What is the unit of measurement in this X-Ray?

[Gary_T2018]

Hi I hope I'm not posting under the wrong forum but I'm pretty sure this is physics related.

If you go to have an X-ray, in the film there will be information detailing the dosage you just received. However I encountered a rather unusual one like this:

70kV 100mAs 100mS -- dGycm² El_s:300

As far as dGycm² goes, the figure following it should well below 1, most likely 0.2 or something, yet it has 300.

What IS that? The X-Ray wasn't done in the US.

My apologies again if it has been posted under the wrong subforum.

 

[davenn]

70kV 100mAs 100mS -- dGycm2 El_s:300

I'm assuming that 100 mS should really be 100 mSv ?? as in 100 milliSieverts ?

or maybe it really is 100mS = milli Seconds ?? as in dosage (exposure) time

I don't know what 100 mAs is ?100 mSv = 1 dGy

@ZapperZ help please Dave

 

[Asymptotic]

mA is current in milliamps applied for 100 milliseconds? At 70 kV, this is 700 joule (watt-seconds).

dGycm2 El_s:300

decigray⋅cm²?

Found this ... Understanding Radiology Exposure Indicators

 

[Gary_T2018]

mA is current in milliamps applied for 100 milliseconds? At 70 kV, this is 700 joule (watt-seconds).

decigray⋅cm²?

Found this ... Understanding Radiology Exposure Indicators

What is El_s then? If 300 is Gycm2 then it's nothing much better than a gass chamber.

 

[Gary_T2018]

I'm assuming that 100 mS should really be 100 mSv ?? as in 100 milliSieverts ?

Most likely miliseconds. 100mSv is enough to cause someone symptoms.

or maybe it really is 100mS = milli Seconds ?? as in dosage (exposure) time

Then how do you really calculate the effective dosage?

 

[davenn]

decigray⋅cm2?

that's the easy part haha deciGrey per cm²
1 dGy = 1 deciGrey is 1/10 of a Grey = 100 mSv = 10 Rad (10,000 milliRad)

Yeah, I have no idea what "EL_s" is either haven't found a link

hence why I called on ZapperZ for help in the threadDave

 

[davenn]

Most likely miliseconds. 100mSv is enough to cause someone symptoms.
Then how do you really calculate the effective dosage?

From
https://www.translatorscafe.com/uni...n-absorbed-dose/18-25/milligray-millisievert/

Effective Dose
The units above are used for radiation that is uniformly absorbed by the tissue, usually in a localized area. They help determine how much radiation affects a particular organ. To calculate the effect on the entire body when only some part of the body is absorbing radiation, an effective radiation dose is used. This unit is needed because the increase in the risk of cancer is different for different organs, even if the amount of radiation absorbed is the same.

Effective dose calculations account for that by multiplying the absorbed radiation by the coefficient of the seriousness of the impact of radiation on each type of tissue or organ. When determining values of coefficient for different organs, researchers weighed not only the overall cancer risk but also the duration and quality of life of the patient, once cancer is contracted.

Effective dose is also measured in sieverts. It is important to understand when reading about radiation measured in sieverts, whether the source refers to the effective dose, or the radiation dose equivalent. It is likely that when sieverts are mentioned in mass media in the general context of talking about radioactivity-related accidents and disasters, the source is referring to the radiation dose equivalent. Often there is not enough information about which body tissues are affected or may be affected by the radioactive contamination, therefore it is not possible to talk about the effective dose.

 

[Gary_T2018]

Also the 700 Joule makes it sound even scarier. I mean if we are talking about 700J per kilogram it's effectively death ray.
700J per gram sounds like a neutron bomb.

 

[sophiecentaur]

In general, I have found that Medics are a lot less fussy about their units than you might expect. They often rely on 'local rules' to specify doses in general - in the same way that they launch into acronyms and groups of capital letters for diseases and symptoms . I think the 'excuse' for this is the historical attitude that kept information away from their patients.
It surprises me that there are relatively few disasters resulting from this habit of shorthand terminology.

 

[Gary_T2018]

In general, I have found that Medics are a lot less fussy about their units than you might expect. They often rely on 'local rules' to specify doses in general - in the same way that they launch into acronyms and groups of capital letters for diseases and symptoms . I think the 'excuse' for this is the historical attitude that kept information away from their patients.
It surprises me that there are relatively few disasters resulting from this habit of shorthand terminology.

Ok then. Now, another question: how long after a large dose of exposure to gamma radiation should you able to observe abnormalities in white cell quantities?

 

[Asymptotic]

What is El_s then? If 300 is Gycm2 then it's nothing much better than a gass chamber.

From the Understanding Radiology Exposure Indicators article,

On digital imaging systems, an exposure indicator provides useful feedback to the radiographer about exposures delivered to the image receptor (ASRT, 2010). An over- or under-exposed image will deliver an incorrect exposure indicator; whereas a correct exposure will provide a corresponding exposure indicator. The indicator is a vendor-specific value that provides the radiographer with an indication of the accuracy of their exposure settings for a specific image (ASRT, 2010). The exposure indicator has as many different names as there are vendors in the market. The names include S-number, REG, IgM, ExI and Exposure Index.

Carestream’s computed radiography (CR) and digital radiography (DR) systems both reference their exposure indicator as the exposure index or EI. After an exposure is made, the resulting image appears on the monitor and displays a number in the Exposure Index field. The number is a representation of the average pixel value for the image in a predefined Region of Interest (ROI).

EI_s:300 would fit with it being such an exposure indicator.

70kV 100mAs 100mS -- dGycm2 El_s:300

I'm wondering whether the '--' symbols preceding 'dGycm2' indicate this field wasn't enumerated.

 

[sophiecentaur]

Ok then. Now, another question: how long after a large dose of exposure to gamma radiation should you able to observe abnormalities in white cell quantities?

Surely you can find that from Google. Radiation effects on the human body are such a favourite topic.
The total dose is not the only factor. Several years ago I was given Radiotherapy and the 50Gy total dose was given in less than 3Gy lots spread over many weeks on the grounds that the body can deal better with it than the cancer cells can, over a long period of time. I don't know how that relates to white cell population but I was not aware of any blood test for white cell levels.

 

[Gary_T2018]

From the Understanding Radiology Exposure Indicators article,
EI_s:300 would fit with it being such an exposure indicator.

Well thanks! That's some major progress made! At least I know 300 isn't 300 dGy.

Now, if only it can be figured out how much mSv of radiation were absorbed in taking that shot of digital X-ray...

 

[Gary_T2018]

Surely you can find that from Google. Radiation effects on the human body are such a favourite topic.
The total dose is not the only factor. Several years ago I was given Radiotherapy and the 50Gy total dose was given in less than 3Gy lots spread over many weeks on the grounds that the body can deal better with it than the cancer cells can, over a long period of time. I don't know how that relates to white cell population but I was not aware of any blood test for white cell levels.

Wow. How did it go? Was the tumor eliminated?

 

[sophiecentaur]

Wow. How did it go? Was the tumor eliminated?

Seems to be OK so far - thanks for asking. The surgery was about six years ago and no signs since all the treatment all ended. The Radiotherapy procedure and equipment was very interesting for me (the opportunistic Physicist). They use splines to form an aperture for the beam to fit the appropriate area and use three different radial directions for the beam to reduce damage to surrounding tissue. The beam uses a linear accelerator as an energy source for an electron beam which hits a target and produces the X rays (also interesting). It's very high precision stuff (they work to about a mm) and I lay totally motionless during the exposure to help the beam avoid nearby important bits. Nearly seven weeks of commuting up to London for it was far more knackering than the treatment itself, I think. So far so good!

 

[sophiecentaur]

As far as dGycm2 goes,

Looking at the units of that:
A Gray is one J of Energy per kg. I'm not sure what the meaning of one Gy times 1cm₂ could be indicating.
Perhaps, if the density is in gm/cm³ then XGycm² = X J cm/ρ
If ρ is 1 (reasonable) then the thickness of the tissue that a 1cm² beam passes through will dissipate X Joules of energy per cm as it passes through. I guess that's reasonable because the thicker the tissue being imaged, the less dose does the body get from a given beam power and area. Obvs, a good Xray image will use just enough radiation to register the most dense tissue of interest.
It seems a funny approach to units though. What do you think?

 

[PSRB191921]

Hi,
Gy.cm2 is a dose per fluence unit (D/phi)

For example for k Gy.cm2 and for a parallel beam with a radius r the fluence rate is N/(pi.r.r) and the dose rate in Gray per second is k.N/(pi.r.r) (N the particles flux in s-1)

 

[sophiecentaur]

Hi,
Gy.cm2 is a dose per fluence unit (D/phi)

For example for k Gy.cm2 and for a parallel beam with a radius r the fluence rate is N/(pi.r.r) and the dose rate in Gray per second is k.N/(pi.r.r) (N the particles flux in s-1)

That has confused me a bit, I'm afraid.
The basic Definition of 1Gy is in terms of Energy per kg and that is how it seems to be defined everywhere I look. Using a derivative of the Gy is not an intuitive thing to do and it must be for a pretty subtle reason. The thing of interest if you want to assess potential damage must surely (once you have eliminated frequency variation etc.) still be the Gy. I can see how a source can be calibrated in terms of Power Flux or Flux density, which gives the Energy involved when the time is specified. That is independent of the mass of the receiving piece of body.
Gy includes the mass of tissue.
I have been looking athttp://www.npl.co.uk/upload/pdf/20101117_irmf_bailey.pdf which has helped a bit and it sort of suggests to me that the way doses are specified could usefully be looked at again. But I guess that it would all make perfectly reasonable sense to someone in the business.

 

[gleem]

Since the dose which is specified by the energy deposited in tissue per unit mass does not really provide a risk estimate from a radiation exposure due to the fact that the amount to tissue receiving the dose must be taken into account it has become fashionable in the last decade or so to specify the dose area product (DAP) for a given film. This number is automatically calculated by the machine based on the collimator setting, the tube current, the time of exposure, and the KVP used. The larger the dose and or area exposed the greater the risk. The maximum area for a film is about 1000 cm² . For 70 kVp (3 phase unit) the dose rate is about 0.06 mGy/mAs.. For 100mAs you get 6mGy or 0.06dGy. I am not familiar with the term EL_s (European?) in conjunction with DAP and for this exposure the 300 cannot be the DAP. If the DAP were cGycm² then it would be reasonable.

 

[Gary_T2018]

Seems to be OK so far - thanks for asking.

Hey no problem.

So 6 years and you haven't developed anything malignant due to radio-therapy? That's really interesting, I am under the impression that one spine x-ray which blasts you with 2 mSv worth of X-ray dooms you for life. I'm really worried.

Anyway, glad to know you are OK!

 

[Gary_T2018]

Looking at the units of that:
A Gray is one J of Energy per kg. I'm not sure what the meaning of one Gy times 1cm₂ could be indicating.
Perhaps, if the density is in gm/cm³ then XGycm² = X J cm/ρ
If ρ is 1 (reasonable) then the thickness of the tissue that a 1cm² beam passes through will dissipate X Joules of energy per cm as it passes through. I guess that's reasonable because the thicker the tissue being imaged, the less dose does the body get from a given beam power and area. Obvs, a good Xray image will use just enough radiation to register the most dense tissue of interest.
It seems a funny approach to units though. What do you think?

I haven't the foggiest idea, that's why I'm here asking those who might have the technical side of the knowledge.

 

[Gary_T2018]

For 70 kVp (3 phase unit) the dose rate is about 0.06 mGy/mAs.. For 100mAs you get 6mGy or 0.06dGy. I am not familiar with the term EL_s

0.06dGy equals 6 mSv. For a lumbar spine X-ray it is way too high. Heck for a CT that is way too high.

 

[Gary_T2018]

If the DAP were cGycm2 then it would be reasonable.

In terms us laymen could understand, the radiation does for this 1 shot/view, in mSv, would be??

 

[Gary_T2018]

For 70 kVp (3 phase unit) the dose rate is about 0.06 mGy/mAs.. For 100mAs you get 6mGy or 0.06dGy.

Hi, thanks a lot for the information. Can you explain with a bit more detail how it is calculated? Technical documents are also appreciated :)

 

[Gary_T2018]

Hello folks, thanks for the help so far but I am able to determine that "El_s" should actually be "EI_s", no idea what the "s" at the end stands for still but am pretty sure that "l" should infact, be "i", so it's most likely exposure index, as Asymptotic had suggested

 

[sophiecentaur]

So 6 years and you haven't developed anything malignant due to radio-therapy?

The lesser of the two evils is, so I believe, very much the lesser. For old gimmers, the extended life expectancy due to the treatment is way more than the risk of the treatment producing other kinds of tumor and shortening life. Using 'conformal' radiation makes a big difference to local collateral damage because the beam is quite extreme and other organs could fry (as indeed they used to in the old days). The effect of RT is fairly extreme - so bad that follow up surgery is pretty well impossible due to scar tissue and distortions.
So compared with RT, investigative imaging needs to use much much lower doses to keep it as non-invasive as possible. My introduction of RT into the conversation was more to justify my interest in dosage specification.
I talked with the Oncologist at the time and he confirmed that, for a given dose (in Gy), the total Energy is proportional to the beam size. (amount of tissue that's actually irradiated) so, to calculate the risk of further ill effects, the total energy would need to be taken into consideration. In my case, the RT was post op so it was only the margins of the original tumour that needed radiation - meaning probably quite a bit less total energy was involved. That term "fluence' is important.

 

[gleem]

I cannot answer all your question right now but for now,

I am under the impression that one spine x-ray which blasts you with 2 mSv worth of X-ray dooms you for life. I'm really worried.

Keep in mind that most people get yearly unavoidable radiation doses from natural background fro 2 to 3 mSv depending on location. Background radiation is not considered significant source of exposure and the risk associated with this is for an individual is negligible compared to all other risks we are subject to. I'll get back to you with more info.

 

[gleem]

That's really interesting, I am under the impression that one spine x-ray which blasts you with 2 mSv worth of X-ray dooms you for life. I'm really worried.

The 3mSv you stated for a dose for a lumbar spine might not be the dose you think it is. Typically you would want to state an average or effective dose to the irradiated field. The 3mSv is quite high for an effective dose. One these day should expect less than 1mSv as an effective dose. The exposure is determined by how much radiation is needed by the imaging device i.e., film or these days electronic digital imaging receptors. The skin dose at the entrance of the beam will be quite high and the dose will decrease about exponentially through the body. The dose will depend significantly on thickness of the body part and the kVp used depending about kVP².. Of course it depends linearly on the mA and time. of the exposure. Also there is a dependence on the machine age and power source.

A word of warning about estimated doses for exams, they are estimates sometimes on survey made over decades with large contributions from old technology. Even today you may have significant variations of doses from institution to institution. In the US most hospitals have a medical physicist as consultants or on staff that can attest to the dose from various units.

The bottom line for most people is if an Xray exam is indicated for the determination of a specific diagnosis then the risk/ benefit is a no-brainer don't worry. Xray exam should not be taken on an asymptomatic person, no benefit usually. One of the links of cancer to radiation exposure was back in the 1930's or so patients where treated for various non cancerous conditions using fluoroscopy which resulted in exposure in the neighborhood of 1 Gy, and a number of cancers where produced.

If the DAP were cGycm2 then it would be reasonable.

Something is missing here sorry. I meant to say if the DAP were 60dSvcm2 that would be reasonable. BUT I made an error in choosing the 0.06mGy/mAs for the output by selecting the wrong data. For a real xray machines it is more like 0.20mGy/mAs at 70 kVp AND that is the dose to air at a specified distance (say 60cm) not the dose to the patient . That make the 300 dSvcm² very reasonable. How do you relate DAP to the effective dose to the patient? Well the DAP measures the energy in the form of radiation that is being outputted by the machine. Since almost all of it is absorbed by the patient then the DAP will be a reasonable surrogate for the effective dose to the patient.

In terms us laymen could understand, the radiation does for this 1 shot/view, in mSv, would be??

There are two standard views a lateral ( xray tube from the side) and anterior-posterior xray tube above a supine patient. The doses are a bit different but around 1 mSv. again with significant variation for hospital to hospital. depending on the machine and image receptor used.

 

[Gary_T2018]

I cannot answer all your question right now but for now,Keep in mind that most people get yearly unavoidable radiation doses from natural background fro 2 to 3 mSv depending on location. Background radiation is not considered significant source of exposure and the risk associated with this is for an individual is negligible compared to all other risks we are subject to. I'll get back to you with more info.

Thank you once again for the reply.

I understand that, but xray blast you with that dose in under perhaps 1 second, while "naturally occurring" radiation does that over a course of 356 days. I don't believe they are comparable?

 

[Gary_T2018]

There are two standard views a lateral ( xray tube from the side) and anterior-posterior xray tube above a supine patient. The doses are a bit different but around 1 mSv. again with significant variation for hospital to hospital. depending on the machine and image receptor used.

So 4 view, 1 front, 1 side, 2 45 degrees view puts the approx. dose at around 2mSv?

Combined with 1 front 1 side lumbar earlier roughly 20 days ago, the total dose is expected to be 3 mSv I suppose?

How dangerous is that? Am I expected to develop some form of cancer in the next 10 or 20 years?

That's really awful, rotten news! I'm still kind of young...

 

[gleem]

I understand that, but xray blast you with that dose in under perhaps 1 second, while "naturally occurring" radiation does that over a course of 356 days. I don't believe they are comparable?

That is correct but the data linking radiation exposure to cancer is from high dose exposures over short intervals. It is believed doses over short periods overwhelm the repair mechanism. Smaller doses over the same interval may not do so since the damage is much smaller i.e.damage is proportional to dose.

The repair mechanism for large doses may be complete in as little as six hours.

How dangerous is that? Am I expected to develop some form of cancer in the next 10 or 20 years?

Still negligible compared to all other risks that we face in our daily lives. Estimates for cancer incidence is based on large exposure with significant uncertainty The working assumption has been for many decades that the risk of cancer is linearly related to dose even down to the smallest doses meaning that all exposure carries some risk. However there is not real data that supports this assumption and that it is believed based on animal studies that there is a threshold for cancer induction below which radiation exposure does not produce cancers. Current estimates say that this dose might be as large as 100 mSv/yr. The problem is more psychological/political in backtracking the dose limits until there is irrefutable human data. Human data that does exist on radiation workers generally has shown that over a lifetime there is no statistically significant difference in life expectancy compare to comparable work with no radiation exposure. So lacking good data the general philosophy regarding radiation exposure will probably remain "keep radiation exposure to a minimum".and only when there is a benefit.

 

[sophiecentaur]

How dangerous is that? Am I expected to develop some form of cancer in the next 10 or 20 years?

Way back, when X rays were first used, you would have been justified in worrying. When I was a kid, they had X Ray machines in shoe shops which showed on a green screen your foot bones and the outline of your shoes. And that was mainly to 'keep children's feet healthy!' I was told that hospital radiography departments used to use massive doses for imaging fractures. As films got more sensitive, many were reluctant to back off the dose. It would have been the operators who suffered more in the long run, despite sometimes standing behind a lead screen during the exposure. Things have improved in the light of lots of reputable statistics.
This link shows that the existence of a low level of natural radiation may actually stimulate repair mechanisms, with the minimum risk being when there is actually some degree of exposure.

 

[Gary_T2018]

The repair mechanism for large doses may be complete in as little as six hours.

Thank you for your reply! I do not know of your academic background but forgive me for my zero understanding in medical science if I bore/upset you! I really have no deliberate intention to do that I'm having a major existential? mid-life crisis at this moment so any help would be great!

Do you have any literature that I can read on "6 hours"? That certainly makes me feel better.

Also according to my non-existent knowledge in medicine, aren't some "repairs" done "erroneously" in that they leave the double-helix "mis-assembled"? In which case they will keep replicating over and over and turn into cancer cells? I'm really worried...

Still negligible compared to all other risks that we face in our daily lives. Estimates for cancer incidence is based on large exposure with significant uncertainty

OK I have 2 questions on that:

1, can you help put that into perspective? What risks are greater than my taking xrays too often? For example?

2, What is the estimated risk of cancer for 3mSv of xray exposure? Assuming that's the dose?

And last but not least:

I understand that the 50mSv threshold put by the US CDC( or IAEA? I'm sorry I forgot) was based on studies on Hiroshima and Nagasaki survivors, so surely high energy gamma rays are more destructive than less energetic xrays right?

My sincere apologies once again if I bore you. I need as much data as I can get even though I don't know very well what to deal with probabilities.

 

[Gary_T2018]

Way back, when X rays were first used, you would have been justified in worrying. When I was a kid, they had X Ray machines in shoe shops which showed on a green screen your foot bones and the outline of your shoes. And that was mainly to 'keep children's feet healthy!' I was told that hospital radiography departments used to use massive doses for imaging fractures. As films got more sensitive, many were reluctant to back off the dose. It would have been the operators who suffered more in the long run, despite sometimes standing behind a lead screen during the exposure. Things have improved in the light of lots of reputable statistics.
This link shows that the existence of a low level of natural radiation may actually stimulate repair mechanisms, with the minimum risk being when there is actually some degree of exposure.

Thanks! I got a feeling that you are at least 70 years of age?

What happened to all those xray technicians?

Also this may sound silly but do you know of someone who had taken CT scan(which surely includes dosage much larger) in their 20s or 30s yet alive and well for many decades without developing anything malignant?

 

[berkeman]

Thank you for your reply! I do not know of your academic background

Many of us post our background in our Profile page. Just click on a user's Avatar and select Profile Page. You will see why @gleem is able to be so helpful in threads like this.

 

[sophiecentaur]

I'm having a major existential? mid-life crisis at this moment so any help would be great!

Perhaps the best answer for you is based not on Physics but on statistics. Any treatment* or investigations that are carried out in a half decent medical system is subject to pretty strict regulation. X ray imaging corresponds to a very tiny dose (over a lifetime) and I have read that commercial air crew are far more affected (statistically) by their hours and days at high altitude than patients who may be given a few dozen (max) X Ray exposures. The same is true about people who live in areas of some igneous rocks. Parts of Scotland and Cornwall have levels of natural radiation that would cause raised eyebrows for health and safety regulators but those areas are not roped off.
You should look for reassurance in the statistics that are published all over the web, as long as you avoid the obvious alarmist sources.

*That "any treatment" term may not apply to some forms of specialist surgery where the patient can be subject to a confident surgeon's over-optimism. "We'll have that out in no time, with no ill effects."

 

[gleem]

Thank you for your reply! I do not know of your academic background but forgive me for my zero understanding in medical science if I bore/upset you! I really have no deliberate intention to do that I'm having a major existential? mid-life crisis at this moment so any help would be great!

Your questions do not bore me and I don't get upset I find questions from a person as you challenging for I wish to leave you with the correct impression of my answers. I understand issues related to the concern of those wrt radiation effects. I am a retire medical physicist with over 30 experience and have had to address concerns of nurses participating in radiation treatment procedure. If something does not sit right with you keep pestering me until it does.

Also according to my non-existent knowledge in medicine, aren't some "repairs" done "erroneously" in that they leave the double-helix "mis-assembled"? In which case they will keep replicating over and over and turn into cancer cells? I'm really worried...

Total repairs are never complete. The biological effect of radiation is mostly mediated through the production of free radicals and as you are I hope aware free radicals are produced by many substances in our diets. A problem with radiation induced cancers is that they have nos specific characteristics that separate them from cancers cause by other agents. If a person develops a cancer after a significant dose to radiation say 20 cGy it would be a common reaction to attribute it to the exposure but since the normal occurrence is so much greater for other reasons for a cancer based on probabilities it would be hard to say that it was the reason unless the person belonged to a age group in which this cancer was rare. However if members of a population received to this dose one could attribute those cancers to the dose if the number of cancers was large enough.

1, can you help put that into perspective? What risks are greater than my taking xrays too often? For example?

One way of assessing risk is to estimate the decrease in life expectancy for different risks.

Risk Ave. days of life expectancy lost

smoking 20 cig./day----------------------2400
overweight-----------------------------------990
all accidents---------------------------------430
natural background radiation---------------8
1 cGy/yr for 30 years (calculated)--------30
medical diagnostic xrays (calculated)-----6

This is rather old data but I think it gives the general idea. Medical xray exam are more common today but the dose per exam is generally less now so even if the risk doubled it would be very small.

2, What is the estimated risk of cancer for 3mSv of xray exposure? Assuming that's the dose?

I hesitate to give a number . Data on cancer incidence assumes whole body exposure unless the data is specifically related to a region. The incidence for a specific exam depends on the area and the organs involved. A lumbar spine study is a relatively small field size and the spine is not overly sensitive to radiation. The large and small bowel are more sensitive but again only fraction is exposed. Even if your exam were repeated every year for the rest of your life it still would be small compared to other common risks.

I understand that the 50mSv threshold put by the US CDC( or IAEA? I'm sorry I forgot) was based on studies on Hiroshima and Nagasaki survivors, so surely high energy gamma rays are more destructive than less energetic xrays right?

Threshold is not an appropriate term. It is an administrative limit. like a speed limit. If you go over the speed limit by 1 km/hr there is no dramatic change in the risk of an accident. same with the 50mSv which by the way is for radiation workers at least in the US. For the general public it is 5mSv.

The biological effect of different xray energies is the same. The only difference being that the high energy penetrate more tissue and can deliver a greater dose to a deeper depth.As far a references are concerned I do not know of one that is meant for the general public that will satisfactorily answer all your concerns but I will look.

 

[sysprog]

What is El_s then? If 300 is Gycm2 then it's nothing much better than a gass chamber.

EIS300™ Electrochemical Impedance Spectroscopy

 

[davenn]

co9m

EIS300™ Electrochemical Impedance Spectroscopy

EIS … that appears to be something completely unrelated , instead of the discussed EL_s

 

[Gary_T2018]

EIS … that appears to be something completely unrelated , instead of the discussed EL_s

My apologies - it's EI_s, not EL_s.

Still, assuming EI = exposing index, the "_s" part doesn't make all that much sense.

 

[davenn]

My apologies - it's EI_s, not EL_s.
Still, assuming EI = exposing index, the "_s" part doesn't make al that much sense.

which still has nothing to do with what sysprog posted...

EIS300™ Electrochemical Impedance Spectroscopy

I still cannot seem to find any info on your updated EI_s ... a real puzzle

cheers
Dave

 

[Gary_T2018]

Your questions do not bore me and I don't get upset I find questions from a person as you challenging for I wish to leave you with the correct impression of my answers.

Many thanks. Your replies are very, very valuable to me. Sorry that I'm getting back to you a bit late I was caught in a bit of a jam yesterday.
I hope you don't mind me asking some more questions - please indulge me a bit and I'll try my best to ask researched questions and reasonable ones, even though some of them may not sound so to you but I'm kind of distressed lately.

If something does not sit right with you keep pestering me until it does.

Hah I will! Again I will try my best to ask reasonable, science-related questions. BTW I'm going to ask a lot of "challenging" and at the same time numerous questions again so feel free to answer only a fraction of them at the same time! I'm in no hurry :)

I am a retire medical physicist with over 30 experience and have had to address concerns of nurses participating in radiation treatment procedure.

I understand that over a course of maybe 10 years, they are likely to accumulate the dose to as much as 100 mSv, is there any research done that had demonstrated significant adverse health effect because of that?

Also this is something purely circumstantial and anecdotal - do you know anyone who had received a large dose, like CT scans of about 20 mSv in their 20s , but lived healthily for the rest of their lives? As an ex-medical professional I'm sure you've known one or two? Don't worry, just give it to me straight doc.

Total repairs are never complete.

I think I know roughly what you mean. So, on the repair part, I understand that the following 3 scenarios may happen (please inform me of other possibilities if they matter):

Only one "strand" of the helix got damaged in which case one needs not to worry because kind of like holograms, the damaged sections and strands can be repaired based on the other complete one.

Both strands were destroyed, and 2 situations may arise from this scenario:

A. The DNA wasn't able to correctly repair themselves in which case it leads to cell death, again, no worries there, save for brain cells, most of our body's cells are replaceable and have rather "short" life span.

B. The DNA wasn't able to correctly repair themselves but worst of all it repairs themselves erroneously and eventually leads to uncontrolled cell growth or in most cases, cancer.

I understand that the last case, although worrying, is rather rare, it kind of requires a lot of bad things happening all at the same time, it's an "AND" calculation which would render the event rather improbable - but given how many cells we have, it's not under any circumstances omissible. So my question is: how much should I worried about this possibility? And I'm not in anyway suggesting that it is the primary cause of cancer - it could be caused by "free-radicals" as you noted.

Again suppose some cells fell into the last category but never got taken care of my the immune system - will they lurk around for years without being detected or will they grow and spread quickly within one or 2 years?

A problem with radiation induced cancers is that they have nos specific characteristics that separate them from cancers cause by other agents.

So as of now are we able to identify them by extracting live tissues? I'm talking about the possibility of a lawsuit should it be the case.

Medical xray exam are more common today but the dose per exam is generally less now so even if the risk doubled it would be very small.

Here's another thing... the tones of serious scientific research literature that I read vary so much that it's literally unsettling. For example a CDC (I believe so, or it could be EPA) article said that no threshold exist and no amount of xray is too small and will likely cause cancer "many years to come" at the same time, another article from a not-for-profit website stated that "any xray screening may involve a "small dose of radiation"", as a layman I find it rather difficult to comprehend. How "small" should a dose be to be considered "small"? Is 20 mSv small? What about 5? That is practically confusing. Can you please shed some professional insight?

Also thank you so much for the statistics - it certainly helped me have a better idea of what to look out for.

The large and small bowel are more sensitive but again only fraction is exposed. Even if your exam were repeated every year for the rest of your life it still would be small compared to other common risks.

I kind of was exposed front, side, then 45 and 135 degrees... so I suppose it was pretty thorough? Again I have no hard background in medical science so I don't know any better.

Also I understand the figures i.e. %0.01 (which is 1 out of 10000) but I have problem relating to it, for that unlucky 1 out of 10,000, it's 100% isn't it? :/

For the general public it is 5mSv.

I hate to sound like a broken record but that's the thing that really irks me - for France (or EU?) it's 1 mSv. But aren't anyone who had gone through a CT scan easily surpass that amount? I don't know what to make of it...

Last two questions but not the least - equipment from my country are kind of known for have less-than-desirable quality (but for medical equipment I have not done any research to back up that claim), what are the chances of the xray machine using a ridiculous amount of radiation?

It's DR I'm talking about. So I understand that the chances are probably pretty slim because the receptor (I hope it's the right word) would have to attenuate what it had received so much that it becomes counterproductive and no longer cost-effective for the image would be so "dark" if not attenuated which means it won't produce a diagnostically viable image. So there is more incentive to use the "right" amount instead of "as much as possible so we have a great picture!" Also please note that I know nothing of how the manufacturing was done, it's likely that the core parts are still manufactured by for example G.E. or Fuji whatnot.

Another question: the image produced by the DR (the white part which are supposed to be bones) is rather "snowflaky" and "dotty" , the boundaries are rather blurry for a layman like me. That can be considered a sign of low/normal dose or ridiculous high dose?

I'm sorry that I asked so many questions - you have been a great help so far! I could use some professional opinion to help me walk out of the current state of mind. Again you don't have to answer all the questions all at once but I'd really appreciate it if you answer all of them. Once again you have my gratitude good Sir!

 

[sophiecentaur]

but worst of all it repairs themselves erroneously

But how many of these erroneous repairs are viable? Clearly not many or complex life wouldn't have managed to evolve. The detailed science of the effects of radiation on cells is very interesting but you cannot come to any valid conclusion about your personal situation from that angle. All you can do is to look at the statistics. Your single exposure is very unlikely to constitute any serious danger. If it were, and the dose was much higher than a level that would satisfy your worries, there would be many other patients involved.
Wouldn't there have been a terrible stink about something like that in the newspapers?

Another question: the image produced by the DR (the white part which are supposed to be bones) is rather "snowflaky" and "dotty" , the boundaries are rather blurry for a layman like me. That can be considered a sign of low/normal dose or ridiculous high dose?

From your description, I would imagine that the level of the radiation that had managed to penetrate through the bones was only just enough for the sensor / emulsion to register. Looks like they got the exposure right. I would have thought that the best indication of the accuracy of the dose would be to look at the feature that the Xray was used to display. If there were too much exposure, those features would be all 'burned out' and black. Personally, I would have been more worried if the bones came through as dark grey! A Google search will yield hundreds of Xray images for you to compare with yours. Is it significantly different from all of them?
My basic message to you is "DON'T PANIC".

 

[gleem]

I understand that over a course of maybe 10 years, they are likely to accumulate the dose to as much as 100 mSv, is there any research done that had demonstrated significant adverse health effect because of that?

I assume you are referring to the nurses. Following proper radiation safety guidelines and no unusual circumstances that would require a nurse to remain close to a patient for an extended time and with one procedure a month for 10 years on average I would only expect an accumulated dose of about 10mSv per person. There is no research that I am aware that has show any link between that level of dose and increased incidence of cancer. The estimated incidence of cancers is produced from higher dose data and extrapolated back to the low dose range assuming no threshold (which has been the working assumption for almost a century but not firmly established. ( a better safe than sorry attitude).

I might add that a repair mechanism implied that the radiation effect should be less at lower doses but this is ignored in determining risk.

Also this is something purely circumstantial and anecdotal - do you know anyone who had received a large dose, like CT scans of about 20 mSv in their 20s , but lived healthily for the rest of their lives? As an ex-medical professional I'm sure you've known one or two? Don't worry, just give it to me straight doc.

No. The closest thing related to your question is a person I know received some amount of radiation exposure as a fetus when her mother was given a nuclear medicine scan during the pregnancy. She is now over 40 with no ill effects. Fetuses are considered very radiosensitive.

So as of now are we able to identify them by extracting live tissues? I'm talking about the possibility of a lawsuit should it be the case.

I do not see how it is possible even by looking at the DNA to determine the cause of a mutation. Most radiation induced tumors are due to quite large dose like 0.5Gy to 2Gy. and at 2Gy you are expecting significant immediate (within 1 month) deaths due to effects on the blood marrow cells and cells in the intestines.

I stress that the only way to use any risk info is for a population of exposed persons and not for individuals. In the US about 30000 persons are killed in auto accidents each year. Taking the ratio of deaths to total population of people who use cars that's about 1/10000 each year. every year we basically go into a lottery for death by car. Using simple probability, repeating 1/10000 chance each year for 70 years you have a 0.7% chance of being killed in an auto accident in your lifetime. Do you accept that? It is estimated that adults will have about a 5% increase in cancers for every Sv of dose in their lifetime. Considering that about 40% of us will develop cancer. Most people will receive less than 200 mSv from background. But keep in mind that medical xray dose tend to be in the 1 to 30 mSv range so unless you get yearly xrays it is unlikely that you will approach 1Sv

Also I understand the figures i.e. %0.01 (which is 1 out of 10000) but I have problem relating to it, for that unlucky 1 out of 10,000, it's 100% isn't it? :/

You should not think of it that way, about the individuals that "loose".. You should think that out of say 1 million person then 100 people will . But it is not a given for maybe only 50 people may get what ever or maybe 150 with equal probability. The risk estimates cannot be applied to an individual. for it assume you are a member of a particular risk group which probably cannot be established.

WRT radiation exposure you can always refuse an xray but that might not be too smart if it may improve your quality of life or even extend it. The worse place to get an infection is a hospital. The worst time is when you are sick or after surgery. So what do you do. Assuming that everything is done correctly by capable people in capable facilities you roll the dice and bet against fate Worrying about some possible negative outcome against a declared benefit is not productive. For anything involving a risk you must assess it value against its risk and take reasonable steps to minimize the risks.

I hate to sound like a broken record but that's the thing that really irks me - for France (or EU?) it's 1 mSv. But aren't anyone who had gone through a CT scan easily surpass that amount? I don't know what to make of it..

The limit you are (and me ) are referring to is probably the amount of radiation that the public might be exposed to from radiation facilities in areas that are occupied by member of the general public who do not know they are receiving some radiation. There is obviously not benefit to this exposure. Because it is expensive to reduce exposure to lower levels they drew the line at 1mSv. Medical xrays can have doses well in excess of have defined benefit and are not regulated except in the ways the machines generate or use the radiation. Physicians determine the exposure factor according to standard of good practice, e.g., no head CT for head aches,
special pediatric exposure factors vis-a-vis adult factors. no repeats - do it right the first time (ask how many views are to be taken and if there are more than that ask why. A usually unacceptable response would be the image did not come out so was it operator error or equipment failure.

 

[gleem]

Last two questions but not the least - equipment from my country are kind of known for have less-than-desirable quality (but for medical equipment I have not done any research to back up that claim), what are the chances of the xray machine using a ridiculous amount of radiation?

By DR is assume you mean digital radiography. This mode is great because it uses less radiation and can be built to turn off the xray machine when the proper amount has be given. So over and under exposures should not be a problem. However positioning of the patient to the satisfaction of the radiologist is still an issue for the inexperienced tech. In the days of film the retake rate was less than 5% due to things like the film was under/overexposed or the film processor had a problem or poor positioning.

The big dose producers are CT, fluoroscopic exams, angiography, intervention radiography (placement of stents, biopsies and embolization using xray imaging).But unless you have a serious medical condition they are not use often by a single person.

I have to stress that the risk estimates associated with radiation exposure refer to the whole body receiving that dose. Since xray exams usually only expose a small part of the body the risk should be reduced accordingly. Thus in a lumber spine xray only about 1% of the dose in the form of scattered radiation will expose the lungs so lung cancers are all but non existent.for example.

 

[Gary_T2018]

Thank you for your replies sophiecentaur.

there would be many other patients involved.
Wouldn't there have been a terrible stink about something like that in the newspapers?

In my country? Maybe, maybe not.

My basic message to you is "DON'T PANIC".

That's comforting, but I just want to be sure. Also there's a slight chance that the receiver attenuated all the energy it received. Kinda like turning on really bright lights in a room but wearing sunglasses.

 

[Gary_T2018]

Hi again gleem, I'm back again for more pestering, hope you don't mind answering a few more questions.

I might add that a repair mechanism implied that the radiation effect should be less at lower doses but this is ignored in determining risk.

I'm not sure what you meant by that?

Also I think I got 4 xrays so possibly as much as 2.5 mSv in seconds, should that be considered "low" dose or "high"? As a layman my only frame of reference is a CT scan, the brain CT uses 2 mSv, so for me my Xray is kind of unreasonably high - since chest Xrays uses only 0.002 or so mSv.

No. The closest thing related to your question is a person...

I know this sounds silly but by "No" you mean people around you are generally very healthy and never had to go through CT scans or people around you who went through CT scans ALL got some ill-effects one way or the other later on??

That fetus example is quite comforting, I'm glad she grew up to be OK.

Most radiation induced tumors are due to quite large dose...

I understand what you mean, but I'm trying to ask a "what if" question: What if a tumor developed much later in life (like in 5 or 10 or even 20 years), how should we identify that? After all I read it on a website by either EPA or CDC that even a small amount of radiation may cause ill-effect "for many years to come"?

Using simple probability, repeating 1/10000 chance each year for 70 years you have a 0.7% chance of being killed in an auto accident in your lifetime. Do you accept that?

Well yes, mainly:
1. I can't go places without cars.
2. I have a say more or less in the way how I or others drive - if someone is tired I'm not riding shotgun with him and I'll try to talk him out of driving.

WRT radiation exposure you can always refuse an xray but that might not be too smart if it may improve your quality of life or even extend it.

The doctor was experienced but nevertheless young ... he demanded a CT scan at first which I refused, but I now regret intensely that I did not refuse the Xray too. I'm not sure if it will extend my life but the final diagnostic is that my spines are fine although some parts of it were "compressed", I don't know what that means.

Worrying about some possible negative outcome against a declared benefit is not productive.

I agree, the problem is now I don't really see the benefit here, it feels more like the doctor was lazy and tried to be sure instead of asking me to return a month later...

A usually unacceptable response would be the image did not come out so was it operator error or equipment failure.

Well the doctor prescribed for my Xray, after view the reports said the xray I gave him the first time had "false imagery"(which led him to believe I may have some sort of existing condition, which "may cause my spine to slip off when I'm older and trying to lift heavy objects"). I'm now really mad because 1. he could have asked if I had xrays from before (which I did) and take a look at it. Instead he was lazy, 2. I asked him at least twice "the radiation involved is rather low, right?" and he answered yes. 3. He prescribed the highest dose, 4 views knowing I had 2 views 20 days ago in a quite casual manner.

So over and under exposures should not be a problem.

I get what you are saying, but, just for sure - can we exclude the possibility that manufactures in my country, in order to compete with imported DRs, deliberately boost the rays emitted and then attenuate it at the receiving panel/receptor (assuming that is the proper term)? So a proper image could be produced? Or that's rather silly and unfeasible?

Since xray exams usually only expose a small part of the body the risk should be reduced accordingly.

Sigh... I think I know what you mean and I find it reaasonable but my entire lower torso was exposed... with that amount... shouldn't the risk for some part like lung be deducted but belly be increased?

Sorry yet again for another wave of questions... and thank you for your answers so far, you are helping me walk out of a somewhat difficult time.

 

[gleem]

That was a big wave.

I'm not sure what you meant by that?

The currently accepted no threshold linear response assumption of biological radiation damage assumes no repair mechanism exists and that all damage accumulates.and the risk increases over time In reality we know there is a repair mechanism that begins immediately and can handle a certain amount of damage. If the dose comes in large fractions and relatively fast the repair mechanism is overwhelmed and leaves some damage unrepaired. Thus at low doses and even high dose rates much of the damage is repair.

The 0.002mSv you quote for a chest xray is about 100 times to low and your CT dose is about 10 times to low roughly speaking

I know this sounds silly but by "No" you mean people around you are generally very healthy and never had to go through CT scans or people around you who went through CT scans ALL got some ill-effects one way or the other later on??

I do not know anybody who had a CT scan and subsequently developed cancer.

I understand what you mean, but I'm trying to ask a "what if" question: What if a tumor developed much later in life (like in 5 or 10 or even 20 years), how should we identify that? After all I read it on a website by either EPA or CDC that even a small amount of radiation may cause ill-effect "for many years to come"?

Everybody agrees that radiation can (and that is the operative word can ) cause cancers. Probably a better phrase is small dose or radiation is linked to.cancer The next question is how many does it cause.

The atomic bomb survivors represent the largest group of persons exposed to excessive amounts of radiation. The number of cancers that where found to be in excess of what might have be expected from an unexposed equivalent population was found to be about 1% of the natural occurring cancers. see
https://bigthink.com/risk-reason-an...out-the-danger-of-excessive-fear-of-radiation This is not a scientific article but is a summary of observed effects after 70 yrs of followup. I hope this can assuage your concern about your radiation dose.

1. I can't go places without cars.
2. I have a say more or less in the way how I or others drive - if someone is tired I'm not riding shotgun with him and I'll try to talk him out of driving.

Some risks are or are perceived as acceptable or necessary. WRT to cars much more innocent persons are hurt by cars than the operators of the vehicles. You really have little control over that risk. Healthcare like driving need consideration of the possible benefits of medical procedures versus any untoward consequences. How much unhealthy processed food do you eat? How much liquid do you drink from plastic bottles, How much food baked at high temperature(>120 deg C) to you eat.

I'm not sure if it will extend my life but the final diagnostic is that my spines are fine although some parts of it were "compressed",

I do not know the reason you went to see a doctor presumably you had a concern. He did what he thought was necessary and found not much out of the ordinary except "a slight compression"

I don't know what that means.

Ask the doctor for any information you need don't go home with questions. My son-in-law is British and my daughter has just been diagnosed with a serious condition. My wife and I have attended may conferences with the doctors about treatment etc. and one thing my wife noted is his reluctance to ask questions or clarification of the doctors comments. In the US it is perfectly natural to as questions and even give the physician the "third degree" if necessary for we are the customers and have a right to know and participate in our medical care.

agree, the problem is now I don't really see the benefit here, it feels more like the doctor was lazy and tried to be sure instead of asking me to return a month later...

The benefit IMO is that he found nothing so for what ever reason you went to see him. Negative tests are a benefit. Would you have been happier if he found a bone tumor compressing your spine?

Well the doctor prescribed for my Xray, after view the reports said the xray I gave him the first time had "false imagery"(which led him to believe I may have some sort of existing condition, which "may cause my spine to slip off when I'm older and trying to lift heavy objects"). I'm now really mad because 1. he could have asked if I had xrays from before (which I did) and take a look at it. Instead he was lazy, 2. I asked him at least twice "the radiation involved is rather low, right?" and he answered yes. 3. He prescribed the highest dose, 4 views knowing I had 2 views 20 days ago in a quite casual manner.

I am not familiar with the term "false imagery" which might mean artifact an unexpected image defect which might have interfered with the part of the image which was of interest. Did he know you had two previous xrays and refused to look at them , was he a different doctor?

I get what you are saying, but, just for sure - can we exclude the possibility that manufactures in my country, in order to compete with imported DRs, deliberately boost the rays emitted and then attenuate it at the receiving panel/receptor (assuming that is the proper term)? So a proper image could be produced? Or that's rather silly and unfeasible?

It seems me that the EU is as picky with xray specs as the US so no I do not think that the machine was buggered say in Volkswagen fashion.

Sigh... I think I know what you mean and I find it reaasonable but my entire lower torso was exposed... with that amount... shouldn't the risk for some part like lung be deducted but belly be increased?

Typically the risk for cancer is given for all possible sites when the whole body is exposed. Each organ has its own sensitivity to radiation but by and large if you restrict the exposed region to a certain part of the body you will not cause cancers in any other part.and the overall risk is reduced.