Getting hurt sucks. It also sucks for the person trying to help because it can be hard to know how you're hurt. Thus the poor rescuer has to guess how poor you is hurt based of the sentences spilling out of your mouth. Mostly made up of variations of "It Hurts!" with plenty of swearing with some useful information sprinkled in. Especially anything involving bones injuries, those suck.

Now wouldn't it be nice if there was a way to see what kind of bone fracture you have on the spot? Well never fear! The Handheld Xray Machine will come! About the size of a radar speed gun, this baby could scan the area its over and present your skeleton to the rescuer so the he/she/they can make the best decision for you!

In theory.

Basically, is such a device possible under the laws of physics as we know them? Modern Xray machines are large machines that require a plate behind the Xray emitter and a lead blanket. .

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    $\begingroup$ -1 for lack of research. This product already exists in the real world. $\endgroup$
    – JBH
    Jul 12, 2022 at 6:45
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    $\begingroup$ In fact, they're already being regulated. $\endgroup$
    – JBH
    Jul 12, 2022 at 6:52
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    $\begingroup$ @JBH Pretty sure that device, like all X-ray imaging that I know of, still requires a receiving plate/film/detector in a separate location/position. In this case, the receiving film is separate (dentists put it into your mouth), which allows them to make the emitter look like a cute gun, but as a consequence it would not provide live imaging either. $\endgroup$ Jul 12, 2022 at 16:11
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    $\begingroup$ Perhaps a hand-portable 3D X-Ray CT scanner? In addition to looking a bit like a mini stargate, you can build it yourself too! $\endgroup$
    – Samwise
    Jul 13, 2022 at 1:34
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    $\begingroup$ Crazy guy is trying to make a DIY MRI scanner as well... $\endgroup$
    – Samwise
    Jul 13, 2022 at 1:56

5 Answers 5


Modern Xray machines are large machines that require a plate behind the Xray emitter and a lead blanket.

"Tell me you haven't had any contact with modern dental procedures without telling me that you haven't had any contact with modern dental procedures"

Hospital x-ray machines are often a bit hefty, but modern digital x-rays can be very small indeed. The ones I've come across are small enough to be hand-held, but generally aren't because the dental staff aim to minimize their radiation exposure. Moreover, the dose of x-rays emitted is very small and well focussed, so there isn't always a need for the victim to wear lead aprons for every procedure, either.

JBH linked a couple of relevant things in the comments above, so I won't repeat them.

Thing is though, dental x-rays tend to be interested in relatively small things (a few teeth at a time) and generally don't have to penetrate very far through a person (just the cheek and jaw/teeth). Sometimes you want to do stuff like x-ray someone's entire chest, and these bits of people tend to be bigger than teeth, and somewhat thicker. The bit that receives the x-rays and makes a picture (whether old-school film, or a modern digital sensor) may have to be as large as the image you're taking, and if it isn't then it needs to be able to move about and have additional clever logic to make it all work nicely. It also becomes more awkward to align the bit that catches the x-rays with the bit that emits the x-rays.

I posit that no matter how tiny your x-ray emitters and detectors get, the key bit will be aligning the whole thing, keeping it still during operation, and keeping your good self out of the way of backscatter as much as possible. Have a look at modern military diagnostic kit:

portable military x-ray equipment demonstrationArmy to modernize battlefield radiography with Canon's mobile X-ray units

(left image from army.mil, Army modernizes portable battlefield radiography system, right image from dotmed.com, Army to modernize battlefield radiography with Canon's mobile X-ray units

Freehanding a chest x-ray is probably impractical, so the entire kit is almost inevitably not going to be simply handheld even if it does pack up nice and small and light and portable.

Consider though that x-rays aren't the only gig in town. There's also ultrasounds, and modern fancy things like POCUS (point of care ultrasound):

handheld ultrasound transducer and mobile phoneenter image description here

This one on the left is apparently a Clarius D3 and the one on the right an Itrason UCS5-2, but there are probably hundreds of similar devices out there useful for all manner of medical procedures. Ultrasound transducers are already little handheld things, and the compute power required to render a nice diagnostic images has been handheld for some years now. No radiation to worry about, always has to be used in contact with the subject, no need for support frameworks.

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    $\begingroup$ Ultrasound is probably the better way to go, since the emitter and detector can be in the same place. $\endgroup$ Jul 12, 2022 at 16:13
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    $\begingroup$ There's also backscatter xray detectors, which are usually used for things like mineral prospecting and assaying, but the downside is that for light elements like those in a human body you need a much higher dose to produce enough backscatter for an image. $\endgroup$
    – Skyler
    Jul 12, 2022 at 18:29
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    $\begingroup$ @Skyler scattered light (or xrays) doesn't give you an image. you'd not only need a lot more radiation, but also a far more elaborate detector able to register the point of incidence AND direction of a photon. $\endgroup$
    – Karl
    Jul 13, 2022 at 10:33
  • $\begingroup$ Interesting, I didn't know that such ultrasound's existed! Though I do wonder if you could use it to check bones. $\endgroup$
    – Seraphim
    Jul 24, 2022 at 0:12
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    $\begingroup$ @Seraphim fracture sonography is very much a thing. It isn't generally done on adults in the real world, because x-rays are readily available and often more useful, but ultrasound can and does work. $\endgroup$ Jul 24, 2022 at 17:07

Modern Xray machines are large machines that require a plate behind the Xray emitter and a lead blanket.

Size and protective measures aside, this is what an x-ray is. Energetic particles are emitted by the transmitter and pass through the subject, and those that aren't absorbed by the target make it to the sensor plate. While we've made a bunch of progress since the days of fuzzy photographic plates and can do all sorts of fun things with volumetric xrays, the basic point of energetic particles being absorbed or not is still the same.

From that perspective no, you can't use an x-ray as a hand-held scanner without a sensor plate on the other side of the subject. And for all the reasons our favorite Starfish has already pointed out, you probably wouldn't want to.

Looking at the other medical imaging technologies isn't going to be hugely helpful either. CT is a multi-slice x-ray machine with smart software that builds 3D models from multiple x-rays, so that's out. MRI is out too since the magnetic field requires hefty generation equipment and an absolute ton of power. All you're left with is ultrasound, which is already a portable technology... which takes a lot of experience to interpret properly. Radiologists get paid big money for very good reasons after all.

Sadly SF medical imaging is, like so many things in SF, pure fantasy. Those fun scenes where they get detailed live views of the internals of your body look cool, but there's just no science behind it. And since you put the science-based tag on there, that's as far as we can go.

  • $\begingroup$ That being said: a sensor plate on the other side is very easily feasible for hand/arm/leg x-ray devices. I can draw the schematic for it in this comment x-ray-gun: d==|_o_| the o in the middle is the leg/arm, the | on the right side the sensor plate. $\endgroup$
    – Hobbamok
    Jul 13, 2022 at 9:06
  • $\begingroup$ Yup, I've watched the screen when my wife was getting an ultrasound more than once. The only thing I have ever been able to identify was the bladder. (Note: Pregnancy not involved, those images are clearer.) $\endgroup$ Jul 14, 2022 at 0:43

I would just hand-wavium the whole concept and basically have the character use what is effectively a Star Trek tricorder. No one ever asked if a Star Trek tricorder was possible under the laws of physics as we know it. It's the fiction part of "science fiction". The science part means it's at least vaguely plausible, i.e., it is not outright magic, sourced from the Demon Pantxolythl from the 8th Plane of Fire, but the exact specifics of how it works are not important to the story and therefore not specifically described or necessary.

I mean, if you really want the exact physics, I would think the physics substack or some medical substack could better answer that question. For world building, what we do is more like help you come up with excuses and explanations for the thing you want to do.

So can a handheld device accurately scan for broken bones over the entire body without any additional backplates or manual image stitching? Yes. Absolutely. It can also give you witty AI dialogue if you'd like. Does the character using it need to know how it works, or even if it uses actual x-rays? Not really. "I don't know, it was $150 on Amazon, now stop moving" should cover any explanation required.

  • $\begingroup$ Actually, it's the same people who asked "is this possible under the laws of physics" who ended up devising the machines we have now that do what those fictional devices once did in our imaginations. $\endgroup$
    – elemtilas
    Jul 13, 2022 at 19:36
  • $\begingroup$ @elemtilas - On the other hand, I suspect in a lot of cases it was the people who said "physics schmisics, I need it for the story" that may have planted a lot of ideas into a lot of heads to begin with. Lots of things from science fiction have eventually just become science. $\endgroup$
    – JamieB
    Jul 13, 2022 at 19:40

Most components are available off the shelf, but you would need a little bit of customization to use it in the field.

First you need an X-ray emitter. This is just a vacuum tube with an electron beam accelerator and a metal plate. It can be tiny if you don't need much power. You also need a high-voltage power supply and enough shielding so the user doesn't get irradiated.

enter image description here

However you won't get a screen on the back of the device showing what's inside the patient, because the sensor has to be placed on the other side. X-rays have to go through the patient.

So you need a sensor plate (sold separately) and means to fasten it to the patient, plus some sort of device to display the picture, like a smartphone.

However, would it work?

The above pistol raygun is cute but it will only irradiate a very small area, a few teeth. It could be okay for a broken finger, but that's not an emergency situation that would justify this expensive field equipment.

The problem with X-rays is that it's not practical to focus them with lenses or mirrors. This means if you want to irradiate a large area with almost-parallel rays, the only solution is to place the source at a distance, like for a chest X-ray. Then you need some kind of support for the emitter, to avoid having to find a different volunteer to hold it each time. And you need a sensor plate to put on the gurney below the patient. The result looks like this.

Not exactly "wearable", but it could definitely be installed inside an ambulance.

However, besides cost, there's a reason why it won't be done: once you have X-rayed the patient in the ambulance (or in a field), what will you do? If it's not an emergency, that's great, but then the patient didn't need to be irradiated. But if the radiography tells you the patient needs to be operated RIGHT NOW... well you're in an ambulance, not in an operating room.

So even if the machine helps reaching a correct diagnosis, it is unlikely to help the patient, besides telling them they should be going to the hospital anyway :D


Live x-ray imaging was a sales gimmick in shoe stores in the 1930s and 1940s. You would try on the shoes, then stick your foot in the x-ray machine to get a picture of how the shoe fit.

The person who told me this recalled that he and his friends had fun sticking hands in the x-ray machine and watching how their bones moved. (That person turns 90 this year, and I’ve lost touch with him since he told me this twenty years ago, but perhaps you also know a nonagenarian who bought shoes as a child and might have a similar story.)

I don’t know what the size of the machine was in the 1930s. But a modern x-ray emitters could easily be briefcase-sized or smaller. My educated guess is that the display was a phosphor screen, like the green display on an analog oscilloscope, or like an antique monochrome computer display. It’s possible that there were some electron-focusing optics, which would make the size of the imager comparable to one of those cathode-ray tubes. (Perhaps one child stuck his hand on the imager, and another child would look at the display). But a digital display could almost certainly be smaller.

It’s possible that the reason this device worked is that they used a dangerous amount of x-rays. But consider that radiological danger depends on total dose, and a bright x-ray machine might be useful for infrequent use in remote triage. When you get an x-ray at the dentist, you wear a lead apron to keep your whole-body dose as low as reasonably achievable (ALARA, in some of the safety literature). The dental assistant who operates the machine does it from the hallway, instead of standing in the room next to you, because they might run the x-ray machine twenty times a day, which has a different dose safety calculus than the patients who receive an x-ray every six or twelve months.

Other posts mention needing to stabilize the source and the emitter. This lets you do precision radiology, where you can find things like hairline fractures. You probably couldn’t get much detail from an antique shoe-store x-ray, but modern imaging systems can do some impressive things with computerized stabilization.

  • $\begingroup$ They are not huge. Little smaller than a standard two drawer filing cabinet. $\endgroup$
    – elemtilas
    Jul 13, 2022 at 19:40
  • $\begingroup$ Yes, the shoe shop machines were hideously unsafe by modern standards in terms of radiation exposure, which is why they were banned. $\endgroup$ Jul 15, 2022 at 6:05

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