what is an x-ray image?

Question 1

what effects radiolucency?

Answer 1

material - more dense are more white

size - bigger but same material will still be more opaque than smaller

shape - can’t see 3d but can see that shape is different

Question 2

effect of beam intensity

Answer 2

increasing exposure time changes what you can see, if exposure increased then photons pass through more, if disappears called ‘burnout’

Question 3

effect of changing position image receptor and xray beam

Answer 3

rotating object changes image because thickness varies from different angles

Question 4

ideal position

Answer 4

parallel xray beam meeting both the tooth and the image receptor at right angles

image receptor and tooth parallel and in contact

otherwise image distorted

Question 4

ideal position

Answer 4

parallel xray beam meeting both the tooth and the image receptor at right angles

image receptor and tooth parallel and in contact

Question 5

main types of images and their limitations

Answer 5

1) conventional film
2 dimensional
affected by geometric distortion and chemical faults
effected by exposure factors

2) tomography/ sectional images
avoids superimposition

3) digital

Question 6

different tomographic images of maxillo-facial skeleton

Answer 6

simple linear tomography - xray tube goes up and film moves down. person stays still
large movement creates thin slice, small movement gives thicker slice

complex multidirectional - spiral motion between tube and film

computed - CT
spirals around patient, multiple slices produced and can create 3D image

cone beam - can produce cross sectional image in any plane, can make 3D with computer software

dental panoramic -
tube starts on the right tomographic layer is curved like jaw
limitation - if teeth are in abnormal position will not fit into slice and are not in focus on film
real image on right creates a ghost shadow on the left
eg ghost L shape of mandible

Question 7

limitations of tomographic images

Answer 7

only represent one slice

blurred by movement

affected by patient shape and positioning

complex with may shadows

affected by exposure factors and processing faults

resolution relatively poor

Question 8

digital images

Answer 8

8 pixel numbers correspond to 8 shades of grey

limitations - 2D
affected by geometrical distortion.

can be altered by processionals g