Talk:CT scan - Wikipedia

an edit was recently made to sinogram (a disambiguation page) such that one of its definitions now points to this article. However, this article does not mention the term. Could someone who is knowledgeable in this area please integrate mention the concept into this article, or change the disambiguation page to point to a more appropriate target? Thanks. Agradman (talk) 18:23, 15 June 2009 (UTC)Reply

added details: Originally, the page only included Radon Transform and Chinese Character (history). Subsequently, someone added tomographic reconstruction (history). Subsequently, someone joined radon transform & tomographic reconstruction with the phrase, "or equivently" (history). This led me to view the concepts as identical, so I brought the page to this version (history). My error was corrected to its current form (history)by Sławomir Biały, an editor who is knowledgeable about the radon transform. Agradman (talk) 18:40, 15 June 2009 (UTC)Reply

According to this article, a CT scanner is a medical device. This is not true, the medical CT scanner is only one of the many applications of this technology! Will someone please help fix this —Preceding unsigned comment added by 193.191.9.29 (talk) 10:22, 13 November 2009 (UTC)Reply

Hi, most of the information below has been thoroughly debunked, and I've added 6 citations that illustrate this (and I was being nice... there are tons more to refute this sensationalist nonsense). Can we jsut remove the original citation about cancer risk until the actual study currently underway for CT patients concludes? — Preceding unsigned comment added by 71.197.146.147 (talk) 01:55, 10 June 2011 (UTC)Reply

I haven't added this due to the insufficient access and time to medical journals for references. I'm sure someone else can find this information out for me? "The amount of cancer-causing radiation exposure in CT scans can vary fourfold or more with different machines, even when identical tests are performed" "Experts have estimated that while the risk of a patient getting a fatal cancer from a chest X-ray is one in 625,000, it is one in 1600 for a chest CT scan and one in 1100 for a pelvic or abdominal CT." referenced from http://www.theaustralian.com.au/news/alarm-grows-over-high-ct-radiation/story-e6frg6no-1225759204933 MrAnderson7 (talk) 00:51, 17 December 2009 (UTC)Reply

• Yes, this information was covered in the US as well..the Today Show, I think?... I googled it and here is a link:

http://www.usatoday.com/news/health/2009-12-15-radiation15_st_N.htm Gandydancer (talk) 02:14, 17 December 2009 (UTC)Reply

The article cites a 23% risk of dying from cancer. Perhaps this is true in some countries, but the worldwide risk is 12.5% as determined by the WHO in 2002, and cited in Wikipedia's article, List of causes of death by rate: http://www.who.int/whr/2004/annex/topic/en/annex_2_en.pdf 98.154.77.115 (talk) 22:19, 13 May 2010 (UTC)Reply

Some peer-review articles and some pop-ed articles (including the previously mentioned USA-Today article) properly mention that that CT scans are (slightly?) more risky for people with rapidly dividing cells. Who would this include? "All young people" and "anyone with cancer in the location to be scanned". Now I guess it goes without saying that a CT scan is preferable to exploratory surgery; so if you are willing to have corrective surgery then a CT scan is probably desired. If you will not authorize surgery, and are worried about the risks of a CT scan, then perhaps a CT scan should be avoided. Just my two cents worth. Neilrieck (talk) 10:48, 14 May 2012 (UTC)Reply

It is interesting to me that the subject of computed tomography completely ignores the author of the first example CT software - that is, Richard Gordon of the radiology department at the University of Manitoba. Indeed, if one reviews the material otherwise available through Gabor Hermann, one learns that Richard Gordon wrote the first version of the software product now known at SNARK. 206.45.135.77 (talk) 01:05, 2 May 2010 (UTC)Reply

Moved this improperly placed link from the article to here for inclusion/discussion:

• guidelines for appropriate use of CT, some discussion of MRI and Ultrasound as alternatives

--Lexein (talk) 18:22, 27 May 2010 (UTC)Reply

this link doesn't work as of 13-08-2010

In Jan 2008 User:Radagast83 merged content from article Synchrotron X-ray tomographic microscopy I had started. A previous merge was proposed in Aug 2007, but was voted down.

• Why was it merged?
• Where did this content go? It appears it was simply removed.
• Should Synchrotron X-ray tomographic microscopy be recreated?

- RoyBoy 15:06, 6 June 2010 (UTC)Reply

I wonder what the most commonly used bit-rate for the storage matrix is in current medical CT systems. If a range of 4000 HU is used to describe practically the whole spectrum of tissue in the human body, a 12-bit matrix would allow 4096 distinct values to be stored. A 8-bit window would allow 256 grey values to be used for 100 Houndsfield units. This gives a resolution of 2,5 grey values for 1 HU. This seems nice, but in face the input and storage in the processing matrix is only 12 bit and gives a resolution of 1 value per 1 HU. Therefore, those 2,5 grey values are all and the same. Nowadays physicians still look at CT's to diagnose patients, but more and more computers and their filters are used to guide the physician through the scan and look for trouble before the physician does. For this reason a higher storage matrix bit rate of 16 bits would increase the resolution (in theory) 65 fold and windows can be smaller to distinguish between even more detail (in contrast). - Remi Verhoeven, Eindhoven University of Technology (talk) 10:05, 13 August 2010 (UTC)Reply

A span of 4000 Hounsfield units is actually very reasonable for CT data, and little would be gained by either increasing the dynamic range, or by introducing fractional units. In practice, typical windows are 400 HU wide - mapping 400 HU onto 256 grey levels (or 1 grey-level onto 1.6 HU). Further, image noise is sufficiently high that even a precision of 1 HU is unnecessary - as the noise in a typical CT image has a standard deviation of approximatley 5-10 HU, and considerably more for studies where radiation exposure needs to be minimized.

The typical data format for CT data is 16 bpp of which 12 bpp are used to represent -1024 to 3071 HU. ChumpusRex (talk) 20:30, 15 August 2010 (UTC)Reply

The table under "Typical scan doses" has radiation exposure values markedly less than the commonly given figures. For instance, a chest, abdomen and pelvis CT is listed at 9.9 mSv but numerous sources have 18 mSv. This latter figure is from Mettler FA, et al: Effective Doses in Radiology and Diagnostic Nuclear Medicine: A Catalog, Radiology 2008 248:254-263). Mettler's values are for the U.S. and not the U.K. which the table cites. However, since the U.S. does more CT scans than any other country, I think we should be using U.S. figures. — Preceding unsigned comment added by TL36 (talk • contribs) 07:05, 30 December 2010 (UTC)Reply

Is this a good replacement for the WP:dead link on cite note number 7?--Breawycker (talk to me!) Review Me! 22:03, 27 March 2011 (UTC)Reply

Er, is what a good replacement for etc. etc.? --Redrose64 (talk) 14:09, 28 March 2011 (UTC)Reply

this would be a good replacement.Breawycker (talk to me!) Review Me! 02:14, 1 April 2011 (UTC)Reply

No, because it returns: "Page not found The page you are looking for was not available. This may be because the page was moved or deleted, or because the address in the address bar is incorrect. Please try one of the following: * If you have typed the web address into the address bar yourself, make sure that it is spelled correctly. * Go to the Health Protection Agency home page and use the links available to navigate to the information you are looking for. * Alternatively, use the website search facility available on the home page to find the information you are looking for.". --Redrose64 (talk) 11:52, 1 April 2011 (UTC)Reply

The sentence in the intro that reads, "It is estimated that 0.4% of current cancers in the United States are due to CTs performed in the past..." egregiously misrepresents the source article. From the NEJM article that was cited:

"On the basis of such risk estimates and data on CT use from 1991 through 1996, it has been estimated that about 0.4% of all cancers in the United States may be attributable to the radiation from CT studies."

'may be attributable to' =/= 'due to'. Might sound nit-picky, but to say that cases of cancer are due to CT scans suggests an extremely strong causal link, i.e. that in many cases patients who would not otherwise have developed cancer got cancer directly as a result of having a CT scan. The original statement is not that strong, and suggests a statistically significant increased incidence of cancer in patients who receive CT scans. In addition, 'may be attributable' suggests that in the relevant cancer cases, the CT scan may have contributed to the patient developing cancer, not that it caused it independently of any other conditions.

Instead of paraphrasing the statement in a misleading manner, it makes more sense to just quote the article directly. Vikingurinn (talk) 20:14, 11 December 2011 (UTC)Reply

Typically we paraphrase rather than quote, we also typically use more plane language.--Doc James (talk · contribs · email) 04:58, 13 December 2011 (UTC)Reply

I've done a search for review articles from 2007 to the present, and found:

• Baker JE, Moulder JE, Hopewell JW (2011). "Radiation as a risk factor for cardiovascular disease". Antioxid. Redox Signal. 15 (7): 1945–56. doi:10.1089/ars.2010.3742. PMC 3159113. PMID 21091078. CS1 maint: multiple names: authors list (link)

• Pauwels EK, Bourguignon M (2011). "Cancer induction caused by radiation due to computed tomography: a critical note". Acta Radiol. 52 (7): 767–73. doi:10.1258/ar.2011.100496. PMID 21742785.

• Schonfeld SJ, Lee C, Berrington de González A (2011). "Medical exposure to radiation and thyroid cancer". Clin Oncol (R Coll Radiol). 23 (4): 244–50. doi:10.1016/j.clon.2011.01.159. PMID 21296564. CS1 maint: multiple names: authors list (link)

• Lin EC (2010). "Radiation risk from medical imaging". Mayo Clin. Proc. 85 (12): 1142–6, quiz 1146. doi:10.4065/mcp.2010.0260. PMC 2996147. PMID 21123642.

• Roobottom CA, Mitchell G, Morgan-Hughes G (2010). "Radiation-reduction strategies in cardiac computed tomographic angiography". Clin Radiol. 65 (11): 859–67. doi:10.1016/j.crad.2010.04.021. PMID 20933639. CS1 maint: multiple names: authors list (link)

• Kelly RM, Doyle P, Bennett J, McKavanagh P, Donnelly P, Ball PA (2011). "Re.: Radiation-reduction strategies in cardiac computed tomographic angiography". Clin Radiol. 66 (5): 485–6. doi:10.1016/j.crad.2010.12.007. PMID 21315323. CS1 maint: multiple names: authors list (link)

• Scaife ER, Rollins MD (2010). "Managing radiation risk in the evaluation of the pediatric trauma patient". Semin. Pediatr. Surg. 19 (4): 252–6. doi:10.1053/j.sempedsurg.2010.06.004. PMID 20889080.

• Hendrick RE (2010). "Radiation doses and cancer risks from breast imaging studies". Radiology. 257 (1): 246–53. doi:10.1148/radiol.10100570. PMID 20736332.

• Goske MJ, Applegate KE, Bell C; et al. (2010). "Image Gently: providing practical educational tools and advocacy to accelerate radiation protection for children worldwide". Semin. Ultrasound CT MR. 31 (1): 57–63. doi:10.1053/j.sult.2009.09.007. PMID 20102697. ; CS1 maint: multiple names: authors list (link)

• Romano S, Romano L (2010). "Utilization patterns of multidetector computed tomography in elective and emergency conditions: indications, exposure risk, and diagnostic gain". Semin. Ultrasound CT MR. 31 (1): 53–6. doi:10.1053/j.sult.2009.10.002. PMID 20102696.

• Birnbaum S (2010). "Radiation protection in the era of helical CT: practical patient based programs for decreasing patient exposure". Semin. Ultrasound CT MR. 31 (1): 46–52. doi:10.1053/j.sult.2009.09.006. PMID 20102695.

• Tsapaki V, Rehani M, Saini S (2010). "Radiation safety in abdominal computed tomography". Semin. Ultrasound CT MR. 31 (1): 29–38. doi:10.1053/j.sult.2009.09.004. PMID 20102693. CS1 maint: multiple names: authors list (link)

• Huppmann MV, Johnson WB, Javitt MC (2010). "Radiation risks from exposure to chest computed tomography". Semin. Ultrasound CT MR. 31 (1): 14–28. doi:10.1053/j.sult.2009.09.003. PMID 20102692. CS1 maint: multiple names: authors list (link)

• Shetty MK (2010). "Abdominal computed tomography during pregnancy: a review of indications and fetal radiation exposure issues". Semin. Ultrasound CT MR. 31 (1): 3–7. doi:10.1053/j.sult.2009.09.001. PMID 20102690.

• Devine CE, Mawlawi O (2010). "Radiation safety with positron emission tomography and computed tomography". Semin. Ultrasound CT MR. 31 (1): 39–45. doi:10.1053/j.sult.2009.09.005. PMID 20102694.

• Gunn ML, Kohr JR (2010). "State of the art: technologies for computed tomography dose reduction". Emerg Radiol. 17 (3): 209–18. doi:10.1007/s10140-009-0850-6. PMID 19936808.

• Street M, Brady Z, Van Every B, Thomson KR (2009). "Radiation exposure and the justification of computed tomography scanning in an Australian hospital emergency department". Intern Med J. 39 (11): 713–9. doi:10.1111/j.1445-5994.2009.01956.x. PMID 19323702. CS1 maint: multiple names: authors list (link)

• Mayo JR (2008). "Radiation dose issues in longitudinal studies involving computed tomography". Proc Am Thorac Soc. 5 (9): 934–9. doi:10.1513/pats.200808-079QC. PMID 19056720.

• Brenner DJ, Hall EJ (2007). "Computed tomography--an increasing source of radiation exposure". N. Engl. J. Med. 357 (22): 2277–84. doi:10.1056/NEJMra072149. PMID 18046031.

I haven't looked at them yet, but I hope they'll provide a picture of the current state of the science on risk and CT. I'll get back to this later. --Anthonyhcole (talk) 09:12, 28 April 2012 (UTC)Reply

"Effective dose estimates are best used to assess the general level of radiation risk and not to determine the exact radiation dose from an imaging study. Effective dose estimates for individual patients are subject to a substantial level of uncertainty." FROM http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996147/?tool=pmcentrez — Preceding unsigned comment added by 79.177.205.166 (talk) 17:01, 28 April 2012 (UTC) "The effective dose is not measured but is a theoretical calculated dose based on the organs exposed by the applied radiation multiplied by tissue-weighting factors. Because the tissue-weighting factors can change with new data and continuing analysis of existing data, the effective dose estimates can change over time." FROM http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996147/?tool=pmcentrez — Preceding unsigned comment added by 79.177.205.166 (talk) 17:06, 28 April 2012 (UTC)Reply

I haven't read yet all the linked articles, but please pay attention that the cited source of the risk estimates, is usually the study of the Japanese survivors of the nuclear attack. This teach us that the scientific community lack theoretical capacity of estimation of the consequences of the molecular damage to the DNA, and thus attempt to estimate consequences that are easy to diagnose, i.e. cancer, statistically from that event. However radiation damage from a nuclear explosion may be different (lower or higher) than from pure x-ray, Japanese may have different (more/less) susceptibility to cancer (or other health conditions), and conditions that are difficult to diagnose were ignored.

The fact that radiation is certain to cause the molecular damage to the DNA was demonstrated in many experiments, and it is a matter that is related to physics/chemistry rather than medicine.

After the damage is caused, the process of repair of the damage was demonstrated experimentally to have certain odds of faults, due to which some faults remain. Conversely, the studies that showed reduced IQ, and more diseases, in people that were exposed to radiation, indicate that the function of the irradiated cells was altered, and that indicate that DNA alterations remained.

The diseases due to radiation are not limited to cancer: "The indices of morbidity of liquidators for endocrine system diseases exceed by 18.4 times the control ones, for psychical disorders - 9.6 times, for blood circulation diseases - 4.3 times, and all classes of diseases - 1.5 times." FROM http://www.rri.kyoto-u.ac.jp/NSRG/reports/kr21/kr21pdf/Burlakova.pdf , there is also the Swedish study of IQ at adulthood of irradiated infants, and also studies that showed that the IQ of children that were irradiated for cancer were reduced significantly and in a gradual way in a manner over time, each year the IQ was lower than the previous year, and children that started with above average IQ ended up with below average IQ: "The estimated decline in FSIQ after 4 years was 17.4 points." http://jco.ascopubs.org/content/19/15/3470.full http://jco.ascopubs.org/content/19/15/3470/F4.expansion.html — Preceding unsigned comment added by 79.177.205.166 (talk) 18:36, 28 April 2012 (UTC)Reply

About this: "CT scans use a high level of ionizing radiation, which may cause DNA double strand breaks at a rate of 35 double strand breaks per Gray,[11]" - something is missing: the rate of "35 double strand breaks per Gray" is per cell. This point was included in the previous version. The number of DSBs is probably the average i.e. a particular cell may have more, or less DSBs. E.g. a chest CT cause 0.45 DSBs/cell which means that in 100 cells, on average, there would be 45 new DSBs due to the irradiation. Also about "which may cause DNA double strand breaks" - "may" is too relaxed - it would be very improbable that no DSB would occur, or that they would occur at a significantly lower rate. 79.177.205.166 (talk) 01:24, 29 April 2012 (UTC)Reply

I apologise for the delay in getting back to you. It will take me some time to absorb all this, and I have a bit on at work. It may take a week or more before I can respond. --Anthonyhcole (talk) 16:37, 30 April 2012 (UTC)Reply

[1] Doc James (talk · contribs · email) 18:54, 7 June 2012 (UTC)Reply

We have an IP adding a great deal of unsupported content and content that does not pertain to CT.

Studies showed that radiation of ionizing radiation caused cognitive problems. Radiation of 60-310 mGy at the 8 to 15 weeks of gestation, or of 280-870 mGy at the 16 to 25 weeks of gestation caused mental retardation.^[1] Radiation of 100 mGy to the head at infancy caused cognitive deficits.^[2] Radiation of 1300-1500mGy to the head at childhood caused schizophrenia, and lowered IQ scores.^[1] Exposure of adults to 150−500 mSv caused cerebrovascular pathology, and exposure to 300 mSv caused neuropsychiatric, neurophysiological, neuroimmune, neuropsychological, and neuroimaging dose related effects.^[1]

This ref does not even mention CT in it [2].

All of the refs supporting this text are primary research papers

CT scans use a high level of ionizing radiation. Ionizing radiation has the capacity to break molecular bonds, and thus alter the molecular structure of the irradiated molecules. In the human body, a cell's operation is controlled by the chemical structure of the DNA molecule included in the cell. Experiments showed that ionizing radiation cause DNA double strand breaks at a rate of 35 double strand breaks per cell per Gray,^[3] and removes a portion of the epigenetic markers of the DNA,^[4] which regulate the gene expression. At the radiation doses, which typical CT scans impose, a DNA molecule of 40%-100% of the irradiated cells is damaged by one or more double strand breaks. This insult is followed by an effort of the cell in attempt to repair the damaged and broken DNA, however, the repair process is not perfect,^[5] and faults that are not properly repaired can cause the cell to stray from its original design of operation. The improper operation can manifest in cell death, cancer, and in other puzzling health conditions, as can be expected from an operation, which randomly alter cell's DNA, and epigenetic markers.^[6] A portion of the population possess a flawed DNA repair mechanism, and thus suffer a greater insult due to exposure to radiation.^[3] Unlike CT, MRI does not use ionizing radiation, and does not cause double strand breaks to the DNA.^[7]A Study found, that the contrast agent increased the radiation damage to the DNA that was caused by CT examination: The presence of iodinated contrast agent during CT increased the double strand breaks levels in peripheral lymphocytes by approximately 30%.^[8]

The refs supporting this also do not refer to CT contrast.

The amount of iodine that is administered with the contrast agent is way above the Tolerable Upper Intake Level (UL) for adults, which is 1,100 μg/day (1.1 mg/day), and thus side effects of excess iodine intake may occur. The tolerable upper limit was assessed by analyzing the effect of supplementation on thyroid-stimulating hormone. "Iodine supplementation over this limit has been shown to potentially contribute to an underlying thyroid pathology in those with Hashimoto’s thyroiditis, Graves’ disease, or exacerbation of nodularities in euthyroid individuals if intake exceeds 20 mg iodine or iodide. Population studies have shown excessive iodine intake may increase the prevalence of autoimmune thyroiditis in animals and humans, increasing the risk of overt hypothyroidism."^[9]

Doc James (talk · contribs · email) 21:23, 9 June 2012 (UTC)Reply

Agreed, sources that do not explicitly mention CT do not belong here, per WP:SYNTH. Yobol (talk) 21:29, 9 June 2012 (UTC)Reply

Response of 79.179.224.214 (talk) 22:43, 9 June 2012 (UTC) to First section: CT use high energy x-ray ionizing radiation, that cause the body to absorb a large dose of ionizing radiation. At the UK study page 96, during routine head, up to 140 mGy were absorbed. Now, this procedure would be performed twice, once with and once without iodine, thus multiplying the amount of radiation by two. Thus 280 up mGy would be absorbed. This page is from a hospital stating "Our shuttle mode CTP scanning protocol described above results in a radiation exposure, the volumetric CT dose index (CTDIvol), of 349 mGy.". The FDA allow radiation of up to 500 mGy, a limit that was imposed due to adverse effects, that did occur when CT machines output radiation exceeded that. In this document hosted on US governmental public health web site, it is stated on page 12, that at Ceder Sinai hospital, 269 patients each absorbed 4286mGy of ionizing radiation, more than twice of what radiation therapy patients absorb in a fractionated radiation therapy session. These patients experienced adverse effects of radiation therapy as can be seen at page 13, showing images of their hair loss. (Could someone upload these pictures?)Reply

Now, given the fact, which I assume is not under dispute, that CT machines commonly subject patients to hundreds of mGys, and sometimes to thousands of mGys of ionizing radiation, it is important to described the studied adverse effects of ionizing radiation. This is not original research. CT inflict ionizing radiation on patients, and ionizing radiation cause adverse effects.

Response to Second section: You complain about use of primary research papers in the second section, however, I have reviewed the rules of Wikipedia, and found no rule forbidding use of primary research papers.

Response to Third section: I will think about it, and respond later.

Note, someone have deleted the section about kidney problems due to contrast media. That contribution was not mine, and I don't know where are the refs required for it. Why did that someone just delete stuff without asking for the refs, like by marking ^{[citation needed]} next to the wanted refs? 79.179.224.214 (talk) 22:43, 9 June 2012 (UTC)Reply

79.179.224.214 (talk) 22:52, 9 June 2012 (UTC): I think that "Contrast" is not an adverse reaction. Death is, allergy is, etc. DNA damage is also an adverse reaction, but eating fried food cause DNA damage, being in the sun cause DNA damage, but not to the extent that the CT does. Thus the title should be extensive DNA damage, and not just DNA damage. 79.179.224.214 (talk) 22:52, 9 June 2012 (UTC)Reply

You said

Now, given the fact, which I assume is not under dispute, that CT machines commonly subject 
patients to hundreds of mGys, and sometimes to thousands of mGys of ionizing radiation, it is important 
to described the studied adverse effects of ionizing radiation.

Everything on Wikipedia is continually under dispute. I think that the way to post this is to provide a source which states the range of radiation to which CT machines expose patients, then state that range and reference a source which says what happens at that range. Also link to a full article on ionizing radiation for sources which are not explicitly about CT scans. When you use a source which does not explicitly mention the article's subject that is WP:SYNTH.

Here is the requested Wikipedia rule which talks about primary sources - WP:PRIMARY. The ideal source is a secondary source which talks about the first paper.

You asked why a section was deleted for not having references when a citation needed tag could have been used. For health articles many editors use the Medical Manual of Style - WP:MEDMOS. This is because it is often easy to see when information is not from a secondary source or when it is contrary to popular understanding. On popular culture articles sometimes Wikipedia rules get relaxed and broken; in health articles editors tend to follow the rule for having verification for all statements per WP:V. Thanks a lot for your interest in this. Blue Rasberry (talk) 23:03, 9 June 2012 (UTC)Reply

Yes we use secondary sources as mentioned by both Blue and Yobol. This [3] is not a secondary source. The key of WP:SYNTH is "Do not combine material from multiple sources to reach or imply a conclusion not explicitly stated by any of the sources". Only a percentage of CTs use contrast and contrast does have some extra risks. Thus it is reasonable to discuss contrast as a section to itself. I in fact added some references to the section on kidney issues. Doc James (talk · contribs · email) 23:09, 9 June 2012 (UTC)Reply

The WP:PRIMARY doesn't state that primary sources can not be used, it just state how they should be used. Instead of helping with the semantics, you (DocJames) just destroy stuff. Why?79.179.224.214 (talk) 00:32, 10 June 2012 (UTC)Reply

Please, I want to help and so many other people do also. If you want other opinions about what you are doing then consider going to the WP:TEAHOUSE, which is a place where new Wikipedia users can ask questions from very friendly people. Also consider registering an account so that you can have sustained conversations. No one wants to destroy work. If you have questions then try to be more specific than asking why things are removed - the answer is that Wikipedia has rules and I think that if you asked other people they would also say that your contributions are not following them. Check out primary and synth again. Blue Rasberry (talk) 02:15, 10 June 2012 (UTC)Reply

The FDA mentions much lower levels of radiation from a CT (in the range of 2-8 mGy / mSv). This [4] is a primary source and it appears to be interpreted wrong. Doc James (talk · contribs · email) 23:28, 9 June 2012 (UTC)Reply

79.179.224.214 (talk) 00:05, 10 June 2012 (UTC)Reply

0.001 Gray = mGy is the real physics kind of unit, that measure radiation. It measure how many Joule are absorbed by one Kg of matter. Head CT as you can see in the UK study inflict about 60 mGy on average, but sometime as high as 140 mGy. This means that a Kg of an average head, that is examined, absorbs on average 0.06 Joule of energy. This doesn't seem as much, except that the energy is in a form of ionizing radiation, which make it large enough to cause a double strand break to two DNA molecules in every cell that was irradiated.

On the other hand mSv=0.001 Sievert is a made up unit, that I don't know who has concocted, that on theory work by estimating the real radiation cancer risk, and then stating the real radiation value, that if all the body would have been irradiated, the same risk would have been. Considering that estimation of cancer risks from radiation is still under debate, this unit should be considered under debate as well. Moreover, that unit hide other adverse effect that could occur, such as the extent of DNA damage.

Example, suppose you irradiate the head with 60 mGy, now they estimate the risk of cancer to be "X", and they estimate that irradiating the whole body with 1.5 mGy would also have cancer risk "X", and so they say that the effective dose is 1.5 mSv. Why the big difference? A. because they think that the head is primarily non proliferating cells, and thus have low cancer risk, B. suppose you spread the energy in joules, that the head absorbs with this 60mGy radiation, over the whole body, suppose the head weigh 2Kg this is 0.12 joules, and suppose the whole body weigh 60Kg, then that is 0.12joules/60Kg=0.002=2[joule/Kg]=2mGy; so if you irradiate with 2mGy the whole body, the same amount of ionizing radiation energy, and interactions with the DNA would occur, and thus the same cancer risk. I think this also helps doctors that like to subdue resistance of their patients, as I have seen stated in some article, the article with instructions for the Dr. went something like - state the radiation from the CT as 2mSv, then compare it to the background radiation level of 3mSv per year, which everyone absorbs anyways. But the head still absorbs 60mGy, and this is more like 20 years of background radiation.

79.179.224.214 (talk) 00:05, 10 June 2012 (UTC)Reply

79.179.224.214 (talk) 00:36, 10 June 2012 (UTC) Oh grate. Now I see that even though you don't have a clue between mSv, to mGy, you have edited out all the sections about the doses in mGy. What is the motivation for that. Please do tell. 79.179.224.214 (talk) 00:36, 10 June 2012 (UTC)Reply

79.179.224.214 (talk) 01:31, 10 June 2012 (UTC) Even better, now I see that you have decided that mGy=mSv for X-RAYs, and have put a dead link to prove it. Why do you change stuff you don't understand without consulting? BTW, mGy=mSv for xrays, only if the whole body is irradiated with the same value of radiation, something that doesn't occur often with CTs, even when the whole body is scanned, since the skull has to be bombard with higher radiation in order to get a clear glimps to what is inside bone. 79.179.224.214 (talk) 01:31, 10 June 2012 (UTC)Reply

Fixed the ref for you. Doc James (talk · contribs · email) 01:33, 10 June 2012 (UTC)Reply

79.179.224.214 (talk) 01:47, 10 June 2012 (UTC) The information at that page is wrong. Do you consider it a primary, secondary (or what kind of a source?) that you allow yourself to reference it? Had you read the UK Study, you would have read page 5-8 describing how the effective dose is calculated, which is clearly different than the CTDIvol, and you would have read page 31, in which side by side the for the same CT examination the mSv value is clearly different than the mGy value determined for the same examination. Why do you torment me?79.179.224.214 (talk) 01:53, 10 June 2012 (UTC)Reply

Keep things simple by putting a reference at the end of every sentence. Do not draw conclusions which are not in your references. No one is tormenting you - Wikipedia's guidelines have been around for a long time and they are available for you to read. I really appreciate your interest and what you are trying to do but follow the rules and be WP:NICE. Blue Rasberry (talk) 02:20, 10 June 2012 (UTC)Reply

I am sorry. I am just a bit frustrated, to see many of my contributions just deleted, without discussion, or attempt to rephrase them to fit the semantic requirements. Without a point by point examination. Etc. And to top it all, the one who have deleted my contributions, due to semantic reasons, has added an error backed up by a simple web page, that has an error in it. I think this is in violation of the rules, since it is not even a research, and there is a research that contradict that simple web page. I guess I can try to rephrase the contributions by myself, however, I don't think my contributions got a fair hearing here, and who is to say, that this will not happen again? and if so what is the point? 79.179.224.214 (talk) 02:55, 10 June 2012 (UTC)Reply