Talk:CT scan/Archive 3

Hair loss - Adverse effect
The following paragraph was removed:
 * "The FDA and CRCPD have recommended to use less than 500 mGy in brain perfusion CT scans, a scan which is commonly performed in the investigation of suspected stroke, and a dose that is sufficient to induce 17 double strand breaks in each cell of the brain. The recommendation was made in response to multiple complaints from patients over a loss of a band of their head's hair, which was traced to be due to CT scans of higher doses, that were performed over them. Hair loss is a common side effect of radiation therapy, and may occur on any hair bearing skin with doses above 1000 mGy. A dose of a session of fractionated radiation therapy, a procedure which is known to have adverse side effect, is typically between 1500 mGy to 2000 mGy, only three to four times more than the FDA approved dose for a CT scan of the head. Due to the capacity of CT machines to produce radiation doses of that range, it is possible that errors, such as hardware faults, software bugs, human operator errors, and performance of several scans over a short time, could result with the absorption of radiation therapy doses, and with the adverse effects related to radiation therapy, which are not limited to hair loss."

It was replaced by the following paragraph, which was just removed:
 * "A few cases of temporary hair loss following multiple CTs in a short period of time have been reported. 

Edit summary of last removal state: "undue weight to primary source, needs secondary source to establish weight"

Question: Why is a secondary source needed to establish weight? The links include two reliable reports, that describe over 200 cases in which hair loss occurred. Is it really necessary to have some secondary source that describe again the hair loss observed by the others? Why?
 * It is necessary because if we included material from all primary sources that discuss CT scans in one way or another, this page would be hundreds of thousands of kb long and unreadable. We use secondary sources to tell us what aspects of CT scan are important to mention. Yobol (talk) 16:28, 19 June 2012 (UTC)
 * Why do you need a secondary source to tell you which adverse effect is important to mention? All adverse effects are worth mentioning. 79.182.199.172 (talk) 21:12, 19 June 2012 (UTC)


 * No, mention of very rare adverse effects would be in violation of WP:WEIGHT. JFW &#124; T@lk  21:23, 19 June 2012 (UTC)
 * JFW, Do you have a secondary source that support that?
 * JFW, Hair loss is not rare, it occurred in 40% of those irradiated with the high doses. 79.182.199.172 (talk) 21:57, 19 June 2012 (UTC)
 * I have inserted the following text which illustrate the weight because 40% of those overexposed, suffered:

'''On October 8, 2009, the US Food and Drug Administration (FDA) notified of a safety investigation of facilities performing brain perfusion CT (PCT) scans. Because of incorrect settings on the CT scanner console, more than 200 patients received a radiation overdose. The magnitude of these overdoses and their impact on the affected patients were significant. About 40% of the patients lost patches of hair as a result of the overdoses. '''
 * I hope the weight is clearer now. 40% occurrence is not rare. People should know that the dose settings could be wrong, and that if they will receive the overdose setting, they could have the hair loss adverse effect, and that they should verify that they don't get the overdose setting, especially in countries which the FDA regulate, and might still be using overdose settings. — Preceding unsigned comment added by 79.182.199.172 (talk) 01:15, 20 June 2012 (UTC)
 * I don't think one set of events for one type of CT scan at one facility requires this much WEIGHT. I'll wait until others add their comments before removing. Yobol (talk) 01:43, 20 June 2012 (UTC)
 * I have added the following refs, that you removed from a previous version, so that you could see that it isn't related to a single facility:

'''The California Department of Public Health disclosed five additional facilities, in which overdoses that exceeded 2300mGy occurred. A 2005 case study described three cases of temporary bandage shaped hair loss following multiple CTs in a short period, and stated that radiologists should be aware that a cumulative or multiplier effect of radiation exposure from multiple diagnostic techniques may result in hair loss and other types of radiation complications. '''
 * and off course you deleted them, Yobol. You said that they were primary, however, the first one is a description by a PhD at the California Department of Public Health, that described a survey performed by an other entity RHB. So I think it is secondary. So please put it back.
 * additionally I base the weight also on the 40% occurrence rate. 79.182.199.172 (talk) 02:26, 20 June 2012 (UTC)

You mean the power point presentation? No that is not a suitable source. It is not peer reviewed. Not published. Not pubmed indexed. Not a review article. This PMID:15351903 is also not suitable as it is not a review article. Doc James (talk · contribs · email) 05:17, 20 June 2012 (UTC)

Recent additions by User:Ytrottier
I have removed these addition as they are not supported by appropriate references per WP:MEDRS:

"An in vitro study found, that the presence of iodinated contrast agent during CT increased the double strand breaks levels in peripheral lymphocytes by approximately 30%. " is references to http://www.ncbi.nlm.nih.gov/pubmed/19789225 which is a primary source looking at just over a dozen venous samples.

I have removed

"Current CTs use 80kV-120kV x-rays, and impart an absorbed dose of 10mGy-500mGy, with proper settings. Thus, the DNA of such cell, that is irradiated with CT x-rays would suffer from 0.35 to 17.5 double strand breaks. Thus, with x-rays operating at the level of normal CTs, 35% to 100% of the cells would suffer one or more double strand brakes in their DNA. Notably, CT settings are not always proper, and it was found that improper settings for head CT caused doses of 2300mGy-4300mGy to be absorbed by more than 200 patients at the Cedars-Sinai Medical Center, overlapping dosage imparted by radiation therapy.  The victims of the incorrect setting suffered a band shape hair loss. That improper dosage correspond with induction of 80.5-150 double strand brakes in the DNA of each cell."

As the references are of poor quality.

The other issue is that case studies of machines which have malfunctioned are being discussed in the "typical scan dose" section when it was already discussed in the section here and does not deal with typical scan doses.
 * This http://www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1194947420292 is a primary references source from 2003. Thus the data of publication already means that it is not current as claimed.
 * This http://www.cdph.ca.gov/programs/DFDRS/Documents/CT%20brain%20perfusion042611.pdf is a power point presentation. The section is about usually dosages not when machines are set improperly which could go lower.
 * This is a report of three cases http://www.springerlink.com/content/38wvd0fg6a9mmvut/
 * This is an editorial http://www.ajnr.org/content/31/1/2

Excellent quality references exist and people should be using them. Doc James (talk · contribs · email)(please leave replies on my talk page) 21:34, 22 June 2012 (UTC)


 * Point taken. I was moving in material written by someone else from ionizing radiation. I'd say my main error was not checking the talk page, and therefore not realizing how much discussion has already taken place over doses. I would suggest that some discussion of off-normal doses would be relevant, and is not adequately covered just by referring to the hair loss. The FDA's investigation has found impressively high CTDI's at several hospitals by now, so it looks like more than just an isolated incident.--Yannick (talk) 22:12, 22 June 2012 (UTC)
 * Yes agree. And no one disagrees that radiation causes health problems. It is just that we insist that proper references be used. The user in question (now User:Nenpog) has added this same content with similar references to a number of pages. Doc James (talk · contribs · email)(please leave replies on my talk page) 22:18, 22 June 2012 (UTC)

Review articles
A couple of recent high quality reviews Doc James (talk · contribs · email)(please leave replies on my talk page) 22:25, 22 June 2012 (UTC)

Primary research
This http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1194947420292 is a primary research paper that is not pubmed indexed. It should be replaced with something better. Doc James (talk · contribs · email)(please leave replies on my talk page) 00:21, 23 June 2012 (UTC)
 * How about the following pubmed Multicenter Study: National survey of doses from CT in the UK: 2003. ? Nenpog (talk) 02:32, 23 June 2012 (UTC)
 * Yes that is pubmed indexed but not a secondary source. Doc James (talk · contribs · email)(please leave replies on my talk page) 03:44, 23 June 2012 (UTC)

Units in use

 * We have table one in this paper (you have to click on it to see it) http://www.nejm.org/doi/full/10.1056/NEJMra072149 that lists organ doses and states mSv=mGy Doc James  (talk · contribs · email) (please reply on my talk page) 03:55, 24 June 2012 (UTC)
 * The table there expresses that the kind of Sievert that they mean in there is the Sievert of an equivalent dose. The value in Sieverts of an effective dose and of an equivalent dose can be very different for the same event. --Nenpog (talk) 05:12, 24 June 2012 (UTC)


 * We have the FDA website that states "A CT examination with an effective dose of 10 millisieverts (abbreviated mSv; 1 mSv = 1 mGy in the case of x rays.)" for effective dose. Doc James (talk · contribs · email) (please reply on my talk page) 03:55, 24 June 2012 (UTC)
 * That FDA site is wrong. It is an error, and there are many sources to prove it, which present the mGy value next to the effective dose mSv value, where the two values are completely different for the same event.--Nenpog (talk) 05:12, 24 June 2012 (UTC)

The units mSv=mGy thus appear equivalent when dealing with CTs. The two quantities we are dealing with are "organ dose" versus "effective dose" in the table. Doc James (talk · contribs · email) (please reply on my talk page) 03:55, 24 June 2012 (UTC)
 * Note my reply above in this section. I think that an organ dose is yet an other thing. I am not sure if I have seen its definition yet.--Nenpog (talk) 05:12, 24 June 2012 (UTC)
 * Sure lets see if others have an opinion. Doc James  (talk · contribs · email) (please reply on my talk page) 05:33, 24 June 2012 (UTC)

I've been asked to weigh in on the matter of units, so I'll try to help. It seems to me that both sources are correct, though they are using shorthand which you may be misinterpreting. I think a key part of the dispute here is confusion between units and quantities, which I will address separately.

With regards to units, 1 Sv is always equal to 1 Gy, since they are both defined as 1 J/kg. The only difference is that grays are used before the application of the radiation weighting factor, and sieverts are used afterwards. For analogy, you might measure the gasoline that goes into a sump pump in litres and the water pumped in cubic decimeters; the quantities will be very different, but that doesn't change the fact that 1 L = 1 dm³ and 1 Sv = 1 Gy. Both the NEJM article and the FDA website use shorthand "1 mGy = 1 mSv in the case of x-rays" where what they really mean is "absorbed dose is equal to equivalent dose in the case of x-rays." I generally try to avoid that kind of shorthand because of the confusion it causes.

With regards to quantities, the "organ dose" (HT) as defined by ICRP publication 103 is an equivalent dose. Conversion to an "effective dose" (E) requires multiplication of each organ dose by its organ weighting factor, and summation across the body. If the dose is uniform across the body, then all the organ doses are equal to each other, and the effective dose is equal to every organ dose. I think that's what the FDA website had in mind. But if you're only doing a head CT and the thyroid and lower organs are well protected, then the effective dose would be about 0.01 a little more than 0.02 times the brain's organ dose, which is consistent with your other sources. Equivalent, organ, and effective doses are all measured in sieverts.

I would recommend looking up sievert for a discussion of units and effective radiation dose for a discussion of the quantities. Does that help?--Yannick (talk) 15:47, 24 June 2012 (UTC)
 * Ytrottier, thanks for the review. I agree with it.
 * I recommend that all the doses (effective dose,equivalent dose, absorbed dose) will be put in the scan dose table, so that all representations of the dose of the same event would be readily available to people.--Nenpog (talk) 00:09, 25 June 2012 (UTC)
 * I agree aswell. The difficulty with adding them all to the table is that different organs receive different amounts for the absorbed dose depending on the body part scanned. Thus the use of effective dose tries to address this. Doc James  (talk · contribs · email) (please reply on my talk page) 00:23, 25 June 2012 (UTC)
 * DocJames, I am not sure if I understand what you wrote, but let's see if the following approximation helps (it is not accurate, but I hope it will help to get the hang of it):
 * Suppose that only one Kg of the body is radiated and that it absorbs 100 photons, then one can say that that Kg of the body absorbed a dose of 100 photons. Now, if the person weigh 100Kg, and the dose would be spread across the body, then each Kg would absorb only 1 photon. However, the 100 photons projected at the whole body, still interact with the same number of body cells, and assuming that these cells are equally susceptible to cancer, the radiation of 1 photon/Kg to the whole body of that person would have the same probability to induce cancer, as the probability of 100 photons/Kg radiated only at 1 Kg of that body. Thus, a radiation of 100 photons/Kg radiated at 1Kg is effectively the same for cancer estimation purposes as 1 photons/Kg radiated at 100Kg. However, the radiation in the two scenarios is of a very different magnitude, and of a very different breadth. This illustrate the different between an absorbed dose, and an effective dose.
 * There are limits after which deterministic effects occur, even if the dose is local to 1Kg, e.g. 3Gy absorbed by 1Kg vs 0.03Gy uniformly absorbed by 100Kg. The same energy would be absorbed in both cases, but at the first case deterministic effects could occur, while at the second case they wouldn't. Thus the absorbed dose is more important than the effective dose, and it convey more information than the effective dose, which is calculated from the absorbed dose.--Nenpog (talk) 01:52, 25 June 2012 (UTC)

No, sorry, that's not the difference between absorbed and effective dose. The concept of effective dose arises out of the fact that different tissue types are not equally susceptible to cancer. It's a weighted average that gives more weight to more sensitive tissues. Let's revise the language in more conventional terms: 1 joule of X-ray deposited in 1 gram of brain tissue is modeled (by ICRP 103) as having the same probability of inducing cancer as 1 joule spread over in 1 kilogram of brain tissue. Assume the total brain mass is 1 kg. The absorbed dose within the beam target is 1 kGy over 1 g in one case and 1 Gy over 1 kg in the other, but the organ dose is 1 Sv in both cases because organ dose is a mass-average over the organ of interest. Now an organ dose of 1 Sv to the brain alone is much less likely to cause cancer than 1 Sv to the stomach; this is reflected by the effective dose, which would be 0.01 Sv if only the brain was hit, or 0.12 Sv if only the stomach was hit.

Note that I highlighted the word "modeled." This model is an industry consensus, but how well it approximates reality in this hypothetical case is another question altogether, one that I'm very unsure about. And when you start talking about deterministic effects of localized doses, I'm not aware of any model that has gained wide acceptance. In the absence of such a model, and knowing that the cancer model is inappropriate to deterministic effects, we usually restrict ourselves to using absorbed doses as a measure. (I think that's an ICRP recommendation too, but I'd have to look it up.) Now over how much mass should the absorbed dose be averaged when linking to deterministic effect? That's an interesting question which currently has no scientific answer that I'm aware of.--Yannick (talk) 02:34, 25 June 2012 (UTC)
 * Yannick, I neglected the radio sensitivity of the tissues from the approximation above, in order to simplify, and focus on the whole body vs. body part aspect. I wrote that its was an approximation intended just for illustration. Your reply seem to focus on that omission, rather than the point: --Nenpog (talk) 03:52, 25 June 2012 (UTC)
 * Then I apologize. I was restricting myself to what I know; perhaps I should have stayed silent.--Yannick (talk) 11:07, 25 June 2012 (UTC)
 * Well, I was just trying to make a simple illustration, so that even someone, who is not an engineer could understand. Don't feel bad. It is not your fault, that you are an engineer, and understand these things. --Nenpog (talk) 15:45, 25 June 2012 (UTC)
 * An effective dose of 1 Sv can be described by a scenario in which the whole body, and thus every body part absorbs the same absorbed dose of 1Gy. The absorbed energy of the whole body would thus total to=body_weight*1Gy which is clearly grater than the energy that one body part absorbs=body_part_weight*1Gy. Thus the same quantities of effective dose 1 Sv, or absorbed dose 1 Gy of a certain body part, refer to different absorbed energies, absorption location, and cancer probabilities. --Nenpog (talk) 03:41, 25 June 2012 (UTC)
 * I know that the deterministic effects of hair loss, did occur due to local dose to the head of 2.3Gy-4.3Gy, in brain perfusion CT exams (see hair loss section). So deterministic effects do occur due to local dose. Cerbro-vascular atherosclerosis occur due to cumulative brain dose of 500mSv (see cognitive effects section). I'd appreciate your support in getting that last fact into the article. --Nenpog (talk) 03:52, 25 June 2012 (UTC)
 * I remain neutral on cerebro-vascular atherosclerosis due to CT scans. Darnit Jim and Nenpog, I'm an engineer not a doctor.--Yannick (talk) 11:07, 25 June 2012 (UTC)
 * All I ask for is high quality sources that pertain directly to the subject matter at hand. We are here simply to reflect the best available science. One useful thing to do when editing controversial topics is to use the "|quote=" parameter of the cite template. And add the exact wording that supports your paraphrasing. Doc James  (talk · contribs · email) (please reply on my talk page) 02:01, 26 June 2012 (UTC)

Extensive DNA damage - Adverse effect
The following is the section that was deleted regarding Extensive DNA damage:
 * 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, and removes a portion of the epigenetic markers of the DNA, 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, 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.  A portion of the population possess a flawed DNA repair mechanism, and thus suffer a greater insult due to exposure to radiation. Unlike CT, MRI does not use ionizing radiation, and does not cause  double strand breaks to the DNA.


 * 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%.

If you like secondary sources, I think, that the following paragraph from a secondary source, that was already in the article, is supporting the part marked in bold letters:
 * "Biologic Effects of Low Doses of Ionizing Radiation
 * "Mechanism of Biologic Damage


 * Ionizing radiation, such as x-rays, is uniquely energetic enough to overcome the binding energy of the electrons orbiting atoms and molecules; thus, these radiations can knock electrons out of their orbits, thereby creating ions. In biologic material exposed to x-rays, the most common scenario is the creation of hydroxyl radicals from x-ray interactions with water molecules; these radicals in turn interact with nearby DNA to cause strand breaks or base damage. X-rays can also ionize DNA directly. Most radiation-induced damage is rapidly repaired by various systems within the cell, but DNA double-strand breaks are less easily repaired, and occasional misrepair can lead to induction of point mutations, chromosomal translocations, and gene fusions, all of which are linked to the induction of cancer.23"

The rest of the facts are supported by primary sources, which is allowed if certain limitations are met, and I think that they are met, or can be met. If anyone think that they don't meet the limitations, please point out why, and suggest how to correct. — Preceding unsigned comment added by 79.182.215.205 (talk) 17:18, 15 June 2012 (UTC)
 * I would support a brief discussion of the radiation effects on DNA, as it is a necessary explanation of why cancer is being discussed. However, we should not go into any significant details (i.e. # of breaks per gray, etc), as that level of detail is not appropriate in an overview article about CT scans, and not particularly helpful to the general reader. I would expect a discussion of relevant clinical endpoint like the rates of cancer to deserve much more WP:WEIGHT.  A couple of sentence introduction to the cancer section that discusses the mechanism in general terms would probably be most appropriate (a rewritten summary of the secondary source above would be adequate, IMO). Yobol (talk) 17:26, 15 June 2012 (UTC)
 * In my opinion because the probability of the extensive DNA damage to occur due to the CT is 100%, while the cancer effect is estimated to occur in low percentage of the cases, the weight of the DNA damage is grater.
 * I think that anyone would prefer to know what is sure to happen over things that just might happen.
 * I think that saying DNA damage, without saying the magnitude of the DNA damage is akin to saying nothing, because people are used to hear, that bad food cause DNA damage, and many other things that they are exposed to in their daily life cause DNA damage. Thus, without describing the magnitude, they might think, that there is no difference between eating bad food, and taking a CT scan, where the difference is really very big.
 * I think, that DNA damage deserve its own section, because cancer represent only one type of DNA code, that the DNA damage can cause. Many other codes occur, and their effect include cognitive decline, increased morbidity, and mortality.
 * I think that all adverse effects have due weight.
 * I agree that the cancer section lack probabilities for cancer induction. I think perhaps the right location for such probabilities to be presented is in a "dose by probability to induce cancer in a 30 year old adult" titled column at the typical dose table. 79.182.215.205 (talk) 18:44, 15 June 2012 (UTC)
 * The secondary source you presented (the NEJM article) does not put any significant WP:weight on specific details like the # of breaks. As such, if secondary sources do not put weight on that, neither should we. Yobol (talk) 19:03, 15 June 2012 (UTC)
 * That secondary resource thinks, that DNA double-strand breaks are a very important kind of DNA lesions: "DNA double-strand breaks are less easily repaired, and occasional misrepair can lead to induction of point mutations, chromosomal translocations, and gene fusions, all of which are linked to the induction of cancer." That secondary source discuss the risk for cancer from radiation doses. Radiation dose is linearly related to DSB induction per cell. It is true, that it wasn't spelled out for us in this article in DSBs but in Grays, but since the relation between the two is linear, the WP:weight of DSBs is just high as the WP:weight of radiation dose.
 * You ignored all my previous points. Especially points 1, 2, 3, 4, and 5. — Preceding unsigned comment added by 79.182.215.205 (talk) 20:56, 15 June 2012 (UTC)
 * What you or I think is less relevant to the weight we get from our secondary sources. I would prefer not to get into an argument about what you or I believe should be in the article, but rather let our secondary sources tell us what should be in the article. In this case, the source you present does not give weight to such detail as # of breaks per gray, neither should we. Yobol (talk) 20:59, 15 June 2012 (UTC)
 * I showed you that according to the secondary source the number of DSBs is important. That is not just my opinion. The secondary source support that.
 * If you don't think that all adverse effect are important, I can search for you for a secondary source that will say so, please let me know. 79.182.215.205 (talk) 21:42, 15 June 2012 (UTC)
 * Nowhere in the secondary source does it discuss specific numbers, or go into that significant detail. I think this is an encyclopedia that discusses only the most important topics (rather than every single minutiae one editor wants to talk about), so we need to select the most important adverse effects, as suggested by high quality secondary sources. Yobol (talk) 22:20, 15 June 2012 (UTC)
 * Are you able to understand, that the secondary source reports, that DSBs are an important adverse effect? 79.182.215.205 (talk) 23:13, 15 June 2012 (UTC)
 * I have already said we should briefly discuss DNA damage in my first reply in this thread. I do not, however, think we should be discussing it at any length or details beyond what our high quality secondary sources say about it. Yobol (talk) 23:19, 15 June 2012 (UTC)
 * Well, our secondary article has devoted a whole paragraph to it, and a large font title. I hope that you agree to devote as much. 79.182.215.205 (talk) 00:42, 16 June 2012 (UTC)

The previous version was replaced by: 
 * The ionizing radiation, that is projected from a CT scanner, in the form of x-rays, alter or brake the DNA molecules of the irradiated cells.  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, and faults that are not properly repaired can cause the cell to stray from its original design of operation. The changed operation can manifest in cell death, or in causing of diseases, such as cancer.


 * Certain CT scans can cause each scanned cell to suffer a DNA double-strand break, which is a type of DNA damage, that is occasionally misrepaired, and which can lead to induction of point mutations, chromosomal translocations, and gene fusions, all of which are linked to the induction of cancer. 

Edit summary state: "redundant to first paragraph in next section, and out of due WP:WEIGHT"

The paragraph that was inserted to the cancer section state "The ionizing radiation in the form of x-rays used in CT scans are energetic enough to create radicals from water molecules that can interact with and damage nearby DNA molecules, or less commonly, directly damage the DNA molecule itself. This damage can come in the form of breaks in the double stranded structure of DNA, or in the base pairs, which if not corrected by cellular repair mechanisms, can lead to cancer."

The cancer paragraph does not convey many of the issues presented by the source, which were conveyed in the DNA damage section, including double strand brakes, occasional misrepair, the amount of the DNA damage, point mutations, chromosomal translocations, and gene fusions.

The DNA damage has WP:WEIGHT, as it is an adverse effect, and it is discussed by the secondary source. Inserting it as a paragraph to the cancer section, is improper. 79.182.199.172 (talk) 21:46, 19 June 2012 (UTC)


 * I have read the WP:WEIGHT section, and discussed it with other editors. That term was misused/misunderstood here. Here it was used as describing the breadth in which the concept was described at some source. However this has nothing to do with WP:WEIGHT. A concept don't have WP:WEIGHT, if it is a concept that is not mainstream science. Here all the facts that were described are mainstream science. With evidence of a lot of supporting sources, and zero objecting sources. --Nenpog (talk) 08:28, 3 July 2012 (UTC)


 * Nenpog did indeed discuss this with other editors, but nobody told him that the term has been misused or misunderstood here. Instead the other editors are telling Nenpog things like "Yes, the sources are correct, however, your attempts to add this material to the CT article are not" and "In summary, I don't think you are right in this case". --Guy Macon (talk) 13:34, 3 July 2012 (UTC)
 * I did not write above that anyone told me anything regarding this debate straw man. I was discussing WP:WEIGHT. Incidentally someone did tell me something regarding evaluation of WP:weight quote:
 * My impression of what other editors meant, when they wrote undue weight, was something else than was meant in WP:DUE. E.g. "The secondary source you presented (the NEJM article) does not put any significant WP:weight on specific details like the # of breaks. As such, if secondary sources do not put weight on that, neither should we."Yobol - the term weight was used to describe the length/detail of a description of the fact, not how common/true/mainstream/important that fact was. --Nenpog (talk) 13:25, 2 July 2012 (UTC)
 * The weight put on one or another detail hardly matters. What is really important is a relative weight. Do some recent works that demonstrate the absence of DSB after CT exist, and, if they do, what is a relative weight of pro et contra?--Paul Siebert (talk) 15:36, 2 July 2012 (UTC)
 * "Again, regarding DSBs, Nenpog's edits are quite correct: he does describe mainstream views"Paul Siebert.
 * You on the other hand left that discussion with a "Sorry about the misunderstanding" Guy Macon.
 * I am sure that anyone who would inspect your recent contributions would immediately be able to see that you have a personal bias against me, and would think less of them. --Nenpog (talk) 17:25, 3 July 2012 (UTC)
 * I have no personal bias against you. I am equally biased against ALL tendentious editors who forum shop and who accuse other editors of having a conflict of interest without evidence. --Guy Macon (talk) 23:39, 3 July 2012 (UTC)

ICRP Statement on Tissue Reactions
Eye cataracts === An accumulated absorbed dose of 500 mGy can cause cataracts, and opacity of the eye lens. Circulatory disease === It is assumed that an accumulated absorbed dose of 500 mGy can cause circulatory disease, including cardiovascular disease, and cerebrovascular disease. Cognitive impairment === Cognitive impairment in adult life was detected after exposure of infants younger than 18 months to doses grater than 100 mGy. 

first source http://www.icrp.org/docs/Tissue%20Reactions%20Report%20Draft%20for%20Consultation.pdf

second source http://www.icrp.org/docs/icrp%20statement%20on%20tissue%20reactions.pdf

Were deleted. Yobol wrote in the edit summary: "source is a "draft" (not published); also, rarely speaks to CT scans, stated purpose is to discuss radiotherapy and accidental/occupational exposures. For the nth time, we need sources that specifically discusses CT scans"

"source is a "draft" (not published)" - it is published, press the link and see. also see here. It is also secondary, review, and quality. The second source is not a draft.

"rarely speaks to CT scans" - The draft state: "(188) Repeated radiological diagnostic or intervention procedures may lead to a significant radiation exposure. In 2006, the per capita dose from medical  exposure (not including dental or radiotherapy) in the U.S. was approximately  3.0 mSv. These exposures were mostly from CT-scans followed by angiography and vascular interventions."

Thus the dose absorbed from CTs counts.

Yobol - please undo your deletion! --Nenpog (talk) 15:18, 25 June 2012 (UTC)


 * I don't think it's been published yet. The consultation period may be over, but that publication doesn't yet show up here. But even if you can establish that your statements are accurate, I don't believe you've addressed the other editors' concern over undue weight. The fact that you have to resort to a document on fluoroscopy suggests that you still can't find articles linking CT scans to these effects. Maybe that's because CT scans don't cause them much, or maybe it's because doctors are overconfident about the safety of CT scans. But either way, Wikipedia's role is to reflect what the doctors think of it. If you want change the way medicine is done, you need to find a different forum for your views.--Yannick (talk) 20:17, 25 June 2012 (UTC)
 * The second source was approved by the commission. See this link: "At its meeting in Seoul in April 2011 the International Commission on Radiological Protection approved a Statement on Tissue Reactions."
 * These documents are not only about fluroscopy, they are on harmful effects of absorbed dose, and they specifically stated that CT contribute to that dose.
 * The first source is a draft that was published. It is a draft because they want more input from other people, before they make it final. However, no other review, that is considered as quality, incorporate comments from other people. So this one should be regarded of same quality as any other review, if not better. --Nenpog (talk) 01:41, 26 June 2012 (UTC)

With respect to

"An accumulated absorbed dose of 500 mGy can cause cataracts, and opacity of the eye lens."

We need a ref that states CTs cause cataracts. Not CTs when used improperly cause cataracts, not radiotherapy causes cataracts, not radiation in general can cause cataracts. We always use references that refer to the subject mater at hand. This page is not about radiation in general but about CTs specifically. Unless you have a secondary source that states that this side effects occurs in x out of 1 million CTs or something similar it does not belong here. Doc James (talk · contribs · email) (please reply on my talk page) 01:55, 26 June 2012 (UTC)


 * The statement say that an accumulated absorbed dose of 500 mGy can cause cataracts. A single average head CT cause absorbed dose of 57mGy. Thus 9 such CTs accumulate to 513 mGy, and thus can cause cataracts. The source state that this is a deterministic effect and occur in more than 1% of cases.--Nenpog (talk) 02:23, 26 June 2012 (UTC)
 * Typically people do not get 9 head CTs. Doc James  (talk · contribs · email) (please reply on my talk page) 02:29, 26 June 2012 (UTC)
 * The 2003 survey showed that doses of 140mGy were common. 4 scans at 140mGy is 560mGy. If each time the scan is with contrast+without contrast, these 4 scans can be performed in two visits to the CT. --Nenpog (talk) 02:38, 26 June 2012 (UTC)


 * Even if they do, it has been noted here, on WT:MED and WT:OR that this is synth and not permissible. I do not understand why we are going over this again. Get an appropriate MEDRS compliant reliable source that discusses CT scans and it can go in. Until we have that, it doesn't. This is settled consensus, I do not want to see further tendentious editing from this editor. Yobol (talk) 02:32, 26 June 2012 (UTC)
 * It is not synth, because the ICRP documents consider a CT as a source for the absorbed dose. --Nenpog (talk) 02:43, 26 June 2012 (UTC)
 * If it does not explicitly tie CT scans to these conditions, it does not belong. That it mentions CT scan once (or 5) times in over 300 pages does not mean it is appropriate. Find a source that explicitly states CT scans cause the adverse effect, and stop wasting everyone's time discussing a paper that isn't even published yet. Yobol (talk) 02:46, 26 June 2012 (UTC)
 * It does tie CT scans to these conditions. You just try very hard to misunderstand everything related to side effects of CTs. I can't make you admit you understand, what you don't want to admit you understand. But I am certain, that whoever will read this, and isn't as motivated as you to not understand, will understand this. --Nenpog (talk) 03:22, 26 June 2012 (UTC)

The primary issue at this point is the ref that does mention CT is a draft. Also discussed here. Doc James (talk · contribs · email) (please reply on my talk page) 02:51, 26 June 2012 (UTC) It does state "(238) Not all recent studies, however, support the observation of a lower 4173 threshold for radiation cataract. The Blue Mountains Eye study (Hourihan et 4174 al., 1999) failed to find an association between radiation exposure in 4175 individuals undergoing CT scans and cataract prevalence, although these doses 4176 were probably below 10 cGy and a threshold between 10-50 cGy can not be 4177 excluded. In recent years a number of new studies have suggested an elevated 4154 risk for cataract development in populations exposed to low doses of ionising 4155 radiation below these assumed thresholds. For example, dose-related lens 4156 opacification has been reported at exposures significantly lower than 2 Gy 4157 among those undergoing CAT scans (Klein et al., 1993)" Doc James (talk · contribs · email) (please reply on my talk page) 02:53, 26 June 2012 (UTC)
 * So what if it is a draft? It is a very extensive review of experts, with expert conclusions, and it is just a step from becoming an authoritative final recommendation of the ICRP, which is more than can be said on any other review.
 * The second source is an approval of several conclusions of that draft by the ICRP.
 * The first source has a section: "(188) Repeated radiological diagnostic or intervention procedures may lead to a significant radiation exposure." "These exposures were mostly from CT-scans"
 * This means that CTs are a source for the radiation exposure, that is talked about in that article.
 * Thus, when they say an absorbed dose of XXX mGy, they don't have to enumerate all the possible sources of that radiation. In fact, they don't have to mention CTs at all, it is obvious that the XXX mGy they talk about can be caused by CTs, lucky for us wikipedians they did mention that CTs count as a source for the radiation. --Nenpog (talk) 03:14, 26 June 2012 (UTC)

'''Notice of Dispute resolution discussion: Hello. This message is being sent to inform you that there is currently a discussion at Dispute resolution noticeboard regarding an issue with which you may have been involved. The thread is "X-ray_computed_tomography". Thank you.''' --Nenpog (talk) 04:18, 26 June 2012 (UTC)

Recent addition regarding math of CT scans
With regard to this edit, we need independent sourcing to mention specific books like this. While they appear on first blush to be reliable sources to describe the mathematics of CT scans, mentioning specific books and authors like this would require independent sourcing establishing that they are noteworthy in the field. Please provide independent sourcing establishing WP:WEIGHT before re-adding this material. Yobol (talk) 16:46, 6 July 2012 (UTC)
 * According to what rule did you get to the erroneous conclusion that you need that? Nenpog (talk) 17:06, 6 July 2012 (UTC)
 * Is this it:"Secondary or tertiary sources are needed to establish the topic's notability"WP:PRIMARY? If it is then you are wrong. Please read it carefully - topic notability would translate here to notability of X-ray computed tomography which is the topic. --Nenpog (talk) 19:08, 6 July 2012 (UTC)
 * Yobol's interpretation of Wikipedia policy is entirely correct. Nenpog is in error. That is why the consensus is overwhelmingly against the changes Nenpog wishes to make to this article. --Guy Macon (talk) 19:35, 6 July 2012 (UTC)
 * Guy Macon, share with us how you got to this conclusion? --Nenpog (talk) 20:01, 6 July 2012 (UTC)
 * No. You have proven yourself to be ineducable, and thus not worth wasting any further time on. My advice to other editors who are attempting to deal with your disruptive behavior is to follow the advice found in Competence is required. --Guy Macon (talk) 20:22, 6 July 2012 (UTC)

Book
This

"The field of the mathematical methods of computerized tomography has seen a very active development since then. A comprehensive overview thereof can be found in “The Mathematics of Computerized Tomography” (published first in 1986, translated to Russian in 1990, new edition in 2001 in the series „Classics in Applied Mathematics“) and its sequel “Mathematical Methods in Image Reconstruction” (2001)) by one of the leaders in this field, Frank Natterer of the University of Münster, Germany."

Looks like someone here to promote their book. Doc James (talk · contribs · email) (please reply on my talk page) 20:29, 6 July 2012 (UTC)


 * I think that it is interesting that "the mathematical methods of computerized tomography has seen a very active development since then.". The book seem to be a source for that statement. I don't think that anything in WP:DUE justify removal - I doubt anyone think of that text as a fringe idea. --Nenpog (talk) 21:57, 6 July 2012 (UTC)
 * According to google scholar, that book is referenced by over 2300 articles. That to me is sufficient. I think we could mention the one book, and then mention the author and his other books in a footnote. Here's one review I found, calling it a treasure and indispensable: --KarlB (talk) 12:17, 7 July 2012 (UTC)
 * Karl.brown, I understand that "These notability guidelines only outline how suitable a topic is for its own article or list. They do not limit the content of an article or list"WP:NOTABILITY. So I think that the request (here) for a proof of notability for (a line in the article's) content is redundant. What do you think? --Nenpog (talk) 12:31, 7 July 2012 (UTC)
 * I think it's a judgment call. yes, this particular question is not about whether that book or Dr. Natterer should have an article of his own; and there would obviously be no problem in *citing* that book to back up a section on mathematics of CT. The question is, should we have a paragraph that highlights the contribution of *that* book to math of CT, and highlighting that Natterer is a leader in this field - those are claims which need separate sourcing. I pointed out above that from what I've seen there is sufficient evidence that this book is significantly cited, and reviewed as "indispensable", so mentioning the book in the article text seems reasonable to me. I didn't do any further digging to see if Natterer or the other books were also at that level, and there may be books by other authors/etc that are equally relevant. Thus, the solution I proposed was a sort of compromise. fwiw, I don't work in this field, and I wouldn't know a CT scan if it hit me in the back of my head, so this is simply my personal opinion. Also, the edit warring has got to stop. Continue the discussion here plz. --KarlB (talk) 12:36, 7 July 2012 (UTC)
 * I agree with you. Additionally, I think that the editor who removed the whole content should have edited out only the not sourced claims such as that the author is a leader in the field. E.g. He could have left something like "The field of the mathematical methods of computerized tomography has seen a very active development since then, as is evident from overview literature. " and could have called for sources for the removed text. --Nenpog (talk) 12:52, 7 July 2012 (UTC)
 * Sure, that seems reasonable. It would also bolster the case somewhat to cite some other significant literature other than Natterer, to avoid questions of promotion of a particular author.--KarlB (talk) 13:06, 7 July 2012 (UTC)
 * OK, I agree, you agree, the contributor would probably not mind, did we reach a consensus? Anyone object? --Nenpog (talk) 14:11, 7 July 2012 (UTC)
 * Ok, I will go ahead as proposed by Nenpog and KarlB and will also start to write the article on NattererJaeljojo (talk) 14:22, 7 July 2012 (UTC)

"When deaths do occur it is more typically in those who are female, elderly or of otherwise poor health..."
Um, needs rewording I think - seems to equate being female with 'poor health'! AndyTheGrump (talk) 14:49, 8 July 2012 (UTC)


 * Definitely. Done. --Anthonyhcole (talk) 16:21, 8 July 2012 (UTC)

British Invention?
Why does this article actually claim that CT is a British invention? It is in my one of the classic things that have been developed by numerous people (and by far not all of them being British) and there is no actual date for its "invention" anyway I would argue Jaeljojo (talk) 15:16, 7 July 2012 (UTC)
 * I don't know, maybe add a template next to it in order to challenge that (press edit to see how the text for it looks). Or just do what all the other editors are doing in here, and just mercilessly delete it! I don't know which is more appropriate in this case. You can get to it by pressing edit for the whole article and search British. --Nenpog (talk) 15:34, 7 July 2012 (UTC)


 * Are there any other views on this? Surely whoever put it in must have a view on this. Jaeljojo (talk) 14:59, 10 July 2012 (UTC)


 * It does seem dubious to include CT scanners in the category 'British inventions', since the article body makes no such claim. I suggest you simply delete the category as invalid. AndyTheGrump (talk) 15:07, 10 July 2012 (UTC)

Administrators' noticeboard/Incidents
You may be interested in this: Administrators' noticeboard/Incidents. --Guy Macon (talk) 01:53, 10 July 2012 (UTC)

Side effects
The archives archive-2 and archive-3 include discussions regarding side effects of cataracts, hair loss, cerebral blood circulation disease, cognitive decline and more. Bob spagio goojio (talk) 13:31, 3 October 2012 (UTC)
 * The discussion regarding these side effects was not finished, and continue here. Bob spagio goojio (talk) 15:27, 3 October 2012 (UTC)


 * A simple question: have you previously edited Wikipedia under another name? AndyTheGrump (talk) 15:46, 3 October 2012 (UTC)
 * We need proper high quality references to address these issues. None where ever presented. Doc James  (talk · contribs · email) (if I write on your page reply on mine) 18:27, 3 October 2012 (UTC)
 * The archives include high quality references that support the statement, that the archived side effects do occur. The opposite statement, that the archived side effect don't occur, is not supported by any reference. The article in its current state implicitly suggest, that the opposite statement is true. This implicit suggestion is not supported by any reference, and should be removed. Bob spagio goojio (talk) 11:34, 5 October 2012 (UTC)
 * A simple question: have you previously edited Wikipedia under another name? AndyTheGrump (talk) 11:42, 5 October 2012 (UTC)

Discussing cancer in the lead
Currently we state "It is estimated that 0.4% of current cancers in the United States are due to CTs performed in the past and that this may increase to as high as 1.5-2% with 2007 rates of CT usage; however, this estimate is disputed. " in the lead.

While the estimate of the percentage of cancer due to CT is controversial there is high quality evidence providing estimates and this adverse effect is notable. IMO it should be keep here. Doc James (talk · contribs · email) (if I write on your talk page please reply on mine) 16:53, 18 July 2012 (UTC)
 * I think that HeSaid/SheSaid stuff should not go in the lead, but be treated in detail later in the article -- which indeed already happens. -- SarekOfVulcan (talk) 16:59, 18 July 2012 (UTC)
 * Agree the lead does not need this level of detail, just say that cancer is a noted adverse effect but that the exact level of risk is disputed. We don't need specific numbers in the lead. Yobol (talk) 17:09, 18 July 2012 (UTC)
 * The lead however is far from being to long. Doc James  (talk · contribs · email) (if I write on your talk page please reply on mine) 17:11, 18 July 2012 (UTC)

Although it does not directly answer this question, the latest issue of the journal Radiology has a very interesting article that provides an extensive explanation how estimates like these have been achieved (article here) and how we still really don't know the effects of medical imaging on cancer risk. The only solid evidence available is for a small increase in leukemia and brain cancer in children who received multiple CT scans at an age younger than 15 years. --WS (talk) 13:06, 24 July 2012 (UTC)

Alzheimer
The following was added as a level 3 heading under "adverse effects"

Alzheimer Exposure to CT scan could trigger mechanisms associated with cognitive dysfunctions seen in normal aging and Alzheimer disease. There is consistent evidence that this might trigger mechanisms that could ultimately favor Alzheimer disease. Additional investigations and better understandings regarding the effects of ionizing radiation are necessary.

This is based on 10.1093/jrr/rrs036, which happens to be a secondary source but concedes that any possible association between computed tomography is based on the extension of first-principles data and not on epidemiological records or even molecular data. I strongly doubt that this is ready for prime time. JFW &#124; T@lk  18:27, 10 October 2012 (UTC)


 * Please specify why you think that the review conceeds that any association between computed tomography is based on extension of first-principles data. Please quote from the source the text that support this and the rest of your assertions. — Preceding unsigned comment added by Bob spagio goojio (talk • contribs) 19:37, 10 October 2012 (UTC)

From the conclusion: "In the absence of conclusive epidemiological or molecular data proving unequivocally that exposure to IR increases the risk of developing AD, the precise relationship between IR and AD pathogenesis cannot be drawn." What follows is a number of conjectures. This article is not even specifically about CT but about ionising radiation in general. JFW &#124; T@lk
 * It is not a conjecture that "Exposure to CT scan could trigger mechanisms associated with cognitive dysfunctions seen in normal aging and Alzheimer disease." - as it is based on recent work. It is not a conjecture that "There is consistent evidence that this might trigger mechanisms that could ultimately favor Alzheimer disease." - as this review present this consistent evidence. It is not a conjecture that "Additional investigations and better understandings regarding the effects of ionizing radiation are necessary." - as even the respected researchers advise it. The supplied quotation is not related to the wikipedia article text above. Are there reservations related to the wikipedia article text above? Bob spagio goojio (talk) 20:51, 10 October 2012 (UTC)


 * 'Could'? 'Might'? Speculation, no data. "Additional investigations and better understandings regarding the effects of ionizing radiation are necessary". Yup, they are... AndyTheGrump (talk) 13:41, 11 October 2012 (UTC)
 * Could and might indicate possibility. The experts indicated that possibility in an appropriate quality source, and the text above reflect that indication of possiblity. Someone who would read the article without the text above, would probably think that it is impossible that CT would induce AD. Is there a quality source that support that thought? no.  Is the article without the text above reflect current knowledge? no.  Why then do you insist to edit the article so that it will not reflect current knowledge, and so that most readers would understand  wrong information from it?


 * I see that we all agree that further investigations and understanding are necessary. Let us put at least that in the article. Bob spagio goojio (talk) 18:33, 11 October 2012 (UTC)


 * I agree that it would seem that further investigations are necessary. When they have been carried out, and reported to the appropriate level required by our WP:RS sourcing policy, and if they show that Alzheimer's disease is indeed a possible adverse effect of CT scans, we can add the relevant material to the article. Until then, it is entirely unwarranted to fill it with speculation concerning things we don't know. AndyTheGrump (talk) 19:26, 11 October 2012 (UTC)
 * The first statement: "Exposure to CT scan could trigger mechanisms associated with cognitive dysfunctions seen in normal aging and Alzheimer disease", is based on empirical data and experiments, and thus is not a speculation at all. The word could is used there as in the sentence - if you do a CT you could get cancer. It is not sure that you would get cancer, but it is possible. This is what "could" means. Hence, this side effect of CT is not speculative, and has an appropriate quality source that backs it up, and thus can be placed in the article right now, even by the standards that you seem to have presented now.
 * The second statement that there is evidence that this might trigger mechanisms that could favor AD, is an expert conclusion, and is not a speculation - there is evidence. Since there is evidence, it is appropriate to report in the side effects section that there is evidence.
 * There was no suggestion to fill the article with speculations regarding things that we don't know. We do know that exposure to CT could trigger mechanisms, we do know that there is evidence, and we do know that further research is needed. If you think that we do not know that, I will be willing to consider your expert opinion after you will succeed to publish it in a WP:MEDRS compliant manner. Bob spagio goojio (talk) 00:18, 12 October 2012 (UTC)
 * I support adding this to the article. It is obvious that the reference is a good quality review published at a peer reviewed journal and that its say has more weight than any comment placed here. I saw the edit summaries in which it was claimed that the article doesn't mention CT, but I found that CT is mentioned in the article. Likewise I found false the claims that the text doesn't reflect the conclusions of the article. Nick Ericsson (talk) 13:55, 12 October 2012 (UTC)
 * I see your comments here are your first contributions to Wikipedia. Can I ask what brought you here? AndyTheGrump (talk) 14:48, 12 October 2012 (UTC)
 * I saw the article's content change back and forth. Nick Ericsson (talk) 15:55, 12 October 2012 (UTC)

Checkuser confirms sockpuppeting by two of the editors in this thread. The thread should be closed and the disputed text removed. Stick a fork in it... Binksternet (talk) 00:39, 14 October 2012 (UTC)
 * I have blocked Bob spagio goojio and Nick Ericsson for abusing multiple accounts based on the obvious behavioral evidence here and the checkuser's unequivocal conclusion. If that individual would like to participate in this discussion, he needs to find a way back using his original Wikipedia account&mdash;not using a new name each week.  TenOfAllTrades(talk) 12:38, 14 October 2012 (UTC)

Need help cleaning up after our sockpuppeteer / vandal
It looks like User:Nenpog, editing through a sockpuppet account, has successfully added his vandalism to Magnetic resonance imaging. Could someone with expertise in this area please examine that page and repair the damage? Thanks! --Guy Macon (talk) 22:37, 14 October 2012 (UTC)

Garage built scanner.
This guy built a CT scanner in his garage, scanned a frozen chicken. http://hackaday.com/2013/01/09/ben-krasnow-builds-a-ct-scanner/ Bizzybody (talk) 12:05, 9 January 2013 (UTC)


 * Interesting, but I doubt that the website linked would pass WP:RS, and even if it did, I don't think it would really merit mention in the article. And I hope the guy knew what he was doing - messing around with X-rays isn't advisable... AndyTheGrump (talk) 12:14, 9 January 2013 (UTC)

Why are they no longer called CAT scans?
Curiosity really, the article says that CAT scan is a no-longer preferred name, but why? Is it because it was too "cute" and non-serious? Sbwoodside (talk) 04:59, 19 December 2013 (UTC)


 * My understanding is that the reason the word "axial" was built into the early term "computed axial tomography (CAT)" is that, at the time, tomographic slices could be taken only in the axial plane (transverse plane), owing to the limitations of how the machines were built. Once the technology was developed further, newer machines could produce images in any desired plane, so the rational term to use was simply computed tomography (CT). One would think that everyone should have realized from the start that this technology would probably evolve to capture more than just one plane, and that maybe CT (not CAT) would be the logical choice of name from the start. But of course nomenclatural choices are often not made with that much foresight or planning. Quercus solaris (talk) 14:35, 19 December 2013 (UTC)

Blausen images
Blausen Medical has donated two images of CT scans showing general configuration of how the patient enters the machine, shown below. This article already has a lot of images, but feel free to use if useful. Dcoetzee 01:08, 10 August 2013 (UTC)

These images are very cool but I would not put them in the article with the watermarks.  Blue Rasberry   (talk)   15:03, 7 January 2014 (UTC)

Background radiation and imaging quality?
Is there any known effect from background radiation on x-ray imaging? I don't see any mention of this in the article. I would assume that this may be an issue for extremely high sensitivity detector systems.

Rooms with x-ray machines are commonly shielded to prevent outward radiation leakage from the x-ray source. But for low-noise imaging it appears that room shielding may be just as important, to minimize background noise affecting the detectors, and thereby allowing reduced x-ray intensity during scanning.

DMahalko (talk) 19:49, 31 January 2014 (UTC)

Unable to edit and remove text from article....
On my PC and the most recent version of the page, February 29, at 00:23 EST, I am unable to remove a phrase occurring at the beginning of the page "Go to Apollo Hospital and do CT Scan, LOL! " It is shown on the article page, but does not appear in the edit page dialog box. --Light show (talk) 05:49, 28 February 2014 (UTC)

Dosage Table Needs Updating
The doses in this table are extremely outdated, and the definition of "typical" has lost any meaningful significance with the wide proliferation of different multislice technologies.

Suggestion: update the table to distinguish the different doses incurred with each multislice tech generation. — Preceding unsigned comment added by 98.100.23.77 (talk) 13:52, 28 April 2014 (UTC)

Description of medical scans
It might be useful to include information about the steps that patients go through to have a medical scan and why: why NPO; if drinking a fluid, what is it and why; if drinking the fluid, why wait an hour before proceeding; why undress completely removing all metals (zippers, under-wired bras, buttons, jewelry, etc); [an explanation of the use of contrast and its side effects are already covered]; if required to drink 6-8 cups of fluid within 2 hours afterwards, why; (what steps the staff takes if something goes wrong, like an anaphylactic reaction or if contrast infiltrates into the tissues?). It will help demystify the process for the uninitiated and reduce fear as I suspect many casual readers come here to find out what is going to happen to them with a scan. Thank you for your time, Wordreader (talk) 00:58, 4 October 2014 (UTC)

Requested move 27 April 2015

 * The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

Moved as proposed. There is a clear consensus to move this article to the more common name for the medical procedure, but there is also substantial support for splitting the article (or creating new articles) with certain materials more appropriately housed at more technical names. I encourage that solution. bd2412 T 15:19, 30 May 2015 (UTC)

X-ray computed tomography → CT scan – replace very rare term with most common term, see for example http://www.mayoclinic.org/tests-procedures/ct-scan/basics/definition/prc-20014610 – --Relisted. Andrewa (talk) 17:14, 5 May 2015 (UTC) Espoo (talk) 21:44, 27 April 2015 (UTC)
 * This is a contested technical request (permalink). Philg88 ♦talk 21:47, 27 April 2015 (UTC)


 * Strong support hard to believe we haven't already done this. "CT scan" is the common name and we're doing a disservice to readers by obfuscating this. --Tom (LT) (talk) 13:06, 28 April 2015 (UTC)
 * Weak oppose The problem is, CT Scan is inherently medical to most people, whilst X-Ray computed tomography is the technique.  Do we want an article on the medical procedure, or the technology.  A similar question to should it be MRI or NMR,the same technology, and as a scientist, both come up equally. 90.194.62.161 (talk)ipuser 90.194.62.161 (talk) 07:06, 29 April 2015 (UTC)
 * Comment why not CAT scan ? -- 65.94.43.89 (talk) 09:55, 29 April 2015 (UTC)
 * Oppose The content of this article is mostly about the equipment and theory. In the domain of physics this is "X-ray computed tomography", so the title fits. I would support a WP:FORK of some of the content here into an article called "CT scan", which could cover the medical applications of this technology and follow the medical manual of style.
 * Changing the title without changing the content will not help readers. Different classes of readers will want the physics information versus the medical information, and putting a medical title on physics content will not serve the readers better.  Blue Rasberry   (talk)  14:11, 29 April 2015 (UTC)


 * The first line starts with "A CT scan...", and the article directly states "the term computed tomography alone (or CT) is often used to refer to X-ray CT". Changing the title will help readers... different readers may expect different titles, but the point of WP:COMMONNAME is that the majority of readers will be more familiar with the title 'CT scan'. If that's the case, why can't we write / speak the language most users are familiar with... the body of the article already uses "CT scan" quite a lot anyway, so why don't we change the article to reflect this? --Tom (LT) (talk) 01:31, 30 April 2015 (UTC)
 * I do not dispute that CT scan is the common name for the health procedure. I dispute that this article is about a health procedure, and I believe that it would be a disservice to readers to suggest that this article is about CT scans as a medical concept.
 * I am not convinced that CT scan is the common name for this phenomena in the field of physics or the use of this technique outside the field of health. 80% of this article is out of scope of the field of medicine and within scope of the field of physics. This article does not follow WP:MEDMOS because it is not a health article. WP:COMMONNAME does not apply because this article's content is mostly about something other than a CT scan in medicine, and while we both agree that CT scan is a common name for a medical concept I disagree that this article is about a medical concept. If this article were about the health concept then I would support it being named "CT scan". I think it would be a disservice to readers to call this "CT scan" when this is not a useful article for someone to read if they want to know about CT scans.
 * Forking medical content into a CT scan article would bring a lot of clarity and do more to serve practically everyone who is coming to this article. I see no benefit in bringing large numbers of people seeking health content to this article on a physics concept.  Blue Rasberry   (talk)  21:30, 30 April 2015 (UTC)
 * OK but please have an actual read of the article, which itself uses "CT scan" or "computed tomography" (the non-abbreviated form of CT scan) throughout the text. The article itself doesn't actually use "X-ray computed tomography" outside of the title. So it is a case of the title not reflecting the current state of the article. --Tom (LT) (talk) 00:23, 1 May 2015 (UTC)
 * I grant that the Wikipedia article uses term "CT scan" but I fail to see how that is an argument to decide the title. I feel that the title and the term used in the article should match the literature of the field which is providing the content which is covered. So far as I can tell, all the support the for the use of the term "CT scan" is because that is the term in medicine and not because anyone is citing the literature in the field of physics. I know nothing about this topic. Checking the literature - here is a heavily cited review paper from the field of dirt science which uses the term "X-ray CT" to describe dirt CT scans.
 * Until and unless medicine and archaeology can be differentiated then the medical term can be used here, but I still think it is bizarre to combine the concepts.  Blue Rasberry   (talk)  02:27, 1 May 2015 (UTC)
 * Until and unless medicine and archaeology can be differentiated then the medical term can be used here, but I still think it is bizarre to combine the concepts.  Blue Rasberry   (talk)  02:27, 1 May 2015 (UTC)


 * Dont think we should abbreviate terms, it is more encyclopedic to say computed tomography imo. Matthew Ferguson (talk) 14:39, 29 April 2015 (UTC)
 * oppose as per Bluerasberry's opinion--Ozzie10aaaa (talk) 15:07, 29 April 2015 (UTC)
 * support CT scan is the common name. no need for us to be WP:TECHNICAL in an article titile (CAT scans have not been used for ~15 years btw) Jytdog (talk) 21:28, 29 April 2015 (UTC)
 * Support CT scan. The medical application of the general technology is why most people will be reading the article.  The (few) physics people will not be confused.  I'd rather not WP:SPLIT the article into medical and non-medical information.  WhatamIdoing (talk) 21:49, 29 April 2015 (UTC)
 * Split into a CT scan article on the medical test and an article on the physics at the current title. No opinion on which one gets the history. Yes, the medical applications will be the target of the majority of readers, and most of them don't care about the physics. The two natural audiences for this topic can be divided fairly easily and each have their own obvious natural title., why don't you think a split is a good idea? I'd be more concerned about the audience for the medical article being confused by excess physics than the other way around. Opabinia regalis (talk) 03:50, 30 April 2015 (UTC)
 * It's still a reasonable WP:SIZE for a reader (so no pressing need to split), and I have a Mergism orientation. WhatamIdoing (talk) 03:55, 30 April 2015 (UTC)
 * Quick comment on this, beyond this specific case (on which I entirely agree with Bluerasberry). I agreed with the merger/lumper preference until recently, when I started doing some browsing on mobile (mostly while stuck at the airport). AFAIK mobile readers are rapidly growing as a percentage of the audience, and there it is much much easier to navigate multiple short articles than one long one. Opabinia regalis (talk) 03:44, 1 May 2015 (UTC)


 * Support CT scan. Better to use the common term where it can be used without loss of specificity. Would also support separate articles on Medical Uses of CT scanning and Physics of X-ray computed tomography, for example, both of which could be linked to from the more general page titled CT scan. BakerStMD 15:26, 30 April 2015 (UTC)
 * Support I am happy with CT scan. It is simpler and means the same thing more or less. We can than have the technical definition afterwards. Doc James  (talk · contribs · email) 15:28, 30 April 2015 (UTC)
 * Support --WS (talk) 07:30, 1 May 2015 (UTC)
 * Support, just because CT Scan is a WP:COMMONNAME. Even well educated people may not be aware of term X-ray computed tomography while even illiterate village people do know about term CT Scan. This is my personal experience about village people, I can't give source for it. Term "CT Scan" is obviously very popular. Thank you. --Vtk1987 (talk) 13:40, 2 May 2015 (UTC)
 * Support, per WP:COMMONNAME. Dyrnych (talk) 18:48, 5 May 2015 (UTC)
 * Support, never understood the decision to move to the current title. JFW &#124; T@lk  20:55, 10 May 2015 (UTC)
 * Support, not so much because "CT scan" is the *most* common, but more-so because the current title is difficult to recognize. --SmokeyJoe (talk) 02:00, 13 May 2015 (UTC)

Discussion
Relisting. There is consensus above for change but I think there's also a quite correct undercurrent of disquiet.

I think we need to look at the whole gammut of computed tomography articles to come to a solution that best fits WP:AT and serves all readers adequately. At first I thought it might even need some tweaks to the policy but I think if we look carefully (and it's a complex case) the policy will probably work out fine as is.

Computed tomography for example itself currently redirects to this article, with an inadequate hatnote which is not good at all as this article does not cover for example computed tomography in nuclear medicine. The term computed tomography is a very wide one I would suggest, covering X-ray, PET and other computed tomographic techniques, both medical and other.

I invite everyone to take a step back. What do the terms such as CAT scan, CT scan, computer assisted tomography, tomography, mean both technically and in the public mind? Where do we need overview articles, and what do we call the more technical ones? A look at all articles in Category:3d nuclear medical imaging will also help, and we probably need a higher level category Category:3d medical imaging and an overview article 3d medical imaging as not all (medical) computer assisted tomography is nuclear medicine. And that's just for a start. Andrewa (talk) 20:14, 5 May 2015 (UTC)
 * Good idea to have a look what else we can help fix up. However I suggest we first respect the consensus above by renaming this article and then while we're at it have a look at the whole gammut. --Tom (LT) (talk) 01:08, 6 May 2015 (UTC)
 * Let's let it run one relisting. My concern is that if the move goes ahead as proposed we'll actually end up with a worse setup than now, and that it may then stay like that indefinitely. Better to get the big picture sorted out while we have a team to do it. It may not work. Andrewa (talk) 02:06, 7 May 2015 (UTC)
 * That seems fair enough. CAT scan, CT scan and computer assisted tomography are all currently redirects. --Tom (LT) (talk) 04:09, 9 May 2015 (UTC)

at least the minority opinion was heard --Ozzie10aaaa (talk) 00:06, 29 May 2015 (UTC)
 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

local vs body irradiation
"The equivalent dose is the effective dose of a case, in which the whole body would actually absorb the same radiation dose, and the sievert unit is used in its report. In the case of non-uniform radiation, or radiation given to only part of the body, which is common for CT examinations, using the local equivalent dose alone would overstate the biological risks to the entire organism."

This statement reflects an impossible ignorance of the issues involved. Is this provided by a CT organization? — Preceding unsigned comment added by Wikibearwithme (talk • contribs) 06:10, 19 August 2016 (UTC)

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Computed vs. computerized (or -ised) Suggestion
There is no mention of the usage computerized. I'm not sure if this is a synonym or a slightly different technique – that's what I came to the article to find out. Anyone have any ideas? DavidCh0 (talk) 11:46, 16 December 2016 (UTC)

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Thankyou for your assistance. It was my first try to nominate an article. I will be pleased to work on these issues and submit it. Iflaq (talk) 03:09, 19 March 2021 (UTC)

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