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RADT 412
Exposure- unit 1
| Question | Answer |
|---|---|
| Define dimensional stability in regards to radiographic film | The base keeps its size and shape under all processing conditions |
| Explain why blue tint is added to radiographic film | Blue tint is added to the base when the base is manufactured. It makes the film more pleasing to the eye and reduces eye strain on radiologists. Also helps to enhance radiographic contrast |
| Where is the image formed? | The image is formed in the silver bromide crystals |
| Explain the important characteristics of gelatin | Colloid (capable of suspending the silver bromide crystals). Amphoteric (used with either an acid or alkali. |
| Explain non-screen film | Designed to be used without intensifying screens |
| Describe where the 105mm camera is used | Used as a spot film device during fluoroscopy when rapid exposures are required |
| Explain where cinefluorography roll film is used | Special procedures and cardiac catheterization |
| Explain mammography film | Able to display high contrast and very good recorded detail |
| Explain duplicating film | Copy film is a single-emulsions film used to make a copy of a radiograph |
| Explain subtraction film | subtract the superimposing bone away from the angiographic image |
| Describe the four parts of the film processor | Developer, fixer, wash, dryer |
| Describe developer temperature in automatic processors | Regulated between 93-98 degrees Fahrenheit |
| Define fog | Excessive density |
| Explain what fog does to radiographic contrast | Reduces radiographic density |
| What type of solution is the fixer? | Acidic solution |
| Explain the purpose of the fixer | Removes unexposed and undeveloped silver bromide |
| Explain the wash | Constant circulating water to wash away chemicals |
| Explain the dryer | Blows hot air onto both sides of film to dry it |
| Explain turnabout rollers | At the bottom |
| Describe the function of the guide shoes | Metal guides that help the film make the turns |
| Explain when contamination of the chemicals occurs | When fixer is accidentally splashed into the developer |
| What light does calcium tungstate screens emit? | Blue-violet light |
| What type of screens have replaced calcium tungstate screens? | Rare earth elements such as gadolinium, lanthanum, and yttrium |
| List the three silver halides used in radiographic film | Silver bromide, silver iodide, and silver chloride |
| Explain how single-emulsion film must be loaded into the cassette | The emulsion toward the intensifying screen, and the emulsion side of the film always appears dull, the nonemulsion side shiny. |
| Describe the main parts of radiographic film | Base (polyester) and emulsion (gelatin substance) |
| State what the film base was originally composed of | Originally composed of a glass plate |
| Know what substance was used as the radiographic film base during WWI | Cellulose nitrate |
| Know the serious deficiency with cellulose nitrate being used as the radiographic film base | Cellulose nitrate was flammable causing several tragic hospital fires |
| Know what substance was used as the radiographic film base during the mid 1920s to the early | Cellulose triacetate |
| Know what substance was used as the radiographic film base during the 1960s | Polyester |
| Know what substance was introduced as the radiographic film base during the early 1960s | Polyester |
| List three reasons why the polyester base took the place of cellulose triacetate | Flexible yet tough, stable, rigid, and uniformly lucent |
| Explain crossover effect | Blurring of the image caused by light from one screen crossing into the light from another screen |
| Explain halation | Caused when light that is reflected from the air interfaces on the back of the base material |
| Know what percent of modern silver halides is silver-bromide | 95-98% |
| List the four stages in the manufacture of film | Crystal production, ripening, mixing, coating |
| State the shape of all silver halide crystals | Crystals are flat and roughly triangular shaped |
| Describe the three atoms that make up the cubic lattice (matrix) | Silver, bromide, and iodine atoms. |
| Know the impurity that is usually added to the silver halide crystals to form sensitivity specks. | Gold-silver sulfide |
| Define Ripening | The period during which silver halides are allowed to grow |
| Panchromatic | Films are sensitive to all colors. |
| Define latent image | Invisible image in the film after it is exposed to radiation that hit the film |
| List six things that the radiography departments must pay attention to when storing and handling radiographic film | Age of the film, heat, humidity, light, radiation, handling |
| List the storage temperature range that should be maintained when storing radiographic film | 20 C (68 F) or lower at all times |
| Know what type of light is used in duplicating machines. | UV light |
| Explain why special application film should be frozen. | To stop the again process |
| List the humidity range that should be maintained when storing radiographic film. | Between 30%-60% |
| Explain what is a danger to storing radiographic film at a humidity at lower than 30%. | There could be static discharge artifacts left on the film |
| Explain what a danger to storing radiographic film is at higher than 60%. | High humidity causes condensation. |
| Explain why film should be stored on end | Prevents pressure marks |
| Define Sensitometry | The measurement of the characteristic responses of film to exposure and processing |
| Define penetrometer | Used to produce a step wedge on film by its exposure to x-rays |
| The number that is displayed on a densitometer | Optical density numbers |
| Know the parts of the “Characteristic Curve” | Base plus fog, toe, Dmax, shoulder, straight line portion |
| List the three names for the D log E curve | Characteristic, Sensitometric, Hunter and Driffield curve |
| Define base plus fog | Density at no exposure and density is inherent in the film |
| Know the range diagnostic densities | Low OD: 0.25-0.5 / High OD: 2-3 |
| Know the range that the majority of diagnostic quality info will measure | Object Density of 0.5-1.25 |
| What is the reducing agent that controls the heavy black tone | Hydroquinone |
| Contrast | Comprise visibility of detail |
| Resolution | The ability to accurately image an object |
| Speed | The amount of density a film produces for a given amount of exposure |
| Latitude | The range of exposures that will produce densities |
| What is resolution also called | Detail, sharpness, definition, or resolving power |
| What determines film resolution? | Size of the silver halide crystals |
| Know the relationship between film resolution and crystal size? | Inverse relationship; the smaller the crystal, the higher the resolution; the larger the crystals, the lower the resolution |
| Controls the speed of film. | The activity of the phenidone because it affects the toe of the D log E curve. Film Speed is directly related to crystal size. Larger the crystal, faster the speed; smaller the crystal, slower the speed |
| Know what controls the film sensitivity | The size of the silver halide crystal, the number of sensitivity specks and the thickness of the emulsion layer |
| Film speed vs. crystal size | Directly related; the larger the crystal, faster the speed; smaller the crystal, slower the speed |
| Know the relationships between film speed and the number of sensitivity. | Directly related |
| Know the relationship between film speed and the thickness of the emulsion layer. | The thicker the emulsion, the faster the film speed; the thinner the emulsion, the slower the film speed |
| Know the location of the speed point | That point on the D log E curve where a density of OD 1.0 + b+f is achieved. |
| Gamma | Simply a measure of the slope of straight line portion of the curve at the speed point. |
| Gradient Point | The slope of any portion of the D log E curve can be calculated. |
| Average Gradient | The overall radiographic film contrast |
| Know the difference between latitude and contract. | Inversely related. As contrast increases, latitude tends to decrease. |
| Orthochromatic | Films are not sensitive to the red spectrum |
| Where are crossover rollers | At the top |
| Latent image theory proposal | 1938 by Gurney and Mott |
| Define straight line portion | The portion between the toe and shoulder |
| Dmax | Max density the film is capable of recording |
| Sensitometer | Used to expose a reproducible, uniform, optical step wedge onto a film |
| Densitometer | Used to provide a readout of the amount of blackening on film |
Created by:
meechthebeech91
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