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Intensifying Screens
Ch. 22
| Question | Answer |
|---|---|
| Purpose of intensifying screens is to ______ the beam. | amplify |
| An intensifying screen will ______ pt dose by converting x-ray photons into ______ photons. | reduce; light |
| ____ percent of light photons is included in the latent image, while ____ percent is x-ray photons. | 99; 1 |
| _______ emissions is a process in which x-ray photons are converted into ____ ____ and creates a luminescence. | Isotropic; light photons |
| Name the four basic components of the intensifying screens. | Base Reflective Layer Phosphor Protective Coating |
| The phosphor layer is also know as the_________. | active layer |
| As conversion efficiency ______ radiation dose to the patient will _______. | increases; decreases |
| _____ _____ is the ability of the phosphor to emit as much light per x-ray photon interaction as possible is a measurement of the screen SPEED. | conversion efficiency |
| A higher Z# will have what two interactions? | photoelectric and Compton. |
| It is important that the spectral emission match the ______ of the film. (blue & blue) | sensitivity |
| ______ is the ability of a material to emit light in response to excitation. | Luminescence |
| ______ and ______ are the two types of luminescence. | Fluorescence; phosphorescence |
| Fluorescence is _____ emission while phosphorescence is _____ emission. | instantaneous; delayed |
| Delayed emission is sometimes called ____ ____ or _____. | screen lag; afterglow |
| Spectral emission is a precise ______. | wavelength |
| The base on an intensifying screen is ____ & _____. | tough; flexible |
| What does the reflective layer do? | It reflects light towards the film |
| The protective coating protects the phosphor layer against _____. | abrasions/fingernails |
| Conversion efficiency means the more light will result in more ___, ____, & _____. | exposure; speed; density |
| The two phosphors used are ____ _____ and ____ _____. | Calcium tungstate; rare earths. |
| Resolution is measured in _____ per mm. | line pairs |
| Resolution has a _____ relation between size of phosphors. | inverse |
| Large phosphors = _____ resolution | less |
| Poor film/screen contact = _____ in image density. | decrease |
| How do we get rid of quantum mottle? | increase mAs |
| Quantum mottle appears _____ on a radiograph | grainy |
| What happens when a phosphor is struck by an x-ray photon? | Isotropic emission |
| What is the lifespan of phosphors? | 5-7 years |
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