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OD/Artifacts
Optical density, artifacts
| Question | Answer |
|---|---|
| When only soft tissue is beng imaged, __ kVp and __ mAs are used. | Low, High |
| ___ kVp and __ mAs results in an image with satisfactory contrast and low patient radiation exposure. | High, low |
| Radiolucent tissue appears ___ on radiographs. | Black |
| Radiopaque tissue appears __ on radiographs. | White |
| Destructive pathology causes tissue to appear __. | Radiolucent |
| Constructive pathology causes tissue to appear __. | Radiopaque |
| What is optical density? | Degree of blackening of the finished radiograph. |
| In OD, black is has an OD of what number? | 4 or greater |
| In OD, clear has an OD of what number? | Less than 0.2 |
| OD is controlled by what 2 factors? | mAs and SID |
| In order to produce a visible change in OD, mAs must be changed by __%. | 30% |
| kVp must be change by __% to produce a perceptible change in OD. | 4% |
| A __% increase in kVp accompanied by a half reduction in mAs results in the same OD. | 15% |
| The simplest method for increasing or decreasing OD on an x-ray is to increase or decrease __. | mAs |
| High kVp produces? | LONG scale, LOW contrast, LESS contrast |
| Low kVp produces? | SHORT scale, HIGH contrast, MORE contrast |
| Detail is controlled by? | Focal-spot size |
| What are the three classes of artifacts? | Processing, Exposure and Handling |
| Pi lines, dichroic stains and chemical fog are examples of what type of artifact? | Processing artifacts |
| Motion, poor screen contact and improper grid position are examples of what type of artifact? | Exposure artifacts |
| Kink marks, radiation fog and scratches are examples of what type of artifact? | Handing and storage artifacts |
| What are two types of roller marks? | Guide-shoe marks and Pi lines. |
| What is the cause of dichroic stains? | Improper squeezing of processing chemicals from film |
| What is the cause of guide-shoe marks? | Improper position or springing of guide shoes in turn-around assembly. |
| What is the cause of pi lines? | Dirt or chemical stains on rollers |
| T/F: Dichroic stain is a type of chemical fog. | True |
| T/F: Processing artifacts in digital radiography are different from those with screen-film because the method of producing the image is electronic instead of chemical. | True |
| Name several handling and storage artifacts. | Fog, kink marks, crown |
| What causes pressure marks? | Improperly or roughly handled film |
| What causes fog? | High temperature or humidity |
| What are the 3 types of static artifacts? | Crown, Tree and Smudge |