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- Physics world.
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- Hello and welcome to the
Physics World Weekly Podcast.
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I'm Hamish Johnston.
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Coming up in this episode,
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we'll be chatting about a
new experimental technique
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that physicists have developed
to study how bacteria
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move about research that's
part of the burgeoning field
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of active matter.
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But first, magnetic
resonance imaging, or MRI
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and proton beam therapy
are two powerful techniques
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of medical physics.
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The former gives us realtime
images of internal structures
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of the body, and the latter
can deliver a high dose
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of radiation to a tumor
while reducing the damage
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to healthy tissue.
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Now, researchers in Germany are
working on combining the two
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techniques as physics world's.
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Tammy Freeman discovers
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- Proton therapy is an advanced
cancer treatment technique
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that can irradiate
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and destroy tumors with
high targeting accuracy.
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And soon it could become
even more precise.
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With the addition of real-time
magnetic resonance imaging,
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or MRI during treatment delivery
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early in January on
koray, the National Center
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for Radiation Research
in Oncology in Dresden,
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officially launched the world's
first research prototype
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for whole body MRI guided proton therapy.
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I'm very pleased to be joined
today by Aswin Hoffman,
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who headed up this research project.
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Welcome to the podcast, Aswin.
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- Well, thank you Tammy, for
inviting me for this, uh,
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interview and for giving
me the opportunity
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to explain the need
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for better image guidance
in proton therapy.
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- Super. So first of all,
could you briefly explain
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how proton therapy is
used to treat cancer?
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- Mm-Hmm. . So,
um, in radiation therapy,
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external beams of ionizing radiation are
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directed onto the tumor in order to
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sterilize the cancer cells
with a therapeutic dose
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with the intention to cure the patient.
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And currently two types
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of beam modalities are used clinically.
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The first one is photon beams
with high energy X-rays.
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And the second one is
particle beams, in particular
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with high energy protons.
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Um, the advantage of proton
therapy over photon therapy
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is its target dose conformity
due to the finer range
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of the protons.
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This means that proton
beams can be made to stop
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inside the tumor volume
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and hence provides, uh, a
better sparing of healthy, uh,
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organs surrounding the tumor.
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Also, the number of beams
in protein therapy as well
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as its slightly increased, um,
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relative biological effectiveness
contribute to lower doses,
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um, in radiation sensitive tissues.
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And, um, these facts offer
the potential benefit
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of less side effects
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and less toxicity than
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with conventional photon
based radiation therapy.
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- Okay, brilliant. So
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how will MRI help improve
proton treatments further?
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- Well, um, proton
therapy is more sensitive
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to tumor motion
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and organ deformation
occurring during those delivery
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fractions than conventional
photon based radiation therapy.
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Therefore, the targeting
accuracy of protein therapy
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for moving tumors in, for
example, the thorax or lung tumors
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or in the abdomen, liver tumors and, and,
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and, um, tumors in the pelvis.
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Like for example, prostate
cancer is currently compromised
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by the lack of fast
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and high soft tissue
contrast image guidance
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during irradiation
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and MRI is, um, expected
to solve this issue
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because it has an excellent
soft tissue contrast.
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And it furthermore also
enables continuous imaging
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to capture organ motion.
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Now the idea is to
synchronize the dose delivery
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with the tumor motion to thereby
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increase the targeting accuracy
of protein therapy, um,
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to reduce the side effects
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and hence potentially allow an
even higher therapeutic dose
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to be delivered to the tumor.
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- So this combination of MRI
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and proton therapy hasn't
been achieved before,
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and for a long time was considered by many
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as a pretty impossible task.
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So what are the main technical challenges
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of combining an MRI scanner
with a proton therapy system?
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- Hmm. So the, the main, um,
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technical challenge is
the mutual electromagnetic
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interactions between the
proton therapy system
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and the MRI system.
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Um, the proton therapy system
produces magnetic fringe
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fields that would overlap with the highly
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uniform static magnetic
field of the MRI system.
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And consequently, the MR images
may suffer from distortions
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and no longer provide reliable
geometrical information
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to guide our beams to the
tumor volume, which for which
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as a consequence, uh, the
tumor would be underdosed
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and the healthy tissues
could be overdosed.
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But also the other way
around the magnetic field
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of the MRI system might interfere
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with the proton beam delivery
system potentially leading
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to a malfunction of that
pro dose delivery system.
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And last but not least, um,
due to the Lawrence Force,
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the protons which are
positively charged particles
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are deflected by the presence
of the MR Magnetic field
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as they are transported from
the proton dose delivery system
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to the treatment volume
inside the MRI system.
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And all these effects
need to be eliminated
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or taken into account or compensated for.
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- So how did your team overcome
all of these obstacles?
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- Well, in 2018, we demonstrated proof
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of concept with a first
generation research prototype in
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beam MRI system in our experimental room
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after, um, first conducting
a magnetic survey in
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that room in which the MRI system
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was intended to be installed.
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And in this way we identified
the dominant sources
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of magnetic interference
and we found ways to avoid
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and to compensate for
these disturbing effects
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during MR Imaging.
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Um, in addition to that, we
also used an open MRI scanner
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to allow an UNP unobstructed
beam transport from
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the beam exit of the
proton delivery device
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to the MR Imaging volume.
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And in addition to
that, we performed a lot
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of those imagery experiments
inside the, um, MRI system
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to characterize the magnetic
field induced effects on,
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on the beam deflection, um, a deformation
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of the radiation field shape
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and also, uh, distortions
on the dose spot.
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And we mapped out a static
magnetic field of DMR scanner,
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um, and incorporated
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that in the proton treatment
planning system such
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that the magnetic field
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of DMR scanner can be taken into account
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during those calculation.
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And so far we have not seen
any adverse effects of the MR.
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Magnetic field onto the
proton beam delivery system.
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- That's great. And you worked
with some industry partners.
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What, what were these
collaborations? How did they help?
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- Well, the industry partners
supported us in installing
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open MR Systems at our
proton research beamlines,
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making it possible to
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initiate technical
feasibility studies, studies
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and demonstrate, um, the
first proof of concept.
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Later on in the project,
we found industry partners
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who took on the challenge to design
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and produce a first
prototype for whole body,
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for a whole body MRI
system that is capable
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of real time imaging.
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And this particular system
went into scientific operation
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and I'm still excited
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and proud that our industry
partners have not hesitated
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to take on this challenge with us.
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- So, yeah, I mean, as you
said this, the, the big news is
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that the first Mr guided
proton therapy prototype was
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launched, um, in early January.
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So how do you see the first few months
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of its operation panning out?
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Have you started it, um,
the initial experiments yet?
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- Mm-Hmm, , so
first commissioning experience
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with the new mr, uh,
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proton therapy system
have already been planned
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for the next month in the first step.
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Um, the electromagnetic interactions
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between our proton pencil beam, uh, line
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and the, the new in beam MR.
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Scanner will need to be assessed.
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And here we will address
two particular questions.
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So the first one is, does the presence
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of the new MR scanner affect
the proton beam delivery system
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due to interferences
coming from the static mag
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magnetic field of ther scanner
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or from the acoustic
noise that is produced
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by this R scanner?
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And the second question
is the other way around,
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does the proton beam delivery
system affect the MR image
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quality during beam scanning?
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And in addition to that, we will also need
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to map out the static magnetic field
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of this new in beam MR scanner in, in,
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in three dimensional space,
since this is needed as input
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for the, uh, proton
treatment planning system
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to enable dose calculations
in the presence
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of the magnetic field of DR R scan.
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- Okay. And once these system
character characterizations
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are complete, um, what will come next?
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- Well, from a medical
physics point of view, we need
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to do a full commissioning both
of the beam delivery system
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in terms of the do metric quality, um,
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but also for the MRI system
in terms of image quality
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and geometrical fidelity of the images.
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Um, our radio biologists here
at OnCore are very interested
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in assessing, um,
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and in understanding the
magnetic field induced effects
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onto the biological effectiveness
as the directionality
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and the strength of the MR
magnetic field might also
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influence cell killing.
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And last
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but not least, from a
medical-legal, um, as, uh,
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perspective, we'll work
on the regulatory aspects
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for future clinical trials,
both in terms of ethics approval
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and, um, certification in accordance
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with the medical device regulation MDR.
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- Okay. So yeah, quite a
lot of work to do coming up.
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Um, do you know,
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are there any other teams
working on a similar system?
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- Well, so far I'm not aware
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of any other groups worldwide
working on a similar system.
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That means a system, um, that is capable
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of real-time imaging.
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That is a whole body MRI system.
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Um, also the fact that
the Nbm MRI system is
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rotatable around a
patient enabling patients
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to be scanned both in a recumbent
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or in an upright position,
makes our system, um, unique.
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And, um, this kind
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of MRI system requires
a relatively large room
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to be installed it because
it's a, it's a big,
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it's a heavy machine.
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However, most of the research
rooms in particle therapy
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centers are not large enough
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to accommodate such a large MRI system.
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And I also think that our
research room here at,
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at OnCore is unique in
its kind with, um, an, uh,
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a floor area of approximately
250 square meters.
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Um, the only other team working on
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MR particle therapy that I know
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of is at the German
Cancer Research Center,
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DKFC in Heidelberg, also in in Germany.
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Um, they have a smaller research room
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and started working on
a compact MRI scanner
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after we showed first of,
um, first proof of concept
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with our compact MI scanner back in 2018,
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that our proton research beamline
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and both of these
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compact MRI scanners have in common common
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that they were originally
designed for diagnostic imaging
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of extremity.
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So these scanners are
not whole body scanners
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like the newly installed
one in our research room.
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And, um, where we have shown
first proof of concept,
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uh, of in beam MRI, in
combination with proton beams,
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our colleagues at Heidelberg
have combined their compact in
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beam MRI scanner with their
horizontal research beamlines
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for heavy iron, so not protons.
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And they performed first
experiments with MRI guided, uh,
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scanned carbon iron beans.
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00:14:24,735 --> 00:14:25,945
- That, that's really interesting.
256
00:14:26,065 --> 00:14:28,265
'cause that's sort of,
that's another, um, type
257
00:14:28,265 --> 00:14:30,705
of particle therapy using the carbon ions
258
00:14:30,705 --> 00:14:31,985
instead of the protons.
259
00:14:31,985 --> 00:14:34,025
That's, it's less prevalent,
260
00:14:34,025 --> 00:14:36,185
but it's certainly, it is another option
261
00:14:36,185 --> 00:14:37,425
under investigation, isn't it?
262
00:14:38,445 --> 00:14:42,905
- Yep. And it also, I think
it also provides less, um,
263
00:14:43,505 --> 00:14:46,425
, let's say scientific
challenges or less problems
264
00:14:46,895 --> 00:14:50,505
because the, um, heavy ions, uh,
265
00:14:50,505 --> 00:14:54,165
heavy iron beams are not
deflected by the presence
266
00:14:54,185 --> 00:14:58,485
of the MR magnetic field as
much as the proton beams are.
267
00:14:58,745 --> 00:15:01,165
So from a treatment
planning point of view,
268
00:15:01,665 --> 00:15:05,125
it is an easier problem to, to
solve than for proton beams.
269
00:15:06,025 --> 00:15:07,285
- Oh, okay. That's interesting.
270
00:15:07,825 --> 00:15:10,405
Um, and then finally my last question.
271
00:15:10,555 --> 00:15:12,645
When do you think that
your system might be used
272
00:15:12,645 --> 00:15:13,725
to treat the first patient?
273
00:15:14,965 --> 00:15:17,405
- Hmm, , I often get that question.
274
00:15:18,025 --> 00:15:21,405
Um, so, so our aim with
the new prototype system
275
00:15:21,515 --> 00:15:24,445
that was installed last week, the one that
276
00:15:25,065 --> 00:15:29,725
offers real-time MRO
imaging, um, well, we hope
277
00:15:29,785 --> 00:15:32,365
to be able to treat a
first patient in about
278
00:15:32,435 --> 00:15:33,685
five years from now.
279
00:15:34,585 --> 00:15:38,565
Um, because there is still a
lot of technical challenges
280
00:15:38,665 --> 00:15:41,525
to solve, but also from a
regulatory point of view.
281
00:15:42,025 --> 00:15:46,565
But with our, our previous,
um, complex prototype system,
282
00:15:46,745 --> 00:15:49,445
so the one without real-time
imaging capabilities,
283
00:15:50,035 --> 00:15:52,605
that is still in our, our research room.
284
00:15:53,105 --> 00:15:54,765
We expect to treat the first patient
285
00:15:54,765 --> 00:15:55,965
within the next two years.
286
00:15:56,785 --> 00:16:00,085
- Oh, okay. And I guess you'll
be using both systems in
287
00:16:00,365 --> 00:16:02,685
parallel to sort of just continue
developing this approach?
288
00:16:03,865 --> 00:16:07,365
- Yes, because the, as I said,
the experimental room is,
289
00:16:07,505 --> 00:16:10,765
is large enough to host two MR scanners
290
00:16:10,825 --> 00:16:13,285
and they will indeed be operated more
291
00:16:13,285 --> 00:16:14,805
or less in, in parallel.
292
00:16:15,715 --> 00:16:17,725
- Okay. That's brilliant.
Well, thanks very much
293
00:16:17,745 --> 00:16:18,925
for talking to us today.
294
00:16:18,925 --> 00:16:19,925
Thank you.
295
00:16:20,555 --> 00:16:24,185
- Thank you, Tammy, for
giving the opportunity to,
296
00:16:24,325 --> 00:16:25,505
to explain the need
297
00:16:25,505 --> 00:16:27,785
for better image guidance
in, in particle therapy.
298
00:16:27,875 --> 00:16:28,875
Thank you very much.
299
00:16:36,305 --> 00:16:38,405
- Our next guest is Katherine Skipper,
300
00:16:38,655 --> 00:16:42,125
who's joined the physics
world team as features editor
301
00:16:42,765 --> 00:16:45,885
after doing a PhD at the
University of Bristol
302
00:16:46,095 --> 00:16:48,125
where she studied active matter.
303
00:16:48,665 --> 00:16:52,365
Hi Catherine, welcome to Physics
World and to the podcast.
304
00:16:53,505 --> 00:16:55,365
- Hi ish.
- Catherine's here
305
00:16:55,365 --> 00:16:58,605
to chat about some fascinating
active matter research
306
00:16:59,025 --> 00:17:02,725
that's been done by scientists
in Germany and China.
307
00:17:03,355 --> 00:17:06,125
They've gained important insights into
308
00:17:06,145 --> 00:17:09,525
how e coli bacteria propel themselves.
309
00:17:10,305 --> 00:17:13,925
So Catherine, before we
discuss this specific research,
310
00:17:13,985 --> 00:17:17,205
can you tell us a bit about
the field of active matter?
311
00:17:17,475 --> 00:17:21,125
What sort of systems do
physicists study and why?
312
00:17:22,425 --> 00:17:26,165
- So if you've taken a
physics undergraduate course,
313
00:17:26,165 --> 00:17:29,285
you've at some point encountered
statistical mechanics
314
00:17:29,285 --> 00:17:33,125
where you're describing a
large system by the statistics
315
00:17:33,125 --> 00:17:35,125
of the individual atoms or molecules.
316
00:17:35,745 --> 00:17:38,925
Um, so I remember using,
you know, the icing model
317
00:17:38,985 --> 00:17:42,485
to predict, um, or to,
to model fair magnetism
318
00:17:42,865 --> 00:17:44,445
or to predict a melting transition,
319
00:17:44,905 --> 00:17:46,325
or you use statistical physics
320
00:17:46,385 --> 00:17:47,845
to describe superconductivity.
321
00:17:48,505 --> 00:17:52,005
Um, and broadly active matter
is a branch of physics that
322
00:17:52,755 --> 00:17:55,645
uses statistical mechanics
to describe living systems
323
00:17:56,275 --> 00:17:58,765
because a lot of the
functions of living systems
324
00:17:59,465 --> 00:18:00,965
are performed by a lot
325
00:18:00,965 --> 00:18:02,645
of biological units that work together.
326
00:18:02,905 --> 00:18:06,965
So, uh, a well-known example is, um,
327
00:18:07,525 --> 00:18:11,005
a murmuration of
starlings where these sort
328
00:18:11,005 --> 00:18:13,605
of beautiful coherent patterns
are produced on length scales
329
00:18:13,605 --> 00:18:15,485
that are much larger than
the individual birds.
330
00:18:16,105 --> 00:18:17,685
Um, but cells do this as well.
331
00:18:17,715 --> 00:18:20,245
Tissues in the body often have
very different properties,
332
00:18:20,905 --> 00:18:22,325
um, to the individual cells,
333
00:18:22,325 --> 00:18:23,485
and they can perform functions
334
00:18:23,485 --> 00:18:24,725
that the individual cells can't.
335
00:18:25,985 --> 00:18:30,005
Um, and actually within a cell,
the cytoskeleton is a bundle
336
00:18:30,065 --> 00:18:33,165
of active fibers that
contracts to move the cell.
337
00:18:33,825 --> 00:18:38,045
Um, and this particular
piece of research is, um,
338
00:18:38,425 --> 00:18:41,285
on swarms of eco bacteria,
which are also an active system.
339
00:18:42,065 --> 00:18:45,205
Um, so these are complicated systems,
340
00:18:45,425 --> 00:18:47,605
but you can turns out,
you can describe a lot
341
00:18:47,605 --> 00:18:49,325
of their behaviors using physics.
342
00:18:50,145 --> 00:18:51,565
So a lot of people
343
00:18:51,625 --> 00:18:54,565
who study active matter
have backgrounds in biology
344
00:18:54,785 --> 00:18:57,605
or biophysics, but I think
one of the key questions
345
00:18:57,605 --> 00:19:02,125
of this field is what's the
smallest amount of knowledge
346
00:19:02,125 --> 00:19:03,525
of biology you can have
347
00:19:03,585 --> 00:19:07,925
and still be able to describe
these biological systems?
348
00:19:08,185 --> 00:19:11,885
How much of this can be
encompassed by statistical physics?
349
00:19:12,915 --> 00:19:15,485
- Okay. And, and you, you
sort of hinted, um, uh,
350
00:19:15,485 --> 00:19:16,845
about this latest research.
351
00:19:16,875 --> 00:19:20,925
This is a study that was
done by Christina Kurtz Toler
352
00:19:21,425 --> 00:19:24,525
of the Max Plank Institute for the physics
353
00:19:24,785 --> 00:19:26,085
of complex systems
354
00:19:26,745 --> 00:19:30,805
and young FZ of Sohow University.
355
00:19:31,385 --> 00:19:33,245
And they've developed a new technique
356
00:19:33,245 --> 00:19:35,805
for studying the motion of bacteria.
357
00:19:36,185 --> 00:19:37,885
So, so what exactly did they do
358
00:19:38,145 --> 00:19:39,325
and and what have they found?
359
00:19:40,785 --> 00:19:42,645
- Um, so it's been observed
360
00:19:42,745 --> 00:19:46,365
before that e coli bacteria,
when they're in, um,
361
00:19:47,115 --> 00:19:51,005
when they're in like a dense
suspension, they produce these,
362
00:19:51,005 --> 00:19:52,285
these coherent patterns.
363
00:19:52,285 --> 00:19:54,645
They've been shown to, uh,
364
00:19:54,645 --> 00:19:56,605
form like rotating elliptical patterns.
365
00:19:56,945 --> 00:20:00,605
Um, motion couldn't, like
turbulent flow with vortices.
366
00:20:00,755 --> 00:20:04,725
They've actually been described
as a super fluid in some,
367
00:20:05,305 --> 00:20:07,845
in some contexts where the
bacteria is actually pushing the
368
00:20:07,845 --> 00:20:10,605
fluid along, so it effectively
has a negative viscosity.
369
00:20:11,105 --> 00:20:12,685
So there's a lot of
interest in understanding
370
00:20:12,825 --> 00:20:14,485
how these behaviors come about.
371
00:20:15,345 --> 00:20:16,525
So, and so the way
372
00:20:16,525 --> 00:20:18,645
that the ooc coli move is quite particular
373
00:20:18,985 --> 00:20:20,885
and it's important for
understanding how they behave.
374
00:20:21,385 --> 00:20:23,245
And it's called, it's called
run and tumble motion.
375
00:20:23,785 --> 00:20:26,765
Uh, so if you look at any
coli bacterium moving,
376
00:20:27,385 --> 00:20:29,845
it will swim forwards for
about, about a second,
377
00:20:30,595 --> 00:20:31,805
then it will suddenly rotate
378
00:20:31,825 --> 00:20:34,525
and start moving often
a different direction.
379
00:20:35,305 --> 00:20:38,885
Um, so that's, that's what
run and tumble motion is.
380
00:20:39,305 --> 00:20:43,165
So scientists who are interested
in e coli bacteria want
381
00:20:43,165 --> 00:20:46,285
to understand how the
patterns that you get.
382
00:20:46,425 --> 00:20:49,445
The, the collective motion that
I was talking about is links
383
00:20:49,545 --> 00:20:52,245
to, um, the motion
384
00:20:52,385 --> 00:20:54,245
and particularly to the length of these
385
00:20:54,885 --> 00:20:57,605
straight line runs
they're doing between, um,
386
00:20:57,605 --> 00:20:59,565
between tumbling, between
changing direction.
387
00:21:00,505 --> 00:21:04,485
Um, and it's possible to
engineer strains of bacteria
388
00:21:04,835 --> 00:21:07,805
that only tumble, they're
constantly changing direction.
389
00:21:08,305 --> 00:21:11,205
Uh, you do this by turning
off, um, the expression
390
00:21:11,205 --> 00:21:14,085
of a gene, and it's been proposed
391
00:21:14,155 --> 00:21:17,205
that if you could take these
genetically engineered e coli,
392
00:21:17,625 --> 00:21:20,445
um, and add, um, a reagent,
a biological reagent,
393
00:21:20,545 --> 00:21:23,045
it would be possible to
slowly turn this gene
394
00:21:23,045 --> 00:21:24,085
expression back on.
395
00:21:24,545 --> 00:21:28,005
So they start moving in
a straight line again.
396
00:21:28,005 --> 00:21:31,485
They start performing these
runs between changing, um,
397
00:21:31,485 --> 00:21:32,885
between changing direction.
398
00:21:33,585 --> 00:21:36,685
Um, and so yeah, scientists
are interested in understanding
399
00:21:36,825 --> 00:21:38,045
how that would change the,
400
00:21:38,045 --> 00:21:39,685
these coherent patterns that you get.
401
00:21:40,785 --> 00:21:43,445
Uh, but the challenge, that
sounds very straightforward when
402
00:21:43,445 --> 00:21:46,085
I describe it, but it's really
hard to do experimentally,
403
00:21:46,085 --> 00:21:47,685
and that's what the paper is about.
404
00:21:48,145 --> 00:21:52,045
- So, so is the, the difficulty
actually following a Yeah,
405
00:21:52,195 --> 00:21:54,165
bacterium, 'cause I
suppose they're very small
406
00:21:54,185 --> 00:21:55,725
and do, do they move very quickly?
407
00:21:55,865 --> 00:21:57,845
Is it difficult to, I suppose they move in
408
00:21:57,845 --> 00:21:59,565
and out of the focus of the microscope
409
00:21:59,705 --> 00:22:03,725
and it's, it's probably very
difficult to, to follow one.
410
00:22:04,395 --> 00:22:08,365
- Well, you can follow, if you
only have one, um, bacterium,
411
00:22:08,465 --> 00:22:12,005
eco bacterium or only a couple
you can follow, you can,
412
00:22:12,385 --> 00:22:13,965
um, you can track them.
413
00:22:14,225 --> 00:22:17,525
Um, you can, you know,
you have a a, an algorithm
414
00:22:17,525 --> 00:22:19,325
that's basically labeling
this as e coli A,
415
00:22:19,325 --> 00:22:21,125
this is e coli B, this is E coli C
416
00:22:21,125 --> 00:22:22,645
and it measures what, how they're moving.
417
00:22:23,025 --> 00:22:25,285
But if you've got a lot
of them, it's really hard
418
00:22:25,345 --> 00:22:27,645
and you can sort of imagine
that you have two e coli,
419
00:22:27,645 --> 00:22:28,885
they come very close together
420
00:22:29,585 --> 00:22:31,365
and it's hard to tell whether they've,
421
00:22:31,635 --> 00:22:33,765
they're going in the straight
line and they've crossed paths
422
00:22:33,765 --> 00:22:35,205
or whether they've both at the same time,
423
00:22:35,205 --> 00:22:36,485
turned in different directions.
424
00:22:37,345 --> 00:22:40,045
Um, so it's really hard to
425
00:22:40,885 --> 00:22:43,805
accurately track the
trajectories over a very
426
00:22:44,355 --> 00:22:45,445
long period of time.
427
00:22:46,185 --> 00:22:47,885
- And so these researchers in China
428
00:22:47,905 --> 00:22:49,765
and Germany, they've, they, they've got
429
00:22:49,765 --> 00:22:51,565
around this problem. Is that,
430
00:22:51,865 --> 00:22:52,865
- Uh, yeah, that's
- The news.
431
00:22:53,465 --> 00:22:55,405
- So they've actually, there are actually,
432
00:22:55,435 --> 00:22:59,725
there's a companion paper
to this paper, um, which uh,
433
00:23:00,205 --> 00:23:02,605
contains a lot of like
mathematical derivation,
434
00:23:03,465 --> 00:23:08,205
but basically, um, what they have done is,
435
00:23:08,355 --> 00:23:10,845
yeah, they, they're not tracking
the individual bacteria.
436
00:23:11,435 --> 00:23:15,285
What they've done is they have a sequence
437
00:23:15,365 --> 00:23:17,805
of three dimensional
images just from a, like a,
438
00:23:18,005 --> 00:23:19,445
a standard optical microscope,
439
00:23:19,545 --> 00:23:22,325
and they're taking the RIA
transform of those images.
440
00:23:23,025 --> 00:23:26,205
And then they have this
second companion paper
441
00:23:26,205 --> 00:23:30,285
where they are doing some
very complicated maths using,
442
00:23:30,625 --> 00:23:33,485
you know, the sta the statistics of run
443
00:23:33,485 --> 00:23:36,925
and tumble motion to extract length
444
00:23:36,945 --> 00:23:40,205
and timescales from these
three A transformed images
445
00:23:40,315 --> 00:23:43,965
that tell them how fast the
bacteria are moving on average
446
00:23:44,185 --> 00:23:47,525
and how far they move, how
447
00:23:47,755 --> 00:23:49,245
between changing direction.
448
00:23:50,025 --> 00:23:51,325
- And, and so what did they find?
449
00:23:51,385 --> 00:23:53,285
Was it a, was it in line with
450
00:23:53,285 --> 00:23:55,565
what people thought e coli were up to
451
00:23:55,625 --> 00:23:57,085
or was it a complete surprise
452
00:23:57,265 --> 00:23:59,645
or as often in science? A bit of both.
453
00:24:00,585 --> 00:24:03,925
- Um, so what they, they do
is, as I, as I mentioned, they
454
00:24:04,755 --> 00:24:06,885
take these genetically engineered e coli
455
00:24:07,825 --> 00:24:12,605
and they add this
reagent that is predicted
456
00:24:12,825 --> 00:24:16,805
to, um, turn on the, the
run motion between the,
457
00:24:16,805 --> 00:24:20,885
between the tumbles and using this, um,
458
00:24:21,025 --> 00:24:23,125
the s mathematical treatment
they have, they're able to show
459
00:24:23,125 --> 00:24:25,765
that that's, that is indeed
what's happening, you know,
460
00:24:25,765 --> 00:24:28,405
even in these quite dense
suspensions of bacteria.
461
00:24:29,025 --> 00:24:31,605
So they're able to, yeah, they're able to
462
00:24:32,645 --> 00:24:34,045
demonstrate something that has been
463
00:24:35,675 --> 00:24:37,765
theorized but hadn't improved. Ah,
464
00:24:37,795 --> 00:24:38,795
- Okay.
465
00:24:38,795 --> 00:24:39,125
And that sounds important
466
00:24:39,125 --> 00:24:42,005
because I suppose now that
we know this technique works,
467
00:24:42,575 --> 00:24:46,885
other scientists can use it,
um, and do, do further studies.
468
00:24:47,755 --> 00:24:50,765
- Yeah, I think if you've
done any kind of research,
469
00:24:50,865 --> 00:24:53,325
you will recognize the
frustration of having a very
470
00:24:53,875 --> 00:24:56,085
cool idea or a very
cool theory that cannot,
471
00:24:56,415 --> 00:24:59,405
where you don't have the methods
to, to test it or prove it.
472
00:24:59,945 --> 00:25:03,925
So, um, I think it's, it's
a really nice, uh, neat way
473
00:25:03,925 --> 00:25:06,125
of getting around the difficulty
of tracking these bacteria.
474
00:25:06,625 --> 00:25:09,525
And it is something that they
talk about this in the paper a
475
00:25:09,525 --> 00:25:12,565
bit that could be applied,
um, to other cells.
476
00:25:13,145 --> 00:25:15,085
- And, and I suppose the e coli, you know,
477
00:25:15,365 --> 00:25:17,605
I suppose if you've
heard of one bacterium,
478
00:25:18,115 --> 00:25:19,525
it's going to be e coli.
479
00:25:19,555 --> 00:25:22,765
It's, you know, it's a
bacteria that lives in our guts
480
00:25:22,785 --> 00:25:26,125
and it's used as a marker
for, for pollution.
481
00:25:26,505 --> 00:25:29,685
So I suppose, um, it, you
know, it's very important
482
00:25:29,685 --> 00:25:32,485
to understand how e coli gets around.
483
00:25:33,315 --> 00:25:36,125
- Yeah. Um, so I think
there's, there's two reasons
484
00:25:36,145 --> 00:25:37,245
to be interested in them.
485
00:25:37,355 --> 00:25:41,485
Firstly is yeah, they, they
are, they are everywhere.
486
00:25:41,705 --> 00:25:45,005
And it is, um, it would be
useful to know whether some
487
00:25:45,005 --> 00:25:48,245
of the collective behaviors
they have are evolutionary,
488
00:25:48,245 --> 00:25:50,885
whether they, they perform,
whether they are enabling the,
489
00:25:51,505 --> 00:25:55,165
um, the bacteria to perform
what perform useful work.
490
00:25:55,745 --> 00:25:58,725
But also, as you said, they
are, they're everywhere.
491
00:25:58,725 --> 00:26:02,205
They're relatively easy to
do experiments on, you know,
492
00:26:02,205 --> 00:26:06,645
that's easier to study than a
swarm of like a, a murmuration
493
00:26:06,645 --> 00:26:08,605
of starlings, for example, in a lab.
494
00:26:09,585 --> 00:26:12,685
So they are used as a,
as a model active system.
495
00:26:13,865 --> 00:26:17,645
Uh, and but to use them as
a, as a model system, we need
496
00:26:17,645 --> 00:26:20,165
to understand exactly how they work.
497
00:26:20,945 --> 00:26:24,045
- And are, are there any
implications in terms of, um,
498
00:26:24,345 --> 00:26:26,925
you know, creating artificial swimmers?
499
00:26:27,525 --> 00:26:29,285
'cause I know that, you
know, some researchers are
500
00:26:29,285 --> 00:26:33,125
interested in, you know, creating
tiny, tiny sort of objects
501
00:26:33,125 --> 00:26:36,485
that can swim in maybe the
same way as a, as a bacterium
502
00:26:37,015 --> 00:26:40,685
swims, or, or is there any,
is there any information there
503
00:26:40,785 --> 00:26:43,045
or, or would that be something
that's further down the line?
504
00:26:43,445 --> 00:26:44,485
- I mean, I think you could,
505
00:26:45,025 --> 00:26:48,165
you could presumably use
this technique to study
506
00:26:49,245 --> 00:26:51,405
synthetic active particles,
which are these, these tiny,
507
00:26:51,455 --> 00:26:52,765
these tiny sort of micro
508
00:26:53,105 --> 00:26:56,405
or micro, uh, tiny beads, a couple of sort
509
00:26:56,405 --> 00:26:57,445
of micross across.
510
00:26:57,865 --> 00:26:59,925
Um, and yeah, if you
can, if you can use this
511
00:26:59,925 --> 00:27:03,245
as study the bacteria, you
can use it, I would presume
512
00:27:03,745 --> 00:27:04,885
to study those.
513
00:27:05,125 --> 00:27:06,925
I, I think one of the, I guess one
514
00:27:06,925 --> 00:27:08,885
of the tough things about
the e coli is that they,
515
00:27:09,795 --> 00:27:11,605
they unpredictably change direction.
516
00:27:11,885 --> 00:27:14,005
I think that does make them,
I would, I would assume
517
00:27:14,005 --> 00:27:16,205
that makes them very, very hard to track.
518
00:27:16,205 --> 00:27:18,845
Whereas synthetic acid particles, they
519
00:27:19,385 --> 00:27:20,805
change direction much more slowly.
520
00:27:20,865 --> 00:27:22,605
So I think they are a
bit easy as to track,
521
00:27:22,605 --> 00:27:24,645
but I, I would assume you
can still use this technique.
522
00:27:25,045 --> 00:27:26,085
- Hmm. Well that's great.
523
00:27:26,105 --> 00:27:28,485
Tha uh, Catherine, thanks
for for explaining that.
524
00:27:28,905 --> 00:27:31,165
Um, if you'd like to learn
more about this study,
525
00:27:31,635 --> 00:27:34,245
it's described in open access papers,
526
00:27:34,705 --> 00:27:37,885
and those papers are published
in physical review letters
527
00:27:38,585 --> 00:27:40,245
and physical review e
528
00:27:40,665 --> 00:27:44,525
and the best way to find both
papers is to read a synopsis
529
00:27:44,545 --> 00:27:48,085
of the research that appears
on the American Physical
530
00:27:48,195 --> 00:27:49,405
Society website.
531
00:27:49,835 --> 00:27:53,525
That synopsis is called
Characterizing the Swimming Gate
532
00:27:53,705 --> 00:27:56,885
of a Bacterium, and it's
by Catherine Wright.
533
00:27:57,305 --> 00:27:58,245
Thanks, Catherine.
534
00:28:06,115 --> 00:28:07,575
I'm afraid that's all the time we
535
00:28:07,575 --> 00:28:08,615
have for this week's podcast.
536
00:28:09,075 --> 00:28:11,975
Thanks to Aswin Hoffman, Catherine Skipper
537
00:28:12,155 --> 00:28:14,415
and Tammy Freeman for joining me today.
538
00:28:14,835 --> 00:28:18,015
And a special thanks to
our producer Fred Isles.
539
00:28:18,585 --> 00:28:20,055
We'll be back again next week,
540
00:28:20,235 --> 00:28:23,055
but in the meantime, do
check out the latest episode
541
00:28:23,075 --> 00:28:25,175
of the Physics World Stories podcast
542
00:28:26,045 --> 00:28:28,655
host Andrew Gluster is in conversation
543
00:28:28,655 --> 00:28:32,215
with the astrophysicist
and author Emma Chapman,
544
00:28:32,915 --> 00:28:36,695
and they chat about the
history of radio astronomy.
545
00:28:37,565 --> 00:28:41,175
Chapman, who is at the UK's
University of Nottingham,
546
00:28:41,585 --> 00:28:45,655
talks about the do it yourself
ethic of radio astronomers
547
00:28:45,995 --> 00:28:49,655
and highlights the valuable
contributions made by people
548
00:28:49,885 --> 00:28:53,415
outside the established
academic community.
549
00:28:54,325 --> 00:28:58,855
That podcast is called Radio
Pioneers, the Enduring role
550
00:28:58,995 --> 00:29:01,895
of amateurs in Radio astronomy.
551
00:29:02,395 --> 00:29:05,055
And you can find it on
the Physics world website.
552
00:29:05,475 --> 00:29:07,935
And at your favorite podcast provider
553
00:29:13,875 --> 00:29:15,045
- Physics World.
00:00:05,045 --> 00:00:06,215
- Physics world.
2
00:00:07,105 --> 00:00:10,175
- Hello and welcome to the
Physics World Weekly Podcast.
3
00:00:10,715 --> 00:00:11,815
I'm Hamish Johnston.
4
00:00:12,195 --> 00:00:13,655
Coming up in this episode,
5
00:00:13,865 --> 00:00:16,855
we'll be chatting about a
new experimental technique
6
00:00:16,925 --> 00:00:20,775
that physicists have developed
to study how bacteria
7
00:00:21,325 --> 00:00:25,375
move about research that's
part of the burgeoning field
8
00:00:25,755 --> 00:00:27,055
of active matter.
9
00:00:28,035 --> 00:00:32,535
But first, magnetic
resonance imaging, or MRI
10
00:00:32,995 --> 00:00:36,895
and proton beam therapy
are two powerful techniques
11
00:00:36,955 --> 00:00:38,375
of medical physics.
12
00:00:39,155 --> 00:00:43,695
The former gives us realtime
images of internal structures
13
00:00:43,795 --> 00:00:47,735
of the body, and the latter
can deliver a high dose
14
00:00:47,735 --> 00:00:51,495
of radiation to a tumor
while reducing the damage
15
00:00:51,715 --> 00:00:52,775
to healthy tissue.
16
00:00:53,715 --> 00:00:57,935
Now, researchers in Germany are
working on combining the two
17
00:00:57,935 --> 00:01:00,175
techniques as physics world's.
18
00:01:00,345 --> 00:01:01,935
Tammy Freeman discovers
19
00:01:09,795 --> 00:01:12,975
- Proton therapy is an advanced
cancer treatment technique
20
00:01:13,045 --> 00:01:14,255
that can irradiate
21
00:01:14,255 --> 00:01:17,135
and destroy tumors with
high targeting accuracy.
22
00:01:17,835 --> 00:01:20,135
And soon it could become
even more precise.
23
00:01:20,485 --> 00:01:23,855
With the addition of real-time
magnetic resonance imaging,
24
00:01:24,155 --> 00:01:26,495
or MRI during treatment delivery
25
00:01:27,705 --> 00:01:30,615
early in January on
koray, the National Center
26
00:01:30,635 --> 00:01:33,775
for Radiation Research
in Oncology in Dresden,
27
00:01:33,945 --> 00:01:37,095
officially launched the world's
first research prototype
28
00:01:37,155 --> 00:01:39,655
for whole body MRI guided proton therapy.
29
00:01:40,875 --> 00:01:43,895
I'm very pleased to be joined
today by Aswin Hoffman,
30
00:01:44,075 --> 00:01:45,615
who headed up this research project.
31
00:01:46,165 --> 00:01:47,895
Welcome to the podcast, Aswin.
32
00:01:48,565 --> 00:01:51,735
- Well, thank you Tammy, for
inviting me for this, uh,
33
00:01:51,735 --> 00:01:54,535
interview and for giving
me the opportunity
34
00:01:54,675 --> 00:01:55,975
to explain the need
35
00:01:56,035 --> 00:01:58,615
for better image guidance
in proton therapy.
36
00:01:59,665 --> 00:02:02,455
- Super. So first of all,
could you briefly explain
37
00:02:02,915 --> 00:02:05,215
how proton therapy is
used to treat cancer?
38
00:02:05,955 --> 00:02:09,735
- Mm-Hmm. . So,
um, in radiation therapy,
39
00:02:10,735 --> 00:02:13,895
external beams of ionizing radiation are
40
00:02:14,735 --> 00:02:16,815
directed onto the tumor in order to
41
00:02:17,455 --> 00:02:20,375
sterilize the cancer cells
with a therapeutic dose
42
00:02:21,125 --> 00:02:23,375
with the intention to cure the patient.
43
00:02:24,235 --> 00:02:25,895
And currently two types
44
00:02:26,115 --> 00:02:28,735
of beam modalities are used clinically.
45
00:02:29,235 --> 00:02:33,655
The first one is photon beams
with high energy X-rays.
46
00:02:34,315 --> 00:02:37,255
And the second one is
particle beams, in particular
47
00:02:37,325 --> 00:02:39,375
with high energy protons.
48
00:02:40,595 --> 00:02:44,215
Um, the advantage of proton
therapy over photon therapy
49
00:02:45,155 --> 00:02:49,735
is its target dose conformity
due to the finer range
50
00:02:49,755 --> 00:02:50,775
of the protons.
51
00:02:51,885 --> 00:02:55,655
This means that proton
beams can be made to stop
52
00:02:55,955 --> 00:02:57,175
inside the tumor volume
53
00:02:58,115 --> 00:03:02,975
and hence provides, uh, a
better sparing of healthy, uh,
54
00:03:03,155 --> 00:03:04,695
organs surrounding the tumor.
55
00:03:05,565 --> 00:03:10,295
Also, the number of beams
in protein therapy as well
56
00:03:10,295 --> 00:03:12,975
as its slightly increased, um,
57
00:03:13,615 --> 00:03:18,575
relative biological effectiveness
contribute to lower doses,
58
00:03:19,475 --> 00:03:22,015
um, in radiation sensitive tissues.
59
00:03:22,315 --> 00:03:25,855
And, um, these facts offer
the potential benefit
60
00:03:26,075 --> 00:03:28,015
of less side effects
61
00:03:28,075 --> 00:03:29,535
and less toxicity than
62
00:03:29,535 --> 00:03:32,015
with conventional photon
based radiation therapy.
63
00:03:32,925 --> 00:03:33,975
- Okay, brilliant. So
64
00:03:34,395 --> 00:03:38,095
how will MRI help improve
proton treatments further?
65
00:03:39,285 --> 00:03:43,575
- Well, um, proton
therapy is more sensitive
66
00:03:43,835 --> 00:03:45,015
to tumor motion
67
00:03:45,315 --> 00:03:49,015
and organ deformation
occurring during those delivery
68
00:03:49,775 --> 00:03:52,335
fractions than conventional
photon based radiation therapy.
69
00:03:53,605 --> 00:03:56,895
Therefore, the targeting
accuracy of protein therapy
70
00:03:57,195 --> 00:04:02,015
for moving tumors in, for
example, the thorax or lung tumors
71
00:04:02,515 --> 00:04:05,175
or in the abdomen, liver tumors and, and,
72
00:04:05,235 --> 00:04:07,175
and, um, tumors in the pelvis.
73
00:04:07,175 --> 00:04:11,535
Like for example, prostate
cancer is currently compromised
74
00:04:12,035 --> 00:04:14,215
by the lack of fast
75
00:04:14,595 --> 00:04:17,575
and high soft tissue
contrast image guidance
76
00:04:17,675 --> 00:04:18,895
during irradiation
77
00:04:19,675 --> 00:04:24,535
and MRI is, um, expected
to solve this issue
78
00:04:24,885 --> 00:04:28,295
because it has an excellent
soft tissue contrast.
79
00:04:28,795 --> 00:04:32,415
And it furthermore also
enables continuous imaging
80
00:04:32,635 --> 00:04:34,295
to capture organ motion.
81
00:04:35,195 --> 00:04:38,975
Now the idea is to
synchronize the dose delivery
82
00:04:39,125 --> 00:04:41,695
with the tumor motion to thereby
83
00:04:42,335 --> 00:04:46,455
increase the targeting accuracy
of protein therapy, um,
84
00:04:46,635 --> 00:04:48,415
to reduce the side effects
85
00:04:48,635 --> 00:04:52,935
and hence potentially allow an
even higher therapeutic dose
86
00:04:52,935 --> 00:04:54,175
to be delivered to the tumor.
87
00:04:55,675 --> 00:04:57,815
- So this combination of MRI
88
00:04:57,815 --> 00:05:00,215
and proton therapy hasn't
been achieved before,
89
00:05:00,915 --> 00:05:03,375
and for a long time was considered by many
90
00:05:03,515 --> 00:05:05,135
as a pretty impossible task.
91
00:05:05,755 --> 00:05:07,975
So what are the main technical challenges
92
00:05:08,355 --> 00:05:11,655
of combining an MRI scanner
with a proton therapy system?
93
00:05:13,255 --> 00:05:15,375
- Hmm. So the, the main, um,
94
00:05:15,525 --> 00:05:18,815
technical challenge is
the mutual electromagnetic
95
00:05:18,975 --> 00:05:22,815
interactions between the
proton therapy system
96
00:05:22,995 --> 00:05:24,135
and the MRI system.
97
00:05:25,185 --> 00:05:29,165
Um, the proton therapy system
produces magnetic fringe
98
00:05:29,165 --> 00:05:32,925
fields that would overlap with the highly
99
00:05:33,435 --> 00:05:36,725
uniform static magnetic
field of the MRI system.
100
00:05:37,385 --> 00:05:41,645
And consequently, the MR images
may suffer from distortions
101
00:05:41,945 --> 00:05:46,765
and no longer provide reliable
geometrical information
102
00:05:46,825 --> 00:05:51,205
to guide our beams to the
tumor volume, which for which
103
00:05:51,265 --> 00:05:54,405
as a consequence, uh, the
tumor would be underdosed
104
00:05:55,065 --> 00:05:57,645
and the healthy tissues
could be overdosed.
105
00:05:58,305 --> 00:06:00,685
But also the other way
around the magnetic field
106
00:06:00,785 --> 00:06:03,965
of the MRI system might interfere
107
00:06:03,965 --> 00:06:07,245
with the proton beam delivery
system potentially leading
108
00:06:07,345 --> 00:06:10,725
to a malfunction of that
pro dose delivery system.
109
00:06:11,425 --> 00:06:16,125
And last but not least, um,
due to the Lawrence Force,
110
00:06:16,465 --> 00:06:19,205
the protons which are
positively charged particles
111
00:06:19,985 --> 00:06:24,325
are deflected by the presence
of the MR Magnetic field
112
00:06:24,945 --> 00:06:28,485
as they are transported from
the proton dose delivery system
113
00:06:29,105 --> 00:06:31,845
to the treatment volume
inside the MRI system.
114
00:06:31,985 --> 00:06:35,525
And all these effects
need to be eliminated
115
00:06:35,785 --> 00:06:38,645
or taken into account or compensated for.
116
00:06:39,985 --> 00:06:42,845
- So how did your team overcome
all of these obstacles?
117
00:06:44,695 --> 00:06:48,985
- Well, in 2018, we demonstrated proof
118
00:06:49,085 --> 00:06:54,025
of concept with a first
generation research prototype in
119
00:06:54,025 --> 00:06:56,665
beam MRI system in our experimental room
120
00:06:57,475 --> 00:07:01,625
after, um, first conducting
a magnetic survey in
121
00:07:01,625 --> 00:07:03,385
that room in which the MRI system
122
00:07:03,525 --> 00:07:04,865
was intended to be installed.
123
00:07:05,805 --> 00:07:09,385
And in this way we identified
the dominant sources
124
00:07:09,525 --> 00:07:14,185
of magnetic interference
and we found ways to avoid
125
00:07:14,445 --> 00:07:17,265
and to compensate for
these disturbing effects
126
00:07:17,265 --> 00:07:18,505
during MR Imaging.
127
00:07:19,725 --> 00:07:24,505
Um, in addition to that, we
also used an open MRI scanner
128
00:07:25,005 --> 00:07:29,345
to allow an UNP unobstructed
beam transport from
129
00:07:30,085 --> 00:07:33,665
the beam exit of the
proton delivery device
130
00:07:34,245 --> 00:07:35,705
to the MR Imaging volume.
131
00:07:36,605 --> 00:07:39,305
And in addition to
that, we performed a lot
132
00:07:39,305 --> 00:07:43,705
of those imagery experiments
inside the, um, MRI system
133
00:07:43,845 --> 00:07:48,105
to characterize the magnetic
field induced effects on,
134
00:07:48,525 --> 00:07:52,505
on the beam deflection, um, a deformation
135
00:07:52,525 --> 00:07:54,185
of the radiation field shape
136
00:07:54,245 --> 00:07:56,985
and also, uh, distortions
on the dose spot.
137
00:07:58,125 --> 00:08:01,905
And we mapped out a static
magnetic field of DMR scanner,
138
00:08:02,485 --> 00:08:04,545
um, and incorporated
139
00:08:04,545 --> 00:08:07,985
that in the proton treatment
planning system such
140
00:08:07,985 --> 00:08:09,065
that the magnetic field
141
00:08:09,065 --> 00:08:11,505
of DMR scanner can be taken into account
142
00:08:11,505 --> 00:08:12,825
during those calculation.
143
00:08:13,445 --> 00:08:18,265
And so far we have not seen
any adverse effects of the MR.
144
00:08:18,505 --> 00:08:21,385
Magnetic field onto the
proton beam delivery system.
145
00:08:22,695 --> 00:08:25,435
- That's great. And you worked
with some industry partners.
146
00:08:25,435 --> 00:08:27,755
What, what were these
collaborations? How did they help?
147
00:08:28,665 --> 00:08:33,035
- Well, the industry partners
supported us in installing
148
00:08:33,225 --> 00:08:36,755
open MR Systems at our
proton research beamlines,
149
00:08:36,775 --> 00:08:38,995
making it possible to
150
00:08:39,675 --> 00:08:42,035
initiate technical
feasibility studies, studies
151
00:08:42,175 --> 00:08:46,315
and demonstrate, um, the
first proof of concept.
152
00:08:47,815 --> 00:08:50,765
Later on in the project,
we found industry partners
153
00:08:50,765 --> 00:08:53,405
who took on the challenge to design
154
00:08:53,625 --> 00:08:57,245
and produce a first
prototype for whole body,
155
00:08:57,625 --> 00:08:59,965
for a whole body MRI
system that is capable
156
00:09:00,145 --> 00:09:01,285
of real time imaging.
157
00:09:01,985 --> 00:09:06,205
And this particular system
went into scientific operation
158
00:09:06,345 --> 00:09:08,245
and I'm still excited
159
00:09:08,305 --> 00:09:11,085
and proud that our industry
partners have not hesitated
160
00:09:11,085 --> 00:09:12,965
to take on this challenge with us.
161
00:09:14,505 --> 00:09:17,245
- So, yeah, I mean, as you
said this, the, the big news is
162
00:09:17,245 --> 00:09:20,565
that the first Mr guided
proton therapy prototype was
163
00:09:20,805 --> 00:09:22,485
launched, um, in early January.
164
00:09:23,225 --> 00:09:25,445
So how do you see the first few months
165
00:09:25,465 --> 00:09:27,085
of its operation panning out?
166
00:09:27,085 --> 00:09:29,565
Have you started it, um,
the initial experiments yet?
167
00:09:30,265 --> 00:09:33,405
- Mm-Hmm, , so
first commissioning experience
168
00:09:33,405 --> 00:09:35,605
with the new mr, uh,
169
00:09:35,605 --> 00:09:38,165
proton therapy system
have already been planned
170
00:09:38,305 --> 00:09:41,605
for the next month in the first step.
171
00:09:42,065 --> 00:09:44,805
Um, the electromagnetic interactions
172
00:09:44,875 --> 00:09:49,045
between our proton pencil beam, uh, line
173
00:09:49,225 --> 00:09:51,445
and the, the new in beam MR.
174
00:09:51,445 --> 00:09:53,045
Scanner will need to be assessed.
175
00:09:53,865 --> 00:09:57,805
And here we will address
two particular questions.
176
00:09:57,825 --> 00:10:00,845
So the first one is, does the presence
177
00:10:01,145 --> 00:10:04,765
of the new MR scanner affect
the proton beam delivery system
178
00:10:05,545 --> 00:10:09,085
due to interferences
coming from the static mag
179
00:10:09,885 --> 00:10:11,325
magnetic field of ther scanner
180
00:10:11,345 --> 00:10:14,205
or from the acoustic
noise that is produced
181
00:10:14,225 --> 00:10:15,365
by this R scanner?
182
00:10:15,745 --> 00:10:17,845
And the second question
is the other way around,
183
00:10:18,555 --> 00:10:22,085
does the proton beam delivery
system affect the MR image
184
00:10:22,085 --> 00:10:23,605
quality during beam scanning?
185
00:10:25,145 --> 00:10:28,685
And in addition to that, we will also need
186
00:10:28,785 --> 00:10:31,325
to map out the static magnetic field
187
00:10:31,345 --> 00:10:34,125
of this new in beam MR scanner in, in,
188
00:10:34,185 --> 00:10:38,325
in three dimensional space,
since this is needed as input
189
00:10:38,425 --> 00:10:41,045
for the, uh, proton
treatment planning system
190
00:10:41,545 --> 00:10:43,965
to enable dose calculations
in the presence
191
00:10:43,965 --> 00:10:45,725
of the magnetic field of DR R scan.
192
00:10:47,195 --> 00:10:50,485
- Okay. And once these system
character characterizations
193
00:10:50,485 --> 00:10:52,965
are complete, um, what will come next?
194
00:10:53,835 --> 00:10:57,925
- Well, from a medical
physics point of view, we need
195
00:10:57,925 --> 00:11:02,285
to do a full commissioning both
of the beam delivery system
196
00:11:03,145 --> 00:11:06,605
in terms of the do metric quality, um,
197
00:11:06,905 --> 00:11:11,205
but also for the MRI system
in terms of image quality
198
00:11:11,385 --> 00:11:13,485
and geometrical fidelity of the images.
199
00:11:14,705 --> 00:11:19,445
Um, our radio biologists here
at OnCore are very interested
200
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in assessing, um,
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and in understanding the
magnetic field induced effects
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onto the biological effectiveness
as the directionality
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and the strength of the MR
magnetic field might also
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influence cell killing.
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And last
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but not least, from a
medical-legal, um, as, uh,
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perspective, we'll work
on the regulatory aspects
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for future clinical trials,
both in terms of ethics approval
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and, um, certification in accordance
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with the medical device regulation MDR.
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- Okay. So yeah, quite a
lot of work to do coming up.
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Um, do you know,
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are there any other teams
working on a similar system?
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- Well, so far I'm not aware
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of any other groups worldwide
working on a similar system.
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That means a system, um, that is capable
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of real-time imaging.
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That is a whole body MRI system.
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Um, also the fact that
the Nbm MRI system is
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rotatable around a
patient enabling patients
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to be scanned both in a recumbent
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or in an upright position,
makes our system, um, unique.
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And, um, this kind
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of MRI system requires
a relatively large room
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to be installed it because
it's a, it's a big,
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it's a heavy machine.
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However, most of the research
rooms in particle therapy
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centers are not large enough
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to accommodate such a large MRI system.
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And I also think that our
research room here at,
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at OnCore is unique in
its kind with, um, an, uh,
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a floor area of approximately
250 square meters.
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Um, the only other team working on
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MR particle therapy that I know
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of is at the German
Cancer Research Center,
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DKFC in Heidelberg, also in in Germany.
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Um, they have a smaller research room
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and started working on
a compact MRI scanner
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after we showed first of,
um, first proof of concept
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with our compact MI scanner back in 2018,
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that our proton research beamline
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and both of these
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compact MRI scanners have in common common
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that they were originally
designed for diagnostic imaging
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of extremity.
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So these scanners are
not whole body scanners
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like the newly installed
one in our research room.
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And, um, where we have shown
first proof of concept,
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uh, of in beam MRI, in
combination with proton beams,
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our colleagues at Heidelberg
have combined their compact in
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beam MRI scanner with their
horizontal research beamlines
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for heavy iron, so not protons.
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And they performed first
experiments with MRI guided, uh,
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scanned carbon iron beans.
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- That, that's really interesting.
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'cause that's sort of,
that's another, um, type
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of particle therapy using the carbon ions
258
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instead of the protons.
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That's, it's less prevalent,
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but it's certainly, it is another option
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under investigation, isn't it?
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- Yep. And it also, I think
it also provides less, um,
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, let's say scientific
challenges or less problems
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because the, um, heavy ions, uh,
265
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heavy iron beams are not
deflected by the presence
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of the MR magnetic field as
much as the proton beams are.
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So from a treatment
planning point of view,
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it is an easier problem to, to
solve than for proton beams.
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- Oh, okay. That's interesting.
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Um, and then finally my last question.
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When do you think that
your system might be used
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to treat the first patient?
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- Hmm, , I often get that question.
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Um, so, so our aim with
the new prototype system
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that was installed last week, the one that
276
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offers real-time MRO
imaging, um, well, we hope
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to be able to treat a
first patient in about
278
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five years from now.
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Um, because there is still a
lot of technical challenges
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to solve, but also from a
regulatory point of view.
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But with our, our previous,
um, complex prototype system,
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so the one without real-time
imaging capabilities,
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that is still in our, our research room.
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We expect to treat the first patient
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within the next two years.
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- Oh, okay. And I guess you'll
be using both systems in
287
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parallel to sort of just continue
developing this approach?
288
00:16:03,865 --> 00:16:07,365
- Yes, because the, as I said,
the experimental room is,
289
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is large enough to host two MR scanners
290
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and they will indeed be operated more
291
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or less in, in parallel.
292
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- Okay. That's brilliant.
Well, thanks very much
293
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for talking to us today.
294
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Thank you.
295
00:16:20,555 --> 00:16:24,185
- Thank you, Tammy, for
giving the opportunity to,
296
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to explain the need
297
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for better image guidance
in, in particle therapy.
298
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Thank you very much.
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- Our next guest is Katherine Skipper,
300
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who's joined the physics
world team as features editor
301
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after doing a PhD at the
University of Bristol
302
00:16:46,095 --> 00:16:48,125
where she studied active matter.
303
00:16:48,665 --> 00:16:52,365
Hi Catherine, welcome to Physics
World and to the podcast.
304
00:16:53,505 --> 00:16:55,365
- Hi ish.
- Catherine's here
305
00:16:55,365 --> 00:16:58,605
to chat about some fascinating
active matter research
306
00:16:59,025 --> 00:17:02,725
that's been done by scientists
in Germany and China.
307
00:17:03,355 --> 00:17:06,125
They've gained important insights into
308
00:17:06,145 --> 00:17:09,525
how e coli bacteria propel themselves.
309
00:17:10,305 --> 00:17:13,925
So Catherine, before we
discuss this specific research,
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can you tell us a bit about
the field of active matter?
311
00:17:17,475 --> 00:17:21,125
What sort of systems do
physicists study and why?
312
00:17:22,425 --> 00:17:26,165
- So if you've taken a
physics undergraduate course,
313
00:17:26,165 --> 00:17:29,285
you've at some point encountered
statistical mechanics
314
00:17:29,285 --> 00:17:33,125
where you're describing a
large system by the statistics
315
00:17:33,125 --> 00:17:35,125
of the individual atoms or molecules.
316
00:17:35,745 --> 00:17:38,925
Um, so I remember using,
you know, the icing model
317
00:17:38,985 --> 00:17:42,485
to predict, um, or to,
to model fair magnetism
318
00:17:42,865 --> 00:17:44,445
or to predict a melting transition,
319
00:17:44,905 --> 00:17:46,325
or you use statistical physics
320
00:17:46,385 --> 00:17:47,845
to describe superconductivity.
321
00:17:48,505 --> 00:17:52,005
Um, and broadly active matter
is a branch of physics that
322
00:17:52,755 --> 00:17:55,645
uses statistical mechanics
to describe living systems
323
00:17:56,275 --> 00:17:58,765
because a lot of the
functions of living systems
324
00:17:59,465 --> 00:18:00,965
are performed by a lot
325
00:18:00,965 --> 00:18:02,645
of biological units that work together.
326
00:18:02,905 --> 00:18:06,965
So, uh, a well-known example is, um,
327
00:18:07,525 --> 00:18:11,005
a murmuration of
starlings where these sort
328
00:18:11,005 --> 00:18:13,605
of beautiful coherent patterns
are produced on length scales
329
00:18:13,605 --> 00:18:15,485
that are much larger than
the individual birds.
330
00:18:16,105 --> 00:18:17,685
Um, but cells do this as well.
331
00:18:17,715 --> 00:18:20,245
Tissues in the body often have
very different properties,
332
00:18:20,905 --> 00:18:22,325
um, to the individual cells,
333
00:18:22,325 --> 00:18:23,485
and they can perform functions
334
00:18:23,485 --> 00:18:24,725
that the individual cells can't.
335
00:18:25,985 --> 00:18:30,005
Um, and actually within a cell,
the cytoskeleton is a bundle
336
00:18:30,065 --> 00:18:33,165
of active fibers that
contracts to move the cell.
337
00:18:33,825 --> 00:18:38,045
Um, and this particular
piece of research is, um,
338
00:18:38,425 --> 00:18:41,285
on swarms of eco bacteria,
which are also an active system.
339
00:18:42,065 --> 00:18:45,205
Um, so these are complicated systems,
340
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but you can turns out,
you can describe a lot
341
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of their behaviors using physics.
342
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So a lot of people
343
00:18:51,625 --> 00:18:54,565
who study active matter
have backgrounds in biology
344
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or biophysics, but I think
one of the key questions
345
00:18:57,605 --> 00:19:02,125
of this field is what's the
smallest amount of knowledge
346
00:19:02,125 --> 00:19:03,525
of biology you can have
347
00:19:03,585 --> 00:19:07,925
and still be able to describe
these biological systems?
348
00:19:08,185 --> 00:19:11,885
How much of this can be
encompassed by statistical physics?
349
00:19:12,915 --> 00:19:15,485
- Okay. And, and you, you
sort of hinted, um, uh,
350
00:19:15,485 --> 00:19:16,845
about this latest research.
351
00:19:16,875 --> 00:19:20,925
This is a study that was
done by Christina Kurtz Toler
352
00:19:21,425 --> 00:19:24,525
of the Max Plank Institute for the physics
353
00:19:24,785 --> 00:19:26,085
of complex systems
354
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and young FZ of Sohow University.
355
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And they've developed a new technique
356
00:19:33,245 --> 00:19:35,805
for studying the motion of bacteria.
357
00:19:36,185 --> 00:19:37,885
So, so what exactly did they do
358
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and and what have they found?
359
00:19:40,785 --> 00:19:42,645
- Um, so it's been observed
360
00:19:42,745 --> 00:19:46,365
before that e coli bacteria,
when they're in, um,
361
00:19:47,115 --> 00:19:51,005
when they're in like a dense
suspension, they produce these,
362
00:19:51,005 --> 00:19:52,285
these coherent patterns.
363
00:19:52,285 --> 00:19:54,645
They've been shown to, uh,
364
00:19:54,645 --> 00:19:56,605
form like rotating elliptical patterns.
365
00:19:56,945 --> 00:20:00,605
Um, motion couldn't, like
turbulent flow with vortices.
366
00:20:00,755 --> 00:20:04,725
They've actually been described
as a super fluid in some,
367
00:20:05,305 --> 00:20:07,845
in some contexts where the
bacteria is actually pushing the
368
00:20:07,845 --> 00:20:10,605
fluid along, so it effectively
has a negative viscosity.
369
00:20:11,105 --> 00:20:12,685
So there's a lot of
interest in understanding
370
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how these behaviors come about.
371
00:20:15,345 --> 00:20:16,525
So, and so the way
372
00:20:16,525 --> 00:20:18,645
that the ooc coli move is quite particular
373
00:20:18,985 --> 00:20:20,885
and it's important for
understanding how they behave.
374
00:20:21,385 --> 00:20:23,245
And it's called, it's called
run and tumble motion.
375
00:20:23,785 --> 00:20:26,765
Uh, so if you look at any
coli bacterium moving,
376
00:20:27,385 --> 00:20:29,845
it will swim forwards for
about, about a second,
377
00:20:30,595 --> 00:20:31,805
then it will suddenly rotate
378
00:20:31,825 --> 00:20:34,525
and start moving often
a different direction.
379
00:20:35,305 --> 00:20:38,885
Um, so that's, that's what
run and tumble motion is.
380
00:20:39,305 --> 00:20:43,165
So scientists who are interested
in e coli bacteria want
381
00:20:43,165 --> 00:20:46,285
to understand how the
patterns that you get.
382
00:20:46,425 --> 00:20:49,445
The, the collective motion that
I was talking about is links
383
00:20:49,545 --> 00:20:52,245
to, um, the motion
384
00:20:52,385 --> 00:20:54,245
and particularly to the length of these
385
00:20:54,885 --> 00:20:57,605
straight line runs
they're doing between, um,
386
00:20:57,605 --> 00:20:59,565
between tumbling, between
changing direction.
387
00:21:00,505 --> 00:21:04,485
Um, and it's possible to
engineer strains of bacteria
388
00:21:04,835 --> 00:21:07,805
that only tumble, they're
constantly changing direction.
389
00:21:08,305 --> 00:21:11,205
Uh, you do this by turning
off, um, the expression
390
00:21:11,205 --> 00:21:14,085
of a gene, and it's been proposed
391
00:21:14,155 --> 00:21:17,205
that if you could take these
genetically engineered e coli,
392
00:21:17,625 --> 00:21:20,445
um, and add, um, a reagent,
a biological reagent,
393
00:21:20,545 --> 00:21:23,045
it would be possible to
slowly turn this gene
394
00:21:23,045 --> 00:21:24,085
expression back on.
395
00:21:24,545 --> 00:21:28,005
So they start moving in
a straight line again.
396
00:21:28,005 --> 00:21:31,485
They start performing these
runs between changing, um,
397
00:21:31,485 --> 00:21:32,885
between changing direction.
398
00:21:33,585 --> 00:21:36,685
Um, and so yeah, scientists
are interested in understanding
399
00:21:36,825 --> 00:21:38,045
how that would change the,
400
00:21:38,045 --> 00:21:39,685
these coherent patterns that you get.
401
00:21:40,785 --> 00:21:43,445
Uh, but the challenge, that
sounds very straightforward when
402
00:21:43,445 --> 00:21:46,085
I describe it, but it's really
hard to do experimentally,
403
00:21:46,085 --> 00:21:47,685
and that's what the paper is about.
404
00:21:48,145 --> 00:21:52,045
- So, so is the, the difficulty
actually following a Yeah,
405
00:21:52,195 --> 00:21:54,165
bacterium, 'cause I
suppose they're very small
406
00:21:54,185 --> 00:21:55,725
and do, do they move very quickly?
407
00:21:55,865 --> 00:21:57,845
Is it difficult to, I suppose they move in
408
00:21:57,845 --> 00:21:59,565
and out of the focus of the microscope
409
00:21:59,705 --> 00:22:03,725
and it's, it's probably very
difficult to, to follow one.
410
00:22:04,395 --> 00:22:08,365
- Well, you can follow, if you
only have one, um, bacterium,
411
00:22:08,465 --> 00:22:12,005
eco bacterium or only a couple
you can follow, you can,
412
00:22:12,385 --> 00:22:13,965
um, you can track them.
413
00:22:14,225 --> 00:22:17,525
Um, you can, you know,
you have a a, an algorithm
414
00:22:17,525 --> 00:22:19,325
that's basically labeling
this as e coli A,
415
00:22:19,325 --> 00:22:21,125
this is e coli B, this is E coli C
416
00:22:21,125 --> 00:22:22,645
and it measures what, how they're moving.
417
00:22:23,025 --> 00:22:25,285
But if you've got a lot
of them, it's really hard
418
00:22:25,345 --> 00:22:27,645
and you can sort of imagine
that you have two e coli,
419
00:22:27,645 --> 00:22:28,885
they come very close together
420
00:22:29,585 --> 00:22:31,365
and it's hard to tell whether they've,
421
00:22:31,635 --> 00:22:33,765
they're going in the straight
line and they've crossed paths
422
00:22:33,765 --> 00:22:35,205
or whether they've both at the same time,
423
00:22:35,205 --> 00:22:36,485
turned in different directions.
424
00:22:37,345 --> 00:22:40,045
Um, so it's really hard to
425
00:22:40,885 --> 00:22:43,805
accurately track the
trajectories over a very
426
00:22:44,355 --> 00:22:45,445
long period of time.
427
00:22:46,185 --> 00:22:47,885
- And so these researchers in China
428
00:22:47,905 --> 00:22:49,765
and Germany, they've, they, they've got
429
00:22:49,765 --> 00:22:51,565
around this problem. Is that,
430
00:22:51,865 --> 00:22:52,865
- Uh, yeah, that's
- The news.
431
00:22:53,465 --> 00:22:55,405
- So they've actually, there are actually,
432
00:22:55,435 --> 00:22:59,725
there's a companion paper
to this paper, um, which uh,
433
00:23:00,205 --> 00:23:02,605
contains a lot of like
mathematical derivation,
434
00:23:03,465 --> 00:23:08,205
but basically, um, what they have done is,
435
00:23:08,355 --> 00:23:10,845
yeah, they, they're not tracking
the individual bacteria.
436
00:23:11,435 --> 00:23:15,285
What they've done is they have a sequence
437
00:23:15,365 --> 00:23:17,805
of three dimensional
images just from a, like a,
438
00:23:18,005 --> 00:23:19,445
a standard optical microscope,
439
00:23:19,545 --> 00:23:22,325
and they're taking the RIA
transform of those images.
440
00:23:23,025 --> 00:23:26,205
And then they have this
second companion paper
441
00:23:26,205 --> 00:23:30,285
where they are doing some
very complicated maths using,
442
00:23:30,625 --> 00:23:33,485
you know, the sta the statistics of run
443
00:23:33,485 --> 00:23:36,925
and tumble motion to extract length
444
00:23:36,945 --> 00:23:40,205
and timescales from these
three A transformed images
445
00:23:40,315 --> 00:23:43,965
that tell them how fast the
bacteria are moving on average
446
00:23:44,185 --> 00:23:47,525
and how far they move, how
447
00:23:47,755 --> 00:23:49,245
between changing direction.
448
00:23:50,025 --> 00:23:51,325
- And, and so what did they find?
449
00:23:51,385 --> 00:23:53,285
Was it a, was it in line with
450
00:23:53,285 --> 00:23:55,565
what people thought e coli were up to
451
00:23:55,625 --> 00:23:57,085
or was it a complete surprise
452
00:23:57,265 --> 00:23:59,645
or as often in science? A bit of both.
453
00:24:00,585 --> 00:24:03,925
- Um, so what they, they do
is, as I, as I mentioned, they
454
00:24:04,755 --> 00:24:06,885
take these genetically engineered e coli
455
00:24:07,825 --> 00:24:12,605
and they add this
reagent that is predicted
456
00:24:12,825 --> 00:24:16,805
to, um, turn on the, the
run motion between the,
457
00:24:16,805 --> 00:24:20,885
between the tumbles and using this, um,
458
00:24:21,025 --> 00:24:23,125
the s mathematical treatment
they have, they're able to show
459
00:24:23,125 --> 00:24:25,765
that that's, that is indeed
what's happening, you know,
460
00:24:25,765 --> 00:24:28,405
even in these quite dense
suspensions of bacteria.
461
00:24:29,025 --> 00:24:31,605
So they're able to, yeah, they're able to
462
00:24:32,645 --> 00:24:34,045
demonstrate something that has been
463
00:24:35,675 --> 00:24:37,765
theorized but hadn't improved. Ah,
464
00:24:37,795 --> 00:24:38,795
- Okay.
465
00:24:38,795 --> 00:24:39,125
And that sounds important
466
00:24:39,125 --> 00:24:42,005
because I suppose now that
we know this technique works,
467
00:24:42,575 --> 00:24:46,885
other scientists can use it,
um, and do, do further studies.
468
00:24:47,755 --> 00:24:50,765
- Yeah, I think if you've
done any kind of research,
469
00:24:50,865 --> 00:24:53,325
you will recognize the
frustration of having a very
470
00:24:53,875 --> 00:24:56,085
cool idea or a very
cool theory that cannot,
471
00:24:56,415 --> 00:24:59,405
where you don't have the methods
to, to test it or prove it.
472
00:24:59,945 --> 00:25:03,925
So, um, I think it's, it's
a really nice, uh, neat way
473
00:25:03,925 --> 00:25:06,125
of getting around the difficulty
of tracking these bacteria.
474
00:25:06,625 --> 00:25:09,525
And it is something that they
talk about this in the paper a
475
00:25:09,525 --> 00:25:12,565
bit that could be applied,
um, to other cells.
476
00:25:13,145 --> 00:25:15,085
- And, and I suppose the e coli, you know,
477
00:25:15,365 --> 00:25:17,605
I suppose if you've
heard of one bacterium,
478
00:25:18,115 --> 00:25:19,525
it's going to be e coli.
479
00:25:19,555 --> 00:25:22,765
It's, you know, it's a
bacteria that lives in our guts
480
00:25:22,785 --> 00:25:26,125
and it's used as a marker
for, for pollution.
481
00:25:26,505 --> 00:25:29,685
So I suppose, um, it, you
know, it's very important
482
00:25:29,685 --> 00:25:32,485
to understand how e coli gets around.
483
00:25:33,315 --> 00:25:36,125
- Yeah. Um, so I think
there's, there's two reasons
484
00:25:36,145 --> 00:25:37,245
to be interested in them.
485
00:25:37,355 --> 00:25:41,485
Firstly is yeah, they, they
are, they are everywhere.
486
00:25:41,705 --> 00:25:45,005
And it is, um, it would be
useful to know whether some
487
00:25:45,005 --> 00:25:48,245
of the collective behaviors
they have are evolutionary,
488
00:25:48,245 --> 00:25:50,885
whether they, they perform,
whether they are enabling the,
489
00:25:51,505 --> 00:25:55,165
um, the bacteria to perform
what perform useful work.
490
00:25:55,745 --> 00:25:58,725
But also, as you said, they
are, they're everywhere.
491
00:25:58,725 --> 00:26:02,205
They're relatively easy to
do experiments on, you know,
492
00:26:02,205 --> 00:26:06,645
that's easier to study than a
swarm of like a, a murmuration
493
00:26:06,645 --> 00:26:08,605
of starlings, for example, in a lab.
494
00:26:09,585 --> 00:26:12,685
So they are used as a,
as a model active system.
495
00:26:13,865 --> 00:26:17,645
Uh, and but to use them as
a, as a model system, we need
496
00:26:17,645 --> 00:26:20,165
to understand exactly how they work.
497
00:26:20,945 --> 00:26:24,045
- And are, are there any
implications in terms of, um,
498
00:26:24,345 --> 00:26:26,925
you know, creating artificial swimmers?
499
00:26:27,525 --> 00:26:29,285
'cause I know that, you
know, some researchers are
500
00:26:29,285 --> 00:26:33,125
interested in, you know, creating
tiny, tiny sort of objects
501
00:26:33,125 --> 00:26:36,485
that can swim in maybe the
same way as a, as a bacterium
502
00:26:37,015 --> 00:26:40,685
swims, or, or is there any,
is there any information there
503
00:26:40,785 --> 00:26:43,045
or, or would that be something
that's further down the line?
504
00:26:43,445 --> 00:26:44,485
- I mean, I think you could,
505
00:26:45,025 --> 00:26:48,165
you could presumably use
this technique to study
506
00:26:49,245 --> 00:26:51,405
synthetic active particles,
which are these, these tiny,
507
00:26:51,455 --> 00:26:52,765
these tiny sort of micro
508
00:26:53,105 --> 00:26:56,405
or micro, uh, tiny beads, a couple of sort
509
00:26:56,405 --> 00:26:57,445
of micross across.
510
00:26:57,865 --> 00:26:59,925
Um, and yeah, if you
can, if you can use this
511
00:26:59,925 --> 00:27:03,245
as study the bacteria, you
can use it, I would presume
512
00:27:03,745 --> 00:27:04,885
to study those.
513
00:27:05,125 --> 00:27:06,925
I, I think one of the, I guess one
514
00:27:06,925 --> 00:27:08,885
of the tough things about
the e coli is that they,
515
00:27:09,795 --> 00:27:11,605
they unpredictably change direction.
516
00:27:11,885 --> 00:27:14,005
I think that does make them,
I would, I would assume
517
00:27:14,005 --> 00:27:16,205
that makes them very, very hard to track.
518
00:27:16,205 --> 00:27:18,845
Whereas synthetic acid particles, they
519
00:27:19,385 --> 00:27:20,805
change direction much more slowly.
520
00:27:20,865 --> 00:27:22,605
So I think they are a
bit easy as to track,
521
00:27:22,605 --> 00:27:24,645
but I, I would assume you
can still use this technique.
522
00:27:25,045 --> 00:27:26,085
- Hmm. Well that's great.
523
00:27:26,105 --> 00:27:28,485
Tha uh, Catherine, thanks
for for explaining that.
524
00:27:28,905 --> 00:27:31,165
Um, if you'd like to learn
more about this study,
525
00:27:31,635 --> 00:27:34,245
it's described in open access papers,
526
00:27:34,705 --> 00:27:37,885
and those papers are published
in physical review letters
527
00:27:38,585 --> 00:27:40,245
and physical review e
528
00:27:40,665 --> 00:27:44,525
and the best way to find both
papers is to read a synopsis
529
00:27:44,545 --> 00:27:48,085
of the research that appears
on the American Physical
530
00:27:48,195 --> 00:27:49,405
Society website.
531
00:27:49,835 --> 00:27:53,525
That synopsis is called
Characterizing the Swimming Gate
532
00:27:53,705 --> 00:27:56,885
of a Bacterium, and it's
by Catherine Wright.
533
00:27:57,305 --> 00:27:58,245
Thanks, Catherine.
534
00:28:06,115 --> 00:28:07,575
I'm afraid that's all the time we
535
00:28:07,575 --> 00:28:08,615
have for this week's podcast.
536
00:28:09,075 --> 00:28:11,975
Thanks to Aswin Hoffman, Catherine Skipper
537
00:28:12,155 --> 00:28:14,415
and Tammy Freeman for joining me today.
538
00:28:14,835 --> 00:28:18,015
And a special thanks to
our producer Fred Isles.
539
00:28:18,585 --> 00:28:20,055
We'll be back again next week,
540
00:28:20,235 --> 00:28:23,055
but in the meantime, do
check out the latest episode
541
00:28:23,075 --> 00:28:25,175
of the Physics World Stories podcast
542
00:28:26,045 --> 00:28:28,655
host Andrew Gluster is in conversation
543
00:28:28,655 --> 00:28:32,215
with the astrophysicist
and author Emma Chapman,
544
00:28:32,915 --> 00:28:36,695
and they chat about the
history of radio astronomy.
545
00:28:37,565 --> 00:28:41,175
Chapman, who is at the UK's
University of Nottingham,
546
00:28:41,585 --> 00:28:45,655
talks about the do it yourself
ethic of radio astronomers
547
00:28:45,995 --> 00:28:49,655
and highlights the valuable
contributions made by people
548
00:28:49,885 --> 00:28:53,415
outside the established
academic community.
549
00:28:54,325 --> 00:28:58,855
That podcast is called Radio
Pioneers, the Enduring role
550
00:28:58,995 --> 00:29:01,895
of amateurs in Radio astronomy.
551
00:29:02,395 --> 00:29:05,055
And you can find it on
the Physics world website.
552
00:29:05,475 --> 00:29:07,935
And at your favorite podcast provider
553
00:29:13,875 --> 00:29:15,045
- Physics World.
