13 exposures are taken at 200, 400, and 800 mA. what are we testing for and what is the criteria for passing this test.
We are testing for linearity. The criteria for passing this test is that the exposures obtained when operated at Adjacent mA stations, should not vary more than 10% when expressed as mR/mAs
2What is the coincidence of the xray beam and how do we measure this
The error of coincidence cannot exceed 2% of SID on any side of the field. To test this, cassette is placed at 100-cm SID. Paper clips are then placed on the outlines of the light field and an exposure is made. Using the paperclips, the deviation can be measured in both directions in order to determine the if degree of coicidence is acceptable or not.
310 secquental exposers are taken at the same technique, what are we testing for and what are the criterias for passing this test?
Reproducibility is being tested. The criteria for passing this test is that exposures cannot vary more than +/- 5% of the original exposure
4What is the definition of HVL?
Thickness of a material to reduce the original exposure to one half the original value.
5Describe the procedure to measure beam quality.
To measure beam quality, we use the half value layer. In order to do this, all filtration from the xray tube is removed and made an exposure with no filtration. After, layers of .5mm aluminum is added until half of the original value is produced. After which, more layers are added until 1/4th value layer is reached and then 1/8th and 1/10th. 2.5mm aluminum is the minimum requirement for primary beam filtration.
6what factors are effected as grid ratio increases, 4 things
Factors that are affected as grid ratio increases are patient dose increases, a decrease in fog from scatter and, an increase in contrast and contrast resolution.
7what factors are effected when proper collimation is not used (4 factors)
The factors effected, when proper collimation is not used, are increase of patient dose, increase of fog from scatter, increase of dose area product, decrease contrast resolution and contrast.
8What are some possible errors when using AEC? (4 errors)
Four possible errors are improper position, wrong photo cell selected, wrong bucky selection, insufficient back-up time.
9what is the relationship between S value and Noise?
S value is used in CR. S value and noise have a direct relationship. If S value is increased, noise is increased. If S value is decreased, exposure is increased.
10What is relationship between EI value and noise?
EI value is used in DR. EI and noise have an indirect relationship. As EI goes up, noise goes down and as EI goes down, noise increases. Noise being quantum mottle .
114 ways to reduce patient exposure?
Four ways to reduce patient exposure are decrease repeats, increase filtration, use shielding, increase collimation, increase compression, and increase kVp and lower mAs.
12Is it ethical to use an apron for gonadal shielding?
It is not ethical to use an apron for gonadal shielding. It would be ethical if the apron was .5mm pb or more or if two 2.5mm pb equivalent is used. As long as .5mm pb equivalent is used, it would be ethical.