Pelvic Girdle Imaging Flashcards
Positioning and Technique- Routine Projection
pelvic girdle
- AP Pelvis
- AP Single Hip
- Lateral Turned Hip
- Lateral HBL (Horizontal Beam
Lateral) Hip - Frog Legs (paediatric)
All projections use broad focus
settings
Patient Preparation for pelvic girdle
- 3 or 4 point ID check – does it
match your worklist? - Is the request justified? Are the
standard projections sufficient? - Radiation safety and protection:
- LMP (Last Menstrual Period)
- ALARA
- Is the patient changed?
- Explanation of procedure
AP Pelvis Positioning
- Patient is supine, in the true AP position
- ASIS to be equidistant to the image receptor
- MSP (Medial Sagittal Plain) perpendicular with table
- Arms out of the way either above head or across the patient’s chest
- Centring Point (CP) = Mid way between the ASIS and the symphysis pubis
- Heels separated and toes pointing together (slight abduction and internal rotation of the hips)
AP Pelvis- Impact of Foot Positioning
internal rotation of the foot
femoral neck elongated lesser trochanter obscured by shaft of femur
antero-Posterior (AP) Pelvis
- Image receptor/ Expected
collimation area- 35cm x 43cm - Cassette Orientation - Landscape
- Radiographic Marker
- Suggestion – Superio-laterally to the
iliac crest - Tube needs to be centred to the
bucky- moving grid used - SID 110cm
- Exposure factors;
- 75 Kv and 25 mAs (AEC with grid-
side chambers used)
Antero-Posterior (AP) Pelvis (2)
- Collimation;
- Superiorly to the Iliac crest
- Inferiorly to the proximal 1/3 of
femur - Laterally to the skin margins
AP Pelvis Positioning
collimation to skin margin
cassette in landscape position and in bucky
toes pointed inwards
hands of patient on their chest or head.
AP Pelvis Anatomy
iliac fossa
sacro - iliac joint
hip joint
neck of femur
greater trochanter
lesser trochanter
obturator foramen
symphysis pubis
body of pubis
inferior pubis ramus
superior pubic ramus
ischial tuberosity
ischial spine
anterior inferior iliac spine
superior iliac spine
2nd sacral arches
1st sacral arches
iliac crest
5th lumbar vertebra
AP Single Hip/ Turned Lateral Hip Preparation
- Same as the AP Pelvis
- 3 or 4 point ID check
- LMP (Last Menstrual Period)
- Is the patient changed
- Explanation of procedure
AP Single Hip
- Same starting position as the AP Pelvis
- Image receptor – 24 x 30cm
- Cassette Orientation - Portrait
- Radiographic Marker
- Suggestion – Supero-laterally to the iliac crest
- Tube needs to be centred to the bucky- grid use
- SID 110cm
- Exposure factors
- 75kV and 16mAs (use of central chamber)
AP Single Hip Positioning
- Centring point
- 2.5cm below the perpendicular
bisector of a line drawn from
the ASIS to symphysis pubis - Collimation;
- Superiorly to the ASIS
- Inferiorly to the proximal 3rd
part of the femur - Medially to the
- Laterally to the skin margins
AP Single Hip Anatomy (right)
ilium
pelvic brim
anterior inferior iliac spine
neck of femur
greater trochanter
intertrochanteric
lesser trochanter
shaft of femur
superior pubic ramus
ischium ischio pubic ramus
skin crease
teardrop fovea centralis
roof of acetabulum
lateral border of sacrum pelvic brim
Turned Lateral Hip
- Image receptor – 24 x 30cm
- Cassette Orientation –
Landscape - Radiographic Marker
- Tube needs to be centred to
the bucky (grid to be used) - SID 110cm
- Exposure factors:
- 75kV, 16mAs (AEC, Centre
Chamber)
Turned Lateral Hip Position
- Turn patient onto the affected side and rotate the pelvis 35-40°
- Flex the patient’s hip and knee on the affected side
- Centring point =
- Midpoint between the anterior superior iliac spine (ASIS) and pubic
symphysis - Collimation;
- Superiorly to include acetabulum
- Inferior to include the proximal third of the femur
- Laterally to include skin margins
Turned Lateral Hip Position
Anterior-
posterior to
include borders
of the femur
Superiorly to
include
acetabulum
CP= midpoint
between (ASIS)&
pubic symphysis
Cassette
landscape
position
Turned Lateral Hip Anatomy
acetabulum
femoral head
femoral neck
greater trochanter
lesser trochanter
femur
Horizontal Beam Lateral (HBL) Positioning
- Image receptor - 24 x 30cm
- Cassette Orientation – Landscape (with grid)
- Radiographic Marker
- Radiograph can be achieved by centering to the AEC chamber or utilising air gap technique
- (The reduction in scattered radiation reaching the detector by increasing the distance between the tube and the image receptor)
- SID:
- 110cm NO air gap, 180cm WITH air gap
- Exposure factors will vary greatly depending on technique
- HBL with no air gap= 80kV, 80mAs (with grid, AEC centre chamber)
- HBL with air gap= 125kV, 40mAs (no grid)
Horizontal Beam Lateral (HBL) Hip – Positioning (2)
- Patient is in the supine AP position
- Patient’s arms are either above their head or across chest
- You must clear the elbows, so they cannot be resting on the bed
- The affected side is positioned against the image receptor
- The knee and hip of the unaffected side needs to be elevated in
a vertical position ( so a clear view is obtained of affected side) - The image receptor and x-ray tube are angled approximately
45° to match the angle of the neck of femur
HBL Hip Positioning (3)
- Centring Point =
- Through the affected groin, midway between the femoral pulse and the
palpable prominence of the greater trochanter, directed at right angles
to the IR. - “Perpendicular to the femoral neck”
- Collimation:
- Anteriorly and posteriorly to soft tissue skin margins
- Superiorly to include the acetabulum
- Inferiorly to include proximal aspect of the femur
HBL Hip Positioning (4)
Central ray
perpendicular to
femoral neck as well
as the IR
The image receptor & x-ray
tube are angled approximately
45° to match the angle of neck
of femur