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Sensitometry
| Terms | Definitions |
|---|---|
| Sensitometry | measure's film's response to exposure and processing; the study of the response of an IR to x rays;scientific study of light-sensitive materials |
| What equipment is used to measure film's response to light? | sensitometer (optical step wedge) and densitometer |
| Measures films sensitivity to light; shows the range of densities on an image | Sensitometer |
| Measures optical density | densitometer |
| What is the formula for optical density? | OD = log 10 Io/It |
| Blank film that has not been exposed. | Control film |
| Shows the relationship between optical density and radiation exposure. Measures exposure to film and percentage of light transmitted through processed film. | Characteristic curve |
| what is another name for the characteristic curve? | H & D curve |
| Which axis is the log relative exposure (LRE) located on? | x axis |
| Which axis is exposure located on? | y axis |
| What are the 3 parts to the curve? | toe, straight-line portion, shoulder |
| Which portion of the curve is considered the useful density range? | straight-line portion |
| What are 4 proper storage conditions for radiographic film? | store at < 68 degrees F and 30-60% humidity, keep film unexposed, first in first out, keep shelf life 45-60 days |
| Invisible image created after exposure but before processing. | Latent image |
| Manifest image | visible image after developing |
| Optical density inherent in the base and is controlled by the manufacture. | base density |
| How fast film responds to a minimal exposure | speed (sensitivity) |
| Base plus fog | inherent base density blus chemical fog; what we read and measure |
| Dmin | lowest density of exposed area (toe on curve) |
| Dmax | highest density of exposed area (shoulder on curve) |
| Film graininess | clumping of the silver halide crystals |
| Found with double emulsion film; two latent images on emulsions not perfectly superimposed. | crossover |
| What are four sensitometric properties that can be identified on a characteristic curve? | Dmin, Dmax, base plus fog, base density |
| An exposed image is ____ more sensitive to radiation than an unexposed image. | 8x |
| Base plus fog is measured on a film on a/an ___. exposed or unexposed area | unexposed area |
| State 3 things film is sensitive to. | light, heat, humidity |
| Crown, smudge, tree are examples of what. | 3 types of static artifacts seen on film. |
| Range of exposures that will produce an acceptable density. | latitude |
| If the slopes of the straight line portion of a characteristic curve are parallel, what does that mean concerning contrast scale? | It means that they both have the same contrast scale. |
| If you have a long scale of contrast you will have high or low contrast? | low contrast |
| Amber safelights are used with what kind of sensitive film? | blue |
| Film speed and resolution are indirectly/directly related. | indirectly |
| How can the manufacture control the speed of the film? | crystal size, emulsion thickness, mAs |
| kVp controls ______. | contrast |
| Film latitude and contrast are directly realated. True/false | false - indirectly |
| What is an advantage of having a high speed film? disadvantage? | lower dose; loss of resolution |
| State a disadvantage of high contrast film. | With high contrast film you will get a narrow latitude. |
| Name 3 types of equipment used for processor monitoring. | sensitometer, densitometer, control film |
| How often should processor monitoring be performed? | every day |
| The toe of the characteristc curve is controlled by ________. | phenidone |
| The shoulder of the characteristic curve is controlled by ________. | hydroquinone |
| The ability to image an object faithfully. | Resolution |
| Resolution depends on _____. | crystal size |
| Speed or _______ is controlled by ____. | sensitivity;crystal size |
| What affects speed? | number of sensitivity specks and the thickness of the emulsion. |
| Name 3 things that speed is affected by. | developement time, developemnt temp. and chemical activity |
| Film contrast | density differences that film can demonstrate |
| Film contrast is demonstrated by _________ on the H&D Curve. | slope of curve |
| Film Latitude | range of exposures that produce appropriate densities |
Created by:
sr4095
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