xray film
X-ray film is a medium used to record the image of an exposed body part for x ray. This film is generally similar to photographic film. The difference in radiographic film is that one side or both of it is radiosensitive or light sensitive. The emulsion material is coated or coated so that it can be used with the intensifying screen by exposing it on top of this radiographic film and creating a latent image And later, by processing it, the latent image is converted into a visible image. The structure of the radiographic film is as follows
Structure of x ray film
Often the film is produced from a lower layer or layer which is as follows -
1.base layer
It is the central or central part of the x ray film that supports the photographic emulsion layer from both sides.
This base part should be non-folding and non-breaking. It should be able to bear any type of geometric distortion (temperature, pressure) so that it can be processed.The base provides a transparent, uniform visual background to the film.
First the x ray film plate consisted of an emulsion layer on both sides of a glass base. But during the First World War, belzium shut down its supply of photographic glass. Then the demand for xray film base started coming up all over the world.
In 1914, cellulose triacetate was first used as a film base. And by 1924 completely cellulose tri acetate was used for the base.Cellulose tri acetate is a flammable material. Hence polyester base was manufactured in the 1960s and polyester base is also used at present. The dimensional stability of the polyester base is very good. The film base is a transparent material. Blue tint was given inside the film base for the first time in 1933 to reduce the fatigue of the radiographer's eyes. Blue tint is also currently used.The thickness of the CTA (cellulose tri acitate) base is 8 miles and the thickness of the polyester base is 7 miles. Which is 0.01 inch = 1 mile.
2.adhesive layer
Most emulsion layers do not attach easily to the base layer. Hence, its main function is to glue two layers together. That persist between the emulsion and the base layer.
3. Emulsion layer
This is the most active layer of the Xray film. Which are located between the protective layer and the adhesive layer. Radiographic images are produced on this layer. This layer mainly consists of two components.
A. Gelatin medium
B. Silver halide crystal (grain)
Which are found as particles in the silver halide gelatin medium. Apart from these, other chemical substances such as weighting agent, centicogluent, and hardner are also added to the emulsion.In order to obtain a good quality image on the film, 90–99% silver bromide (AgBr) and 1–10% silver iodide (AgI) are found in the silver halide crystals. The emulsion is the part of the xray film on which xray photons work and produce the image. For this, the emulsion must be cleaned so that the xray photon can easily enter the emulsion. And the processing solution can easily enter the emulsion evenly. The silver halide crystals have a thickness of 0.1 –1.5 micrometers.
Property of emulsion
To increase the quality of the radiograph, the emulsion of the film should have the following qualities
A. Speed / sensitivity -: Speed or sensitivity emulsion has the ability to react with xray, ie when the emulsion is able to provide good density and good contrast to the film at very low exposure, then this type of emulsion is called fast or high speed emulsion. is. Normal films are fast films.
B. Latitude -: Latitude has the ability to show contrast of radiographic images of emulsions over a long scale from white to black with a long range of Tons. The letitude of the emulsion should be high so that the mistakes in the exposure have the least impact on the image of the film.
4. protective layer
During the film handling, a protective layer is used to protect the emulsion part from scratching and damage. These layers are also made of gelatin.
