WEBVTT - How do MRIs work? 0:00:08.280 --> 0:00:10.600 Hey, Daniel, have you ever broken a bone? I have, 0:00:10.760 --> 0:00:13.920 but it's kind of embarrassing. What happened? Well, the first 0:00:14.040 --> 0:00:16.960 and last time I ever went snowboarding, the first time 0:00:17.000 --> 0:00:19.959 down the mountain broke my wrist. Really the first time? 0:00:20.280 --> 0:00:23.040 What happened? You didn't see that tree coming? No, honestly, 0:00:23.079 --> 0:00:25.840 I was trying to avoid snowboarding over my girlfriend at 0:00:25.840 --> 0:00:27.840 the time, so it was a bit chivalrous. You took 0:00:27.840 --> 0:00:30.560 a hit for the for the team. That's exactly right. 0:00:30.600 --> 0:00:32.319 And then what happened? Did they take an X ray 0:00:32.360 --> 0:00:34.320 of you? Or how did they? How did they know 0:00:34.360 --> 0:00:36.400 it is broken? Yeah, well it hurt a lot, and 0:00:36.400 --> 0:00:38.040 then it took an X ray and you can actually 0:00:38.080 --> 0:00:41.080 see inside right, You could see that little bone was 0:00:41.159 --> 0:00:43.600 snapped off and in the wrong spot. Isn't that amazing? 0:00:43.600 --> 0:01:03.040 How signs can see inside of you? Hi am RhE. 0:01:03.200 --> 0:01:06.479 I'm a cartoonist and the creator of PhD comments. Hi, 0:01:06.640 --> 0:01:10.479 I'm Daniel. I'm a particle physicist by day and a 0:01:10.560 --> 0:01:12.600 sleeper by night. How did it where you just close 0:01:12.680 --> 0:01:15.760 your eyes and it happens. You should try it sometime. 0:01:16.080 --> 0:01:18.840 It really does help because you never remember the moment 0:01:18.880 --> 0:01:21.600 you fell asleep, right it's sort of mysterious. Yeah. I 0:01:21.640 --> 0:01:23.800 remember actually trying to teach my kids how to fall asleep, 0:01:23.840 --> 0:01:26.080 and then I realized I don't really know how, you 0:01:26.160 --> 0:01:27.840 just sort of do it. To teach in to a 0:01:27.840 --> 0:01:30.240 podcast where we sleep, I know we should do a 0:01:30.240 --> 0:01:32.560 whole podcast episode about that, like why do we sleep? 0:01:32.600 --> 0:01:34.800 What happens do we when we sleep? Why do we 0:01:34.840 --> 0:01:37.240 need to sleep? What would happen if you didn't sleep? 0:01:37.440 --> 0:01:40.840 So Welcome to our podcast, Daniel and Jorge Explain the Universe, 0:01:41.080 --> 0:01:43.880 a production of I Heart Radio in which we try 0:01:43.920 --> 0:01:46.280 to take your sleeping mind and wake it up to 0:01:46.319 --> 0:01:49.600 the amazing mysteries of the universe. We zoom all around 0:01:49.640 --> 0:01:52.240 and find interesting stuff and explain it to you. Yeah, 0:01:52.280 --> 0:01:55.200 we try to permeate your dreams with thoughts of the 0:01:55.320 --> 0:01:59.920 universe and the amazing, incredible things that are happening all 0:02:00.040 --> 0:02:02.880 around you. That's right. We are spurring the great awakening 0:02:02.920 --> 0:02:05.560 in physics by making sure everybody out there who listens 0:02:05.600 --> 0:02:08.880 to this podcast really knows what's going on. Because the 0:02:08.960 --> 0:02:11.400 universe is a crazy, amazing place and we want to 0:02:11.440 --> 0:02:12.880 share it with you. Part of what we like to 0:02:12.880 --> 0:02:16.440 do is to explain how even everyday things around you 0:02:16.480 --> 0:02:19.359 that you made use on a regular basis work. That's right, 0:02:19.400 --> 0:02:21.840 because there's incredible physics and the heart of the star 0:02:22.040 --> 0:02:24.959 and in the birth of the universe and in particle collisions. 0:02:25.000 --> 0:02:28.680 But there's also really amazing physics happening all around us 0:02:28.720 --> 0:02:31.200 in technology that we take for grant and technology that 0:02:31.240 --> 0:02:34.320 we use that our lives sometimes depend on but we 0:02:34.400 --> 0:02:38.519 don't really understand. Yeah, it's technology that saves lives and 0:02:38.680 --> 0:02:41.160 can sort of tell you and help people. Right, that's right. 0:02:41.200 --> 0:02:44.240 And it seems sort of like futuristic and awesome. You know, 0:02:44.360 --> 0:02:47.400 it's incredible that you can see inside somebody without cutting 0:02:47.440 --> 0:02:49.920 them open. So today on the podcast, we'll be talking 0:02:49.919 --> 0:02:58.240 about m r ees. How do they work, Why do 0:02:58.320 --> 0:03:01.240 they work? Do they work? Why do physicists want to 0:03:01.240 --> 0:03:04.040 see inside you? Anyway? Who gave in permission to look 0:03:04.080 --> 0:03:06.400 inside of you? I think it's a real question. What 0:03:06.480 --> 0:03:08.880 are you hiding that you don't want physicists to look 0:03:08.919 --> 0:03:10.959 inside you? I mean, if you're innocent, you have nothing 0:03:11.000 --> 0:03:13.840 to hide, right, Yeah, m RIS these are its tands 0:03:13.880 --> 0:03:18.360 for magnetic resonance imaging, right, that's right. And if you've 0:03:18.400 --> 0:03:20.720 ever been to the doctor and you have an injury 0:03:20.840 --> 0:03:24.080 or a broken bone or something funny going on inside you, 0:03:24.240 --> 0:03:26.440 or you just curious, like what's going on inside of me? 0:03:26.520 --> 0:03:29.080 Let's get myself checked out. Then you know you have 0:03:29.120 --> 0:03:31.160 several options for looking inside you. You You can do an 0:03:31.240 --> 0:03:33.240 X ray, you can do a cat scan, or you 0:03:33.280 --> 0:03:35.720 can do an m r I. You can do the lobotomy, 0:03:35.800 --> 0:03:37.800 you can they can just slice you like a Deli 0:03:37.840 --> 0:03:40.120 ham and check you out. But the nice thing about 0:03:40.280 --> 0:03:42.760 some of these is that they don't need to open 0:03:42.800 --> 0:03:45.640 you up. Right, it's non invasive, and you know that 0:03:45.680 --> 0:03:47.640 there are risks every time you do surgery, and so 0:03:47.760 --> 0:03:49.920 it's a great advantage to get to figure out what's 0:03:49.920 --> 0:03:52.480 going on before they go in and cut anything. So 0:03:52.760 --> 0:03:55.400 m r s are These are the kind that you 0:03:55.440 --> 0:03:57.800 sort of go, you lie down in a little platform 0:03:57.880 --> 0:04:00.720 and then they roll you into this kind of giant 0:04:01.360 --> 0:04:05.360 donut looking thing. Right. Yeah, it's like a big physics machine. Right. 0:04:05.640 --> 0:04:09.040 It's big, it's round, it glows, it makes really loud 0:04:09.160 --> 0:04:12.560 clunking noises. It takes a while, and uh, I've bet 0:04:12.600 --> 0:04:14.720 everybody who lies in an mri I is wondering like, 0:04:14.800 --> 0:04:17.520 what is this thing doing? Like is it zapping my brain? 0:04:17.880 --> 0:04:20.479 How does this thing actually work? Yeah, and it's because 0:04:20.480 --> 0:04:22.760 it doesn't really touch you, right, You just lie on 0:04:22.800 --> 0:04:27.880 this little platform and somehow it takes pictures inside of 0:04:27.920 --> 0:04:30.800 your body. Yeah, exactly. It can show you what's going on, 0:04:31.120 --> 0:04:34.000 and that's pretty powerful. If you're wondering if you have cancer, 0:04:34.080 --> 0:04:36.160 or if you have a tumor, or if there's you know, 0:04:36.440 --> 0:04:38.720 if your body is filled with bananas or something, m 0:04:38.800 --> 0:04:41.120 rs can answer that question, right. And what's amazing about 0:04:41.200 --> 0:04:43.480 m R I s I think is that they don't 0:04:43.520 --> 0:04:45.760 just take sort of like a picture, you know, like 0:04:45.800 --> 0:04:49.919 a like an impression, like a like a whole body picture. 0:04:49.960 --> 0:04:53.840 They really just kind of capture a slice of your body, 0:04:53.960 --> 0:04:57.200 and so you can get a really detailed model or 0:04:57.279 --> 0:04:59.880 reconstruction of your your entire all your all the tissues 0:04:59.880 --> 0:05:02.000 and a body. Right. Yeah, it's really pretty incredible. We 0:05:02.040 --> 0:05:03.799 had an m R I done of our daughter once 0:05:04.040 --> 0:05:06.360 and you can sort of turn the knob and see 0:05:06.360 --> 0:05:08.279 how like all the bits of the brain and the 0:05:08.320 --> 0:05:11.240 ear and stuff are all connected. It's it's amazing. It's 0:05:11.240 --> 0:05:13.680 like taking somebody and slicing them like a Deli hym 0:05:13.680 --> 0:05:18.400 without actually slicing them. Thank goodness for physics. Have you 0:05:18.400 --> 0:05:21.240 ever seen that Body Works exhibit where they actually take 0:05:21.279 --> 0:05:24.159 corpses and slice them super thin. I have, yeah, a 0:05:24.200 --> 0:05:27.360 few times. It's pretty shocking. It's pretty shocking, but that's 0:05:27.360 --> 0:05:29.280 basically what an m r I does. Also, right, gives 0:05:29.279 --> 0:05:31.640 you all these little slices that lets you look back 0:05:31.680 --> 0:05:33.880 and forth and see how things are connected and what's 0:05:33.920 --> 0:05:36.479 going on inside you. It's an incredible machine the body. Yeah, 0:05:36.560 --> 0:05:37.880 I guess what I mean is, you know, like when 0:05:37.880 --> 0:05:39.520 you I think a lot of people are familiar with 0:05:39.680 --> 0:05:40.800 X rays, you know, like if you go to the 0:05:40.880 --> 0:05:43.880 dentist or you broke a bone, will take an X 0:05:43.960 --> 0:05:45.960 ray of you. But an X rays is really just 0:05:46.000 --> 0:05:48.840 like they shoot you with rays, they go through your 0:05:48.880 --> 0:05:52.000 body and then they capture them on the other side, right, 0:05:52.360 --> 0:05:55.680 and so you're you're getting everything. You're getting like everything 0:05:55.920 --> 0:05:59.159 inside of your body's mushed into one image. That's right. Yeah, 0:05:59.160 --> 0:06:01.599 it's like integrated along the line of the X ray. Yeah, 0:06:01.600 --> 0:06:04.440 you're learning about the whole body that way. X rays 0:06:04.480 --> 0:06:06.560 can't do slices, yeah, and so the image is very 0:06:06.600 --> 0:06:09.080 like fuzzy, and it's hard to tell what's bone and 0:06:09.120 --> 0:06:11.200 what's an organ. But with an m r I you 0:06:11.320 --> 0:06:14.800 really get like a detailed, step by step slice of 0:06:14.839 --> 0:06:18.200 the entire the volume of your body. Yeah, and the 0:06:18.200 --> 0:06:22.120 benefit is you don't get cancer causing radiation. You get 0:06:22.160 --> 0:06:26.520 other kinds of cancer possibly, So I mean, you do 0:06:26.560 --> 0:06:28.880 get other kinds of radiation. But you know X rays 0:06:28.880 --> 0:06:32.239 are dangerous. They are ionizing radiation, and they deposit energy, 0:06:32.279 --> 0:06:34.680 and they can break up your DNA, And there's reasons 0:06:34.680 --> 0:06:37.320 why you should be careful when you make the decisions 0:06:37.320 --> 0:06:39.680 about having an X ray. You know X rays are great, 0:06:39.880 --> 0:06:41.720 but you know you wouldn't want an X ray every 0:06:41.720 --> 0:06:44.039 five minutes, um, you wouldn't want an X rays on 0:06:44.120 --> 0:06:47.360 tiny babies. An anti X rayer, I'm a judicious X 0:06:47.440 --> 0:06:53.719 rayer that you should start any movement there with MC 0:06:54.120 --> 0:06:56.560 say no to X rays every other time. No X 0:06:56.640 --> 0:06:58.640 rays or are wonderful, but you shouldn't just do them 0:06:58.680 --> 0:07:00.560 without thinking about it, because there really is the health cost. 0:07:00.640 --> 0:07:02.680 But with m R S it's different. You don't have 0:07:02.720 --> 0:07:05.800 that ionizing radiation and so you're not increasing your cancer risk. 0:07:06.480 --> 0:07:08.560 Even though it does sound crazy and feel weird to 0:07:08.640 --> 0:07:10.520 lie inside this two for an hour, have you ever 0:07:10.640 --> 0:07:12.920 taken an m R I of yourself like I've had 0:07:12.920 --> 0:07:15.280 my m R I taken. Have you ever done it 0:07:15.320 --> 0:07:17.600 and done it on yourself? I have had an m 0:07:17.680 --> 0:07:20.000 R I done once of my leg because I tore 0:07:20.000 --> 0:07:21.760 a muscle. I had the m R of my brain 0:07:21.880 --> 0:07:24.040 and my head done and they gave me the data. 0:07:24.400 --> 0:07:26.880 Whoa and what question were they looking to answer? There? 0:07:27.480 --> 0:07:29.640 How does this guy survive with no sleep? It's just 0:07:29.680 --> 0:07:31.880 a bunch of monkeys and bananis inside there? Where did 0:07:31.960 --> 0:07:35.760 all those amazing funny ideas and creative genius come from? 0:07:35.880 --> 0:07:40.280 That's what they wanted to know, surely for posterity, But no, 0:07:40.400 --> 0:07:42.600 it's weird. It's weird first of all because you you 0:07:42.800 --> 0:07:45.280 kind of get you get a sense of what your 0:07:45.320 --> 0:07:49.080 head looks like without hair. I mean no offense to 0:07:49.200 --> 0:07:51.240 bald people out there, but it's kind of shocking if 0:07:51.240 --> 0:07:53.680 you've always had hair to suddenly see kind of like 0:07:53.760 --> 0:07:55.920 the outline of what your head looks like. It's kind 0:07:55.960 --> 0:08:00.000 of that's bizarre, think number one. But then it's really 0:08:00.160 --> 0:08:02.960 weird to see all the you know, your eyeballs and 0:08:03.000 --> 0:08:06.960 the passages of your nose and and your tongue, and 0:08:07.560 --> 0:08:10.040 to think that like that's also you see all the 0:08:10.080 --> 0:08:13.680 fillings in your teeth, which is you know, a little embarrassing. Yeah. 0:08:13.720 --> 0:08:16.320 For me, it really highlights how much our bodies really 0:08:16.360 --> 0:08:18.160 are a machine. You know. I like to think of 0:08:18.200 --> 0:08:21.239 myself as a person and the mechanics of what supports 0:08:21.280 --> 0:08:22.920 that are, like to sort of abstract that away and 0:08:22.920 --> 0:08:26.200 think of myself with my identity, my personality, my thoughts. 0:08:26.680 --> 0:08:28.720 But when you look inside yourself, you see your this 0:08:28.840 --> 0:08:32.720 basically this meat machine, right, and this this organic robot, 0:08:33.000 --> 0:08:34.800 and it all has to work and pump and move 0:08:34.840 --> 0:08:36.920 and squish all the time, and it's incredible that it 0:08:36.960 --> 0:08:40.000 actually works. Ever, not to mention like mostly working for 0:08:40.040 --> 0:08:42.160 like seventy years at a time. No, I think that's 0:08:42.160 --> 0:08:45.800 the name of a heavy metal band meat machine machine. 0:08:46.240 --> 0:08:48.320 But anyway, so we were wondering how many people out 0:08:48.360 --> 0:08:51.280 there know how m R machine works. You know, a 0:08:51.320 --> 0:08:54.120 lot of people get them for various reasons and they 0:08:54.120 --> 0:08:58.240 can help save lives. But we were wondering if people 0:08:58.240 --> 0:09:01.200 out there new how this is amazing to achnology works. Yeah, 0:09:01.240 --> 0:09:03.160 So I walked around campus does I usually do, and 0:09:03.200 --> 0:09:05.439 I ask people if they knew what is an m 0:09:05.520 --> 0:09:07.440 R I and how does it work? Would you know 0:09:07.440 --> 0:09:10.120 how to respond if somebody asked you how an m 0:09:10.200 --> 0:09:13.360 R I works. Here's what people had to say. I 0:09:13.360 --> 0:09:16.960 have to do with strong magnetic fields. Okay, so how 0:09:17.000 --> 0:09:18.360 does that let you take a picture of the inside 0:09:18.360 --> 0:09:23.120 of your body? I'm not really sure. I'm probably there. 0:09:23.160 --> 0:09:26.280 The magnetic field will go through a certain part of 0:09:26.320 --> 0:09:29.040 your body, and depending on I guess how dense or 0:09:29.040 --> 0:09:32.120 how that the properties of the body part, it shows 0:09:32.200 --> 0:09:36.439 up differently with an image. It's a machine which scans 0:09:36.600 --> 0:09:40.400 you for abnormalities within the body. Do you know how 0:09:40.400 --> 0:09:42.760 it works? How does it see inside you? My guess 0:09:42.800 --> 0:09:46.720 would be radiation of some sort and punny, I think 0:09:46.920 --> 0:09:49.480 you drink something and they're able to see it. Um, 0:09:49.520 --> 0:09:51.520 I guess something's wrong with you. You know, you would 0:09:51.520 --> 0:09:53.240 get an MRI to pretty much figure out. It's more 0:09:53.280 --> 0:09:55.679 kind of like an extra scan. I think it's extra 0:09:55.880 --> 0:10:03.000 or something an MRI is or yeah, it's scan your 0:10:03.040 --> 0:10:04.920 your brain? Right. How does it work? How does it 0:10:05.000 --> 0:10:08.800 scan the brain? I would assume like similar to what 0:10:08.920 --> 0:10:12.800 they used like for X rays. So like maybe like 0:10:13.440 --> 0:10:15.440 some sort of laser. I don't know, laser. I don't know, 0:10:16.000 --> 0:10:19.080 no m R I actually I think it it's scans 0:10:19.120 --> 0:10:22.720 your brain or your organs and like it gives your 0:10:22.760 --> 0:10:26.559 the estimation of where is the tomorrow whatever it is. 0:10:26.800 --> 0:10:34.320 I m hmm, I don't know. I have no idea. 0:10:34.440 --> 0:10:36.719 So what do you think of those answers? Impressed or not? Well, 0:10:36.760 --> 0:10:39.560 it's interesting. Most people, um sort of knew what it was, 0:10:39.880 --> 0:10:41.679 so they know that it's kind of a scan of 0:10:41.720 --> 0:10:46.720 your body for medical reasons, and they kind of related 0:10:46.720 --> 0:10:48.839 it to X rays. Yeah, that's right. Everybody seemed to 0:10:48.840 --> 0:10:50.880 have an understanding of what it's for why you might 0:10:50.960 --> 0:10:54.000 do it, but almost nobody actually knew how it worked. 0:10:54.360 --> 0:10:56.120 And you're right, people thought about the same way they 0:10:56.120 --> 0:10:59.120 sort of think about like X rays or lasers or something. 0:10:59.120 --> 0:11:02.040 Everybody thought it was shooting something into you. Yeah, but 0:11:02.080 --> 0:11:04.199 and they're not too far off, right, Like, it does 0:11:04.320 --> 0:11:10.920 involve electromagnetic radiation, right, and pulses and things that go 0:11:11.000 --> 0:11:13.320 through you. Yeah, And of course it has to. If 0:11:13.360 --> 0:11:16.200 you want to see inside something, then you have to 0:11:16.240 --> 0:11:19.640 probe it somehow, right, You have to somehow gather information 0:11:19.679 --> 0:11:22.439 about what's beyond the skin or through the wall or 0:11:22.480 --> 0:11:24.520 whatever it is you're trying to look past. And the 0:11:24.520 --> 0:11:26.000 only way we really to do that is to send 0:11:26.080 --> 0:11:28.800 some kind of radiation in. But remember radiation is a 0:11:28.840 --> 0:11:31.360 broad term. We had a whole episode about that. Radiation 0:11:31.440 --> 0:11:33.520 can just mean sound, you know, like when you get 0:11:33.520 --> 0:11:37.400 an ultrasound done, you're sending sonic radiation into your body 0:11:37.440 --> 0:11:39.760 and you're seeing how it bounces around and comes back. 0:11:40.120 --> 0:11:43.240 And that's basically the the idea behind all medical imaging 0:11:43.760 --> 0:11:47.040 is shoot some radiation in there, see how it bounces around, 0:11:47.120 --> 0:11:49.160 because you know, if it's this kind of goop, it's 0:11:49.200 --> 0:11:50.959 going to bounce around differently than if it's that kind 0:11:50.960 --> 0:11:54.240 of group, you know, fat versus bone versus brain, and 0:11:54.280 --> 0:11:56.400 then you can reconstruct the picture. Yeah, so it's very 0:11:56.400 --> 0:11:59.120 different than X rays. But let's maybe for those of 0:11:59.200 --> 0:12:02.160 us who aren't not at all i'm there with medical imaging, 0:12:02.280 --> 0:12:04.360 maybe it steps us through. First of all, it's started 0:12:04.400 --> 0:12:06.920 with X rays. How do how do X rays work? Right? 0:12:06.960 --> 0:12:10.560 So X rays are also electromagnetic radiation. Remember X rays 0:12:10.600 --> 0:12:14.280 are just light, right, a very very high frequency, and 0:12:14.320 --> 0:12:17.080 so they shoot them into your body and X rays 0:12:17.120 --> 0:12:20.000 are very powerful. They can penetrate like most light, like 0:12:20.120 --> 0:12:22.160 photons that come from the sun that you can see, 0:12:22.520 --> 0:12:24.199 don't go through your body. That's why your body is 0:12:24.240 --> 0:12:27.120 not transparent. Right, your opaque, but X rays are much 0:12:27.160 --> 0:12:30.040 more powerful. They can go all the way through your body. Um. 0:12:30.080 --> 0:12:32.440 But it turns out that X rays are absorbed differently 0:12:32.480 --> 0:12:34.720 by different kinds of stuff in your body. So, for example, 0:12:34.800 --> 0:12:38.200 bone is really good at absorbing X rays. So shoot 0:12:38.200 --> 0:12:40.720 a bunch of X rays through somebody and then try 0:12:40.760 --> 0:12:43.040 to capture them those X rays on the other side. 0:12:43.400 --> 0:12:45.720 What you'll see is that where there was bone, for example, 0:12:46.160 --> 0:12:48.880 very few of the X rays passed through, whereas whereas 0:12:48.920 --> 0:12:51.760 mostly like gas from your lungs, then a lot of 0:12:51.760 --> 0:12:53.800 the X rays do pass through. So what you'll see 0:12:53.880 --> 0:12:56.600 is like the shadow of the bones. It's like doing 0:12:56.600 --> 0:12:59.800 shadow puppets. Right. You hold up a light bulb and 0:13:00.120 --> 0:13:02.240 your hand and you can make a shadow on the wall, 0:13:02.280 --> 0:13:04.439 so you can see where your hand was, right X 0:13:04.559 --> 0:13:07.719 raysor like that, except that your body is mostly transparent 0:13:07.760 --> 0:13:09.880 to X rays except for some of the stuff inside, 0:13:09.920 --> 0:13:12.959 like bones. So you're really sort of getting the difference 0:13:13.320 --> 0:13:17.000 in transparency between the different kinds of things inside of you. 0:13:17.160 --> 0:13:20.440 That's right, and different kinds of light. UM, find different 0:13:20.440 --> 0:13:23.880 things transparent like visible light can pass through air, no problem, right, 0:13:23.920 --> 0:13:26.040 But it can't pass through a rock or your hand. 0:13:26.600 --> 0:13:28.200 X rays are a different kind of light, so they 0:13:28.240 --> 0:13:29.920 have a different set of stuff that they can go 0:13:30.000 --> 0:13:32.560 through or not. So, yeah, you're right, you're seeing the 0:13:32.600 --> 0:13:37.360 difference in transparency between bone and fat or tumors and 0:13:37.679 --> 0:13:39.400 gas and all the kind of stuff that makes up 0:13:39.400 --> 0:13:41.680 your body. Yeah, and you sort of get the shadow 0:13:41.720 --> 0:13:44.000 of them, the impression of them on the other side 0:13:44.240 --> 0:13:47.679 on the on like a sensor or a film. Yeah, exactly. 0:13:48.000 --> 0:13:49.559 And you know it used to be filmed. They used 0:13:49.559 --> 0:13:51.360 to like take a picture and have to develop it. 0:13:51.559 --> 0:13:53.719 These days they use a digital camera, which is why 0:13:53.720 --> 0:13:56.439 it's so fast. And the thing X rays are good 0:13:56.480 --> 0:13:59.160 at is telling like bone from other tissue. X ray 0:13:59.200 --> 0:14:01.840 is not that good telling the difference between like water 0:14:02.360 --> 0:14:04.760 or fat or that kind of stuff. It all comed 0:14:04.760 --> 0:14:06.920 out about the same and X rays. And the other 0:14:06.960 --> 0:14:09.040 thing is you mentioned is that the X rays passed 0:14:09.120 --> 0:14:10.880 all the way through you, so you're just seeing sort 0:14:10.920 --> 0:14:14.480 of like the overall shadow. You can't see slices. And 0:14:14.520 --> 0:14:16.240 that's why when you take an X ray sometimes ask 0:14:16.240 --> 0:14:17.839 you to turn so they can take it from the 0:14:17.880 --> 0:14:19.440 front and they can take it from the side or 0:14:19.480 --> 0:14:21.560 from a different angle so they can get a sense 0:14:21.600 --> 0:14:24.120 for what's going on inside from shooting X rays through 0:14:24.120 --> 0:14:27.200 you at different at different angles. With that, let's take 0:14:27.240 --> 0:14:41.240 a break. We'll be back in just a short minute. 0:14:42.400 --> 0:14:45.280 So that's one way to look inside of you. But 0:14:45.520 --> 0:14:47.720 m r I is sort of smarter, right, Like, it 0:14:47.760 --> 0:14:50.760 doesn't shoot radiation through you. It it just sort of 0:14:50.800 --> 0:14:54.680 like kind of it does something a lot cleverer. Right, Well, 0:14:54.720 --> 0:14:57.040 it actually does shoot radiation through you, right, I mean, 0:14:57.040 --> 0:15:02.360 it does send electromagnetic pulses, but they're safer, right, It's 0:15:02.440 --> 0:15:05.800 not really high energy. In fact, they're very very low energy. 0:15:05.800 --> 0:15:09.240 They're radio waves, which means a very long frequencies, So 0:15:09.280 --> 0:15:11.760 they're not the kind of radiation that cannet deposit energy 0:15:11.840 --> 0:15:14.480 and break up your DNA and cause cancer. And that's 0:15:14.480 --> 0:15:15.880 the problem with X rays. And that's why when you 0:15:15.880 --> 0:15:17.600 take an X ray sometimes they give me like a 0:15:17.680 --> 0:15:20.440 lead skirt or a lead helmet or something, you know, 0:15:20.560 --> 0:15:22.600 or a lead jock strap or whatever to protect your 0:15:22.640 --> 0:15:24.640 all of your important bits that you don't want to 0:15:24.680 --> 0:15:27.480 send radiation into. But an m r I you can 0:15:27.560 --> 0:15:30.920 use much lower energy radiation uses the same radiation as 0:15:31.160 --> 0:15:33.880 like what you listen on the radio that's pumped out 0:15:33.880 --> 0:15:37.000 by radio antennants exactly the same kind of radiation. You 0:15:37.000 --> 0:15:39.120 don't usually think of that as light because you can't 0:15:39.120 --> 0:15:42.880 see it, but it's all part of the electromagnetic radiation spectrum. 0:15:42.880 --> 0:15:45.520 You know. It starts out really low frequency with radio waves, 0:15:45.800 --> 0:15:48.160 comes up to visible light, and then you can UV 0:15:48.320 --> 0:15:51.160 lighted higher frequencies, and then gamm or X rays and 0:15:51.160 --> 0:15:54.600 gamma rays at very high frequencies. It's also part of 0:15:54.640 --> 0:15:57.400 the same family, but you know, just like in families 0:15:57.400 --> 0:16:00.240 were all different, and so radio waves feel very front 0:16:00.240 --> 0:16:02.640 of the body than X rays because they don't deposit 0:16:02.760 --> 0:16:05.360 very much energy, so they can't really do much damage. 0:16:05.440 --> 0:16:07.440 All right, So step us through Daniel. How does an 0:16:07.520 --> 0:16:09.320 m r I work? So, and let's start maybe with 0:16:10.040 --> 0:16:12.400 the ideita is that in an m r I you 0:16:12.440 --> 0:16:15.160 are sending radiation into your body, but you're sort of 0:16:15.160 --> 0:16:19.040 doing it proton by proton, right like yours. You're trying 0:16:19.040 --> 0:16:21.560 to poke one proton inside of your body. And so 0:16:21.600 --> 0:16:24.040 how does that work? Like if you if there's a 0:16:24.040 --> 0:16:25.720 proton inside of your body, how do you get it 0:16:25.760 --> 0:16:28.760 to light up or to see it? Yeah? Exactly, Well, 0:16:28.760 --> 0:16:32.440 remember the protons can absorb energy sometimes, so you're sending 0:16:32.440 --> 0:16:34.840 these radio waves in, and the radio waves have energy, 0:16:35.360 --> 0:16:37.120 and the idea is that you want to poke those 0:16:37.160 --> 0:16:40.560 protons and give them that energy, so they get like excited, 0:16:41.080 --> 0:16:43.360 and then they relax and they send the energy back. 0:16:43.880 --> 0:16:46.040 And the interesting thing, the reason that you can see 0:16:46.120 --> 0:16:47.680 inside the body with an m R I you can 0:16:47.720 --> 0:16:50.280 see the different kinds of tissue, is that different kinds 0:16:50.280 --> 0:16:53.720 of tissue take different amounts of time to absorb that 0:16:53.840 --> 0:16:56.920 energy and then send it back. So like fat or 0:16:57.040 --> 0:17:00.320 bone or water or whatever, you poke the proton in 0:17:00.320 --> 0:17:02.520 those different kinds of tissue, some of them will hold 0:17:02.520 --> 0:17:04.760 that energy for a while and then send it back, 0:17:04.960 --> 0:17:06.919 and some of them will send it right away. So 0:17:06.960 --> 0:17:09.560 you can tell what different kind of tissues there are 0:17:10.119 --> 0:17:12.159 by telling by seeing how long it takes for that 0:17:12.320 --> 0:17:14.919 energy that you're deposited to to get sent back to you. 0:17:15.560 --> 0:17:18.439 So it's not like you're sending X rays through and 0:17:18.440 --> 0:17:20.159 then whatever makes it out to the other end you 0:17:20.200 --> 0:17:24.200 see it. This is more like you're you're sending rata 0:17:24.240 --> 0:17:28.920 waves in and then that lights up the protons inside 0:17:28.920 --> 0:17:31.560 of you in different ways, And depending on how they 0:17:31.640 --> 0:17:34.760 light up and how long they take to stop lighting up, 0:17:34.800 --> 0:17:36.720 then you can tell what kind of tissue it is, 0:17:36.840 --> 0:17:39.159 or what kind of whether it's bone or fat or 0:17:39.480 --> 0:17:42.120 bananas exactly. And it's it's just like you know when 0:17:42.119 --> 0:17:44.320 you walk along a wall and you're looking for a stud, right, 0:17:44.320 --> 0:17:46.159 what do you do? You knock on the wall, and 0:17:46.160 --> 0:17:48.359 you're sending a wave in and you're waiting for that 0:17:48.400 --> 0:17:51.280 wave to come back, right, And if the wave sounds 0:17:51.280 --> 0:17:53.200 this way or sounds that way, it takes a long 0:17:53.280 --> 0:17:55.440 time or a short time to come back. That tells 0:17:55.440 --> 0:17:58.320 you about what's behind the wall. It's the same basic idea. 0:17:59.160 --> 0:18:00.800 It's also the way we kind of like an echo, 0:18:00.840 --> 0:18:07.240 more like an echo, but with electromagnetic radiation and pantum mechanics. Yes, exactly, 0:18:07.560 --> 0:18:10.160 it's like an echo and the radio wave goes in 0:18:10.240 --> 0:18:12.920 and gets and tickles those protons and makes them excited, 0:18:13.119 --> 0:18:14.760 and then it sends a radio wave back. So you 0:18:14.760 --> 0:18:17.919 have to have a radio emitter and a receiver, so 0:18:17.960 --> 0:18:20.040 it like it talks to the protons and then it 0:18:20.080 --> 0:18:22.960 waits for the protons to talk back, and based on 0:18:23.000 --> 0:18:25.520 how long it took for them to talk back, it says, Oh, 0:18:25.560 --> 0:18:29.040 this one's probably fat, this one's probably bone, this one's 0:18:29.040 --> 0:18:32.520 probably brained, this one's probably water. This is probably brilliant 0:18:32.640 --> 0:18:39.600 in the brain exactly. Okay, cool, all right, So it's 0:18:39.640 --> 0:18:42.120 it's kind of like you're sending a signal in your 0:18:42.600 --> 0:18:45.679 how it gets reflected back. Then you you recorded how 0:18:45.680 --> 0:18:48.080 when it bounces back, and then that tells you that 0:18:48.160 --> 0:18:50.240 sort of gives you the image of what's inside of 0:18:50.280 --> 0:18:53.040 your body exactly. And then there's some really cool quantum 0:18:53.040 --> 0:18:55.879 mechanics about how you get those protons to absorb that 0:18:56.040 --> 0:18:59.320 radio information and why they send it back, and that's 0:18:59.320 --> 0:19:01.359 where the magnets come in. And the way understand it, 0:19:01.359 --> 0:19:03.439 it's sort of like a spinning top, right, Like you 0:19:03.480 --> 0:19:06.320 need to think of a proton as a spinning top, 0:19:07.080 --> 0:19:09.159 and so you when you put it inside of this 0:19:09.240 --> 0:19:11.960 giant magnet, it makes all the tops sort of a 0:19:12.040 --> 0:19:14.840 ligne in a particular way or in one direction. Right, 0:19:15.000 --> 0:19:17.640 that's right, because remember we talked on our quantum Spin 0:19:17.680 --> 0:19:21.240 episode about how all these little particles they're not really spinning, 0:19:21.280 --> 0:19:23.520 but they have this thing about them called spin, which 0:19:23.560 --> 0:19:26.080 gives them a little magnetic field. To think of, every 0:19:26.119 --> 0:19:28.720 little particle is having a little magnet in it, and 0:19:28.800 --> 0:19:31.040 so if you put a really big magnet on the 0:19:31.040 --> 0:19:33.439