5 ms·

In case you're not up on your conversions, that is ~1 banana equivalent dose.

by patio11 11y ago

mikeyouse 11y ago
The requisite XKCD chart: https://xkcd.com/radiation/ https://xkcd.com/radiation/ Interestingly, it's nearly the same radiation dose as is living within 50 miles from a nuclear power plant for 1 year. Which is only interesting since the Indian Point nuclear power plant is ~35 miles from Manhattan.
Retric 11y ago
This assumes it's a full body exposure. The top layers of your skin is ~5% of your body weight and your only getting that on one side of your body so ~2% of your body weight. Thus, even if the average is 1 banana equivalent dose, your skin is getting ~50 times that which may or may not be safe, but it sounds worse. PS: Of course this also assumes nothing breaks and it stays in motion, if the vehicle stops without turning off you might get hundreds or thousands of times that.
- refurb 11y ago
  Isn't all x-ray exposure one sided based on the radiation source? Doesn't all radiation exposure start with the skin? X-ray penetrate so not all energy is deposited on the skin's surface.
  - Retric 11y ago
    Backscatter only works because the frequency does not penetrate very well. https://en.wikipedia.org/wiki/Backscatter_X-ray https://en.wikipedia.org/wiki/Backscatter_X-ray PS: Airport scanners are estimated at 1 death per 200 million scans so if used in every airport they would kill ~4 Americans a year. http://www.rita.dot.gov/bts/press_releases/bts016_13 http://www.rita.dot.gov/bts/press_releases/bts016_13
    - deleted 11y ago
      [deleted]
    - mortehu 11y ago
      > The radiation doses emitted by the scans are extremely small; the scans deliver an amount of radiation equivalent to 3 to 9 minutes of the radiation received through normal daily living. Furthermore, since flying itself increases exposure to ionizing radiation, the scan will contribute less than 1% of the dose a flyer will receive from exposure to cosmic rays at elevated altitudes. http://www.ncbi.nlm.nih.gov/pubmed/21444831 http://www.ncbi.nlm.nih.gov/pubmed/21444831
      - toufka 11y ago
        Backscatter deposits that radiation disproportionately in areas of the body that are prone to cancer - skin, testes, breast tissue, etc. So those areas that are particularly sensitive take a disproportional hit with this technology. This [1] is a letter from a group of prominent scientists and oncologists at UCSF who wrote a letter to the White House about the uncertainties of the technology when it was used by the TSA at airports. [1] https://www.whitehouse.gov/sites/default/files/microsites/ostp/ucsf-jph-letter.pdf https://www.whitehouse.gov/sites/default/files/microsites/os...
      - eric_h 11y ago
        <slightly OT> I was lucky enough to ride on the Concorde from Heathrow to JFK when I was about 12 (the 747 (seats ~400) we were supposed to take broke down, and they only had a 737 (seats ~300) and a concorde (seats 100) available; my dad, having many tens of thousands of airline miles and super double platinum status on basically every airline, including british airways, was able to get our family of four as part of the hundred that got on the concorde for that flight). The cruising altitude of the concorde at mach ~2 is between 60 and 65k feet, basically double a normal airplane (wikipedia says 60k, but I distinctly remember the monochrome LCD in the plane that said we were traveling 1350 mph at 64k feet) I'm curious, now, what my cosmic radiation dosage was at that altitude. Surely, given the nature of atmosphere and radiation, the dosage at twice the normal altitude is considerably more than twice what it is at 30k feet. I wonder what that did to my chances of getting a radiation induced cancer now ;) As an aside, that happened well before 9/11, so I was actually able (/invited by the flight attendants) to go to the cockpit and talk to the pilots while were cruising along at mach 2. I remember asking the pilot what the actual takeoff speed was (he said about 175 mph, if I recall correctly. Given the glued-to-the-seat acceleration we experienced on take off, sounds about right), and all sorts of other nerdy questions about the technology. I'm gonna pour one out for the pre 9/11 days when curious kids could visit the cockpit of an airplane and be a nerd with the pilots. I'll pour another one out for the Concorde. I still remember it pretty vividly (though memories can of course be deceiving ;), but we made it from heathrow to jfk in 3.5 hours. I believe, also, that with the time change, we landed about 15 minutes before we took off. </OT> I've now been living in NYC for ~15 years (moved here about 3 weeks before 9/11), and have watched the NYPD develop it's various anti-terrorism tactics. From the weird aluminum devices I've seen in penn station next to the armed-with-assault-rifles national guard folk on major travel days, to the stickers on the street food carts citing their affiliation with some NYPD anti-terrorism program, I've been concerned for years about the NYPD overstepping reasonable bounds on their behavior. Where does this end? How do we encourage the police to actually be reasonable? I do have an acquaintance in the NYPD (we went to college together), but conversation on this topic is more or less not possible. The thin blue line is very much a thing, and it appears to be impenetrable for us 'civilians' (the general attitude I got from said acquaintance is "you wouldn't understand").
- saulrh 11y ago
  Bananas throw out beta radiation. It's not as penetrating as alpha - attenuation depth in water on the order of centimeters rather than millimeters? - but I think a banana-equivalent dose will be pretty solidly concentrated in your digestive tract.
  - VLM 11y ago
    Its mostly the fault of one isotope of potassium and many hiker types eat bananas specifically to boost their blood K levels because otherwise they get really annoying muscle cramps. Its a moderately strong beta emitter and the range in water (close to human body) is about 2 cm or so. There are probably no parts of your innards more than 2 cm from the nearest bodily fluid (blood or whatever). Humans are surprisingly radioactive BTW. We each have about a hundred grams of potassium happily radiating away. An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. For security sensing or something. Maybe in a 100 years automatic supermarket style doors will sense humans radioactively rather than current microwave doppler and infrared systems. Maybe.
    - Florin_Andrei 11y ago
      > An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. Beta is super-easily stopped. A piece of cardboard or tinfoil reduces it dramatically, or stops it completely, depending on energy per particle, total flux, etc. I've a Luminox watch, the dial is visible in darkness all the time, you don't have to "recharge" it. It works by having small amounts of tritium decay within luminescent tubes. The radiation produced is beta - but the levels of radiation outside the watch are essentially zero. The body of the watch is enough to contain it.
      - onnoonno 11y ago
        Again, and as others pointed out in other contexts here, it depends on the energy. Tritium has 20keV betas AFAIR. Some elements produce multi-MeV beta decay. That is not stopped by thin cardboard.
- patio11 11y ago
  You're presumably thinking alpha particles if you're thinking of radiation which is stopped by, and therefore concentrates measured exposure at, your skin. I rather strongly doubt this machine uses alpha particles. Considerations which make me doubt this: they would get blocked by insulating materials such as e.g. the side of the surveillance van, the side of your vehicle, 3 cm of open air, etc.
  - Retric 11y ago
    No, X-rays have different penetrating power based on frequency. There using a back-scatter approach as it's just one van which means very low penetrating power. https://en.wikipedia.org/wiki/Backscatter_X-ray https://en.wikipedia.org/wiki/Backscatter_X-ray
rnovak 11y ago
On it's face, this may seem completely harmless, but what about when you consider how the device is going to actually be used? I imagine constant-scanning over a period of several hours would be on the order of several hundreds/thousands of bananas. Would that be banana-boarding?
- TeMPOraL 11y ago
  Several thousands bananas a day add up to about the background radiation level. Most people won't be spending all day sitting next to this van, and even if, there are some other radiation sources one is exposed to daily that just dwarf the emissions from the scan-van, per this handy chart[0] that I'll soon get banned for constantly posting in this thread. TL;DR: it's harmless, please focus on the actual problem - i.e. police taking nudes of you without your knowledge or consent. [0] - https://xkcd.com/radiation/ https://xkcd.com/radiation/
  - rnovak 11y ago
    I'm sorry, but if someone were being forced to eat thousands of bananas a day, people would be pretty outraged. I'm all for keeping this about privacy, but don't dismiss the health stuff. Dentists still give you a lead bib to protect against x-rays (2doses worth according to XKCD), so yeah, don't dismiss it.
    - TeMPOraL 11y ago
      > I'm sorry, but if someone were being forced to eat thousands of bananas a day, people would be pretty outraged. Yes, but not because radiation. There's a difference between scanning someone and force-feeding them. X-rays are emitted by many processes, including playing with an office tape. If, say, relays in traffic lights emitted equivalent amounts of X-rays in the course of their normal operation (don't they? did anyone check?), nobody would be talking about it. The reason we're talking about vans is because police is taking nudes without consent; radiation is only used as an additional, powerful argument, because it sounds scary. > I'm all for keeping this about privacy, but don't dismiss the health stuff. Dentists still give you a lead bib to protect against x-rays (2doses worth according to XKCD), so yeah, don't dismiss it. I think those are 2 doses afer taking into account the shielding you get. I wouldn't expect it to be much higher without shielding though, but medical profession is both extremely sensitive about legal issues and not beyond doing weird things to cater for irrational fears of people. For instance, the reason you get "a MRI" and not NMR - for Nucler Magnetic Resonance, as it is called everywhere else in science - is because patients were afraid of the word "nuclear".

In case you're not up on your conversions, that is ~1 banana equivalent dose.

by patio11 11y ago

In case you're not up on your conversions, that is ~1 banana equivalent dose.

The requisite XKCD chart: https://xkcd.com/radiation/ https://xkcd.com/radiation/ Interestingly, it's nearly the same radiation dose as is living within 50 miles from a nuclear power plant for 1 year. Which is only interesting since the Indian Point nuclear power plant is ~35 miles from Manhattan.

Retric 11y ago

This assumes it's a full body exposure. The top layers of your skin is ~5% of your body weight and your only getting that on one side of your body so ~2% of your body weight. Thus, even if the average is 1 banana equivalent dose, your skin is getting ~50 times that which may or may not be safe, but it sounds worse. PS: Of course this also assumes nothing breaks and it stays in motion, if the vehicle stops without turning off you might get hundreds or thousands of times that.

refurb 11y ago
Isn't all x-ray exposure one sided based on the radiation source? Doesn't all radiation exposure start with the skin? X-ray penetrate so not all energy is deposited on the skin's surface.
- Retric 11y ago
  Backscatter only works because the frequency does not penetrate very well. https://en.wikipedia.org/wiki/Backscatter_X-ray https://en.wikipedia.org/wiki/Backscatter_X-ray PS: Airport scanners are estimated at 1 death per 200 million scans so if used in every airport they would kill ~4 Americans a year. http://www.rita.dot.gov/bts/press_releases/bts016_13 http://www.rita.dot.gov/bts/press_releases/bts016_13
  - deleted 11y ago
    [deleted]
  - mortehu 11y ago
    > The radiation doses emitted by the scans are extremely small; the scans deliver an amount of radiation equivalent to 3 to 9 minutes of the radiation received through normal daily living. Furthermore, since flying itself increases exposure to ionizing radiation, the scan will contribute less than 1% of the dose a flyer will receive from exposure to cosmic rays at elevated altitudes. http://www.ncbi.nlm.nih.gov/pubmed/21444831 http://www.ncbi.nlm.nih.gov/pubmed/21444831
    - toufka 11y ago
      Backscatter deposits that radiation disproportionately in areas of the body that are prone to cancer - skin, testes, breast tissue, etc. So those areas that are particularly sensitive take a disproportional hit with this technology. This [1] is a letter from a group of prominent scientists and oncologists at UCSF who wrote a letter to the White House about the uncertainties of the technology when it was used by the TSA at airports. [1] https://www.whitehouse.gov/sites/default/files/microsites/ostp/ucsf-jph-letter.pdf https://www.whitehouse.gov/sites/default/files/microsites/os...
    - eric_h 11y ago
      <slightly OT> I was lucky enough to ride on the Concorde from Heathrow to JFK when I was about 12 (the 747 (seats ~400) we were supposed to take broke down, and they only had a 737 (seats ~300) and a concorde (seats 100) available; my dad, having many tens of thousands of airline miles and super double platinum status on basically every airline, including british airways, was able to get our family of four as part of the hundred that got on the concorde for that flight). The cruising altitude of the concorde at mach ~2 is between 60 and 65k feet, basically double a normal airplane (wikipedia says 60k, but I distinctly remember the monochrome LCD in the plane that said we were traveling 1350 mph at 64k feet) I'm curious, now, what my cosmic radiation dosage was at that altitude. Surely, given the nature of atmosphere and radiation, the dosage at twice the normal altitude is considerably more than twice what it is at 30k feet. I wonder what that did to my chances of getting a radiation induced cancer now ;) As an aside, that happened well before 9/11, so I was actually able (/invited by the flight attendants) to go to the cockpit and talk to the pilots while were cruising along at mach 2. I remember asking the pilot what the actual takeoff speed was (he said about 175 mph, if I recall correctly. Given the glued-to-the-seat acceleration we experienced on take off, sounds about right), and all sorts of other nerdy questions about the technology. I'm gonna pour one out for the pre 9/11 days when curious kids could visit the cockpit of an airplane and be a nerd with the pilots. I'll pour another one out for the Concorde. I still remember it pretty vividly (though memories can of course be deceiving ;), but we made it from heathrow to jfk in 3.5 hours. I believe, also, that with the time change, we landed about 15 minutes before we took off. </OT> I've now been living in NYC for ~15 years (moved here about 3 weeks before 9/11), and have watched the NYPD develop it's various anti-terrorism tactics. From the weird aluminum devices I've seen in penn station next to the armed-with-assault-rifles national guard folk on major travel days, to the stickers on the street food carts citing their affiliation with some NYPD anti-terrorism program, I've been concerned for years about the NYPD overstepping reasonable bounds on their behavior. Where does this end? How do we encourage the police to actually be reasonable? I do have an acquaintance in the NYPD (we went to college together), but conversation on this topic is more or less not possible. The thin blue line is very much a thing, and it appears to be impenetrable for us 'civilians' (the general attitude I got from said acquaintance is "you wouldn't understand").
saulrh 11y ago
Bananas throw out beta radiation. It's not as penetrating as alpha - attenuation depth in water on the order of centimeters rather than millimeters? - but I think a banana-equivalent dose will be pretty solidly concentrated in your digestive tract.
- VLM 11y ago
  Its mostly the fault of one isotope of potassium and many hiker types eat bananas specifically to boost their blood K levels because otherwise they get really annoying muscle cramps. Its a moderately strong beta emitter and the range in water (close to human body) is about 2 cm or so. There are probably no parts of your innards more than 2 cm from the nearest bodily fluid (blood or whatever). Humans are surprisingly radioactive BTW. We each have about a hundred grams of potassium happily radiating away. An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. For security sensing or something. Maybe in a 100 years automatic supermarket style doors will sense humans radioactively rather than current microwave doppler and infrared systems. Maybe.
  - Florin_Andrei 11y ago
    > An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. Beta is super-easily stopped. A piece of cardboard or tinfoil reduces it dramatically, or stops it completely, depending on energy per particle, total flux, etc. I've a Luminox watch, the dial is visible in darkness all the time, you don't have to "recharge" it. It works by having small amounts of tritium decay within luminescent tubes. The radiation produced is beta - but the levels of radiation outside the watch are essentially zero. The body of the watch is enough to contain it.
    - onnoonno 11y ago
      Again, and as others pointed out in other contexts here, it depends on the energy. Tritium has 20keV betas AFAIR. Some elements produce multi-MeV beta decay. That is not stopped by thin cardboard.
patio11 11y ago
You're presumably thinking alpha particles if you're thinking of radiation which is stopped by, and therefore concentrates measured exposure at, your skin. I rather strongly doubt this machine uses alpha particles. Considerations which make me doubt this: they would get blocked by insulating materials such as e.g. the side of the surveillance van, the side of your vehicle, 3 cm of open air, etc.
- Retric 11y ago
  No, X-rays have different penetrating power based on frequency. There using a back-scatter approach as it's just one van which means very low penetrating power. https://en.wikipedia.org/wiki/Backscatter_X-ray https://en.wikipedia.org/wiki/Backscatter_X-ray

rnovak 11y ago

On it's face, this may seem completely harmless, but what about when you consider how the device is going to actually be used? I imagine constant-scanning over a period of several hours would be on the order of several hundreds/thousands of bananas. Would that be banana-boarding?

TeMPOraL 11y ago
Several thousands bananas a day add up to about the background radiation level. Most people won't be spending all day sitting next to this van, and even if, there are some other radiation sources one is exposed to daily that just dwarf the emissions from the scan-van, per this handy chart[0] that I'll soon get banned for constantly posting in this thread. TL;DR: it's harmless, please focus on the actual problem - i.e. police taking nudes of you without your knowledge or consent. [0] - https://xkcd.com/radiation/ https://xkcd.com/radiation/
- rnovak 11y ago
  I'm sorry, but if someone were being forced to eat thousands of bananas a day, people would be pretty outraged. I'm all for keeping this about privacy, but don't dismiss the health stuff. Dentists still give you a lead bib to protect against x-rays (2doses worth according to XKCD), so yeah, don't dismiss it.
  - TeMPOraL 11y ago
    > I'm sorry, but if someone were being forced to eat thousands of bananas a day, people would be pretty outraged. Yes, but not because radiation. There's a difference between scanning someone and force-feeding them. X-rays are emitted by many processes, including playing with an office tape. If, say, relays in traffic lights emitted equivalent amounts of X-rays in the course of their normal operation (don't they? did anyone check?), nobody would be talking about it. The reason we're talking about vans is because police is taking nudes without consent; radiation is only used as an additional, powerful argument, because it sounds scary. > I'm all for keeping this about privacy, but don't dismiss the health stuff. Dentists still give you a lead bib to protect against x-rays (2doses worth according to XKCD), so yeah, don't dismiss it. I think those are 2 doses afer taking into account the shielding you get. I wouldn't expect it to be much higher without shielding though, but medical profession is both extremely sensitive about legal issues and not beyond doing weird things to cater for irrational fears of people. For instance, the reason you get "a MRI" and not NMR - for Nucler Magnetic Resonance, as it is called everywhere else in science - is because patients were afraid of the word "nuclear".