Image Formation Word Scramble
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| Question | Answer |
| What is recorded detail? | Distinctness or unsharpness |
| What is umbra? | Pure, true, complete shadow. |
| An increase in detail causes a ________ in unsharpness (blur) | Decrease |
| What is blur? | Also referred to as penumbra, edge gradient and geometric unsharpness, partial shadow of the edge of an object. |
| What is the controlling factor for recorded detail? | Focal spot size |
| What are the influencing factors of recorded detail. | SID OID Film Screen Speed Patient Motion |
| How does focal spot size effect recorded detail? | Inversely. Increased focal spot size = decreased recorded detail |
| How is focal spot size and blue related? | Directly. Increase focal spot size, decrease in recorded detail = increase of blur |
| What is the size range of a small focal spot? | .5mm-.6mm |
| What is the size range of a large focal spot? | 1.0mm-1.2mm |
| How does SID influence recorded detail? | Increased SID, decrease in blur = increased recorded detail |
| How does OID influence recorded detail? | Increased OID, increased blur = decrease in recorded detail |
| Blur Formula? | Focal Spot Size x OID = _____mm SOD |
| How do you fine SOD? | SID-OID=SOD |
| When there is an excessive amount of OID the amount of blur can be decreased by? | Increasing SID |
| What is image receptor blur? | Variations in construction and composition of film screen systems affect photographic properties and geometric properties |
| How does film screen speed effect recorded detail? | High speed screens required less X-rays, decrease patient dose, increase blur = decrease in recorded detail. |
| What is quantum mottle? | Blotchy appearance of a radiograph that has been exposed by means of a fast intensifying screen. Looks like salt and pepper ****faster screen = more artificial light*** |
| What tool do you use to test film screen contact? | Wire mesh |
| What is resolution? | Ability of the image system to resolve or distinguish between two adjacent structures. |
| What is spatial resolution? | Minimum distance between two objects at which they can be recognized as two separate objects. (Physical distance) |
| What is contrast resolution? | The ability of the imaging system to distinguish between small objects having similar subject contrast. (Depends on your system) |
| What is a line pair? | A line and a space |
| How many line pairs can the human eye discern? | 5Lp/mm |
| 2 types of blur | 1. Voluntary (within patient control) 2. Involuntary (outside patient control) |
| What 3 things can you do to limit patient movement? | 1. Communication 2. Immobilization 3. Short exposure time |
| What is distortion? | Radiographic misrepresentation of size or shale compared to the actual size and shape of the structure. |
| What factors influence distortion? | SID OID Central ray angle |
| What is spatial distortion? | The intentional distortion used to avoid superimposition Ex: inlet/outlet pelvis, lateral knee, sacrum/coccyx |
| Define magnification | The equal enlargement (both length and width) of the recorded image as compared to the actual size to the structure |
| How is magnification and OID related? | Directly. Increase OID = increase magnification |
| How is magnification and SID related? | Inversely. Decrease magnification = increase SID |
| Formula to calculate image and object size. | Image size = SID Object size SOD |
| What is magnification factor? | Indicates how much he size distortion is demonstrated on the image |
| What is the magnification factor formula? | SID Or Image SOD Object |
| Formula to calculate object size using magnification factor. | Object = Image Magnification factor |
| Formula to calculate percent of magnification | Image - object x 100 Object |
| 2 types of shape distortion | 1. Elongation 2. Foreshortening |
| Elongation happens when... | The tube is angled |
| Foreshortening happens when... | When the part is angled |
| When angling the tube you must decrease your SID by... | 1inch for every 5 degrees |
Created by:
Aborys88
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