3 ms·

I have a proposal for anyone who wants to go digging on Google. In order to simplify this whole nonionizing EM radiation cancer debate, it would be awfully nice

by scythe 3y ago

I have a proposal for anyone who wants to go digging on Google. In order to simplify this whole nonionizing EM radiation cancer debate, it would be awfully nice if we could identify a subpopulation of people exposed to very high levels of nonionizing EM radiation at work. So if anyone can find a survey of cancer rates in MRI technologists, that would be helpful. Twenty seconds of Google exhausted my patience.

Podgajski 3y ago
MRIs do not admit the same kind of radiation that radio towers, TV, antennas, cell phones, and other devices do. MRIs admit magnetic fields. Magnetic fields alone. And The typical MRI worker is not commonly in the magnet room during scanning; therefore she is only occasionally exposed to gradient or radiofrequency fields. Plus, there are several regulations regarding exposure to fields from MRIs. So this is comparing apples to bumblebees as far as health risks go. https://mriquestions.com/personnel-exposure.html https://mriquestions.com/personnel-exposure.html
- billfor 3y ago
  An MRI emits RF fields as well to snap back the magnetic field. That's the banging noise that you hear when you are inside an MRI. https://mriquestions.com/radiofrequency-waves.html https://mriquestions.com/radiofrequency-waves.html
- scythe 3y ago
  I am a medical physicist. I know how the MRI works. The goal of the MRI machine is to make the patient's body emit radio waves, which are then measured. Obviously there is some RF going on! (This corresponds to a spatial Fourier transform etc.) And while it might not seem "often" to you, it's worth considering that the RF levels in the room are enough that we care about tissue heating and sparks on nonmagnetic conductors. This is many thousands of times stronger than a TV signal. There are many cases where the patients require "assistance", which is used in roughly the same sense that cats require assistance in taking a shower. Then there are spectrometrists and so forth — not every MRI is like the one you get as an outpatient with a broken leg.
  - methou 3y ago
    I think people could measure the forward/reflected energy at home, do sum calculations, it shouldn't be very hard, unsure why there's no such a product available.
- methou 3y ago
  MRI uses quite a lot RF, the coils are tuned to the B0 field frequency, there's a TX as well as RX. Commonly TX freq as at 63.87Mhz (1.5T) or 127.74 MHz (3.0T). While most of the workers are well shielded from the room, but people have to be extra careful to not microwave heat your patient to much (usually +1C hotter). But don't worry too much, there's a SAR limit on it. Most of the RF components, equipment, including our phones, are all strictly regulated by SAR (specific absorption rate). Each of them might be safe, but if you are having too many of them around you can be a problem (?).
pton_xd 3y ago
> In order to simplify this whole nonionizing EM radiation cancer debate UV radiation is non-ionizing and causes cancer. End of debate.
- sieste 3y ago
  Specifically, UV radiation affects DNA by forming new chemical bonds in the DNA strand, creating pyrimidine dimers[1]. These can lead to mutations and, ultimately, cancer. [1] https://en.wikipedia.org/wiki/Pyrimidine_dimer https://en.wikipedia.org/wiki/Pyrimidine_dimer
- scythe 3y ago
  A clever abuse of terms to match my own, I guess. UV generates localized molecular excited states, particularly in double bonds. The process is basically similar to ionization even though electrons are not actually ejected. These excited bonds undergo Paterno-Buchi reactions and other things that just don't happen without radiation. This is readily detectable established chemistry that occurs in particular known conditions. It's not really ionizing (steal your electron), but it generates excited molecules (that react quickly like ions do) according to similar quantum thresholds to those which govern ionization — it is almost-ionizing radiation. But RF doesn't do any cool stuff like that. The only interesting bit is that some cellular structures may be of comparable size to the wavelength. But the conductivity of tissue — even myelinated neurons — is poor. Attempts to generate non-thermal microwave effects by literally putting stuff in microwaves has mostly failed, so we are left with this mesoscale hoodoo.

by scythe 3y ago

Podgajski 3y ago

MRIs do not admit the same kind of radiation that radio towers, TV, antennas, cell phones, and other devices do. MRIs admit magnetic fields. Magnetic fields alone. And The typical MRI worker is not commonly in the magnet room during scanning; therefore she is only occasionally exposed to gradient or radiofrequency fields. Plus, there are several regulations regarding exposure to fields from MRIs. So this is comparing apples to bumblebees as far as health risks go. https://mriquestions.com/personnel-exposure.html https://mriquestions.com/personnel-exposure.html

billfor 3y ago
An MRI emits RF fields as well to snap back the magnetic field. That's the banging noise that you hear when you are inside an MRI. https://mriquestions.com/radiofrequency-waves.html https://mriquestions.com/radiofrequency-waves.html
scythe 3y ago
I am a medical physicist. I know how the MRI works. The goal of the MRI machine is to make the patient's body emit radio waves, which are then measured. Obviously there is some RF going on! (This corresponds to a spatial Fourier transform etc.) And while it might not seem "often" to you, it's worth considering that the RF levels in the room are enough that we care about tissue heating and sparks on nonmagnetic conductors. This is many thousands of times stronger than a TV signal. There are many cases where the patients require "assistance", which is used in roughly the same sense that cats require assistance in taking a shower. Then there are spectrometrists and so forth — not every MRI is like the one you get as an outpatient with a broken leg.
- methou 3y ago
  I think people could measure the forward/reflected energy at home, do sum calculations, it shouldn't be very hard, unsure why there's no such a product available.
methou 3y ago
MRI uses quite a lot RF, the coils are tuned to the B0 field frequency, there's a TX as well as RX. Commonly TX freq as at 63.87Mhz (1.5T) or 127.74 MHz (3.0T). While most of the workers are well shielded from the room, but people have to be extra careful to not microwave heat your patient to much (usually +1C hotter). But don't worry too much, there's a SAR limit on it. Most of the RF components, equipment, including our phones, are all strictly regulated by SAR (specific absorption rate). Each of them might be safe, but if you are having too many of them around you can be a problem (?).

pton_xd 3y ago

> In order to simplify this whole nonionizing EM radiation cancer debate UV radiation is non-ionizing and causes cancer. End of debate.

sieste 3y ago
Specifically, UV radiation affects DNA by forming new chemical bonds in the DNA strand, creating pyrimidine dimers[1]. These can lead to mutations and, ultimately, cancer. [1] https://en.wikipedia.org/wiki/Pyrimidine_dimer https://en.wikipedia.org/wiki/Pyrimidine_dimer
scythe 3y ago
A clever abuse of terms to match my own, I guess. UV generates localized molecular excited states, particularly in double bonds. The process is basically similar to ionization even though electrons are not actually ejected. These excited bonds undergo Paterno-Buchi reactions and other things that just don't happen without radiation. This is readily detectable established chemistry that occurs in particular known conditions. It's not really ionizing (steal your electron), but it generates excited molecules (that react quickly like ions do) according to similar quantum thresholds to those which govern ionization — it is almost-ionizing radiation. But RF doesn't do any cool stuff like that. The only interesting bit is that some cellular structures may be of comparable size to the wavelength. But the conductivity of tissue — even myelinated neurons — is poor. Attempts to generate non-thermal microwave effects by literally putting stuff in microwaves has mostly failed, so we are left with this mesoscale hoodoo.