xray geometry

Question 1

SID

Answer 1

source to image distance eg anode/focal spot to IR

Question 2

OID

Answer 2

object to image distance eg patient to receptor

Question 3

SOD

Answer 3

source to object distance eg the anode to patient

Question 4

add sod and oid

Answer 4

to get sid

Question 5

must project at 90 degrees

Answer 5

so we dont get a distorted image

Question 6

if reduced the distance between beam and ir

Answer 6

the image will be closer to size

Question 7

put body part as close as possible to ir

Answer 7

to avoid magnification

Question 8

increase sid

Answer 8

to reduce magnification

Question 9

sod

Answer 9

sid minus oid

Question 10

foreshortening

Answer 10

improper body alaignment(looks short)

Question 11

elongation

Answer 11

improper ir alaignment(looks long)

Question 12

patient movement

Answer 12

sandbags, ensure comfort,

Question 13

geometric unsharpness

Answer 13

focal spot and penumbra

Question 14

large sod and oid

Answer 14

will reduce the penumbra so u get better image

Question 15

fine focal spot

Answer 15

sharper image

Question 16

fine focal spot creates alot of heat

Answer 16

giving xray short life span

Question 17

inverse square law

Answer 17

double distance quater the dose

Question 18

xray beams are

Answer 18

divergent and isotropic

Question 19

triple the distance

Answer 19

one ninth the dose

Question 20

parrallel to imagine receptor

Answer 20

perpindiculer to beam