FAQs
Some of the frequently asked questions on cassette and screen are listed below. For any other questions and queries, please contact us.
What is the useful life of cassettes and screens?
Useful life may vary between 2 to 5 years depending on the extent of use and quality / frequency of maintenance.
Why do some screens have a colour tint, while others are nearly white?
A colored dye is used to tint the phosphor in case of certain types of screens. The color in dye increases resolution or detail perception.
It is customary in lower speed but higher resolution screens, e.g.
Green FINE
What is the cause of loss of film-screen contact?
Film-screen contact is a result of use of correct
construction elements in a cassette.
Use of a 100% open cell foam allows trapped air to escape within a short time and is an essential requirement to
film-screen contact.
What is the difference between green and blue screens? Which one should be used?
The screen is grouped as green or blue depending on the predominant wavelength range emitted by the X-Ray phosphor on excitation by X-Rays. Hence, green or blue emitting screens should be used with the corresponding film.
Use of a mismatching screen to film will result in destroying the radiographic image.
How can light leakage be prevented?
Light leakage is prevented by use of correct
construction elements in a cassette.
What is the purpose of incorporating lead in the back of cassette?
Incorporation of lead prevents backscatter during radiography and is a radiation safety feature.
Are the front (tube side) and back screen same?
They can be same or different for each screen manufacturer.
Sometimes, a screen manufacturer produces a lower demand product by combining a front foil of one type of screen with the back foil of another type.
How does the choice of aluminum quality affect cassette quality?
A type of aluminum alloy used in a cassette is critical to its quality.
The aluminum sheets must contain correct quantities and types of hardeners for durability. At the same time, they must possess a spring action to revert back to original position, after withdrawal of pressure.
Why is it better to use rare earth screens compared to calcium tungstate?
Rare earth phosphor has typically 5 times the absorption efficiency of calcium tungstate.
Their use results in faster speeds and reduction in dosage.
What is the effect of yellowing or discoloration of screen surface?
Certain amount of yellowing and / or discoloration of screen is natural as a result of wear and tear. If the extent of yellowing or discoloration does not result in lowering of
speed and resolution of screen, it can be kept in use.
What is a curved profile incorporated in design of back of a cassette?
A curved profile of a hardened aluminum results in building pressure around the central part of diagnostically important area) of a film-screen.
It results in escape of air trapped in the foam from this area to the edges and then exits the cassette. This results in a good
film-screen contact.
