C Spine Technique

Question 1

how is the pt positioned for a lateral c spine? - 5 points

Answer 1

pt stands with affected side closest to the image receptor, feet slightly apart for stability, pt’s head adjusted so EAMs are superimposed to bring MSP parallel to image receptor, pt’s shoulders relaxed, hands by side/back

Question 2

why should the chin be raised slightly in a lateral c spine?

Answer 2

to ensure anterior aspect of C1/C2 and isn’t obscured by angle of mandible and posterior arch of atlas not obscured by occipital bone

Question 3

how is the tube positioned?
where is the tube centred to?
where to collimate to?

Answer 3

horizontal ray directed at 90 degrees
2.5cm behind and below the angle of the mandible (approx C4 - midpoint of neck)
EAM superiorly, just below C7/T1 junction inferiorly and anterior & posterior soft tissue borders laterally

Question 4

where is an alternative centring point for a lateral c spine?
why would you centre here instead?
what is a disadvantage of using this centring point?

Answer 4

2.5cm behind the angle of the mandible
higher centring point to make use of the diverging rays which project the shoulder to a lower level so more cervical vertebrae can be visualised
it hinders close collimation

Question 5

what is the SID for a lateral c spine and why?

what is the breathing for a lateral c spine and why?

Answer 5

180cm - to combat magnification of c spine apparent due to the air gap between the neck and the image receptor

on arrested respiration - assists in lowering the shoulders

Question 6

what would be seen on an ideal lateral c spine? - 4 points

Answer 6

superimposition of anterior and posterior vertebral bodies so no rotation
superimposition of superior and inferior vertebral bodies to give clear joint spaces
angle of mandible free from c1 and occipital bone free from neural arch of c1
odontoid peg seen in close proximity to the posterior aspect of arch of c1

Question 7

what is the image criteria for a lateral c spine - 5 points

Answer 7

corticol outlines of vertebrae should be intact
trabecular pattern throughout vertebrae should be uniform
interspinous distance should be approx equal throughout - no widening or less of a joint space
spinous processes should be aligned
no disruption of normal air shadows

Question 8

what are the 4 lines to follow when checking spinal alignment?

Answer 8

anterior vertebral line
posterior vertebral line
spina-laminar line
posterior spinous line

Question 9

what should be the gap between the anterior spine and the surface of skin at c1-c4 and c5-c7?

Answer 9

c1-c4 = 7mm
c5-c7 = 22mm

Question 10

what are the names of the 3 spaces around the c spine?

Answer 10

naso-pharyngeal space
retro-pharyngeal space
retro-tracheal space

Question 11

what should be the distance between the anterior arch of c1 and the anterior aspect of peg?

Answer 11

3mm

Question 12

how is the pt positioned for an AP c spine? - 3 points

Answer 12

pt sits/stands with posterior aspect in contact with the image receptor
midline fot he pt coincident with the midline of the image receptor
EAMs are equidistant from image receptor to ensure MSP is 90 degrees to receptor to minimise rotation

Question 13

why is the pt’s chin raised for an AP c spine?

Answer 13

so the mandible and the occipital bone are superimposed

Question 14

how is the tube positioned for an AP c spine?
what is the SID?
where is the tube centred and why?

Answer 14

horizontal central ray
100cm
to sternal notch and then cranially tilted to thyroid cartilage (5-15 degrees) to help superimpose the symphysis menti over the occiput

Question 15

what do you collimate to include in an AP c spine? - 3 points

Answer 15

c2/3 intervertebral space superiorly
c7/t1 joint space inferiorly
lateral soft tissue borders laterally

Question 16

what would be seen on an ideal AP c spine? - 3 points

Answer 16

occiput superimposed over the body of the mandible
vertebral bodies to coincide with the midline of the image receptor
spinous processes midline to vertebral bodies so there is no rotation

Question 17

what is the image criteria for an AP c spine? - 5 points

Answer 17

corticol outlines of vertebrae should be intact
trabecular pattern throughout vertebrae should be uniform
interspinous distance should be approx equal throughout - no widening or less of a joint space
spinous processes should be aligned
no disruption of normal air shadows

Question 18

how is the pt positioned for an open mouth AP c spine?

Answer 18

pt asked to open their mouth with their chin raised so the inferior aspect of the upper incisors (or hard palate in the edentulous pt) and the occiput are superimposed

Question 19

how is the pt positioned for an open mouth AP c spine if they were a trauma pt?

Answer 19

likely to present in a hard collar so the extent the pt is able to open their mouth is determined by the collar

Question 20

how is the tube positioned for an open mouth AP?
what is the SID?
where is the tube centred to?

Answer 20

horizontal ray (or vertical ray for trauma pt’s)
100cm
to the middle of the open mouth

Question 21

what do you collimate to include in an open mouth AP c spine? - 2 points

Answer 21

c1/c2 and related joint spaces

lateral soft tissue areas either side of the vertebrae

Question 22

what would be seen on an ideal open mouth AP c spine? - 3 points

Answer 22

occiput superimposition over lower border of incisors
atlanto-axial joint & odontoid process clear of overlying structures
lower incisors superimposed over c3

Question 23

what is the image criteria for an open mouth AP c spine?

Answer 23

corticol outlines of vertebrae should be intact
trabecular pattern throughout vertebrae should be uniform
interspinous distance should be approx equal throughout - no widening or less of a joint space
spinous processes should be aligned
no disruption of normal air shadows

Question 24

what is the Mach Effect

Answer 24

the awareness of pseudo-shadows caused by overlying soft tissue which can mimic #s - if the shadow/line continues outside the cortical margins then a # can be ruled out

Question 25

Describe the Swimmer’s View - 3 points
when is it contraindicated?
what is an alternative view to this?

Answer 25

done if c7/t1 isn’t fully visualised on the lateral view
positioned the same as a lateral view but adjacent to upper limbs, the arm nearest reaches above pt and opposing limb reaches inferiorly so the shoulders are no longer superimposed
trauma pt’s require much larger dose
if not done correctly then it’s difficult to interpret
contraindicated if pt has upper extremity #s
Trauma Obliques - visualise c7/t1

Question 26

Describe Flexion and Extension Views - 3 points
who is it performed on?
who is it not performed on?

Answer 26

Flexion = neck anteriorly towards ground
Extension = neck posteriorly looking upwards
NOT FORCED
performed on pt’s with degenerative disease/history of RA for pre-anaesthetic
NOT ON TRAUMA PT’S