Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
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
Physics Ch 11
Control of Scatter Radiation
| Question | Answer |
|---|---|
| X-rays that exit and interact with the IR are called ____ ____ x-rays. | image forming |
| _____ reduces patient radiation dose and improves contrast resolution. | Collimation |
| As scatter increases, the radiographic image loses _____. | contrast |
| As kVp is increased, the number of Compton interactions _____. | increases |
| Low kVp and high maAs result in an ______ pt dose. | increased |
| Approximately ____% of x-rays incident on the patient reach the IR. | 1 |
| When kVp is increased, image contrast is ____. | reduced |
| Scatter radiation increases as the x-ray beam field size _____. | increases |
| What are the three primary factors to reduce scatter to the IR? | Collimation, patient thickness and kVp |
| Thinner anatomy will have reduced _____ and increased detail, compared with that of thicker anatomy. | scatter |
| _____ of anatomy improves spatial resolution and contrast resolution and lowers the patient radiation dose. | Compression |
| _____ is the visible difference between the light and dark areas of an image. | Contrast |
| Reduced image ____ results from scattered radiation. | contrast |
| What two devices reduced amount of scatter that reaches the IR? | beam restrictors and grids |
| What are three types of beam restrictors? | aperture diaphragm, cones/cylinders and variable aperture collimator |
| Collimation reduces the patient radiation dose and ____ contrast resolution. | improves |
| Positive beam limiting (PBL) devices were mandated by the US in ___ and removed in ____. | 1974, 1994 |
| Total filtration = ____ + _____ | Total filtration = Inherent filtration+Added filtration |
| The added filtration of the collimator assembly is equivalent to approximately __ mm Al. | 1 |
| Who demonstrated the technique for reducing the amount of scatter radiation that reaches the IR? | Gustave Bucky |
| Grid ratio = ___/___ | Grid ratio=h/D |
| High grid ratios _____ patient radiation dose. | increase |
| The number of grid strips per centimeter is called the grid _______. | frequency |
| The principal function of a grid is to improve image ______. | contrast |
| What is the contrast improvement factor? | k=image contrast with grid/image contrast without grid |
| Most grids have contrast improvement factors between ___ to ___. | 1.5;2.5 |
| The contrast improvement factor is ____ for high ratio grids. | higher |
| The higher the grid ratio, the ____ is the Bucky factor. | higher |
| The Bucky factor increases with increasing ___. | kVp |
| As the Bucky factor increases, radiographic technique and patient radiation dose ____ proportionally. | increase |
| What are the four types of grids? | parallel, crossed, focused and moving |
| The main disadvantage of parallel and crossed grids is ____ _____. | grid cutoff |
| Focused grids coincide with the _______ of the beam. | divergence |
| High ratio grids have less positioning latitude than ___ ratio grids. | low |
| ____-____ grid can occur across the image and when the IR sinks into the patients bed during mobile radiography. | Off level |
| An ____-____ grid is more a result of positioning the x-ray tube than the grid. | off center |
| ___-___ grid occurs when radiographs are taken at unspecified SID's. | Off focus |
| ____ ____ grid occurs when the grid is placed upside down and results in severe grid cutoff. | Upside-down |
| The ___-___ technique will reduce scatter and increase image contrast. | air-gap |
| ______ is one disadvantage of the air gap technique. | Magnification |
| At ____ kVp and above, grid ratios greater than 8:1 are used. | 90 |
Created by:
teachable monkeys
Popular Radiology sets