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Physics RAD math
midterm physics BSHP
| Question | Answer |
|---|---|
| improper handling or processing can cause what on processed radiographs? | Artifacts |
| Heat _____ the fog of a radiograph | increases |
| When fog increases on a radiograph it reduces ______ | contrast |
| Radiographic film should not be stored at temps lower that _____ degrees F | 68 |
| With higher storage temps the longer the storage the more loss ___________ that results from the _______ in _____ | of contrast; increase; fog |
| Radiographs should be kept at a temp of _______ degrees F or _____ degrees C | 50; 10 |
| Radiographs should be stored where? | In refrigerated storage |
| Storage for a year or longer is acceptable if _____ | it's maintained at a temp of 50 degrees F |
| Storage in humidity over 60% _______ contrast because of ____ fog | reduces; increased |
| _________ are possible when relative humidity dips below ______ | static artifacts; 40% |
| if light exposes a film ______ is produced | a gross, obvious artifact |
| _____ creates an artifact by increasing fog and reducing contrast. | ionizing radiation |
| Film fog is | dull, uniform optical density that appears if the film has been exposed to light , xrays,heat,or humidity |
| the fog level for unprocessed film is | 0.2mR |
| Darkrooms are lined with____ | lead |
| Film is more sensitive after/before (choose one) an exposure? Why? | after; an exposure post exposure has an immediate effect on optical density |
| monthly turnover of film requires ______ the lead shielding is required than ____ | 4 times; weekly turnover |
| boxes of film should be stored ____ rather than ____ because ____ | on edge; laying them flat; when stored on edge they are less likely to wrap,stick to eachother, or suffer from pressure. |
| storage of film should be sequenced how? | Oldest film is used first |
| what's the equation for total filtration? | inherent filtration + added filtration |
| what's the equation for grid surface x-ray absorption? | width of grid strip/width of grid strip +width of interspace all x 100 |
| grid with 50-um strips and 350-um interspace what percentage will be absorbed by it's entire surface? | 50um-350um+50um = 0.125 * 100 = 12.5% |
| lead strips 40um wide separated by interspaces 300um wide what percent is absorbed? | 40um/300um+40um= 40um/340um=0.118*100 = 11.8% |
| equation for grid ratio | height of grid strip/thickness of interspace |
| are grid strips radiopaque or radiolucent? | radiopaque |
| grid strips alternate with _______ material called ______ | radiolucent; interspace material |
| xrays that exit the patient and strike the radiopaque grid strips are ____ and _____ the image receptor | absorbed; do not reach |
| what is grid frequency? | the number of grid strips per centimeter |
| grids with high frequency show ____ grid lines compared to low frequency grids which are the opposite | less distinct |
| if grid strip width is constant the higher the frequency of of a grid the ______ it's interspace must be and the ______ the grid ratio. | thinner; higher |
| higher frequency grids require _____ of technique and results in ____ | higher technique; increased patient dose |
| most common grid frequency range is in the rang of ___to ___ | 25;45 per centimeter |
| equation for grid frequency? | 10,000um (per cm) /thickness of grid strip+width of interspace material (per line pair) |
| what id the grid frequency of a grid that has a grid width of 30um and an interspace width of 300um? | 10,000/300+30 = 10,000/330= 30.3 |
| most grids consist of what kind of interspace material? | aluminum or plastic fiber |
| what interspace material has a low atomic number causing it to show less visible grid lines and have some selective filtration of scatter x-rays not absorbed? | aluminum |
| high frequency grids are more effective than low ones because? | the angle of deviation is smaller |
| what is nonhygroscopic? what is the term used for in grids? | doesn't absorb moisture ; aluminum (used in grid interspace) |
| what is the principle use of a grid? | improve contrast |
| bucky factor values no grid; 5:1, 8:1, 12:1, 16:1 | 1,2,4,5,6 |
Created by:
b.xray
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