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Could use some pronunciation text? Is it "g-ray" or just "gray?" 76.226.54.17 ( talk) 20:21, 1 December 2013 (UTC)
I deleted the following recent addition:
"Some users of very large amounts of nuclear radiation - for example, the food irradiation industry - have shifted from rads to grays, since the larger scale of the unit results in a smaller number. For example, 100,000 rads, an enormous amount of radiation (more than 1,000 times the lethal dose for human beings), can be described as 1 kilogray, or 1kGy, which to the lay audience seems like a smaller amount than a measurement that uses the number 100,000."
Ascribing political motives to a shift to internationally accepted standards seems a bit of a stretch. The food industry could just as well have used the megarad, in which cast the usage cited would be only 1/10 of an Mrad. In any case, this seems inappropriate in an article about the unit. -- agr 00:53, 16 September 2005 (UTC)
The Goiânia accident article data suggests that exposure to even 4+ Grays is often fatal for humans.
Dialectric ( talk) 21:24, 19 January 2008 (UTC)
Bushong describes the Mean Lethal Dose (LD50/30) as the dose estimated to kill 50% of organisms in 30 days. This dose varies per organism, the cockroach being listed as the most radioresistant. Because reports of outcomes were more accurate if given more time (60 days rather than 30 days), the use of LD 50/60 is preferred. Assuming whole-body exposure, the mean lethal dose estimate for humans is 3.5 Gy (350 rad). If 100 healthy humans were irradiated with 3.5 Gy, 60 days later, roughly 50 would survive. This would seem to be consistent with the Goiania accident report, above. Comorbidities of the victims can affect the outcome. The largest known survivable acute radiation dose is reported to be 8.25 Gy. (This needs to be verified). [1]
Of course, surviving an acute radiation dose does not take into account stochastic effects. Ohiovince ( talk) 16:34, 29 March 2018 (UTC)
References
In our laboratory we use 1Gy = 0.00876 R, that gives 114.155 instead of 107.185 from article. Since I don't know the calculations leading to this coefficient, I feel I am not the right person to change it in this article. I have a feeling that this is because of the energy used to create an ion pair in the air is 33.9 [eV] and it is usually not equal to the chemical ionisation energy, even if it is called the same thing.
I don't have access to ICRU report 31 which should be source of this value.
Regards,
213.25.33.100 ( talk) 07:16, 13 August 2008 (UTC)Tomasz Sztejka
I've checked in a lot of places to see if the Gray unit was actually an SI base unit. But I can't find anything. If this isn't actually an SI unit, then the article shouldn't state that it is. I don't know enough about the SI or radiation in general to feel comfortable editing tis article. But could someone please find the truth!
Helixer ( talk) 17:05, 5 October 2008 (UTC)
It is a derived unit http://en.wikipedia.org/wiki/SI_derived_unit -- Efa ( talk) 16:08, 26 November 2009 (UTC)
I am new to this subject and would like somebody to explain to me the following: If the Gray is the unit of absorption of radiation energy, how can a fatal dose be defined as a dose of 5 Grays or more at one time. If the exposure is for only a nanosecond, how can this be a fatal absorbed dose of energy? Maximillions
the article is too much focused on Biological effect, while Gy and rad are unit of absorbed dose by matter, inanimated too. They are intended to measure the matter damage, but mainly for non biological matter. For biological effect there's Sievert and rem units.-- Efa ( talk) 16:14, 26 November 2009 (UTC)
Do we really need to repeat the conversion between rads and grays? This is covered in the first paragraph of the article.
Also do we really need the table listing all the SI prefixes? If the reader has a sufficiently sound scientific background to understand the article, then (s)he almost certainly understands the SI prefixes as well.
I suggest that this section be stripped of everything apart from the discussion on röntgens and that the section be renamed "Grays and röntgens". Martinvl ( talk) 20:07, 2 February 2010 (UTC)
Where does the "strongly discouraged" quote come from? It is not cited, so it probably shouldn't be there. —Preceding unsigned comment added by 134.174.21.5 ( talk) 19:20, 20 August 2010 (UTC)
A figure I always find interesting in a discussion about the health effects of radiation, which could be of interest to the reader, is this one:
"The total energy absorbed by a 75 kg individual with a whole body exposure of 600 rads (fatal in most cases) is 450 joules. It is interesting to compare this to the kinetic energy of a .45 caliber bullet, which is about 900 joules." (from http://nuclearweaponarchive.org/Nwfaq/Nfaq5.html but easily calculated)
After some adjustments for context, and taking a smaller bullet, I suggest adding it to the article after the comment about 5 Gy usually being lethal:
The total energy absorbed by a 80 kg individual with a whole body exposure of 5 gray is about 400 joules. It is interesting to compare this to the kinetic energy of a 9 mm bullet, which is about 450 joules."
Thomas Thomasonline ( talk) 08:06, 26 September 2010 (UTC)
There is a dispute regarding the roentgen section of this article. First, I would point out that this article is about the gray, and it might make more sense to take this discussion to the roentgen article. But currently the dispute is here.
One editor wishes to include a definition of the roentgen, along with some calculations to arrive at a conversion of 1 Gy = 111 R, supported by a citation to an online dictionary. There are several problems with this. First, the citation does not support any conversion from Gy to R. As a minor note, a dictionary is not necessarily the most reliable source for this kind of thing anyway, but in this case it's OK as far as it goes. Second, the air ionization energy of 35 J/C is unsupported. A google search finds alternate values of 36.16 J/C and 33.97 J/C just on the first page of results, so it seems to be a contested value that needs a citation. Another reader disputed the figures 4 years ago, see above on this talk page. Third, the way the statement is written suggest that 1 Gy = 111 R is a conversion constant. In fact it is not constant; it depends on the material exposed, and I provided citations to support that.-- Yannick ( talk) 12:37, 12 May 2012 (UTC)
OK, I think I see what you're getting at, and I would like to work with you to figure out what's the best way to explain everything. I was not aware that Gray was the first to see the flaws in the roentgen unit, and I'm wondering where you got that from. I'm aware of him defining a roentgen equivalent quantity for neutrons in 1940, but I was under the impression that this was a common and evident thing to do at the time as scientists realized that particles did not ionize matter the same way as photons do. Your citation from Guill and Moteff (great find, by the way!) seems to suggest that V. I. Ivanov was first. The verbal lore that I was taught was that Sievert's and Gray's roles as the chairman and vice chairman of the ICRU had more to do with the naming of the units. See for example here.
I am not comfortable with the word "kerma" myself because it is inconsistently used, but it does appear in many important texts. It's right in the SI brochure in table 3 as one of the quantities that can be measured in Gray, so technically we could open the article by saying the Gray is a unit of absorbed dose or kerma. But my personal experience, and what I think I've seen most often in writing, is that it's primarily the radiologists who use the word "kerma." The explanation they usually give me is that their ionization chamber (used for calibration) measures radiation concentration, or kerma, in roentgen or C/kg, and they assure me that this is a different quantity from absorbed dose that the doctor prescribes in Gy. So I'm trying to reflect that prevalent practice. Another way I've seen the word used is to describe the calibration medium, e.g. 5 roentgen air kerma. Used this way, "kerma" doesn't quite match it's written definition, but that's real-life for you. Here are some sources that try to explain kerma, though they don't fully support what I've just said: [1] [2] [3] [4] [5]
As for the word "deposits," I really don't see what's wrong with it. I have commonly seen it used in serious radiation protection texts. See for example the SI brochure or this radiation protection manual. I could come up with a thousand citations for this. Could you clarify your objection?
Finally, I take issue with saying that the reference to x-rays or gamma rays was dropped. Although you are technically correct on paper, this restriction is still widely seen as implicit. See this recent textbook for example. The reason is that using roentgens or C/kg generally reflects the use of an ionization chamber, which won't work right under particle radiation. You might say that I have a double standard here, with the dry air restriction on one hand and the gamma restriction on the other, but from my experience and reading, that reflects how the roentgen has been used and abused in practice.-- Yannick ( talk) 01:09, 16 May 2012 (UTC)
There were a couple of citations that originally pointed to books.google.de, with a long untrimmed URL. I switched them to point to books.google.com and trimmed the URL to the minimum using the tool. But now I see that they've been switched back to the books.google.de, and seemingly back to their original length. What's the logic for preferring the german version on english wikipedia, and what's the benefit of the additional URL queries?-- Yannick ( talk) 03:10, 20 May 2012 (UTC)
Hello, there is one thing I do not understand about this unit. Can someone enlighten me? Gray is defined as absorption of one joule by one kilogram of matter. But I suppose that one kg of lead absorbs more energy that 1 kg of iron when exposed with the same "amount" of radiation. So when I set my X-ray unit to let's say 70 kV, 500 mAs and I expose 1 kg of iron and then 1 kg of lead, it will be a different dose expressed in grays (even when the setting of X-ray device stays the same)? Or maybe better question - my Unfors measuring unit does show me the dose in grays. But to which matter is this dose calculated? Is it the average human tissue?
Chrabros ( talk) 10:22, 30 May 2012 (UTC)
Is the plural "gray" or "grays". I checked the Oxford English Dictionary and they gave two instances of the word "grays" being used, one of which was taken from New Scientist. I checked the SI brochure. It was silent apart from saying that the normal rules of English grammar are applied. Does anybody have access to any other authoritative view on the matter? Martinvl ( talk) 18:16, 8 May 2013 (UTC)
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The new fast-growing hierarchy represents death rates in terms of radiation dose in GY.
I originally discovered this hierarchy in Survival Probability Comparison.
2GY radiation dose = 5% death rate
4GY radiation dose = 25% death rate
7GY radiation dose = 75% death rate
15GY radiation dose = 99% death rate
>30GY radiation dose = 100% death rate
In the video, the highest death rates are at the end. "Transmissible Spongiform Encephalopathies" and "Dying" came after ">30GY radiation dose".
Watch the video and write down the comparison in terms of radiation dose in GY.
video: Survival Probability Comparison
written down comparison: fill in the blanks
Chickenpox (children): _GY radiation dose
Chickenpox (adults): _GY radiation dose
Influenza: _GY radiation dose
Hepatitis A: _GY radiation dose
Malaria: _GY radiation dose
Cutaneous Anthrax: _GY radiation dose
Lassa Fever: _GY radiation dose
Smallpox: _GY radiation dose
Hepatitis A (adults over 50): _GY radiation dose
Brucelosis: _GY radiation dose
Measles: _GY radiation dose
Smallpox (Variola major): _GY radiation dose
Going to Space: _GY radiation dose
Climbing Everest: _GY radiation dose
Yellow Fever: _GY radiation dose
Attempting Suicide: _GY radiation dose
Diptheria: _GY radiation dose
Botulism: _GY radiation dose
Capillariasis: _GY radiation dose
Spanish Flu: _GY radiation dose
SARS: _GY radiation dose
Legionnaire's Disease: _GY radiation dose
Anorexia: _GY radiation dose
Meningoccal Disease: _GY radiation dose
Typhoid: _GY radiation dose
Leptospirosis: _GY radiation dose
Chickenpox (newborns): _GY radiation dose
Tularemia: _GY radiation dose
Septicemic Plague: _GY radiation dose
Reye's Syndrome: _GY radiation dose
Tuberculosis: _GY radiation dose
Anthrax (Gastrointestinal): _GY radiation dose
Pneuomonic Plague: _GY radiation dose
Tetanus: _GY radiation dose
Bubonic Plague: _GY radiation dose
Cryptococcal Meningitis: _GY radiation dose
Inland Taipan Bite: _GY radiation dose
Marburg Virus: _GY radiation dose
Ebola Virus: _GY radiation dose
AIDS: _GY radiation dose
Anthrax (Pulmonary): _GY radiation dose
Glanders: _GY radiation dose
Rabies: _GY radiation dose
Balamuthia: _GY radiation dose
Transmissible Spongiform Encephalopathies: _GY radiation dose
Dying: _GY radiation dose