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Scatter Control 177
Part 2
| Question | Answer |
|---|---|
| Convergent Point: | Point where angled lead lines would meet if extended |
| Convergent Line: | Line created by the connection of the infinite convergent points along the entire length of the grid |
| Focal Distance (grid radius): | Distance between the grid and the convergent line or point |
| Focal Range: | Possible SIDs that can be used |
| It's Possible to see the grid lines on the radiographic image taken with a _________ | Stationary Grid |
| A ________ Blurs grid lines | Moving or Reciprocating Grid |
| Wafer Grid: | Placed on top of the IR, often taped down |
| Grid Cassette: | An IR that has a grid permanently mounted to its front surface |
| Grid Cap: | Contains a permanently mounted grid and allows the IR to slide in behind it |
| Grid Conversion Factor= | mAs with grid Divided By mAs without grid |
| When changing from one grid ratio to another, the following formula should be used to adjust the mAs | mAs1 = GCF1 Divided by mAs2 GCF2 |
| A decrease of transmitted photons reaching the IR because of grid misalignment | Grid Cutoff |
| Darker center and loss of exposure along the lateral edges- | Upside-Down Focused |
| Loss of exposure along all the edges- | Off Focus |
| Overall loss of exposure- | Off Center & Off Level |
| Describe an Upside-Down Focused Grid Error | Grid is placed upside down on the IR Grid lines now go opposite/against the divergence of the x-ray beam |
| Describe an Off Focus Grid Error | SID is outside of the recommended focal range (greater or less than focal range for the grid) |
| Describe an Off Center Grid Error | CR is not aligned from side to side with the center of a focused grid |
| Describe an Off Level Grid Error | Grid is not level so the Beam is angled across lead strips |
| The______ happens in both CR and DR and appears as a zebra pattern | Moiré Effect |
| Moiré Effect cause in CR: | When the grid frequency is similar to the laser scanning frequency inside the reader |
| Moiré Effect cause in DR: | Insufficient sampling frequency – has nothing to do with grids |
| We should use a grid when: | Part thickness greater than 10 cm (4 in) The kVp is greater than 60 |
| What is the most common grid error? | Off Level (heavier paitent whos been in bed for a long time, Bed isn't level) |
| The _______ Can be an alternative to using a grid & Should be used anytime that there is significant OID | Air Gap Technique |
| Any individual in the radiographic room during an exposure must wear a _______ to prevent exposure to scatter radiation | Lead Apron |
| _______ allow more Transmitted Photons to reach the IR | Focused Grids |
| ________ Are More prone to Grid Cutoff | Cross-Hatched Grids |
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user-2016295