Could we actually do this in a safe way? Having ill fitting shoes can cause a lot of long term damage. There could be a case that it's worth the X-ray risk...
Modern xray machines deliver low enough radiation doses that they could probably be used for this reasonably safely. They are routinely used in medical settings after all, but I suspect it would still be a liability nightmare.
But there's no real need to see the bones for fitting shoes. There's plenty of 3D scanning technologies today that do not involve ionizing radiation and would probably be more useful for fitting shoes anyway.
Not only are there technologies that could be used for this, there are working products in the market that do it already. I work for one of the technology providers in this area.
Having x-ray images or such would actually be somewhat helpful, as you could much more easily identify the metatarsophalangeal joints (the joint where the toe meets the foot), the locations of which do influence shoe fit to some extent.
However, the cost, safety, usability etc. of using x-ray machines in a retail setting makes it infeasible by a wide margin compared to optical measurement methods, and those generally take you far enough anyway. I'd rather go for dynamic analysis (i.e. scanning the foot while it is in motion taking a step) if more data on the skeletal structure is required.
Perhaps most obviously, you just can't try a shoe on if you buy online. You can if you buy five pairs and return four, as some do, but it's a lot of hassle and a waste of resources for all the shipping back and forth.
Secondly, a significant portion of the population (tens of precent) have "problems" enough that most shoes in a store don't fit, meaning you have to try on a lot before you find one that does. And even if you don't have such issues, sizing between brands (and even styles) is so inconsistent that you usually have to try multiple different sizes to decide which one fits you. Having a 3D model paired with an AI system that tells you which shoes fit and what sizes to pick saves a lot of time for a lot of people, both shoppers and staff.
Finally, if you ever want to order custom made footwear, there is really no way around measuring your feet. And arguably the only reliably well-defined and repeatable way of doing that is to do a 3D scan to capture the shape.
My aunt would knit socks for me as a kid. I'd stand on a sheet of paper and my mom would draw the outline of my foot, and mail her the sheet. Worked great!
That method is actually used by many shoemakers when you order a pair of bespoke shoes (in combination with a series of tape measurements). It's not accurate enough to produce a fitting shoe in a single attempt, however, so what usually happens is they make a "test shoe" based the measurements and drawing, then modify the last after having you try that on. This procedure can be repeated more than once if needed.
Knitted socks are quite a lot more forgiving than leather shoes, fortunately, since the material accommodates by stretching when you put it on. I'm not surprised it worked well for you and your aunt!
Thanks this is interesting. Is part of the problem that people's feet change size with weight?
I have the impression that this is half the battle with finding shoes myself. Probably the bones are the same size left and right, but I think they deform differently as I stand (or walk) in a way that depends on the contours of the shoe... and that sounds like a problem that would be hard to model with laser scanning or whatever.
I think you could just use photographs to make a 3d model.
As someone with hard to fit feet, I have often wished for custom footwear made with modern materials and design. I envision a system where you go to the store, they create a 3d model, you pick a design, and it is sent off to a factory that has been tooled to efficiently build the footwear from the model.
I think you could charge 150 or even 200% over off-the-shelf versions for modern custom fit running shoes/hiking boots/ski boots, etc. These markets already spend extra money for premium products. I know I would pay it, gladly.
Runners seem to go through shoes like clockwork. You could setup a subscription service.
My understanding is that digital dental x-rays deliver an order of magnitude less radiation dose than traditional film x-rays. So maybe there's a way to do this with an extremely small dose, especially because you might not need to produce super-sharp images.
Randall Munroe's radiation dose chart (https://xkcd.com/radiation/) says that a cross-country flight delivers a higher dose than a typical dental x-ray or even a chest x-ray. Maybe it would already be worth it with really modern imaging equipment.
The thing is, the X ray cannot tell you much about the fit, other than that your bones are roughly fitting into the bounding box. Which you already know from the ability to put the shoe on at all.
The X-ray image can't possibly tell you things like that the shoe's upper is too tight over the metatarsals, or that a seam inside the shoe is rubbing on your pinky toe, which will cause blistering.
At the end of the day, a good shoe fit is a simple matter of feel.
Even if the risk were worth it for the person being fitted, it might not be for the techs using it. Remember that this was only affordable at the time because there was zero health and safety. If you take proper precautions and only use trained personnel, it’s going to be cost prohibitive. I think sonagrams and laser scanning would be the better choice, safer, and cheaper.
Medical/dental techs leave the room when they're taking these X-rays for precisely this reason. You could have a separate room in a shoe store just for the X-rays ... but realistically I can't see that happening. How many people would even go for this? I sure as hell wouldn't want X-rays taken in a shoe store.
But there's no real need to see the bones for fitting shoes. There's plenty of 3D scanning technologies today that do not involve ionizing radiation and would probably be more useful for fitting shoes anyway.