X-Ray Imaging

Hello Mrinny,

Mr Google's Search Engine using Search Terms: lead thickness xray medical quickly produced this

Have a look here, please:

http://www.hps.org/publicinformation/ate/q1317.html

also this:

http://registration.ncrponline.org/Publications/Reports/Misc_PDFs/Section%204.pdf

Kind Regards.....

You can't stop it. You just reduce it to an acceptable level. Look at the concept of half-thickness to see how this works.

Why not stop?

see the series, 1,1/2,1/4,.. 1/zn...

its a convergeny series. has ofcause limit.

In fact, for medical shield. 2--3mm is enough.

Exponential curves approach zero; they do not converge to zero. Even a kilometer of lead will let the odd x-ray through. You have to decide how much you can allow. But, you cannot stop it all.

Of course you can stop it. Medical x-ray levels are very low compared to industrial radiation as used in non destructive testing. Even some of those levels were comfortably stopped by enough mass between you and the source.

Question is , why do you want to stop it? If it is medical film, the purpose is for the radiation to reach it right? If you are thinking about protecting the film against unwanted radiation you should go overkill to be confident you do not get stray soiling of the film. We always kept our ndt films in titanium lead boxes weighing well over 25 Kg each and they could only contain 10 or so films. Heavy work.

I am doing an experiment that requires me to place special labels for samples that are to be imaged using x-rays. I have to place certain symbols etc on the film. These are very tiny.

The problem is that the hospitals have small lead letters for names etc but no symbols. Thus I need to design small id tags and get them made.

The problem is that the hospitals have small lead letters for names etc but no symbols. Thus I need to design small id tags and get them made.

You have answered your own question, make them the same thickness, size and density as type letters you are using now.

Branson

I know but u see, these institutions in my6 area have their rules regarding entry and they are giving me enough trouble already.

I have to go as a regular person wanting a regular x-ray done. They do not answer questions. I noticed their letters and requested for a few to be arranged as symbols but in vain.

Now I simply bring the stuff i want imaged wearing whatever it needs to on itself (only lead is allowed) and pay and leave.

Sadly such is the case here. My community here is much more approachable.

There are a number of companies who provide custom letters and symbols. Simply Google "lead markers x-ray" to find them. But, if you want to do this yourself, use 0.125" lead (or 3 mm). Check to see if that fits the film holder; if not drop down to 0.094" (or 2 mm). Actually, I don't know the standard thicknesses for lead, but it doesn't much matter for this application - 2.6 mm or 3 mm will both stand out against a human body.

Do you know any typesetters? (Are there any typesetters left other than in the grave marker business?). Ask them for samples.

I'm guessing you know that, if you cast these characters, you want to use an alloy and a whole, whole, lot of precautions.

Why not simply buy some "ready-made" that you can carve-&-solder as necessary to make the exact figures that you want?... See:

http://www.buckscountyimaging.com/idmarkers.asp

or

http://www.pnwx.com/Accessories/Markers/?Sr=Go&gclid=CJiW8Yy4y5ACFQcygQodx0eONw

or a multitude of other "Google-sources". It ain't rocket science, really... even though TVP45 was (in Post 6) 100% correct that you can't completely stop all xrays from any "worthy" source, you most certainly CAN reduce the passage of xrays thru shielding to an acceptable level (meaning "Safe", for either the technicians OR for the exposure-factor of the film).

Thicker I.D. markers will simply make the image-ID appear in different contrast than if they were thinner. They'll still be legible, so long as you're in-the-ballpark.

Surely the strength of the radiation needs to be calculated into the answer in some way? and you did not tell us either the power or the distance......!!!!

He told its for medical use, eventually, its below 150Kv max. and energy is low as well.

3mm enough to shield. no any problem.

if he need lead number and alphabits, I can offer that, include dark bag etc whole tools.

Thanx guys,

Some of the links were actuaaly selling custom made symbols.

as thin as aluminum foil.

foil is at 0.03mm level.

Then that meatal is not lead right? Coz everyone here says 3mm lead would suffice.

If your material is as thin as aluminium foil then what material are you using? Does it just show as a grey patch on the screen or shows clearly?

We used some lead alloy and it was only 1mm thick max. We did not use medical x-ray but industrial all sorts for non destructive testing. Get a set from those guys and be done with it.

Hi, case491,

I guess you use x-ray diffraction instument. because your shield material is only 1mm.

No we used (long time ago as it was in my apprentice period) isotope cobalt 60 and others as permanent sources and electrical x-ray tubes as generated sources. We shot photos through steel pipes, bends, apertures and vessel walls for safety on oil refinery plants and weld quality control.

The shields were enormous and our bunker was 1.5 meter thick concrete and 3 meter under ground. Out in the field we used no shields, only calculated distance for protection and Geiger counters to check.

When I said 1 mm thick, we were talking about the ident letters. I suppose 3 inches of lead would have stopped what we were playing with but there was no need. Most of our work was out in the refinery with our set exclusion zones or in the deep of night with no personnel around.

oh, I see.

Hello, I have worked in the x-ray industry for over 15 years and think I can answer your question.

If you are talking about stopping it from exposing your x-ray film, it's not so much the x-rays that make the exposure as the screens. The radiation passes through the object and strikes the x-ray screen then the screen glows - exposing the film. The areas where the screen does not glow will remain unexposed to x-rays.

The lead markers people use block the beam before it reaches the cassette, these are something like .3mm. You also see people aluminum foil tape on the inside of the screens to block the emitted light, hence not exposing the film. They use this for the ID paper that prints the name on the film after it's removed from the cassette and before processing. The foil is much thinner than regular aluminum foil.

As far as lead blocking x-rays, it does to some extent. If you use enough radiation however, nothing will stop it. I have seen people x-ray their fingers right through lead gloves. It depends on the kVp - Over 80kVp and you could fog film inside a cassette if it did not have a screen, provided you use enough MAS with it.

If your using a low kVp, like 10 or 20 with a short time and low MA, heavy cardboard will stop it. I would think you can answer your particular question with a simple test. Find some thin metal sheets at the hardware store and stack them up into a wedge (one thickness, then two, three etc, like steps) do your exposure and select the minimum thickness need to get a DMIN exposure on your film. Measure the thickness and use that value to cover what you need blocked.

My store is at www.buckscountyimaging.com, please contact me with any questions...

I can offer exposure suit as well.

Depends on the output power of the x-ray machine?