TRIUMF Day 2 - Life Sciences

 Today started off with a Science Week presentation on Particle Physics.  This started with a presentation from Nausheen Shah on The Status and Future of Particle Physics. Here she spoke about the standard model of particle physics and work currently being done to try to break it. She also looked at the Higgs boson and how it could be possible that Higgs field is actually a two-component doublet.  She also shared current thoughts on dark matter and where we go from here.

Chukman So talked about the Alpha-G experiment at CERN and how TRIUMF is working on that experiment.  Particularly interesting was seeing how they combine an antiproton with a positron to create antihydrogen.

Marco Valente spoke on TRIUMF's contributions to CERN's ATLAS experiment in developing and building the small wheel and ITK inner detector.

In the afternoon, I got to sit down with Dr. Valery Radchenko to talk about his work with radionuclides, creating them at TRIUMF, and their uses in medicine. This was a fascinating discussion and, as someone with no background in chemistry, I learned a ton! The chart of radionuclides is everywhere at TRIUMF and now I know why. The cyclotron is capable of creating a large number of radionuclides and a large number of them are explored for their feasibility in medical applications. For example, they use beta- and alpha emitters for radionuclide therapy in cancer patients as beta- (or electrons, as they're more commonly known) particles will interact with oxygen in the blood and create free radicals to damage cancer cells while alpha emitters are large enough to blow holes in the DNA killing the cancer cell.  They also use beta+ and photon emitters for diagnostic imaging. This is where physics, chemistry, and biology all meet. To make use of these radionuclides, they have to consider how long the biological process takes. If the doctor suspects a certain type of cancer that would see the radionuclide move through that system in 5 days, then a radionuclide with a half-life of 5 hours is completely useless at imaging it (at most you can get ~10 half-lives before the sample is so degraded that there's realistically nothing useable left, meaning a max of 50 hours or a little over 2 days in this example). If they look at treatment, then a radionuclide with a half-life of 5 hours might be the ideal candidate for treating a certain type of cancer, but that also means that patients need to be near a particle accelerator to receive that treatment, something that is not always feasible. They use the particle accelerator as the injection of a proton from the TRIUMF cyclotron into a nucleus causes a neutron to be ejected, thereby creating a potentially desired radionuclide (you can think of this as a Newton's cradle where pulling back a ball on one side will result in a single ball being ejected on the other side). This really amounts to the fact that alchemy, as it was classically known, is now possible in the world of particle accelerators! One of Valery's grad students is actually working on a project in turning mercury into gold at TRIUMF! He also told me of challenges that he works on and faces.  One way of treating cancer using radionuclides is to find which antibodies naturally attack cancer cells and then find a way to bind a radionuclide with a suitable half-life to it so that it can be deposited directly on the cancer cells. This approach leads to almost no damage to healthy tissue or other organs and allows for treatment of widespread cancers, such as leukemia. We also got to talk a bit about the use of radionuclides in diagnosis and treatment of neuro diseases, such as Parkinson's and Alzheimer's. From there we went to Meson Hall to look at the facilities at TRIUMF that focus on medical diagnosis and treatment.

After this, I had the incredible opportunity to talk with Dr. Connie Hoehr about her work running the proton therapy facility for 10 years and her transition into using that lab for research since 2019. We talked about various cancer treatments, similar to what I had learned five years ago at CERN from Dr. Manjit Dosanjh. Surgery being the worst and most invasive option for cancer treatment and chemotherapy amounting to an attempt to give a patient poison in hopes that the poison kills the cancer before it kills the patient. The issues of traditional x-ray radiotherapy with extensive damage to healthy tissue, including a risk of creating new cancers as a result. This lead us to her work with proton therapy and the curing of eye cancer. In her lab, they would treat about 40 patients per year with a ~95% success rate and ~85% survival rate beyond 5 years. When the lab first started, they treated using pions as the particle for treatment (TRIUMF stands for Tri-University Meson Facility as their original purpose was to create and study mesons, the pion being on of them). These particles proved to be not the best when treatment cancer and so they moved to electrons due to their ease of working with. However, electrons are good at killing cancers by interacting with oxygen in blood to create free radicals that then damage the cancer cells, but this is certainly not the most efficient way of killing cancer and still results in damage to healthy tissue (just less than with x-ray radiotherapy). They then moved to protons, that have a Bragg peak such that there is minimal damage done to healthy tissue on the way in, the protons then collide with the DNA in the cancer cell and kill it, with no residual energy on the way out meaning no damage to healthy tissue on the other side of the cancer. While I was at CERN, Dr. Dosanjh had also mentioned treatment using Carbon-12 ions and so I asked Dr. Hoehr about this. She explained that using heavier nuclides like Carbon-12 are great for certain cancers as they have a much higher Bragg peak breaking the DNA in multiple locations, but the fact that it has lots of nucleons means that it often breaks apart after impact and can damage healthy tissue on the other side of the tumour. This is why a hadron therapy facility should be capable of treating cancers using a variety of techniques and not just focus on one. She also talked about the use of boron around a cancer to create a target that can create a very aggressive attack on the cancer and the latest potential treatment in the form of FLASH therapy where they give a full dose (enough to theoretically kill all of the cancer in one shot) in a very short pulse. During this discussion, I got to see the now decommissioned proton therapy facility and how they now use it for research into very specialized aspects of proton therapy (such as the development of rotating disks that help square off the Bragg peak across the entire tumour evenly) as well as for commercial/industrial experimentation by various organizations and companies to test materials. One being space applications where cosmic rays (neutrons) can collide with metal exteriors of satellites and cause a shower of protons that can damage electronics.

This was an absolutely fascinating day and I got to learn so much! I have ideas of using the chart of radionuclides to create a lesson where students have to navigate around the chart to solve different puzzles such as "what target would you have to start with to turn lead into gold?" I'm also thinking about a series of lessons on how to diagnose and treat cancer patients using radionuclides and hadron therapy.