M2 L6 grid errors

Question 1

what are the 4 common use errors

Answer 1

off level grid
off center grid
off focus grid
upside down grid

Question 2

what is grid cut off

Answer 2

reuslt when a grid is not used properly, it cuts off some of the primary beam bc grid is not aligned w tube

Question 3

what is quantum noise

Answer 3

a grainy appearance on an image due to too few photons reaching IR

Question 4

what is off level grid

Answer 4

grid is tilted or tube is angled against grid lines.

cut off occurs on the entire image and there may be quantum noise as well as low contrast

Question 5

which way do you want central ray and grid surface to be in relation to each other

Answer 5

perpendicular

Question 6

if the tube is angled the same direction as strips will there be cut off

Answer 6

no

Question 7

what is off centre grid/lateral decentering

Answer 7

tube and grid are perpendicular, but central ray is lateral to the centre of the grid (off to the side).

grid cut off of entire image and some quantum noise and decrease image contrast

Question 8

what visibly happens to an image if theer is off centre grid

Answer 8

contrast is decreased therefor image is super bright

Question 9

what is off focus grid

Answer 9

focused grid is used w wrong SID

the farther from the specified SID the more severe of cut off. cut off will mainly be around edges of image

Question 10

what is upside down grid

Answer 10

upside down focused grid

grid cut off on either side of central ray (edges) bc strips are angled upside down therefor the angle of the strips doesnt match xray beam

Question 11

why do we like using 8:1 grid ratio

Answer 11

because it has a wider latitude for centering that wont show errors as much as other ratios would

Question 11

what do grid does gen duty typically use

Answer 11

8:1 , 10:1 , or 12:1

Question 12

what does an increase in grid ratio mean for grid cut off

Answer 12

severity of grid cut off increases as grid ratio increases

Question 13

the margin for error decreases as the…..

Answer 13

grid ratio increases