Hello, and welcome to the Physics World Weekly podcast, which is supported by Research Laboratories. I'm Hamish Johnston. Our theme this week is diagnosing and treating disease. How physicists keep you safe during health care procedures. This episode was created in collaboration with IPEM, the Institute of Physics and Engineering in Medicine, which owns the journal Physics in Medicine and Biology. Our guests are 2 medical physicists working at the heart of the UK's National Health Service or NHS. They are Mark Knight, who is chief health care scientist at the NHS Kent and Medway Integrated Care Board, and Fiammetta Fidele, who is head of non ionizing radiation at Geis and St. Thomas NHS Foundation Trust in London. They're in conversation with Physics World's Tammy Freeman, and that's coming up after this message from Research Laboratories. This podcast is supported by RaySearch Laboratories, which unifies industry solutions, empowering healthcare providers to deliver precise and effective radiotherapy treatment. RaySearch's AI driven solutions reshape cancer care by accelerating workflows, delivering consistent and reliable results, with less manual work. RayStation is a treatment planning system that brings tranquility to treatment planning. No more bouncing between different treatment machines, techniques and modalities. RayStation is a comprehensive software. RayCare is an oncology information system and a trusted ally. It automates and streamlines adaptive oncology workflows while securely guiding users through the entire patient treatment journey. Ray Intelligence empowers confident decision making by unifying clinical data into actionable insights. This cloud based oncology data analytics system offers a clear view of clinical operations. Raysearch products transform scattered technologies into clarity, elevating the radiotherapy industry. Many of the health care procedures routinely delivered in hospitals rely on the work of medical physicists. Medical physicists are responsible for developing and commissioning advanced diagnostic and treatment systems. They design radiotherapy plans that accurately target tumors, make sure that the hospital's imaging equipment is operating as expected, and much more. But one of their most important tasks is to ensure the safety of all these procedures for the patient as well as the health care staff. To discuss how physicists keep you safe during health care procedures, I'm joined today by Mark Knight, chief health care scientist at NHS Kent and Medway ICB, and Fiammetta Fidele, head of non ionizing radiation at Guy's and Saint Thomas NHS Foundation Trust. Welcome both to the podcast. Hello, Tammy. Hello. So looking at the safety of medical treatments, one of the first things that comes to mind is radiotherapy. So this involves firing beams of ionizing radiation at the patient to destroy cancer cells. So how do the medical physicists ensure that these treatments are safe? For example, that the patient doesn't receive too much radiation and that the radiation only hits the tumor and doesn't damage healthy parts of the body. Thank you, Tammy. So I thought the best way to look at this was to take a step by step approach through the radiotherapy process. So we start with a scan, which will show us precisely where the tumour is in the patient and what shape it is. And in the modern world, we might, use a hybrid imaging technique to do this. So a a CT scan perhaps which tells you where the anatomy is combined with a with a PET scan or an MRI scan, which might tell you more about the dynamics of the the tumor, physiology. So the the next stage is that a clinician will outline the tumor, to show us exactly where, that is on the visual image, and then they'll extend the size of those margins a bit to take account of microscopic disease, and uncertainties in the location of the tumor that that would come about through all sorts of, things during the treatment process. So the patient's bladder might be more full on one day, which could affect the position of the prostate, for example, in a prostate treatment. And the next stage then is to take a computerized treatment planning system, to plan a bespoke radiation treatment for every single patient. So based on that scan, the delineation of the tumor volume, we would then use a series of radiation beams to mathematically model, in a treatment planning system, a radiation dose to that tumor. And and the aim here then is to deliver the prescribed radiation dose, which comes from our clinician. We we want to deliver this much radiation to exactly that shape, and size of tumor, to, and whilst minimizing the organs, at risk, radiation exposure. So for example, we know that the bowel, the spinal cord, for example, are much more sensitive to radiation than other organs, and so we would need to ensure that, the dose is is minimized. So on a on a conventional radiotherapy treatment, we would use then a linear accelerator or LINAC to deliver those radiation treatments to the tumor. And we've got lots of technologies available. So for example, tiny, lead sheets, which are very thick but very narrow, which can be used to shape the radiation dose coming out of the machine. We can change the intensity of the radiation, and we can move the linear acceleration around the patient while we deliver the treatment. And all of that combines to give us a very precise delivery of radiation exposure to the tumor volume that we've decided we need to treat from our scans. Okay. Great. So that's, I mean, that's a super example of sort of physics based techniques for, as you say, shaping the radiation and planning where it needs to go exactly. Now x rays are also used for diagnosing medical conditions, and this includes conventional x-ray scans, CT images, mammography. Now here, the aim is very much not to destroy any tissue, but to create images. What are the potential risks of x-ray imaging, and and how are these addressed? So firstly, it's important to say that the risk to individuals from imaging with x rays are relatively small, and it's important to keep those risks in context. So for example, we expose ourselves to risk in everyday life through our day to day activities such as traveling in a car and, eating and drinking in excess of foods that that may be bad for us. And they they have risk to human health as well, but we tend to not worry about those so much as radiation risks, because that's a bit of an unknown thing. We we must remember as well that we're exposed to background radiation all the time, which comes from the outside the Earth's atmosphere and also in the food we eat and the air we breathe. So humans have evolved in an environment where we protect ourselves very well against dionising radiation exposure. A chest x-ray, for example, gives us the same radiation exposure as a few days of background radiation. So the key to protection of patients, is that each, medical imaging procedure is justified by an expert in medical imaging, and it would only go ahead if the benefit to the patient outweighs the risk from undertaking that exposure, and that is a legal requirement. Medical physics professionals are closely involved with the quality assurance of X-ray imaging equipment. And during this process, they'll review radiation dose, image quality, and check that all of the radiation dose saving devices for the patient are being used in an optimal manner. And this process then of balancing the reduction of radiation exposure, with the, best image quality is known as optimization. Optimization is a huge part of our daily work in medical physics. I should have said before, of course, that it's exactly the same in radiotherapy. Our our physicists are closely involved with all of the processes around inner accelerators, the treatment planning processes, and the scanning processes that go into delivering that safe therapy. And finally, we would reduce risk further by ensuring that all of the professionals connected with each imaging procedure are trained, and they follow best practice guidelines. So that would include our medical physics professionals who carry out that quality assurance and optimisation process, on the x-ray equipment itself. Okay. And and there's lots of other techniques used for diagnostic imaging, For example, ultrasound, which uses high frequency sound waves to create images inside the body. Now if this technique just uses sound waves, are there any safety concerns here? Fia, perhaps you could answer this question? Yes. Hi, Tommy. Good question. Yes. Ultrasound still produces some effects in the body. It produces some heat and can interact with gases in the body, like, for example, the air in the lungs. But sonographers in UK are trained to keep scanning times and as well the level of the sound waves that they use well below the levels that could produce any of these effects. And so it's perfectly safe to use. And the role of the medical physicist is that to make sure the scanners are working as they say they're supposed to work from manufacturers so that they can, keep those levels within the limits sonographers know. Okay. And you also work with a treatment technique called phototherapy, and this uses UV light to treat skin conditions. So how do you make sure that patients receive the correct dose to treat them and not to cause harm? Yeah. So phototherapy carbines are a bit like huge, UV ton inverts. And the point is that in that case, the UV is being given to the patients for, for treatment. But they need to have a precise dose. And what we do, we use light meters to check the output of the cabins. And then we can reassure the nurses, the specialist nurses that usually deliver this treatment. So what is the output of those units so that they can make sure that they register the dose, they track the dose, and so they know when it's time to complete the course of treatment for the patient? Okay. So it sounds like in a lot of these, techniques that the medical physicist, one of their big jobs is making sure that the equipment is working safely. But I guess, you can do that and and and there can still be issues. So another imaging technique that's used all the time in hospitals is MRI. And MRI scanners present a unique hazard due to their extremely strong static magnetic field. And there have been reports of some serious accidents caused by ferromagnetic metal objects being pulled into the scanner. So, you know, even if the scanner is working perfectly, sometimes these accidents can happen. So how do we present prevent this from happening? So, Tammy, linking to what we were discussing before measurements, but then another big, element of our job is training training of the clinical teams. So in MRI, for example, the at the key prevention is, training the staff, making sure that all those that can have access to MRI scanners, have had specific training that let them know of all the hazards that are connected with this huge magnet being there. And my colleagues that work in MRR, they run periodic colleague training sessions in, for geographers, researchers, everyone that might have access to that to those scans. 2nd to training, there are the hazard control prevention measurements. So there's labeling. There's that indicates what are the higher risk areas. Whereabouts you have the limits when you can carry a magnetic objects? And, again, labeling of 8 entrances. Everything that makes it easy in a high pressure environment for those operating it to know that that it's, their limit of operation. Yeah. I mean, if if you if you see an MRI scanning area, there there's loads of big signs everywhere warning people to sort of make sure they're not bringing any objects near that they shouldn't. And then there's huge yellow labels, huge red labels on those pieces of equipment. You know, the ones that, yes, it's fine. That can go to ones that can't go. So. Okay. And then, I mean, I've seen sort of issues with things like, you know, oxygen cylinders being brought in that, that shouldn't be there and, and being attracted to the magnet. And obviously, as you say, training and making sure everyone knows about these hazards, that can help prevent that. But what about if the patient have got the patient has metallic implants that they can't remove? So if a patient has a pacemaker or a cochlear implant, something like that, is that a problem for MRI? Yes. It is a problem, and this is one of the biggest data that works for the MRI physicist, because they play a key role in advising the clinical team. First, they need to, determine whether that's how what's the classification of that specific implant? So the newest implant will be as being MRI safe, so they can go anywhere in an MRI environment. Then there'll be the ones that are called conditional, so they can be used under certain conditions. And then there are the ones that are called unsafe. So there are the ones where it's not recommended to have a patient in an MRI, scanner. And but also in those cases, it's always a discussion between a multidisciplinary team. So between the physics team and then the consultant and the clinical team to discuss the health benefit for the patient. Because you might have a patient that has an implant that is not one of those that is MRI safe, but it's really important for them to have their scanner. And the likelihood of something happen comparing to other implants might be lower if if it makes sense. So it's always a balance. It'd be like with ionizing radiation. There is always a balance, and the physicists have a key role in trying to explain to the medical teams what are they, the risk that they can, can have. Yeah. So it's the physicists working with the clinicians to sort of optimize optimize it. Okay. Now another area of health care, back onto ionizing radiation. There's another area called nuclear medicine, which includes things like PET, positron emission tomography. And here, the radioactive materials are actually introduced into the patient's body for diagnosis or for treatment. How do we ensure patient safety here? Thank you, Tammy. It's a it's a good question. So, it's probably worth having a think about how nuclear medicine and PET imaging work initially. So so as you say, radioactive substances are typically labeled onto a pharmaceutical, and that pharmaceutical is designed to target disease processes in the body. So so we're all familiar that when we take paracetamol or aspirin, that's able to seek out the pain areas and reduce the pain in that specific location. So we call that a radiopharmaceutical, and that's injected into the patient, and you would expect then that that concentrates in the process where, in the place where the disease process is most strong. So, when you then put that patient into a camera or a or a scanner, what you find is that the the areas where the radiopharmaceutical is concentrated will glow brighter than other areas, and that allows us to see where the disease, is happening. So, in simple terms then, medical physics professionals will be carrying out very similar optimization processes to those that we've discussed before. So, very broadly ensuring that the minimum radiation dose is given, to allow for the production of diagnostic quality images. But if we want to take a bit of a deeper dive into this, think about the physics a little bit more, we could think about, how do we design our radionuclide diagnostic processes to minimize that radiation dose. So let's let's take a think for a for a moment about the half life of the radioactive substance that we use, for our imaging. This is quite critical. It it takes up to 2 hours perhaps to, for the pharmaceutical to label onto the disease process once it's inside the patient. And during that 2 hour time period, the radioactive substance is decaying. So, obviously, if we use a radioactive substance with a half life that's too short, we we'll end up having to inject a very high activity at the start of the scan, which gives a high dose to the patient. And similarly, if we give a radioactive substance with a half life that's too long, it will remain in the body for a long time after the scan is finished. And again, we'll deliver a high radiation dose to the patient. So we need to optimise our half life. It's a similar argument with the energy of the radiation emitted. If we choose, radio radioactive substance with an energy that's too low, then the gamma rays won't be able to escape the body, and they'll just deliver a radiation dose and won't contribute to our useful image. But if we choose an energy that's too high, the gamma rays will pass straight through the imaging equipment and won't contribute to the image either. So we have to optimise the radiation energy that we use. And again, this is where our medical physics professionals come in and have a very interesting time thinking about all of those different physics processes that that make, up the image. And if I could just talk for a minute then about therapy, because we also use radioactive substances in therapy. It's a similar process. So we would either inject, or ask the patient to swallow a radioactive substance to treat, medical condition, usually cancer. So common treatment, and this one dates back to the middle of 20th century, is to use radioactive IID 131, following the surgical removement, removal of the thyroid gland. And so what happens is the iodine concentrates in any remaining tissue that's left after the surgery, and it's a it's a great radioactive substance for this purpose because it contains 2 elements, beta particles that that are, of course, don't travel very far in tissue. So they deliver a very high dose to the thyroid tissue that's left and minimize the radiation dose to other organs in the body. So we destroy the thyroid tissue that's left and and spare the other tissues. And it also contains a gamma emission, which is quite useful because we can then use that to image any of that leftover thyroid tissue at the end of the treatment. So with that particular treatment, we use high levels of radioactivity, and the patient would need to remain in a shielded bedroom with special bathroom and drainage arrangements for a few days after receiving the therapy. Yeah. I mean, that, that was going to be my next question. If the patient's got a radioactive source of some sort inside them, do they pose a risk to other people and, and what's done about this? That's absolutely right. So every medical procedure that involves the use of radioactive materials does carry a risk to members of staff and, of course, to members of the public. So as you would imagine, the procedures are, rigorously risk assessed. So somebody will look at all of the risks from that, procedure. So we think about the external radiation that comes from the radioactive substance. If the patient travels home on the bus, for example, someone will calculated what the radiation dose would be to somebody sitting next to them on the bus. The radioactive substances are also excreted, from the patient in in urine, in sweat, saliva, for example. So we need to do calculations to ensure that if those substances get into, the environment, that they're not going to give, an exposure to members of the public that are too high. So, for our therapeutic procedures, the risk can be be higher still. And for those procedures, we need a bespoke risk assessment for each individual patient. So for example, in the iodine therapy we we talked about earlier, there, is a risk, when the patient goes home from the external radiation and from contamination from their urine and and bodily fluids. So, we would need to do a bespoke risk assessment for for them, and that will be based on their own particular circumstances. So you can imagine somebody who works as a park keeper where they don't meet members of the public very much, they're in a big wide open space all day, is much less risky than a primary school teacher who's sitting very close to small children all day. And then they would then go home with a different set of restrictions on their their own, activities. Okay. And, is this the same for brachytherapy? Because that's it's slightly different, but it also involves putting radioactive sources inside people. That's right. So, for brachytherapy, it's probably worth having a think about the difference between sealed and unsealed radioactive sources to start with. So in our nuclear medicine, and PET procedures, we inject unsealed sources, so they're liquid radioactive substances. They're free to move around the body and free to come out in our bodily fluids. But in brachytherapy, we use sealed radioactive sources where all of the radioactivity is encapsulated inside, for example, a metal capsule. So, generally, there's no risk that those will be released into the environment, and that whole contamination risk, goes down, to to 0. Having said that, the sealed source then can be thought of a little bit like, an X-ray source, which which we would use in imaging or in our linear accelerators. The big difference is you can't switch it off. It's radioactive. It's gonna be there until it's decayed. So we do have particular issues with a brachytherapy. For example, we would do a treatment where a source goes into the patient for, say, a 5 minute period and then is withdrawn. It's a very high activity sealed source, but sometimes that source could become stuck, and that poses a very big risk to the patient, and of course to to the staff. So they have procedures in place with regular rehearsals to make sure that if that does happen, they're they're they're right ready to go or the equipment's ready. The staff know exactly what they're doing to go in and and do that emergency source removal. Okay. That's really interesting. Now looking ahead to the future, researchers are continually developing sort of innovative new medical techniques, both for diagnosis and treatment. How do we ensure the safety of these advanced approaches when when they're first introduced into the clinic? Maybe you could both comment on that. So maybe before Mark comes in, what I will say is not is not much different from what is done for drug trials. So before you introduce them in common use, you need to test them under control, technology trials. And and I don't know, you know, Mark, if you wanna say a bit more about normally the conditions we would do those tests. Yes. We're doing, trials. So, essentially, when we're introducing new technology, I think the key is that we need to we need to do it very carefully, and in a very, considered manner. So, for first of all, with any new technology, we don't know at the start immediately how how things are going to work, and how they're gonna affect our patients. So you do a very tightly controlled clinical trial under those circumstances, and and you would expect that there's ongoing research, and, clinical trials into how do those technologies perform over a period of time. Then, devices you would expect to be certified, and regulated where where before they go into use. So that is a a process where the device is is rigorously examined, and given a certification to ensure that it's safe to use on patients. So again, you you would need expert support in the in the process of introducing this. And I and I think to me, this is where multidisciplinary approach comes in in healthcare. For sure, you need your medical physics teams. They're they're gonna be very well versed on the the types of risks that might come from these new technologies. They can, do do, extensive calculations for you on on what it might mean when we start to use those in patients, and and they will need to lurk work alongside, the doctors, perhaps the radiographers who are delivering the treatments as a multidisciplinary group to really understand how we're gonna best implement that into our medical pathways. And sometimes, if it's a diagnostic technique, to be safe, what they will have to do is they will have to give the same exam they already give patients, and then they would have to to use the new device. So sometimes they will inform the patients. They can accept to take part in the trial or cannot not accept to take part in the trial. But if they're doing it, it's for future benefit, and they will be, having to stay a little longer. So, again, most people are very happy to help because, you know, they are are aware that they're doing it for, for the future of everyone. Okay. And then, also looking ahead into the future, can you comment on the use of artificial intelligence in medical procedures? So AI is increasingly being touted for things such as creating radiation treatment plans or analysing medical images. What do you think are the risks of introducing AI into health care? So AI is a hot topic. Course keeps being is one of those where we get all the ethical and all the questions. In the end, like for other techniques, is a matter of controlled trials under expert guidance and under standardized processes. And the point is we can't just have, a black box introduced in everyday use without knowing what that black box is supposed to do when comparing what what we have before. But then again, there's bigger ethical issues. So I don't know, Mark, if you'd like to pop in. Yeah. Thank you. So so I think it's it's gonna be really important to make sure that AI is introduced in an ethical manner. So so one of the big concerns, might be just as Fimeta said there, we may not know exactly how the AI is coming to its decisions, because that that's the nature of the the way in which these machines work. And therefore, what we can look at is the data that we've used to actually train that AI system to make those decisions in the first place. So if you look at example, where we might be trying to diagnose, medical conditions from chest X rays using an AI system, We have systems that have been trained on on huge populations, millions of patients, but but in India. And and how do we know that the population in India has the same anatomy, the same physiological, conditions, the same, medical conditions that we have in the UK. So we may we may have an issue there with introducing a system that's been trained using a different population from our own. We we need to think the same in the UK. We have a wide range of nationalities. We have, people of, both sexes in the UK. We we need to make sure that when we train the systems, the right data is used so that we get, the the the right diagnostic processes out. So again, I think, Fimete, you're right. It's the ongoing research, the clinical trials, and of course, incident reporting is really important. If you have an incident with a medical device, and report that to the to the regulators, it's something that then the whole, world can learn from those mistakes, those errors, and and fix it so that it doesn't happen again? As far as AI is introduced in this multidisciplinary team with the contribution of the medical physicist, the clinical engineers, but also the the team the clinical teams are going to use them is going to help us. Because in the end, we have to think that in the past, even some of the measure automatic measurements that we use these days and some of the technology that we use these days, they were at those times equivalent of what AI might be now. AI is just bringing this to the to next level. But on the other side, we know that we are at the time of, you know, time being pressured for time, being pressured for being able to see more patients, treat more patients. So any tool that enables our clinicians to reach those decisions in a quicker time, it's it's going to be of of good shape. So I'm one of those, and I I don't know about Mark, but I'm one of those that is very hopeful about AI, but if done in a co design way with health care staff and in in safe clinical trials. I I agree. I I think that's absolutely right. To to me, I think if we were sitting here in 10 years' time having this discussion, the the the world will have changed. It's like when the the Internet was first introduced in the early 19 nineties, Maybe we didn't know what what we would use that for, but but today, nobody can imagine life without it. And I I imagine, myself that this will be, very similar. Excellent. Well, it's, it's great to find out what we may have to look forward to in the future and also to, you know, to learn about all the work that medical physicists are doing to keep everyone safe. So thank you both for joining me today. Thank you. Our pleasure. That was Fiamada Fidele and Mark Knight in conversation with Tammy Freeman. That interview is produced in collaboration with IPEM, which owns the journal Physics in Medicine and Biology. You can find the journal at IOP Science. Next week, the scholarly publishing community is celebrating peer review week. And here on the podcast, we will be looking at how journals can eliminate unhelpful or outright rude reviewer comments from the peer review process. That episode will go live on Tuesday, 24th September instead of the usual Thursday. That's because on Thursday, 26th, we are presenting the future of particle physics. This is a physics world live event produced in partnership with the journal reports on progress in physics. The live panel discussion will feature Tara Shears of the University of Liverpool, Phil Burrows at the University of Oxford, and Talika Bowes of the University of Wisconsin, Madison. They will explore what the future holds for high energy physics, and where the next particle collider should be built. You can register now for this free event on the Physics World website. Just click on the Physics World Live tab at the top right of the home page. I'm afraid that's all the time we have for this week's podcast, which was produced in partnership with IPEM. Thanks to Fiammetta Fideli, Mark Knight, and Tammy Freeman for a fascinating conversation. And a special thanks to our producer, Fred Iles. And we would like to acknowledge the support of RaySearch Laboratories for this podcast. This podcast is supported by RaySearch Laboratories, which unifies industry solutions, empowering healthcare providers to deliver precise and effective radiotherapy treatment. RaySearch's AI Driven solutions reshape cancer care by accelerating workflows, delivering consistent and reliable results, with less manual work. RayStation is a treatment planning system that brings tranquility to treatment planning. No more bouncing between different treatment machines, techniques, and modalities. RayStation is a comprehensive software. RayCare is an oncology information system and a trusted ally. It automates and streamlines adaptive oncology workflows while securely guiding users through the entire patient treatment journey. Ray Intelligence empowers confident decision making by unifying clinical data into actionable insights. This cloud based oncology data analytics system offers a clear view of clinical operations. Research products transform scattered technologies into clarity, elevating the radiotherapy industry.