What is an Intensifying Screen In X-ray ?
Intensifying screens are the thin sheets of fluorescent material which are used in the x-ray cassette. The intensifying screen converts an x-ray photon energy into visible light. It reduce the patient radiation dose and increase the film contrast. In conventional radiography , The double emulsion film is used. The cassettes have a pair of screens that both side of the x-ray film.
The intensifying screen consists of four layer.
1) Protective layer.
2) Phosphor.
3) Reflecting layer.
4) Base.
1) Protective layer :- The protective layer is outer layer of intensifying screen, which is facing the x-ray film. It help to protect the screen from abrasion and damage caused by handling. It also provide formation of static electricity, and provides a surface for cleaning.
2) Phosphor layer:- The phosphor is called fluorescent material of the intensifying screen. In phosphor, calcium tungsten, zinc cadmium sulfide, cesium iodide and barium strontium sulfate. The phosphor absorb x-ray photon energy and convert the absorbed radiation into many light photons. Now-a- days in phosphor, rare earth phosphor such as Gadolinium Oxysulfide and Lathanaum Oxysulfide, Lathanaum bromide and Yttrium tantalate are used in screen.]
3) Reflecting layer :- The Reflecting layer is white substance, such as titanium dioxide or magnesium oxide. It is reflects light towards the phosphor and make the light emission isotropic. The reflecting layer increase the efficiency of the intensifying screen by doubling the number of light photon.
4) Base :- The base is made of polyester or cellulose acetate. The size of base is 1 mm thick. The base is must be strong, chemically inert , flexible, moisture resistant.
What Are The Types Of Intensifying Screens.?
Following types of intensifying screens.
1) Diagnostic Intensifying Screens.
2) Fluorescent intensifying Screen.
3) Photofluorographic intensifying screen.
1) Diagnostic Intensifying Screens :- The diagnostic intensifying screen is used in medical radiography. The diagnostic intensifying are mounted in pair in a x-ray cassette. The front side of intensifying screen is slightly thinner then the back side of intensifying screen of the cassette. This tend to even out the exposure of light to both sides of the x-ray film. The intensifying screen are mounted inside the cassette and the emulsion are kept between the both intensifying screen in the cassette. The x-ray energy absorbed by the screen and converted into visible light. Some x-ray film contain single intensifying screen which is slower but produce fine details in x-ray film. In this screen made up of calcium tungsten.
2) Fluorescent Intensifying Screen :- The fluorescent intensifying screen was commonly used in fluoroscopy system. The fluorescent intensifying screen made up of Zinc cadmium sulfide ( ZnCdS ) material which emitted a yellow green light that was more easily seen in a darkened room. The fluoroscopy screen has property of phosphorescence means the phosphor continues to be luminescent after the exciting energy is removed. The Radiologist viewed the fluoroscopic screen directly. It was necessary to cover the screen with lead glass to provide protection from the ionizing x-rays.
3) Photofluorographic intensifying screen:- The Photofluorographic intensifying screen was used in the procedure of Photofluorographic. It provided a technique for mass chest radiography in which exposure to patient and intensifying screen was continuous until the fluorescence from the screen reached a level that triggered a camera shutter. Now a photograph was made of the image on the screen from the opposite side and made of zinc sulfide. This screen used because this unit made for portable and proper uniform exposure to the film was assured. So that the radiation dose of the patient is high.
What Are The Advantages Of Intensifying Screen?
The main advantages of Intensifying screen are :-
a) The intensifying screen help to decrease patient motion due to shorter exposure time.
b) The intensifying screen help to decrease patient exposure level.
c) The intensifying screen help to decrease scatter radiation level to personnel.
d) The intensifying screens give permit use of smaller focal spot size hence better details.
e) The intensifying screen help to keep increase tube life because of lower mAs required.
f) The intensifying screen give permit greater selection in KVp settings.
What is the speed of intensifying screen?
The speed of an intensifying screen refers to its ability to absorb and convert X-ray photons into light photons. Intensifying screens are rated according to their speed, with faster screens being more sensitive to X-ray photons and producing higher-quality images with less radiation exposure to the patient.
There are several factors that can affect the speed of an intensifying screen, including the thickness of the screen, the type of material it is made from, and the size of the grains or crystals in the screen. In general, thicker screens, screens made from materials with higher atomic numbers, and screens with larger grains or crystals are faster and more sensitive to X-rays.
Intensifying screens are classified into several speed categories based on their performance characteristics. The most common categories are high speed, medium speed, and low speed. High-speed screens are the fastest and are used for imaging small or densely packed structures, such as the bones in the hand or the spine. Medium-speed screens are used for general imaging purposes, while low-speed screens are used for imaging large or less densely packed structures, such as the chest or abdomen.
How to maintenance the intensifying screen?
Intensifying screens are an important part of X-ray imaging systems and need to be properly maintained to ensure optimal performance. Here are some tips for maintaining intensifying screens:
A) Handle the screens with care:- Intensifying screens are delicate and can be easily damaged if they are not handled properly. Be sure to use clean hands and handle the screens gently to avoid damaging them.
B) Store the screens properly:-Intensifying screens should be stored in a clean, dry place that is free from dust and other contaminants. They should also be stored in a protective sleeve or bag to prevent them from being scratched or damaged.
C) Clean the screens regularly:- Dust and dirt can accumulate on the surface of intensifying screens, which can affect their performance. Be sure to clean the screens regularly using a soft, dry cloth or a cloth that has been dampened with a mild cleaning solution. Avoid using abrasive cleaning materials or chemicals, as they may damage the screens.
D) Replace the screens as needed:- Intensifying screens have a limited lifespan and may need to be replaced after a certain number of exposures or if they become damaged. It is important to follow the manufacturer’s recommendations for replacing the screens to ensure that they are functioning properly.
By following these tips, you can help maintain the performance and longevity of your intensifying screens.
What is the main purpose of an intensifying screen?
The main purpose of an intensifying screen is convert the x-ray energy in to light which reach the film and form the latent image. The other main purpose of an intensifying screen is to improve the visibility and contrast of an image, making it easier to interpret and analyze.
