3 ms·

If the sensor is so small why are the X-ray machines at my hospital almost room sized? You know those huge mechanical arms hanging from the ceiling that look li

If the sensor is so small why are the X-ray machines at my hospital almost room sized? You know those huge mechanical arms hanging from the ceiling that look like they could crush you or irradiate you to death. Also can this project be used on flesh and will I accidentally cook myself doing it?

blululu 5y ago
The size of an x-ray grows with power for two reasons: higher voltages require much more insulation, and higher energies require much more shielding. In medical contexts shielding is the big issue. I forget the exact figures but the mass attenuation coefficient for large energy is something like Z/E^3, so a dental x-ray at 15 kev will has much less radiation leakage than a chest x-ray at 150 kev. (Note that the beam is not monochromatic and the 1000x change in attenuation passes through an exponential decay relation so it is not a simple relation, but you need a lot of lead to keep the x-ray tech safe).
jcrawfordor 5y ago
Besides offering much higher power levels, the bulk of most hospital X-ray equipment seems to just be positioning... i.e. the actual X-ray generator is fairly small (although things like a projected light illuminator to help the technician with aim make it bigger), but there's a lot of "accessory" equipment just to make it easy for the technician to position it in the right place and have it stay there. Ceiling tracks and a specially designed patient bed with a pretty x-ray transparent material that the sensor can be placed under, for example. Dental X-ray machines for example are very small, but I think it's because they operate at pretty low power and have pretty simple/consistent positioning requirements. Panoramic dental x-ray machines on the other hand are pretty big because of the specific positioning. On top of that I think a lot of hospitals just have pretty old X-ray machines... they're expensive and can operate for a long time with maintenance and tube replacements. I've seen clinics that upgraded their x-ray process to digital by using a standalone digital sensor like this, but are still using a 20+ year old analog machine as the x-ray source. I think that's why this particular sensor doesn't accept triggering information over the digital interface... that seems kind of weird at first glance, but I assume it was designed as a drop-in replacement for film, so it would be used with an older machine that didn't have any kind of digital trigger output. Instead it just detects when the exposure has started. Presumably the manual told the technician what parameters they needed to use on the emitter for it to get a full scan. The author here mentioned using a hand-held X-ray emitter for sports medicine which I'm curious about because I've never seen such a thing. I assume the power and exposure time must be pretty limited, even the dental X-ray machines have a regulatory requirement that the operator be behind a shield during use---although the implementation is usually pretty lax, just putting the exposure button in the hallway outside the x-ray nook so they have to step outside briefly.
- SiempreViernes 5y ago
  Just stepping away is in all likelihood exactly as much precaution as is needed: the machine itself ought to have shielding in all directions except the for the beam itself, so it doesn't emit significantly in the other directions anyway and getting some distance kills even that on its own. Honestly, going outside as a way to ensure you don't stand in the beam by mistake might be the most important part.
willcipriano 5y ago
They have dental x-ray sensors[0] that are about 2 cm thick and 4 x 4 inches in size with a usb plug on the other end. You put them in the mouth and then can use a portable x-ray gun[1] to image the tooth to your laptop. No more films or anything like that. [0]https://www.atlasresell.com/used-dental-equipment/digital-x-ray-sensors/suni-suniray-2-dental-digital-x-ray-sensor-radiography-0 https://www.atlasresell.com/used-dental-equipment/digital-x-... [1]https://www.kavo.com/en-us/imaging-solutions/kavo-nomad-pro-2-intraoral-xray https://www.kavo.com/en-us/imaging-solutions/kavo-nomad-pro-...

blululu 5y ago

The size of an x-ray grows with power for two reasons: higher voltages require much more insulation, and higher energies require much more shielding. In medical contexts shielding is the big issue. I forget the exact figures but the mass attenuation coefficient for large energy is something like Z/E^3, so a dental x-ray at 15 kev will has much less radiation leakage than a chest x-ray at 150 kev. (Note that the beam is not monochromatic and the 1000x change in attenuation passes through an exponential decay relation so it is not a simple relation, but you need a lot of lead to keep the x-ray tech safe).

jcrawfordor 5y ago

Besides offering much higher power levels, the bulk of most hospital X-ray equipment seems to just be positioning... i.e. the actual X-ray generator is fairly small (although things like a projected light illuminator to help the technician with aim make it bigger), but there's a lot of "accessory" equipment just to make it easy for the technician to position it in the right place and have it stay there. Ceiling tracks and a specially designed patient bed with a pretty x-ray transparent material that the sensor can be placed under, for example. Dental X-ray machines for example are very small, but I think it's because they operate at pretty low power and have pretty simple/consistent positioning requirements. Panoramic dental x-ray machines on the other hand are pretty big because of the specific positioning. On top of that I think a lot of hospitals just have pretty old X-ray machines... they're expensive and can operate for a long time with maintenance and tube replacements. I've seen clinics that upgraded their x-ray process to digital by using a standalone digital sensor like this, but are still using a 20+ year old analog machine as the x-ray source. I think that's why this particular sensor doesn't accept triggering information over the digital interface... that seems kind of weird at first glance, but I assume it was designed as a drop-in replacement for film, so it would be used with an older machine that didn't have any kind of digital trigger output. Instead it just detects when the exposure has started. Presumably the manual told the technician what parameters they needed to use on the emitter for it to get a full scan. The author here mentioned using a hand-held X-ray emitter for sports medicine which I'm curious about because I've never seen such a thing. I assume the power and exposure time must be pretty limited, even the dental X-ray machines have a regulatory requirement that the operator be behind a shield during use---although the implementation is usually pretty lax, just putting the exposure button in the hallway outside the x-ray nook so they have to step outside briefly.

SiempreViernes 5y ago
Just stepping away is in all likelihood exactly as much precaution as is needed: the machine itself ought to have shielding in all directions except the for the beam itself, so it doesn't emit significantly in the other directions anyway and getting some distance kills even that on its own. Honestly, going outside as a way to ensure you don't stand in the beam by mistake might be the most important part.

willcipriano 5y ago

They have dental x-ray sensors[0] that are about 2 cm thick and 4 x 4 inches in size with a usb plug on the other end. You put them in the mouth and then can use a portable x-ray gun[1] to image the tooth to your laptop. No more films or anything like that. [0]https://www.atlasresell.com/used-dental-equipment/digital-x-ray-sensors/suni-suniray-2-dental-digital-x-ray-sensor-radiography-0 https://www.atlasresell.com/used-dental-equipment/digital-x-... [1]https://www.kavo.com/en-us/imaging-solutions/kavo-nomad-pro-2-intraoral-xray https://www.kavo.com/en-us/imaging-solutions/kavo-nomad-pro-...