Use of X-ray film: technical discussion with example images

[seezee]

I have read and I think, I have understood how the X-ray film works. I will mention what I know hoping that someone may correct me if I am wrong. Regular current film is panchromatic and has light sensitive silver emulsion on one side. They also place another emulsion (anti-halation) in the reverse. This is the layer that many remove by washing the film prior to development.

The X-ray film does not need to be panchromatic, so it is orthochromatic (like the old original films). They (Kodak and Fuji) place a light sensitive silver emulsion on one side, and maybe an anti-halation emulsion in the other side. However, the x-rays do not produce light to impress the sensitive emulsion. That is when the manufacturers, place another emulsion on the back of the film that react to the x-rays by ignition producing light during the reaction. That light is the one that is going to create the image on the silver emulsion. My thought is that that emulsion that reacts with the x-rays to produce light is also mixed with anti-halation. I am not sure if this emulsion gets washed with the pre-washed, it may be. I am pre-washing for 5 minutes the x-ray film. I have heard that some photographers scrap or remove the not needed emulsion. The problem for me would be identifying which one is the side holding the image. Any comments or enlightenment?

In a clinical setting, the x-rays pass thru the film and excite pixels on a phosphorescent screen (an "intensifier screen"). The phosphors emit visible light of a wavelength that matches the sensitivity of the silver halides on the film and exposes both layers. 2 layers = double film sensitivity; increased sensitivity reduces the patient's exposure to hard radiation. Conventional (double-emulsion) x-ray film has no anti-halation layer.

The big exception is dental x-rays. A much higher dose of x-rays is needed because no one has invented a tiny fluorescing screen that could go in a patient's mouth.

[seezee]

I always treat these like single sided sheet film, so the side of the film that faces the lens is treated as the emulsion side and is kept up in throughout development. You could notch it, but if you are used to darkroom work it should be simple to keep track since that side always stays up.

The x-ray film I've used has rounded corners. Since I cut each sheet into 4 negatives there's always a rounded corner that acts as the film notch for me. Always place it the same way and Bob's your uncle.

[seezee]

Argh, wish I saw that earlier! Now I'm stuck with 100 sheets of double-sided green Fuji HR-U

I've learned about how X-Ray film works from this Instructable, interesting read:

https://www.instructables.com/id/Homemade-Xray-Machine/

No sweat. It's cheap and it's a great way to learn. The main things is to handle it carefully. Your cutting area needs to be very clean; lay down an old, but laundered, cotton sheet under your guillotine cutter to keep the film from dropping onto an abrasive surface. Wipe down the cutter itself before using. Wear exam gloves while working with the film. Once the film is wet it becomes very soft; that's when most scratches occur. The other times are when loading / unloading the holders and during processing. A sheet of glass in the bottom of your tray may help. If the film gets stuck to the tray bottom slide a piece of scrap film under it and gently pry it up.

[seezee]

Use whatever fixer you have.

I use TF5 mixed with distilled water, but fixer only must be fresh enough, meaning not exhausted.

Save exposed but not processed scraps of X-ray for testing 'clearing time'.

I've used TF-4 and Kodafix. Plan to use TF-5 when I run out of TF-4. Supposedly acid-based fixers (Kodafix) can bleach staining developers, e.g., Pyro, but since you're using Rodinal it won't matter.

[seezee]

My qualm with sharpness is/was mostly with processes like salt prints, where I use an exposure box with uv tubes; this is a diffuse light source, which I think is an important factor. I also like to make fairly small prints, so fine detail is important to me.

I've tried just about any development approach within my reach. I either got uneven development, scratches, or both. Plastic trays, plastic trays with a sheet of glass on the bottom, glass trays, oven baking trays - you name it, I probably tried it at some point. Continuous agitation, with or without flipping the sheet, intermittent...no luck. The best results I got with a non-stick oven baking tray with at least 500ml of developer, but even then, I used to get small scratches in the corners of the film.

With Ektascan BR/A, no scratches at all. Frankly, because single sided film (xray or eg Foma) is still within reach, I just don't see the point in trying to make an in my view inferior alternative work. I've gone through 2-3 100 sheet boxes, most of them cut to 4x5, trying to find a dependable and reproducible method. I guess I'm just clumsy!

It's okay though, I learned a lot doing this. And anyone who insists on the beauty of double sided film has my blessing, honestly. It's just not for me.

I have to agree that single-sided is sharper. I've used both & it's pretty clear from my results.

[Tin Can]

Perhaps Ray parallelism or lack thereof creates unsharp as the 2 emulsions are a distance apart.

In actual X-Ray usage of X-Ray films the light emitting conversion plate would act as a 1 to 1 contact print. Both emulsions would be sharp and identical. Backup as it were. A safety factor built into X-Ray 2X films to lessen any scratches.

Using large sheets of X-Ray film pictorially with a small lens would create a spreading cone of light rays and non identical imaging.

Ektascan 1X was made for 1 to 1 copying of CRT screens, developed for data storage. Common still at 8X10", but was available as 14X17".

Long ago I used a special Polaroid camera to capture fleeting oscilloscope images.

Data acquisition has come a long way.

I have to agree that single-sided is sharper. I've used both & it's pretty clear from my results.

[pepeguitarra]

In a clinical setting, the x-rays pass thru the film and excite pixels on a phosphorescent screen (an "intensifier screen"). The phosphors emit visible light of a wavelength that matches the sensitivity of the silver halides on the film and exposes both layers. 2 layers = double film sensitivity; increased sensitivity reduces the patient's exposure to hard radiation. Conventional (double-emulsion) x-ray film has no anti-halation layer.

The big exception is dental x-rays. A much higher dose of x-rays is needed because no one has invented a tiny fluorescing screen that could go in a patient's mouth.

THAT is very informative. I am worried now about my dentist and his insistence to take x-rays every time I go there. My dentist now uses digital sensor for the x-rays. Do you know if the amount of x-rays used is less than before? I hope it is less. Thanks, Pepe.

[Corran]

I printed (digitally) one 8x10 double-sided x-ray negative to 40x32 and it was plenty sharp. Mostly I just contact print 8x10 though, and IMO anyone shooting 8x10 for contact prints should be plenty happy with the results, if they develop it well and don't scratch it of course. The most noticeable thing to me about Fuji HR-T x-ray film is the lack of anti-halation layer, making things have a slight "bloom" depending on the light and contrast. I do agree it's less sharp, I just don't think it matters.

I may be going back to x-ray for a bit for 8x10 shooting. I have been shooting up my remaining normal films and forget that x-ray is a fine alternative, with some carefulness.

In fact, I just remembered I shot side-by-side a sheet of Fuji HR-T and Ilford Delta 100 years ago. You can easily tell which is which from the highlights blooming. Sharpness is obviously more on the Delta, but not significantly. I ended up liking the "bloom" and printed the x-ray image, not the Delta image. Here's a crop from each:

[Tin Can]

And Kodak/Carestream X-Ray films are T-Grain just as Delta and TMax.

Carestream T-Grain® emulsion that delivers high visibility of details without sacrificing speed.

The glow is a plus!

[Corran]

Perhaps I will finally give the single-sided a try - if it results in less scratching then that's a win overall. I see Carestream Green is $58 for 100 sheets at zzmedical (or buy 2 boxes and it's $55 each). Anywhere cheaper? I hadn't priced Ilford Delta in a while since I had a few boxes in the freezer but I see at B&H it's $120 for 25 sheets...

Edit: oops! I guess that Carestream film is double-sided from what I read elsewhere. I'm not that up on the single-sided stuff.