809
Herald Angel: And next question would be
from the Signal Angel please.
00:28:40.809 --> 00:28:45.070
Signal Angel: Yes I have a couple of
questions from the internet. First of all,
00:28:45.070 --> 00:28:51.439
what type of AC frequencies in use? the
asker assumes sinusoidal but he wonders if
00:28:51.439 --> 00:28:54.779
you also tried square wave, triangular and
other shapes.
00:28:54.779 --> 00:29:00.360
Rintoul: That's also a really interesting
question. It's about what kinds of waves
00:29:00.360 --> 00:29:08.580
are used, what kinds of AC signals.
Typically it's done with AC sine waves
00:29:08.580 --> 00:29:14.500
ranging all over the place, depending on
what application you want to use up for. I
00:29:14.500 --> 00:29:19.980
mentioned multi frequency EIT for cancer
detection. That uses a lot of different
00:29:19.980 --> 00:29:26.090
frequencies so if you wanted to use other
waveforms I think that would be really
00:29:26.090 --> 00:29:32.840
interesting. Nobody's tried, you can, that
should be done.
00:29:32.840 --> 00:29:38.740
Herald: So since there's a big queue on
microphone 3 I would go there please.
00:29:38.740 --> 00:29:44.630
Audience member: Yes I have a technical
question. Assuming that you won't use this
00:29:44.630 --> 00:29:50.590
techniques on humans or organic matter at
all and what are the limitations for the
00:29:50.590 --> 00:29:56.190
resolution. The spatial resolution. And is
there a possibility to reduce the spatial
00:29:56.190 --> 00:29:59.100
resolution.
Rintoul: You mean increase the spatial
00:29:59.100 --> 00:30:06.179
resolution or reduce it?
Audience member: Reduce the voxel size
00:30:06.179 --> 00:30:12.470
Rintoul: So increase the spatial
resolution. Yes absolutely. So I was
00:30:12.470 --> 00:30:16.240
trying to go through a few of the next
steps that could get to that. One of them
00:30:16.240 --> 00:30:21.259
is magneto-acousto electrical tomography
because you get two different types of
00:30:21.259 --> 00:30:27.580
information which you could put together
to form a higher resolution image. So
00:30:27.580 --> 00:30:33.320
that's one way and if you didn't need to
worry about human safety I recommend you
00:30:33.320 --> 00:30:39.240
just turn the power up, that will also
work.
00:30:39.240 --> 00:30:46.389
Herald: Okay I think we go back to the
signal angel for one short one please.
00:30:46.389 --> 00:30:49.890
Signal Angel: Yes I have another question
from the internet. from a doctor this
00:30:49.890 --> 00:30:54.340
time. He wonders if there are any clinical
studies that compare pulmonary edema
00:30:54.340 --> 00:30:59.919
diagnostics with EIT to ultrasound and why
don't we just work on cheap ultrasound
00:30:59.919 --> 00:31:03.139
instead.
Rintoul: That's a good question. People
00:31:03.139 --> 00:31:08.289
are working on cheap ultrasounds.
Ultrasound gives different information to
00:31:08.289 --> 00:31:14.360
EIT. It has a problem of the sound
scattering. So it's a different type of
00:31:14.360 --> 00:31:21.289
information which has different pros and
cons. And and I think people should make
00:31:21.289 --> 00:31:27.169
cheap ultrasound. And I would like to see
the hybrid modality come together. You can
00:31:27.169 --> 00:31:31.769
get really good tissue distinction with
EIT so there's pros and cons.
00:31:31.769 --> 00:31:36.680
Herald: Okay then, microphone 2 please.
Audience member: You had a really good
00:31:36.680 --> 00:31:44.649
talk my question so far you always need
direct contact to the electrode, right? So
00:31:44.649 --> 00:31:50.519
it has to be direct contact or in water.
Is there way to detect or measure the
00:31:50.519 --> 00:31:56.659
signal without direct contact? So maybe in
if the if the object is in air or any
00:31:56.659 --> 00:32:01.419
other gas?
Rintoul: Right. I wish there was. No is
00:32:01.419 --> 00:32:07.570
the short answer. Unless ...
Audience member: Any research on making it
00:32:07.570 --> 00:32:11.129
happen?
Rintoul: Well yeah you can you can use
00:32:11.129 --> 00:32:20.129
X-rays. They work wonderfully to to go
through the air. But if you use them I
00:32:20.129 --> 00:32:24.220
mean you do increase your chance of cancer
so don't use them all the time on
00:32:24.220 --> 00:32:29.499
yourself. Again CAT scanners are a little
bit expensive.
00:32:29.499 --> 00:32:35.529
Herald: Thank you and I think we have time
for one more from microphone 3
00:32:35.529 --> 00:32:41.970
Audience member: My question would be
what, so maybe I've missed it, but what's
00:32:41.970 --> 00:32:47.009
the order of magnitude for cost so would
this be feasible at like a hackerspace for
00:32:47.009 --> 00:32:53.749
this to implement. And does the industry
see the possibility to make money.
00:32:53.749 --> 00:33:00.779
Rintoul: Yes a lot of those sort of these
early like R&D papers yeah they should be
00:33:00.779 --> 00:33:06.870
applied and you could make money with it
absolutely. And there's no component in
00:33:06.870 --> 00:33:14.960
there that costs more than a couple of
cents. I suppose a cortex m3 like costs a
00:33:14.960 --> 00:33:19.570
couple of dollars. And I mean I don't know
what your budget is but yes you I think
00:33:19.570 --> 00:33:24.309
you could do this in a hackerspace without
any problems. There's nothing stopping
00:33:24.309 --> 00:33:29.590
anyone from doing this and as we know
microcontrollers are becoming cheaper and
00:33:29.590 --> 00:33:36.460
cheaper. So why not.
Herald: I don't get Hasty's signs from the
00:33:36.460 --> 00:33:40.059
sideline so I think I can take another
question from 2 please.
00:33:40.059 --> 00:33:46.600
Audience member: So far you have showed us
images of 2d planes. What about volumes
00:33:46.600 --> 00:33:52.369
Rintoul: Yes so there's work on solving
for volumes using finite element models
00:33:52.369 --> 00:34:02.759
and solving Maxwell's equations. Basically
I just did the shortest route to reach
00:34:02.759 --> 00:34:07.670
image reconstruction that was available
which was linear back projection which is
00:34:07.670 --> 00:34:12.280
typically done in a 2d plane. So
absolutely, you can do it in three
00:34:12.280 --> 00:34:16.370
dimensions.
Herald: So I'm very sorry we are out of
00:34:16.370 --> 00:34:23.550
time the queue back there you can have the
chance to chat with our speaker just right
00:34:23.550 --> 00:34:31.880
now. The next talk coming up is in about
15 minutes and it's I think also in
00:34:31.880 --> 00:34:36.920
English. See you then and a big round of
applause for our speaker, excuse me.
00:34:36.920 --> 00:34:42.460
applause
00:34:42.460 --> 00:34:47.725
music
00:34:47.725 --> 00:35:04.000
subtitles created by c3subtitles.de
in the year 2017. Join, and help us!