WEBVTT
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What if treating cancer wasn't just about fighting disease, but about precision, compassion, and the delicate balance between science and humanity?
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In this episode of Aussie Med Ed, we step inside the world of radiation oncology.
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Where every beam of energy is carefully calculated to destroy cancer cells while preserving as much healthy tissue as possible.
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It's a field that combines cutting edge physics, advanced imaging, and human empathy in equal measure, and few people who body that balance better than Dr.
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Vincent Pow, a radiation oncologist based in South Australia.
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Dr. Pow joins us to unpack what radiation oncology really involves, how treatment has evolved with technology like IMRT and stereotactic therapy.
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And why communication and patient-centered care remain at the heart of good medicine.
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We'll also explore how telemedicine is transforming access to cancer care for patients in rural and remote regions, and where the future of radiation oncology is heading.
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So whether you're a gp, a medical student, or simply curious about how modern cancer care works, this conversation with Dr.
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Vincent Pow will shine a light on the precision, compassion, and innovation driving today's radiation oncology.
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Good day and welcome to Aussie Med Ed.
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The Aussie style Medical podcast a pragmatic and relaxed medical podcast designed for medical students and general practitioners where we explore relevant and practical medical topics with expert specialists.
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Hosted by myself, Gavin Nimon, an orthopaedic surgeon, this podcast provides insightful discussions to enhance your clinical knowledge without unnecessary jargon.
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I'd like to start the podcast by acknowledging the Kaurna people as the traditional custodians of the land on which this podcast is produced.
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I'd like to pay my respects to the elders, both past, present, and emerging, and recognizing their ongoing connection to land, waters, and culture.
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I'd like to remind you that all the information presented today is just one opinion, and there are numerous ways of treating all medical conditions.
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It's just general advice and may vary depending upon the region in which you're practicing or being treated.
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The information may not be appropriate for your situation or health condition.
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And you should always seek the advice from your health professionals in the area in which you live.
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Also, if you have any concerns about the information raised today, please speak to your GP or seek assistance from health organizations such as Lifeline in Australia.
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Well, joining us today is Dr. Vincent Pow.
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He's an experienced and compassionate radiation oncologist who consults across multiple icons, cancer centers.
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Located in South Australia.
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He completed his medical degree at the University of Adelaide in 2012 and obtained specialist training in 2021.
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He currently serves as head of radiation oncology at both the Royal Adelaide Hospital and the Lyell McEwen Hospital and chairs the Radiation Oncology Quality and Safety Committee.
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His expertise spends a wide range of solid tumor malignancies with special interest in genito-urinary, gynecological, gastrointestinal skin, and prostate cancers, as well as stereotactic radiation therapy.
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He's also an advocate for telemedicine, helping bridge the gap in cancer care for patients in rural and remote regions.
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Welcome, Dr. Vincent Pow.
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Welcome to Aussie Med Ed.
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Thank you very much for coming on board.
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Thank you for having me, Gavin.
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Well, what actually is radiotherapy?
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What actually does it involve
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So I think to put it as simple as possible, radiation therapy is high energy x-ray.
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And it's the clinical use of that.
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So we use, has to be ionizing radiation.
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I can explain the slight differences in, in the different types of radiation, but we use ionizing radiation clinically.
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So not only to treat cancers, but some benign conditions as well.
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So that's what is simply,
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Right.
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what is the difference between ionizing radiation and non-ionizing radiation
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So, ionizing radiation essentially is on the electromagnetic spectrum.
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on the top end of it, x-rays, gamma rays, and it has to, essentially, the energy of it has to kick off an electron and that does the damage.
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So, common things like microwaves and your phones, they're all on the spectrum.
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But they.
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They don't have enough energy or enough power to actually do damage.
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So that's a common misconception about things like microwaves and, but as you push towards the higher end of the electromagnetic spectrum, then certainly that's what we want.
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We actually want to do some damage killing cancer cells.
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So is a light, a form of electromagnetic radiation
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Yeah, so light, it certainly is on.
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And you know, ultra ultraviolet light is sort of in the middle of the spectrum and can do a little bit of damage obviously.
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But we are on the, at the top end Yes.
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Okay.
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And how does that actually kill the cells then?
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You me mentioned that pushes off the electrons out of the atoms.
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Is that how it
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Yeah.
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So, we study this when we when we go through our training it's a big part of our curriculum and an understanding of how we use radiation therapy safely.
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So the key target for us is actually the DNA.
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So we wanna damage the DNA strands and we want to create, basically damage both strands called double stranded, DNA breaks.
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And when we can do that with the high energy x-rays, then that can actually kill the malignant cells, obviously can also harm normal cells, but we can go into how we minimize damage to healthy cells while maximizing damage to the, malignant cancer cells
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are cancer cells more prone to be damaged by the electro-magnetic radiation or there other substances you can use to help protect the normal cells.
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Yeah absolutely.
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So, malignant cells certainly don't repair as well.
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They don't have that repair mechanism as, as robust as normal tissue.
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And there's a few things that we do to maximize tumour kill while minimizing side effects.
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And I mean, that's the whole concept of radio biology.
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I usually describe it I think best with a classic scenario or picture that all radiation oncology trainees.
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will know.
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And it's essentially a picture of the Ram's testicles, the ram's balls.
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right?
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And so what they wanted to do essentially they thought, okay, we wanna sterilize a ram, so let's give it one big dose of radiation.
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And yes, absolutely they sterilize the ram, but their scrotum or the testicles were severely burnt.
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And instead of giving one big dose of radiation, why don't we give smaller packages of doses?
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Let's split it up into 3, 4, 5 little packets equals the same dose that we gave in the first boom, but we give it into five little treatments.
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And they found that giving it that way still created the outcome, the desired outcome of sterilization, but allowed the healthy tissue to recover.
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And the scrotum, although did get a little bit red.
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It didn't certainly get severe, like in the first scenario with a single fraction.
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So it's became the, you know, the basis of what we call in radiation oncology is we fractionate we split apart the doses and we give it over multiple doses
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And does that fractionation vary depending on the organ you're treating then?
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Yeah.
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There are varying schedules.
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Typically when we are treating with a curative intent, then we would do it over a longer period of time.
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And the idea being to give a smaller dose per treatment, although it's more prolonged, you still maximize that cell kill, but you also minimize, damage to healthy tissue and allow it to recover.
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So that's one of the main reasons why we fractionate.
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There are a number of others but I won't bore the audience with some of the other details about our radio biology curriculum.
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But that's the main one that the concept there,
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is the general health of the patient going through the radiotherapy, does that help the actual recovery then?
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Yeah, absolutely.
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Absolutely.
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I think the first thing that we do is we are assessing that patient functionally, and then we typically think about the organ that we are treating or the organs around that we're treating.
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We take that into account when we deliver our radiation dose.
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So for instance, when we're treating lung cancer, we make sure that obviously they're optimized from a lung function point of view.
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We get lung function tests and we have different thresholds, I suppose, where depending on their base level of function, whether or not they're a smoker, et cetera.
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That's just one example.
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What does the process actually involve then for a patient from referral to actual treatment?
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Yeah.
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So, typically the referral comes through, usually from a multidisciplinary team meeting.
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So we very busy being involved in many MDTs.
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We do subspecialize, but we usually, have a few areas of expertise.
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And they're typically discussed in that forum and recommended for treatment there.
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And so the referrals usually come through from the chair of the meeting, the respiratory physician, and most of the time it's actually from the surgical team.
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And we see them in the clinic for an initial consultation.
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And this is where we discuss obviously, the role that radiation plays.
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And we clearly outline whether or not we are trying to provide a cure or trying to preserve an organ.
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We're trying to palliate or help with symptoms.
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So we'll discuss the side effects, obviously the potential outcomes, the success rates and the typical side effects during the treatment and the typical side effects that you could expect long term.
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If they're all okay.
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Obviously with that, then they proceed to their first appointment, which is a planning scan.
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So They need to have a CT scan, that's specific for us.
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We set them up in the treatment position.
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We have a few little things to make sure that they're really immobilized in the right position, set up exactly how we want it, some special techniques depending on where we want to treat so we can track their breathing can really make an individualized mask to keep their head really nice and straight.
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So a few things that we can do to set the patient up and they have their CT scan that gets imported into our system, our planning system.
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And what we can do now as well is we fuse or we bring in MRI PET scan, diagnostic ct, and we put it all into the one, system and we use that to help us with the targeting.
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So that's essentially my surgery or my what.
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How I plan the radiation.
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So I get on the computer with the program.
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It's essentially my daughters call it like paint on CT scans.
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We draw out the tumour where we want to treat, we draw out the areas at risk potentially of that need radiation.
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We draw out the areas where we don't want radiation to go.
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So we'll obviously draw out the critical organs, the organs around it.
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And then once we've provided those volumes, we give that to our planning team.
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So we have department filled with radiation therapists who will help plan the treatment.
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So they'll design a radiation plan to our, to, to the goals.
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So the goals will be set by us as the radiation oncologist.
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We might say, I want this area or the tumour to receive this dose.
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I don't want the this organ to receive this much dose.
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Please come up with a plan based on that.
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And so they'll come up with, you know, a potentially a plan that has a radiation beams going this way.
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They'll have it intensified this way or that way to achieve those goals.
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And then once we approve of that plan, the patient starts their treatment journey.
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So they typically come in, so again, if depends if it's a curative treatment or a palliative treatment, but they'll typically come in as an outpatient.
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Usually it's a daily treatment if it's a curative treat.
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Treatments are like what I describe to patients as having a CT scan.
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It's as really as simple as that.
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Usually roughly a 20 minute appointment, they come in, they lie down on the machine.
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Most of it, most of the time actually, it's setting them up in the right position.
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We have to be extremely accurate.
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A lot of checks and balances.
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And so on top of that, we actually have a whole physics department, medical physics department that checked and QA every single radiation plan to say, this is what we are delivering and we're delivering it safely.
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Patient lies down, they don't feel a thing, so it's painless.
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They don't see anything.
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It is like having a, an x-ray or a CT scan.
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They have their treatment, they hear some noises, that's it.
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They walk out and they come in every day until they finish their treatment.
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We typically see them once a week throughout their treatment as scheduled.
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And they also see, dietician, nurse, all parts of the multidisciplinary team.
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And then they finish their treatment and that goes on to the follow up stage.
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And then obviously we are then monitoring response and recurrence.
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Right.
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So you've got a radiation oncologist, like the, or the conductor of an orchestra.
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You've got the radio therapist.
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Yep.
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who also have a degree in physics, do they or?
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Oh So I think they, they go through like diagnostic radiographer pathway, but then they split out and they have a therapeutic.
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so it is a very niche and highly skilled degree as well.
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So they're like the musicians in the orchestra?
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So they're planning the treatment.
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They're del, they're the ones that actually deliver the treatment.
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So I'm not actually there on the machine pressing the button.
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Our radiation therapists do that,
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And you've got nurses looking after them as well.
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Absolutely.
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So we've got a big nursing team as well that helps with the side effects, dressings education.
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So they play a really important part.
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Just providing that holistic care.
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We've got dieticians, speech path, social worker on board as well.
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So we try to look at the patient, obviously at all facets to get them through their treatment and the physics, I suppose.
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I don't know what analogy you would say that they are, but they're the ones that are making sure that what we say we're doing is correct.
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Very important as well
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Excellent.
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How does it vary from say, chemotherapy or surgery?
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I mean, how do you consider yourself different in that way and how does the treatment feel different?
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So, I think we all play a a part in the whole.
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Any patient's cancer journey or cancer diagnosis?
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Surgery and radiation.
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I would say obviously the, generally the mainstay of trying to cure patients.
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We sort of provide roughly 30 to 40% actually of cures in cancer.
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And I think where we play in, depending on obviously what tumour type, we, sometimes we do it instead of surgery.
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Sometimes we do things to preserve an organ.
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Sometimes we do things to downstage tumours, so some to help the surgeons get a better resection or a clear margin to downstage tumours.
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and sometimes we give the radiation.
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Concurrently with chemotherapy to help our treatment be more effective.
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And sometimes we give it after surgery just to, for those high risk tumours.
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So yeah, I think you can break them down into the main roles that we play is curative or radical organ preservation.
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And those who are not medically fit for surgery, we often play a role there or those who are surgically unresectable.
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And we come in as well.
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Then you go into the neoadjuvant or before surgery to, as I said, to downstage, adjuvant after surgery.
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So usually those at high risk of recurrence, and then there's the palliation.
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And so I think we all combine and we're trying to find novel ways to combine all the time with chemotherapy, obviously chemotherapy gets a little bit more of a, an understanding in the community.
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I think.
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It's more of a systemic treatment.
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It's more of a treatment that strategy that affects the whole body and can kill tumours all over.
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Whereas radiation is more akin to surgery that it's certainly more targeted more for local areas, but we're again combining different approaches all the time.
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looking at it.
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When you talk about the ionizing radiation, what about different types of ionizing radiation there, the different frequencies of the waves you're releasing?
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Or different types too.
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So there's, I guess we can break it down into the different modalities or types of radiation that we give.
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And broadly speaking, it's external radiation, which is the large majority of what we do that's on our linear accelerator or what we call a linac.
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And essentially it shoots an electron beam into the machine, speeds it up to the speed of light, hits a target, and we get our x-rays or photons coming out, and that will be our mainstay of treatment.
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Now we can vary the intensity of that, vary what angles and what beams to deliver the type of dose that we want.
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And then we modulate that, modify it using Different apertures and different ways of creating that beam coming outta the machine.
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We also have things like electron therapy.
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So this time it uses, we just essentially trying to use the best radiation characteristics to suit the tumour.
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So electron therapy is used and what we call superficial radiotherapy is used very commonly for skin cancers.
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So it's actually a different profile in the way it delivers its dose.
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So more superficially that would be the mainstay of our treatment.
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Then we have internal radiation or brachytherapy.
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So this is actually where we use a radioactive source.
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We deliver right into the tumour.
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So brachytherapy is used in things like prostate cancer, cervix cancer, and we are able to get to where the tumour is.
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it's more, a little bit more, certainly more invasive.
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But we deliver a radiation source directly to the area and it delivers the radiation from the actual source itself most of the time, depending on the type of brachytherapy, we will remove it.
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And it's delivered it's dose internally.
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There's no way of putting a substance internally than activating it with a beam externally?
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No, not quite.
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But there is for prostate cancer treatment, we have a low dose rate brachytherapy where we actually put.
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Radioactive pellets into the prostate and it delivers its radiation slowly over time So, and they stay there.
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So those patients are technically radioactive, although the activity is really so low outside that it's very to be in so that there is some types that we actually purposely do that.
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And for thyroid cancers as well we actually give patients radioactive iodine and it actually hones out thyroid cancer cells and kills it that way.
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We're doing a little bit less and less of that now.
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The nuclear Med physicians are are being a bit more involved in that space.
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What about it's always a single beam when you're doing the external radiotherapy or can use dual beams to actually hit each other?
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that's a great question, Gavin.
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So that probably goes on to the history of radiation and how far we've come.
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So it used to be literally four beams.
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One from the front, one from the back, one from the left, one from the right, classically called that the four field box.
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And literally everything in that box got the same amount of dose and radiation.
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Oncologists, not so long ago, were drawing on x-rays, just China graph an x-ray, say, this is where I'd like the dose to go and everything in that area.
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Got it.
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So that's what the era of 2D planning or 2D radiotherapy.
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Then we moved to 3D.
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So then we started using CT scans.
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We started using multiple beams from different angles.
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and now we've evolved to nearly all of our treatments are what we would call IMRT or vmat.
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So a fancy word for volumetric, modulated arc therapy.
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And essentially the radiation is.
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Beam is always on and it's always moving in a continuous clockwise fashion.