radiography

Radiography tests are usually done at night because there are usually less people around. X-rays are harmful/dangerous and people need to remain a specified distance away from the testing.

Do any of those answer what your are asking?

Hi, thank you for your reply ... I am glad to know that radio-lytic by-products are safer than thermo-lytic by-products ... I know that high temperatures create a common cancer causing chemical ... for this reason food should be cooked at lower temperatures ... cooking also destroys nutrients, some methods more than others ... irradiated food is already available in the supermarkets ... this methods kills detrimental bacterium in order to extend the shelf life of the produce and make it safer for the consumption, protecting us among others from the E-coli ... I would like to find out if irradiation or X-ray processes damage our food to the point that it becomes substandard because the nutrients are destroyed ... I assume that enzymes might be killed which would not be good for us ... could Vitamin C be affected by irradiation or X-rays? ... I decided to eat rather cafeteria food, some cooked, because is was not exposed to the X-rays than my own lunch that went through the X-ray machine ... do you know if there is a study regarding the stability of vitamins, minerals, enzymes and antioxidants if exposed to the irradiation or X-rays? ... thank you, Jaan.

I believe radiography uses gamma rays (when I saw it done they used a Co60 source) whereas your lunch would be subject to the far less energetic X rays.

What is damaged is dictated largely by the quantum energy of the photons, ie gamma rays damage things that X rays wont. The total amount damaged is then a function of the number of photons, ie how "bright" the source is. For this reason visible light, even if of high intensity, does little damage to food in the short term, because the energy of the photons is below the threshold at which it can do damage.

Screening X rays are of low intensity and the stainless steel containers would further reduce the intensity, so even if the food is damaged, the amount of damage will be small. If, for example X rays could damage vitamin C (and I don't know if they can), only a small amount of the vit C would be affected because there would be insufficient number of X ray photons to destroy all of it. Your lunch should be quite safe to eat.

The gamma rays used for radiography have a much higher photon energy so if used on your food would damage components that X rays couldn't.

I think food sterilization is done with gamma rays, not X rays, as the X ray photon energy is too low to be effective.

Gamma rays would be able to damage items which have a much higher threshold but even here the irradiated food is still regarded (rightly or wrongly, I don't know) as being safe to eat.

Reading between the lines of this overly superficial question...

For the same reason that film would be developed in a dark room. Penetration (ratio) cannot be answered without some parameters...XRay power and exposure time; nature of object being "tested."

What does radiography test (in any of its applications) have to do with food sterilization? Maybe to test the cow to make sure it has bones?

Hello, Historically we did all weld x-ray testing at night or between shifts because of the harmful effects to the welders fitters etc. In the last few years an new type of weld inspection has gained a good bit of use around here. I am talking about digital x-ray weld inspection. It is a little more expensive than the other type but it does not require a big area to be quarantined. I have seen it being used to safely inspect welds only a few feet from welders working. On big around the clock jobs it pays for the extra expense by not having to shut down production to inspect welds. Another good aspect is that instead of getting a bunch of film that will deteriorate over time I get a cd with the images when the testing is done. Also the development stages are allot faster because there is no film to dry and the film can be erased and reused after the image is recorded and saved on a computer. I think this type of inspection will eventually replace the old type within a few years because of the safety factor alone.

pipewelder

Going back to the original question - it was about darkness - what I had hoped to be gleaned from my earlier post, is that when "shooting" open systems, such as piping and structures, is is not always convenient or practical to confine the imaging medium (exposure emulsion...plate) where incidental light and scattering can be excluded or minimized (such as would be the case, for example: when a film plate/frame is placed inside the mouth [dentistry] or in a darkened room (clinic radiology).... In such cases, it seems, a nightime environment is to be preferred to broad daylight.

As to digitizing of X-Rays, you are correct insofar as this has been and will continue to be a trend - and in large part due to ignorance or shortsightedness of purchasers, who will feel compelled to have the (what they are told is the) "latest and greatest" whether there is an advantage (or disadvantage) or not.

One rather insidious, and mindless adoption of digitized X-Rays is occurring in dentistry offices. This has introduced new problems about which, I've observed, dentists so far remain oblivious--

• Patient chair cove space constraints...requiring the keyboard and display to be situated (not on the wall or lixht fixture but) behind and out of view of the patient.
• The paying patient is out of the loop in terms of consultation...is deprived in child like manner of consultation for which the dentist still collects a fee.
• The dentist (due to "sterile hands" and practicioner lack of skill) must now rely on additional skill sets (personnel) to display and manipulate images...an additional overhead which must be passed on to customer.
• Reduced image resolution in comparison with photo-positive transparencies
• Issues pertaining to X-Ray ownership and possession - a patient's right by law to claim possession of X-rays will be (unduly) complicated and lead to additional patient expense for which no consideration is received:
• Some dentists will be inclined to assert the (legally unsupportable) claim that images on digital media are not "objects" subject to (patient/owner)possession.
• Others will claim an inherent incapacity to provide and image object, whether on disc or as a printout.
• Others still will want to collect an additional fee for repro cost and markup, whether this is permitted/restricted by law or not.
• Invariably (most) dentists will be unable (read, unwilling) to transfer images (via the Internet) to a patient's own system. Thus, in all except the most enlighted practices (which are few and far between) a major benefit of digitizing will not be put to use.

In summary, it will remain the case that the full benefit of digitizing will remain unrealized - the provider (and his imagery equipment supplier will win; the customer will lose.

We routinely shoot welds day or night and very good results either way and always have since I started fooling with code work 30 years ago. I think you are wrong about the digital x-ray, it has many advantages over normal x-ray even though on thicker pipes you still have to crank out the source the exposure time is about 1/2. The main thing that it has going for is that it is safer and that will overrule anything else as it always does. A good friend of mine was shooting boiler tubes once when he started to bring the source back in it hung and it was some ordeal. Cost the mill over a 1/2 million dollars in lost production alone before it was finally over. There is no chance of this with digital x-ray. Also it is ridiculous to shut down production and have all the workers standing there drawing pay when it could be prevented by using digital and continuing with the welding IMO.

pipewelder

pipewelder

Thanks for the elucidation. I was merely stating, and citing example, that digital is not always the panacea...in all applications. It can sometimes depend on who stands to gain and who stands to lose.

Very interesting and informative post, your's. So what, if not exposure, is the shoot at night thing all about, if I may read it succinctly from a hands-on guy?

As succinct as could be expected! When necessary, X-ray when the X-ray'ed equipment is not otherwise needed. Makes inarguable good sense.

Standard radiography, or imaging using radiation, is not done with gamma rays. In standard radiography, which includes medical radiography and parts/component inspections, electrons are accelerated into a metal target. The result of many of these collisions is the removal of inner electrons from the atoms of the metal target. When an electron drops back into an empty inner electron position an x-ray is emitted. Some x-rays are also emitted as Bremsstrahlung as electrons are scattered by the atomic nuclei.

If you are specifically talking about food irradiation (not radiography) which at least some of you are, that can be done with electron beams (although the limit is about 3 inches thick if doing it from one side), ultraviolet light (pretty much surface bacteria), or with x-rays or gamma rays. The reason one would go with x-rays over gamma is that there are no radioactive materials to deal with which include the facilities to handle such materials safely. The system is literally switched on or off. Cobalt 60 gamma ray sources have a half-life of over 5 years (5.3 or something like that). Irradiation takes place for specified periods of time in a chamber lined with thick leaded or otherwise high density concrete.

Cobalt 60 also has medical application in irradiation of cancer for example, but is not used for imaging purposes. For that purpose x-rays are far easier, cheaper, less damaging to the individual being imaged and safer to deal with.

The weld radiography I was referring to earlier was of thick wall pipe used for gathering natural gas from various wells. (The gas was at about 1300psi)

The inspection we did was in daylight and used a Co60 source. I suspect the operation in daylight was possible because the film used was quite insensitive to ordinary light.

For medical radiography of course normal X rays are used as the potential for tissue damage is too high with gamma rays and the extra penetration they give is not needed. In addition X ray dose etc is more readily controllable.

Ans 1. To avoid inadvertent exposure to unwary passers by (or unauthorized radiation workers), RT is usually preferrably carried out at night, i.e after work hours. Exposure to radiation is quite harmful if not done with proper precautions.

Ans 2. Penetration depends on the energy of the radiation source (kV in case X-rays / type of element in case radio-isotopes) and the absorption capacity of the material subjected to radiation; intensity depends on its strength; the overall exposure depends on the time under exposure + all above.

Hope this helps, any more doubts are always welcome.

Nachi

Who says that it works in the night? Our workers work day and night. the issue is you hve to have a good shield room, which is made of lead or cement , the thichness depends on your apparatus's energy.

radiography, or imaging use both x-ray and r-ray. r-ray has more energy than x-ay, so if you work with thickness, say, up to 120mm steel plate, you have to use r-ray. this source can be co-60, ir 192 and se etc. r-ray camera is as safety as x-ray apparatus. dont worry. all is program controlled.

food irradiation is using r-ray at special store.

Not anyone can do the job, he has to be qulified a certificate.

I saw a demo on irradiation of food at my company's meeting because we are one of the suppliers of Co60 ... it is done in a warehouse ... the rods are kept in a chamber below the floor and raised when the food is brought in on a conveyer belt ... the produce is in creates, it does not have to be unpacked ... the irradiation time depends on the type of the produce; it is a quick process ... Jaan.

I have to ask probably what may be considered a dumb question but here goes anyway. Why the heck would you want to irradiate food?

pipewelder

Hi pipewelder

"Why the heck would you want to irradiate food?"

To sterilize it. Irradiated food has a remarkably long shelf life.

I've never tasted it so can't comment on what happens to the flavor, but so what - it can be kept on the shelf longer so supermarkets make more money.

Produce gets bruised, brown and rotten because of the numerous bacterium munching on it ... when the bacterium is killed, the surface becomes sterile and also not prone to bruising from the pressure ... when shipped long distances, the irradiated produce does not change, and stays fresh looking and appetizing for much much longer ... we already eat irradiated produce ... I read that mangoes were irradiated but I could not tell by eating it ... many times I heard government saying that all meat should be irradiated ... some people consider irradiated food dead food and not live food therefore they would like to know what is and what is not irradiated ... Jaan

Ok I am sure I have heard this sometime in my life but it must have just slipped by me. I still think it is pretty creepy though and would have sworn not a very good idea. It seems that it as usual boils down to money and the art of making/saving more by the guys that handle the food. I grow a small garden every year and although its not enough to sustain us through the winter I do usually get plenty of peppers, tomatoes, squash and such. I always wonder at some point in the year why I do this when I don't usually have enough time to tend it as I should. Now I think I have a real good reason to put a little more time into it and maybe even enlarge it some next year.

pipewelder

Congratulations!

Organically grown produce is rated the best ... enjoy yours ... not only you eat food without pesticides and herbicides, your produce also contains more nutrients than the supermarket food ... Jaan