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Homemade X-ray machine question

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Proud Mary

Tue May 03 2011, 09:24PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

James wrote ...

Even 4mA at 70 kVp is dim enough on a fast intensifier screen to need a long exposure with a sensitive camera.

I wouldn't call 0.1 or 0.2 sec 'a long exposure.'

This is a science forum, where a knowledge of exceptions is to be respected, and where doubtful propositions can expect to be queried.

James

Tue May 03 2011, 10:43PM

Registered Member #3610 Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506

Who is managing 0.1 or 0.2 second exposures using a digital camera to image a film intensifier screen? My own experience suggests 10-20 seconds at 4mA for a reasonable exposure, FAR longer than film. The folks using rectifier tubes have mentioned exposure times in the range of minutes.

.1-.2 is around the exposure range for a proper digital x-ray sensor using a 4mA dental head as intended to image a few teeth. The little dental sensors go for around $2K, while the larger size medical diagnostic type my friend's veterinary clinic has was US$80K, a bit out of the typical hobbyist budget. They use a 250 mA rotating anode head with that.

I have to make some assumptions or generalizations, unless I want to write a novel here.

hsieh

Wed May 04 2011, 12:16AM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

James wrote ...

100kV sounds reasonable for a dental machine, but in practice it was probably operated at 60-70kVp. Usually the voltage is adjustable. For a larger general radiography machine utilizing a rotating anode tube, 300kVp is possible, but 100-125 kVp is much more typical. 300mA peak current is not too unusual.

What I see at that time is not a dental X-ray machine.It is an X-ray machine for chest X-Ray.

So if I'm planning to experiment with 50KV and 2x2 rectifier vacuum tube, what should I do to shield the x-ray emit by 2X2?

I'm also curious about that if "glow in the dark" materials can detect X-ray.

magnet18

Wed May 04 2011, 12:39AM

Registered Member #3766 Joined: Sun Mar 20 2011, 05:39AM
Location:

Posts: 624

chest X-ray machines should be able to take pictures just like a dental one, if anything it should be more powerful, and bigger is always better

James

Wed May 04 2011, 12:43AM

Registered Member #3610 Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506

Chest x-rays will be general radiography, rotating anode tube, normally with an adjustable collimator for shaping the beam. Typically double the voltage and several times the current of a dental machine. Most of these machines I've seen are pretty similar to the rest.

Get some lead sheet, 1mm thick should be plenty adequate for 50 kVp x-rays. Form a box or can around whatever you have the tube enclosed in, real x-ray tubes are (almost?) always immersed in oil for both insulation and cooling.

I've seen reports of some glow in the dark materials responding to x-rays, but a rare earth intensifier works far better. I've seen film cassettes containing those sell for less than US$10 on ebay. There are a lot of surplus ones around since hospitals and clinics are starting to switch over to digital.

hsieh

Wed May 04 2011, 04:32AM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

James wrote ...

I've seen film cassettes containing those sell for less than US$10 on ebay. There are a lot of surplus ones around since hospitals and clinics are starting to switch over to digital.

I think it is difficult for me to get these things.In Taiwan,it is illegal to sell medical related things on Internet.And if I buy it on ebay,the shipping may be unacceptably high.

So finding alternatives seems to be the only way.

I have a box my father used to develop dental X-ray films before switch to digital.Maybe I can use it to develop my X-ray photos.

Adam Munich

Wed May 04 2011, 04:53AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Maybe you could find someone to buy the cassete, rip out the intensifier screen and put that in one of those big yellow envelopes for you?

James

Wed May 04 2011, 07:53AM

Registered Member #3610 Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506

That's what I was about to suggest as well. The screens themselves are just a sheet of stiff plastic, it's doubtful that anyone who saw one separately would have any idea what it was.

Also if your father is a dentist, he may be able to legitimately get some cassettes from a place that sells used medical equipment locally, if there is such a place there.

radhoo

Wed May 04 2011, 10:51AM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

Grenadier wrote ...

Maybe you could find someone to buy the cassete, rip out the intensifier screen and put that in one of those big yellow envelopes for you?

This is what I did, just that the seller didn't want to remove the metallic cassette even if I still payed the full price, so I had to have them shipped to someone in the US, this person took them apart and mailed me the screens by regular mail. A bit too much hassle, but in the end got what I needed.

hsieh

Wed May 04 2011, 12:54PM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

After asking a lot of stores,I finally bought a box of B&W photographic paper.

The same store also sells the chemicals necessary to develop it.But I have to buy a large bottle if I want to buy it.So I didn't.

I ask some local photo studio if I can buy small amount of those chemicals,but they say they no longer develop B&W photos.

I remember reading that it is possible to develop photo using easy to obtain things in a book edition of MacGyver story,Is this really possible?

Or my father may have some unused chemicals for develop X-ray film.Can I use them to develop photographic paper?
I don't want to use my father's x-ray films because they are very small(about 3CM*3CM)

I found this.Will this work?

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