Help
Options
Question
What is the main reason for using a grid?
click to flip
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't know
Question
What is the most important grid characteristic?
Remaining cards (85)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Radiographic Grids
Control of Scatter Radiation... Radiographic Grids
| Question | Answer |
|---|---|
| What is the main reason for using a grid? | Improve Contrast, Reduce Scatter |
| What is the most important grid characteristic? | Grid ratio |
| Interspace material is... | radiolucent |
| _____ require sensors in the bucky drawer to measure the size of the cassette. | Automatic shuttering |
| What photon interaction do we get scatter from? | Compton |
| When the bucky drawer locks are adjusted, sensors automatically measure ____ and restrict ______. | cassette size, primary beam |
| Sensors are located on the tube stand to monitor _____. | SID |
| Where do we place the grid? | between the patient & IR |
| Undesirable absorption is______. | grid cut off |
| Guarantee of patient protection, clearer images, more reliable, eliminate error, save set up time are all_______. | advantages of automatic collimation |
| Increasing the OID which allows more scatter to miss the film and scatter emitted in all directions is... | Air gap technique |
| Mostly used inn cervical/chest area and SID must increase to compensate for increase in OID is ________. | Air gap technique |
| The most commonly used grid is .... | focused moving grid |
| _____ can be used to restrict the primary radiation for conventional radiography. | lead rubber masking |
| For the most patient protection use... | high kV |
| Placing sheets of lead rubber dividers on table into position so they absorb unnecessary radiation will ____ of radiograph. | increase contrast |
| Better and least patient exposure use _____ | no grid |
| ____ reduce tissue volume and are helpful in controlling scatter. | compression device |
| What is the downside of using air gap? | increase magnification |
| With compression device by lowering the body part, there is corresponding ____ in scatter. | reduction |
| Grid ratio produce most density with a ____. | 5:1 grid |
| The most effective device for reducing scatter is a _____. | grid |
| Grid ratio produces the least density with _____. | 16:1 grid |
| The most important way to reduce scatter production is ____. | collimation |
| Who built the first stationary grid? | Gustave Bucky |
| Grid composed of parrallel strips of lead/plastic | stationary |
| The grid absorbs ____ of secondary/scattered radiation. | 90% |
| Disadvantage of stationary grids are the lead strips cast a thin white line on radiograph, exposure must be ____ bc of this. | increased |
| The most popular stationary grids vary from ___ to ___ lines per inch. | 60 to 80 |
| Which grid produces the longest scale of contrast? | 5:1 |
| What grid has lead strips parrallel to each other and thickness decreases as they move to the edge? | parrallel |
| The thickness of lead strips decreasing at the edge is to try and overcome primary _____. | grid cut off |
| When the primary beam is absorbed by the lead strips this is called ____. | cut off |
| Which grid produces the highest contrast? | 16:1 |
| Parrallel grids are used with techniques under ____ and with portable units. | 100 kVp |
| When using a grid with a 1 way angle you ____. | angle longitudinally |
| All sides of strips are centered toward a single centered point at predetermined distance (grid of 40" SID) | focused grid |
| When 2 linear grids are accidentally placed on top of each other | Moire Effect |
| Higher grid frequency = | maximum line invisibility |
| less than ___ should be scatter radiation | 25% |
| Stationary to moving will increase patient dose ___. | 15% |
| 2 stationary grids used on top of each other, each at right angles, can be parrallel or focused. | cross hatch grid |
| With a cross hatch grid the least amount of positioning lattitude the ___ grid ratio | higher |
| CR must be centered to both grids and perpendicular to film and cannot have any angle with ___. | cross hatch grids |
| Angiography, trans table lateral fro mylegraphy, and shoot thru lateral hips use | cross hatch grids |
| Who invented the moving grid? | Dr. Hollis Potter |
| Moving the grid perpendicular to the direction of lead strips made them ____ | invisible |
| Exposure starting before grid reaches full speed, exposure continuing afer grid travel slowed/stopped, uneven movements, tube focus not centered, and synchronism off is all... | common causes of grid lines |
| What are the 3 types of moving grids? | Single stroke, reciprocating, oscillating |
| What is the most commonly used moving grid? | reciprocating |
| The process of manufacturing a grid and inclining its lead lines to a fixed focusing distance | canting |
| Because of grid impurities, never accept a grid unless you inspect it with an ____ | industrial radiograph |
| 2 physical properties responsible for efficiency of a grid inn removing scatter | grid ratio/grid frequency |
| The number of lines per inch is ______ | grid frequency |
| Ratio of the height to the distace is | r = h/d |
| As you increase grid ratio you ___ contrast and ____ density | increase, decrease |
| The higher grid ratio the better will be ____ of scatter and ___ radiographic contrast. | clean up, higher |
| The angle of transmission in low ratio grid is ____ than in high ratio(meaning more scatter & primary can pass through a lower ratio grid) | greater |
| Most portable are | 8:1 |
| Most stationary are | 12:1 |
| When converting from non grid to grid, change is best made by adjusting _____ | kVp |
| In grid frequency, the thinner the strips and greater the chance of scatter rays passing through the more _____ | number of lead strips per inch |
| Higher grid frequency the more _____ in the grid | grid material |
| As grid frequency increases grid ratio must also _____ to maintain frequency and also ___ patient dose. | increase, increase |
| Less than _____ of density should be scatter | 25% |
| Contrast improvement factor is ____ for radiographs taken with the grid removed | 1 |
| Use of a moving grid instead of stationary will require ___ more radiation exposure | 15% |
| Most common grid frequency used in rad dept. is ___ per inch | 100 lines |
| Purpose of interspace material is to maintain ___ between strips of lead | precise seperation |
| What are the 2 most used interspace materials | aluminum , plastic fiber |
| May provide soem filtration of scattered x-rays, produces less visible grid lines, absorbs more primary beam requiring higher techniques | aluminum interspace material |
| Usually preferred over aluminum b/c reduces patient exposure | plastic fiber interspace material |
| Does not absorb moisture | nonhygroscopic |
| ____ is easier to form and roll into sheets of precise thickness than ____ | aluminum, fiber |
| Amount of secondary radiation (thickness, density) kilovoltage used, capacity of x-ray generator are all factor in _____ | grid selection |
| The ____ grid ratio the more position lattitude we have | lower |
| _____ is based on positioning lattitude along with other factors | grid selection |
| The ___ the grid ratio the less positioning lattitude | higher |
| Parrallel grids have more ___ than focused and cross hatch have no_____ | lattitude , lattitude |
| Grids should be used when the body part is atleast___ thick (some say ___) | 12cm (16cm) |
| If grid is not used properly, film will exhibit | grid cut off |
| ___ occurs b/c primary beam gets absorbed closer to outside edges. | primary cut off in a parrallel grid |
| To try and overcome ____ in a parrallel grid we make lead strips thinner as they move away from center | primary cut off |
| When the SID is greater or lesser than the focusing distance and shows proper density in the center of radiograph and cut off on lateral edges | off distance cut off in a focused grid |
| In a focused grid when CR is not centered (area below CR will have density & rest white) and the grid is not parrallel with plane of the tube you will have ____ | off center, off level cut off |
| Occurs from stupidity and grid upside down | tube side vs film side |
Created by:
bmiller1226
Popular Radiology sets