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Technical Discussions
Michael
Michael
22:12 Aug-05-2016
Absorbe dose

Hello,
I need little help with absorbe dose mSv from x ray. I am working in PL like NDT operator for 3 years, I have UT2 and VT2. In RT i am just learner/heleper. I was working alone with RT lamp I was after night in job, very tired. Problem is i went on exposition, I have not seen that lamp is working my signaliser was very silent. My mistake my fault.
Main question is how much mSv could i get.
Parameters are below:140 kV; 3,2 mA of direction X ray (ERESCO 300 MF4-R) focal lenght 900 mm; time was about 40 s of my being not directly on beam. I was walking and change negative so I was close, collimator was on the level my calf but i had bend down. I am man 90 kg 186 cm. After 30s to 40 s I saw that lamp is working and I run away. I had dosimetry cassette so after 3 months i will know how much I got but i am little nervous. I dont know if should I be stress ( about health or work)?
Norm is 20 mSv per year. I don't want to ask third level in my company cos they will say or think that I am not proffesional (cos I am not but I am trying and working to be). Also I will response that I shouldnt be alone with out RT 1 and after working night. It can be bad disscusion, I dont need it. I want learn more get lesson from this incident.
I am trying to estimate this but my resoult was 228000 mSv, bull...t The help is although to gauge.
thx and best regards,
Michael

 
 Reply 
 
GK
Engineering,
MSL, Thailand, Joined Dec 2012, 8

GK

Engineering,
MSL,
Thailand,
Joined Dec 2012
8
03:44 Aug-10-2016
Re: Absorbe dose
In Reply to Michael at 22:12 Aug-05-2016 (Opening).

Hi Michael,

Please consult a doctor first without any doubt and get your blood test done. Its a Frequent blood tests over several days enable medical personnel to look for drops in disease-fighting white blood cells and abnormal changes in the DNA of blood cells.
No one in this world is perfect. Just do your job and follow the safety procedure and share your experience to spread the awareness.
Professionalism is to follow the proper procedure, not with hiding the exact situation and finding a bypass.

Cheersss.

 
 Reply 
 
Volodymyr Stypura
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr Stypura

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
10:01 Aug-10-2016
Re: Absorbe dose
In Reply to Michael at 22:12 Aug-05-2016 (Opening).

You can calculate the worst result, and then refine the result.
Imagine that all the energy is converted into the energy of the radiation, the efficiency of 100%.
E=140 kV * 3,2 mA * 40 s = 17920 J (Joule)
Now you have to calculate the specific energy of the radiation on the distance at which you stayed longest near the lamp.
Eo = E / S (area square meters of sphere with radius - distance where you stayed)
I mean, distance was 1m, R = 1m
S = 4 * Pi * R*R = 4 * 3,14 * 1 * 1 = 12,56 sq. meters.
Eo = 17920 / 12,56 = 1427 J - energy per 1 sq.meter where you stayed.

Area of your body front is appx. Mosteller, 1987 formula (90 kg 186 cm)
S (all area) = 2,16,
S (one side) = 2,16/2= 1,08 sq/.meters

E (You max catch) = Eo * S (your one side body) = 1427 J * 1,08 = 1541 J.
1541 J - dose on your body, BUT -----

Parts of your body absorb radiation differently.
20% (testicles) - 5%(more others) Average - 10%.

You absobed average: 1541*10% = 154,1 J
If all current energy transform in x-Ray, BUT -----

Efficiency current energy transform in x-Ray is not 100%, but 0,2-0,05%
the worst result for you - 0,2% (more energy transform to x-Ray)
this way, you recieved not 154,1 J , but less
154,1 J * 0,2% = 3 J

3 J per all your body, but your wight is 90 kg.
3J / 90 kg = 0,034 J/kg = 0,034 Gr (Gray)
We calculated, that only 20%-5% energy transformed to x-Ray.
This way we can compare this energy with Norm - 20 mSv per year.

So, you could catch 34 mSv for one exposition...
BUT -----
radiation is non-evenly distributed, with a maximum of focus.
I mean, you have passport for x-Ray lamp.
There is chart of distribution x-Ray dependly of squint angle of main direction.
(directional chart)
I mean, less than 50% direct aside of focus.
So, you catch 17 mSv for one exposition, and you can calculate
better if you try to make x-film, when film not in front of focus, and in the side where you stayed during accident.
Measure density of film and calculate, what is efiiciency x-Ray on your direction.
34 mSv * efficiency = less than 17 mSv.

FINAL
Worst result for
Parts of your body absorb radiation differently.
We count that average 10%. In two times more 20% (testicles).
17 mSv * 2 = 34 mSv
Not good!
The total time of sperm maturation lasts up to 70 days.
After exposition You sure got sperm DNA damage.
After 70 days you need in ivestigation DNA quality of sperm.
And you also need in monitoring of thyroid gland, I think 2 times per year.
Monitiryng "bad" birthmarks also.
For other parts of body exposition is not critical.

I think ALL WILL BE GOOD!
Best regard's, Volodymyr

 
 Reply 
 
volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
10:14 Aug-10-2016
Re: Absorbe dose
In Reply to Michael at 22:12 Aug-05-2016 (Opening).

BUT you must take in account? than this exposition was fo one time!
I agree with Mr.GK, bllod analise of cource!!!

 
 Reply 
 
Michael
Michael
17:57 Aug-10-2016
Re: Absorbe dose
In Reply to volodymyr at 10:14 Aug-10-2016 .

Thanks for all responses and advises.
Result of Volodymyr is not so optimistic like i wanted. But this is worst option so i think i had not cath so much. I am worry about testicles but I dont plan children in nearest time but cancer is always possible. Result is avarage and theoretical so I will see on cassette, I will share this when I got.
Also i spoke with one guy who had same accident like me but with bigger paremeters (180 kV; 3,2mA). He said that he got 1mSv on dosimetry cassette (he was working in bunker and it was one accident on 3 months).
I cheked negatives, difference betwen was 1,3 D (with good time was 3,6 D; with shorter time was 2,3 D so its for evaluating).
I dont need count this. Everthing is on cassette. I just wanted to know is it reason to worry about health or work. For sure i will chek my blood. I change signalisator for louder and trying to work normal.
again thanks for responses and advises.
Michael

 
 Reply 
 
Volodymyr
Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company, Portugal, Joined Mar 2016, 25

Volodymyr

Engineering, Deputy Director for Technical Issues/Head of Testing Laboratory/Chief of department/NDT
Joint Stock Company,
Portugal,
Joined Mar 2016
25
19:12 Aug-10-2016
Re: Absorbe dose
In Reply to Michael at 22:12 Aug-05-2016 (Opening).

I took into account the strict parameters that the worst-case.
Use as manual and example!
If you could to know some information, could calculate by yourself using proportion.

1. Coefficient energy transform for this lamp. See passport. I use 0,2%, and exist lamps with coefficient 0,03%. Proportion: (17 mSv/0,2%)*0,03%=2,55 mSv!!!

2. Directional chart of x-Ray device. I mean, less than 50% direct aside of focus, but I maked experiments with lamp made in 1963-1970, wich made 40 years ago. With bad chart of distribution x-Ray dependly of squint angle. New lamps are better, for example I have found directional effectivity in direction 30o less than 15%.
(17 mSv/50%)*15% = 5,1 mSv and took in account 1.
(5,1 mSv/0,2%)*0,03% = 0,765 mSv.

3. I have found, that during gastric fluoroscopy in 1980-1995, patients catch
150-50 mSv. For one exposition.
Exist uncertainties of cancer risk at doses less than 50 mSv, patients undergoing laparoscopic bariatric surgery may receive radiation doses from postoperative diagnostic imaging tests that increase their lifetime cancer risk.

I think, that you will continue your career in RT, but next 1-2 months make monitoring your some health options.
Good luck, Michael!

 
 Reply 
 
Joe Buckley
Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT, United Kingdom, Joined Oct 1999, 526

Joe Buckley

Consultant, ASNT L-III, Honorary Secretary of BINDT
Level X NDT, BINDT,
United Kingdom,
Joined Oct 1999
526
21:40 Aug-10-2016
Re: Absorbe dose
In Reply to Volodymyr at 19:12 Aug-10-2016 .

Many things are worrying about this:

"In RT i am just learner/heleper. I was working alone with RT lamp I was after night in job, very tired. "

"my signaliser was very silent."

"My mistake my fault."

" I don't want to ask third level in my company cos they will say or think that I am not proffesional (cos I am not but I am trying and working to be)."

Firstly No way is this your fault. Thats is what learning is about. You carry out things until they become second nature. Even when experienced, tired people, working with dangerous (and in this case maybe defective) equipment, sometimes make mistakes. Any work system should take this into account. A learner/helper should never be working unsupervised. Its your boss who should lose his job.

That you feel unable to consult with the Level 3 is in itself worrying, This implies the kind of work environment where any mistakes will be covered up. This is a salutary lesson for those of us who have spent our lives working in slightly more forgiving environments.

I hope your health is OK and you progress in your career. You sound like the kind of guy the future of our industry needs.

All the very best for the future.

 
 Reply 
 
Michael
Michael
20:51 Aug-11-2016
Re: Absorbe dose
In Reply to Joe Buckley at 21:40 Aug-10-2016 .

Hi Everyone,
tomorow I am going to test my blood. In all I agree but I one I must say not. I am not cover it.
Like I wrote it was 28th hour of my work. It was hard day first, I couldnt catch time for pipes DN 300 I had too long negatives and I couldnt got density in ends of negatives. So I left this and I started to do what I knew how to do it (plates from focal lenght 1000 mm). It was case of accident. When I went on exposition I call to my direct supervisor (enginer with levels 2) and told him what happend, he said pack the lamp and go back.
I am not hiding anything cos I didnt destroy my dosimeter cassette. I could leave it and work without but I didnt. Ok I think I little panic, it was my first serious accident and I was wonder how serious could be. I like work alone cos its real tests of my skills but I agree that system is not good. Normaly we are work in pairs but now is holiday season. They should make me even RT1 but what to do if they didnt. My fault was that I've been to greed of work and knowlege. My bosses fault is they are to greed for orderes - tests - money. System is bad cos I need extrahours to earn average salary but my motivation was also to learn proffesion and in future make certifications in other methods (I have VT2 UT2 but from another work). No matter how much I will try there is always the human factor and my limits, accidents happens.
In case of counting and chek efficiency energy transform in x-Ray I will do it on thusday cos now I am working out of company. When I will got resaults of blood tests I will share it.
thanks
Michael

 
 Reply 
 
Nigel Armstrong
Engineering, - Specialist services
United Kingdom, Joined Oct 2000, 1096

Nigel Armstrong

Engineering, - Specialist services
United Kingdom,
Joined Oct 2000
1096
08:32 Aug-12-2016
Re: Absorbe dose
In Reply to Michael at 20:51 Aug-11-2016 .

'In RT i am just learner/heleper (sic). I was working alone with RT lamp'

' it was 28th hour of my work.'

These circumstances must be illegal and will be in contravention of national and international employment laws and the laws on radiation work / protection. You now know this and must inform yourself on the legal limits and abide by them no matter what your employer requires of you. I do query whether your employer knew of all these conditions and condoned them.

It makes no sense to progress one's career by breaking the law!

 
 Reply 
 
Michael
Michael
15:07 Aug-13-2016
Re: Absorbe dose
In Reply to Nigel Armstrong at 08:32 Aug-12-2016 .

This not sounds good but... You are right. World is not perfect (see industry in third world). In my opinion there is no articles which can replace reasonable attitude. But articles are written for something. Its hard to change specify of branch when You are little gear of this machine. Always I could say not but I trusted (too much) my self. I dont want make career, I just want to do good NDT and earn normal.
I dont know if he know about this cocnrete situation but i think he is aware of whole situation. (First i am trying find my fault later in others)
I made blood tests, simple morphology. Doctor said that everthing is in the norm (RBC, WBC, MCH, LYM, MONO, PLT and others are in avarage) He said that I am able to blood donation for transfusion. Of course It can be more effects and appear later. Now waiting the september and reading from dosimetry cassette.
thanks for posts (especially for Volodymyr who answer direct and explain how to count)

 
 Reply 
 

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