OT!:Re: airport scanner film damage
Hi, "Paris, Leonard" wrote: > > There must be some reason X-Ray techs wear lead aprons in hospitals. > Perhaps because they protect vital parts from X-Rays? If the X-Rays from > airport scanners are strong enough to pass easily through these lead bags, > there's a good chance that they are also hazardous to unprotected people. > It's a slightly different scenario. The rays in hospital are "free", not inside a lead lined box (the airport scanner) which provides primary protection. Scanners "focus" the rays and vary the power to get through denser objects. The power needed to penetrate many of the household objects in luggage is much more than that needed to penetrate tissue. mike - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: airport scanner film damage
On Thursday, December 13, 2001, at 03:59 PM, Paris, Leonard wrote: > Perhaps if you get into the bag and seal it up tightly about three hours > before they dump you on the X-Ray machine conveyor belt, you won't be > harmed > by the X-Rays. LOL -Aaron - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
RE: airport scanner film damage
Perhaps if you get into the bag and seal it up tightly about three hours before they dump you on the X-Ray machine conveyor belt, you won't be harmed by the X-Rays. Len --- -Original Message- From: Aaron Reynolds [mailto:[EMAIL PROTECTED]] Sent: Thursday, December 13, 2001 1:39 PM To: [EMAIL PROTECTED] Subject: Re: airport scanner film damage As to lead aprons vs. lead-lined bags: I have never seen a lead-lined bag as thick as the aprons that medical X-ray techs wear. Those aprons are quite heavy and thick, while lead-lined film protector bags are much lighter and thinner. There is absolutely no way that I'd want to be X-rayed with only a film bag as my protection. -Aaron - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Veering OT RE: airport scanner film damage (PHYSICS)
This gets long. > There must be some reason X-Ray techs wear lead aprons in hospitals. > Perhaps because they protect vital parts from X-Rays? If the X-Rays from > airport scanners are strong enough to pass easily through these lead bags, > there's a good chance that they are also hazardous to unprotected people. The assertion was that lead does not stop 100% of X-Rays, but only reduces exposure; and that thus machine operators could turn up the intensity of the beam to "punch through" lead shielding. Given that lead _does_ stop _some_ of the radiation and thus cut down the dose, it makes sense for medical X-Ray techs to wear the lead aprons (and, for that matter, to cover nearby, non-imaged body parts of patients. This does not contradict the statement that a lead film bag won't stop them from irradiating your film in checked baggage. AFAIK the operators have no control over the beam intensity for the hand-baggage scanners. These are presumably set to lower levels. After all, if they can't see into a bag at the checkpoint, they can just ask you to open it. Presumably the levels are such that the radiation doesn't penetrate the shielding of the machine itself enough to be a problem. X-ray imaging technology is kind of interesting actually. I don't know _much_ about it -- mostly stuff gleaned from being one of those patients who asks an annoying number of questions, and several years out of date -- but enough to have a glimpse into the medical imaging mindset. I do know that over the years, the radiation dose used for medical imaging has decreased significantly. They came out with more sensitive film so they could use less radiation. Then they came up with more tightly controlled machines. Then they came out with even more sensitive film. Then they came out with funky image intensifier thingies (a plate or grid re-emitter placed between the patient and the film, if I understood the explanation from the tech) so that even places using older machines could turn down the intensity. Since then, I'm betting they've upped the film sensitivity even more. (Note that dose also varies with what they're particularly trying to see.) Now obviously they've decided that the tiny amount of damage done by a few sets of X-rays done over a patient's lifetime add up to a whole lot less risk than ignorance of what's going on inside, but being a mostly cautious lot, doctors don't like any _extra_ exposure. So when I had my chest X-rayed, they gave me an apron to cover my groin. As for the techs wearing lead, well usually they go behind a wall containing thicker lead than you can put in a protective garment, but if they need to be right there when the image is made, they wear lead. Well a medical X-ray machine is not a tidy, enclosed box, shut around the body part being examined. It's this emitter and film-carrier assembly that the patient gets in between. Any radiation dispersed by less-than-theoretically-perfect focus gets to bounce around the room. And radiation _scattered_ by the imaging process (say if a photon hits an atom in the patient's body _just_right_ so that it's reflected instead of absorbed) gets to bounce around the room. Do that day after day after day after day, and you're getting more _cumulative_ exposure than the patients. Lead aprons stop enough of that to bring things back into the "acceptable risk" levels. Let's compare this to checked-baggage imaging equipment: like the hand-baggage scanner, items are moving through on a conveyor belt. I've never examined a machine, but some things stand to reason: you can put as much shielding as you like around that conveyor and keep photons from escaping in the Y and Z axes. If there might be enough reflection/scatter to throw things out along X -- along the direction of the conveyor belt, it would be possible to either put in a zig-zag light-trap (X-ray-trap) or to have lead doors come down in front of and behind each bag before turning on the beam. The safe power limits are a whole lot higher. They can crank up the gain a long way without exposing the techs (and you can bet the techs have to wear dosimeters just in case, if I know anything about OSHA). Your limits are the designed power capacity of the beam-generating equipment and the designed level of shielding on the machine. If they put 5 cm lead walls around the imaging chamber, they can crank up the beam intensity enough to push some X-ray photons through an 8 mm thick lead bag. Maybe not _many_ photons, but some. Off into "hope I remember my high-school physics" land... Consider that there are two approaches to "turning up the power", and I have no idea which they use: you can turn up the energy of each photon by increasing the frequency (decreasing the wavelength) of the X-rays you're throwing, which ought to make them a bit harder to stop/absorb; or you can just "throw more light" -- throw more
Re: airport scanner film damage
On Thursday, December 13, 2001, at 01:47 PM, Levente -Levi- Littvay wrote: > > I am sure if you look hard enough you might find a little sticker on the > machine that says no animals or babys... Thank you, that was hysterical. :) As to lead aprons vs. lead-lined bags: I have never seen a lead-lined bag as thick as the aprons that medical X-ray techs wear. Those aprons are quite heavy and thick, while lead-lined film protector bags are much lighter and thinner. There is absolutely no way that I'd want to be X-rayed with only a film bag as my protection. -Aaron - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
RE: airport scanner film damage
> Have you read the mortality rate for airport security scanner > technicians? > :-) > > Sorry, probably in poor taste. Of course it is high. Didn't you hear how many of them make a sport out of scanning poor photographer's films? I mean that old K1000 with that heavy metal lens is sure good enough to beat someone half to death with :)) Sorry... L Levente -Levi- Littvay University of Nebraska-Lincoln -- PGP public key: http://www.kign.org/levilpub.asc Key fingerprint: 8BD8 3CE7 FB1D 625F F268 BFCE 417A C20C 92BF 6225 -- Download free PGP e-mail security software: http://www.pgpi.org/ - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
RE: airport scanner film damage
> There must be some reason X-Ray techs wear lead aprons in hospitals. > Perhaps because they protect vital parts from X-Rays? If the > X-Rays from > airport scanners are strong enough to pass easily through these > lead bags, > there's a good chance that they are also hazardous to > unprotected people. OK, but note that no people go through the inside of the machines now do they? I would assume that those x-ray machines ahd some seruous led shell that does not let much X-rays out. I am sure if you look hard enough you might find a little sticker on the machine that says no animals or babys... That in the US at least. L Levente -Levi- Littvay University of Nebraska-Lincoln -- PGP public key: http://www.kign.org/levilpub.asc Key fingerprint: 8BD8 3CE7 FB1D 625F F268 BFCE 417A C20C 92BF 6225 -- Download free PGP e-mail security software: http://www.pgpi.org/ - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re: airport scanner film damage
Have you read the mortality rate for airport security scanner technicians? :-) Sorry, probably in poor taste. Tom C. - Original Message - From: "Paris, Leonard" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Thursday, December 13, 2001 11:10 AM Subject: RE: airport scanner film damage > There must be some reason X-Ray techs wear lead aprons in hospitals. > Perhaps because they protect vital parts from X-Rays? If the X-Rays from > airport scanners are strong enough to pass easily through these lead bags, > there's a good chance that they are also hazardous to unprotected people. > > Len > --- > - > This message is from the Pentax-Discuss Mail List. To unsubscribe, > go to http://www.pdml.net and follow the directions. Don't forget to > visit the Pentax Users' Gallery at http://pug.komkon.org . - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
RE: airport scanner film damage
There must be some reason X-Ray techs wear lead aprons in hospitals. Perhaps because they protect vital parts from X-Rays? If the X-Rays from airport scanners are strong enough to pass easily through these lead bags, there's a good chance that they are also hazardous to unprotected people. Len --- - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
