For many people, the pandemic sparked pivotal modifications. And Magdelena S. Allen was no exception.
Rising up in Portland, Oregon, Allen needed to study the whole lot. She beloved stargazing and the bodily sciences, however she was additionally fascinated with legislation and writing. Her mother and father, who homeschooled her and her sister till highschool, have been extraordinarily supportive of her varied pursuits. “However the factor I at all times stored coming again to was science,” she says.
An astrophysicist by coaching, Allen accomplished her undergraduate diploma on the College of California at Berkeley. She then spent a 12 months interning at physics analysis labs across the nation, together with the Fermi Nationwide Accelerator Lab, the Brookhaven Nationwide Lab, and the Marshall House Flight Heart at NASA.
Within the fall of 2019, Allen began her PhD within the Nuclear and Particle Experiment Division of MIT’s physics division, finding out cosmic rays with Professor Samuel C. C. Ting. She spent her time analyzing knowledge from the Alpha Magnetic Spectrometer, a cosmic ray detector that sits on the Worldwide House Station.
Round that point, Allen additionally joined the MIT Emergency Medical Providers (EMS), after listening to about it from a good friend who was concerned a pair years prior. “It began out as what I assumed could be a couple of hours every week and rapidly took over my life in one of the best ways potential,” she says.
When the pandemic hit in spring 2020 and the MIT neighborhood scrambled to disperse from campus, Allen was one of many few MIT EMTs who stayed behind. She helped maintain the ambulance in service 24/7, serving MIT in addition to the broader Cambridge and Boston neighborhood. “I wound up placing over a thousand hours into the service” this tutorial 12 months alone, she says.
Spending a lot time in affected person care spurred her curiosity in affected person outcomes. And that received her fascinated about her long-term profession objectives. “I had my existential disaster throughout that interval — as all of us did,” she says with fun. Whereas she beloved her analysis in elementary physics, she needed to have a extra direct impression on individuals.
Allen started in search of analysis teams engaged on biomedical units. In January 2021, she joined a brand new analysis mission to construct mind imaging {hardware}, which makes use of expertise much like some elementary physics experiments. She now works on the intersection of physics and medical analysis, co-advised by Harvard College Professor Ciprian Catana on the Built-in MR-PET Laboratory on the Massachusetts Normal Hospital A. A. Martinos Heart for Biomedical Imaging and MIT Professor Or Hen on the Laboratory for Nuclear Science. “It was an ideal match,” she says.
Uncovering the secrets and techniques of the mind
Immediately, Allen and her collaborators are creating a next-generation mind positron emission tomography (PET) scanner that can be utilized concurrently with 7-Tesla magnetic resonance imaging (MRI). The PET scanner shall be a cylindrical insert that matches instantly inside an MRI machine.
Every imaging expertise supplies a distinct perspective of the mind. Whereas MRI captures anatomical photos, PET captures biochemical processes, equivalent to metabolism. By seeing two synchronized views, scientists have helpful knowledge for finding out mind tumors and neurological ailments, equivalent to Alzheimer’s.
However, PET scans presently take a very long time — often 30 to 90 minutes — and sufferers should maintain nonetheless for your entire length to get clear photos. Within the next-generation PET scanner, Allen goals to make scans a lot faster, down to only a few minutes. Doing so may even open doorways for neuroscience analysis. With shorter imaging instances, the scanner can work concurrently with useful MRI (fMRI) to take fast snapshots of dynamic organic processes. For instance, PET can seize glucose metabolism within the mind as fMRI concurrently captures blood movement. “It’s actually thrilling,” Allen says. “It’s by no means been finished earlier than.”
The explanation why these scans presently take so lengthy lies in how PET works. Earlier than the scan, sufferers are injected with a radiotracer product of organic compounds that the physique usually makes use of, equivalent to glucose, that are barely modified to be radioactive. Because the physique processes these tracer compounds, radioactive gamma rays are emitted. The PET scanner then acts as a digicam to seize these gamma rays and kind a picture.
The issue, although, is that solely small doses of radiotracer are injected in sufferers to restrict adversarial radiation results. So, the emitted gamma rays are very faint, making it onerous for photos to kind. “It’s like a protracted publicity image with a daily digicam the place you’re simply ready for mild to be collected,” Allen says.
To scale back the required publicity time, Allen’s group is redesigning the MR-compatible PET scanner to be 10 instances extra delicate to gamma rays than the present state-of-the-art. And to realize this, a brand new type of gamma ray detector shall be used contained in the scanner. Whereas a typical scanner makes use of detector arrays organized in a cylindrical tube surrounding the pinnacle, the detector arrays of the brand new scanner are configured extra like a motorbike helmet. “You’ll be able to increase the [scanner’s] sensitivity lots simply by getting extra protection,” she says.
One other key half for making a high-sensitivity PET scanner is the person gamma ray detector modules contained in the detector. The detector consists of rings stacked from the neck up, and every ring incorporates a circle of detector modules. “Essentially the most attention-grabbing investigation to this point is [figuring out] totally different geometries for the detector in an effort to get clear data out of it,” she says. One problem is discovering the depth-of-interaction methodology and optimum thickness for the detector. A thicker detector can entice extra gamma rays for extra imaging data. However, a detector that’s too thick yields blurry photos. After some trial-and-error, although, Allen is “very near nailing down a remaining design.”
Astrophysics at coronary heart
Whereas Allen has ventured into the biomedical universe, she hasn’t utterly left particle physics behind. It seems that the PET scanner may also be used to research elementary physics questions.
One query that Allen is fascinated with is symmetry violation. Whereas the universe consists of matter and anti-matter, it’s not a 50-50 cut up, giving us an uneven universe. However, it’s not clear the place this asymmetry comes from. “We’re at all times trying to find sources of asymmetry within the universe,” Allen says.
A possible clue could be discovered within the life cycle of positronium, an unstable atom composed of an electron and its anti-particle, a positron. Positronium lasts for a really quick time period — lower than a millionth of a second — earlier than the electron and positron annihilate one another, emitting gamma rays. Relying on the preliminary state of positronium, totally different distributions of gamma rays are emitted.
“The PET scanner is mainly only a gamma ray detector,” she says, making it “completely tuned” to have a look at gamma rays from positronium decays. To research symmetry violation, Allen plans to watch how appearing on the preliminary states of positronium impacts the orientation of emitted gamma rays. If she sees any asymmetries, this might present perception into understanding symmetry violation.
However first, Allen wants to complete constructing the PET scanner. After finalizing the design of the detector modules, she’ll start assembling them into rings for the helmet this summer season. Within the meantime, she’ll proceed serving in MIT EMS, having simply wrapped up her tenure as chief of MIT EMS this previous 12 months. “It’s a really addicting factor to do,” she says.
