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
HBL Positioning- Trauma
- 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
However, in a trauma setting you would
angle the stretcher to make the patient
approximately 45° to the central ray.
- SID = 110 cm (Sometimes in order to angle the bed
the SID may need to increase – go as far as
necessary)
HBL Positioning- Air Gap Technique
- 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 aligned straight and the patient
is angled approximately 45° to
match the angle of the neck of femur
in the primary beam - SID = 180 cm
- OID = 40-60 cm
HBL Collimation and Positioning Tips
- Position the patient on their stretcher between the x-ray tube and bucky at the desired SID and adjust the heights to match the level of the bedThe tube and bucky heights are now fixed, do not alter them
- Rotate the stretcher until the unaffected leg clear of the central ray and adjust the SID as requiredThe SID is now fixed, do not alter it
- Move the patient on their stretcher clear of the light beamCollimate on the detector/image receptor the size you want the x-ray to be (see image)Place the primary beam marker a corner of your imageThe collimation is now fixed, do not alter it
HBL Collimation and Positioning Tips (2)
- Move the patient back into the field and use the crease in the hip that separates the upper thigh and pubic area to align them to the central rayfor the vertical line
- Then GENTLY feel or estimate the area of greater trochanter and adjust the bed height so that the exit point of the central ray comes out at the greater trochanter for the horizontal line
If you follow these steps correctly, you will not miss the hip. If, however, you are slightly off from the perfect image. Repeating this style is still lower dose than just having the collimators fully open.
NB: Be aware when moving the bed/stretcher so as not to catch the equipment
Modified Lateral Hip Technique- To Consider
- Only required in situations where both neck of femurs are suspected to be fractured
- Usually in such an extreme case a CT scan is more than likely going to be performed
- However, this is the heavily modified lateral hip technique
- SID 100-180 (whatever works but keep it smaller where possible)
- The tube needs to be angle approximately 25° downLook out for the sides of the stretcher
- Angling the patient as much as possible or to 45° will reduce greater trochanter superimposition with the femoral head but means more of the stretcher could appear on the image
Frogs’ Legs Lateral
- The frog leg lateral view is a
special radiograph of the pelvis to
evaluate the hip in paediatrics. - It helps clinicians determine if a
patient has a: - Slipped upper femoral
epiphysis (SUFE) - Perthes Disease
- Cerebral Palsy Integrated
Pathway (CPIP) - Any hip dysplasia
Frogs’ Legs Lateral (2)
- IR Size/Orientation dependent on
patient habitus - Radiographic Marker
- Examination mainly done out of
Bucky however it depends on size
of patient - SID 110cm
- Suggested exposure factors;
CR: 63-70 kV and 2-5 mAs
DR: 63 - 70 kV and 1-4 mAs
Older children may require an
exposure in the bucky, check the local
rules
Frogs’ Legs Lateral (3- Positioning)
*The patient starts supine with no rotation
of hips
* Both limbs are bent at the knee and the
hip is abducted 45◦
* Centring point= midway between the
anterior superior iliac spine (ASIS) and the
pubic symphysis
* Collimation;
* Superior to the iliac crest
* Inferiorly to the proximal third of femur
* Lateral to the skin margins
Other Specialist Views
Judet Views
Used for acetabular fracture
assessment.
Inlet/ Outlet Views
Inlet- caudal angulation to visualise
pelvic rim
Outlet- cranial angulation for
obturator foramen
Assessing Images- Shenton’s Line
Shenton’s line is an imaginary
curved line drawn along the inferior
border of the superior pubic ramus
(superior border of the obturator
foramen) and along the inferior-
medial border of the neck of femur.
This line should be continuous and
smooth.
* Interruption of the Shenton line can
indicate:
Neck of Femur Fracture
DDH
Hip Dislocation
- There are several different types of dislocations:
- Posterior Dislocation (most common 85%)
- Anterior Dislocation (10%)
- Inferior
- Superior
- Central hip dislocation
- Dislocations are normally associated with:
- RTC’s
- High Speed Trauma
- Falls
- Degeneration of Hip replacements
- They are managed by applying traction and using the “closed reduction” method (applying force correctly so that the hip is moved back into the correct position)
Hip Dislocation (2)- Images
Posterior
Dislocation
of
Prosthesis
Posterior
Dislocation
Anterior
Dislocation
Neck of Femur Fracture (#NOF)
- Femoral Neck is the weakest part of the Femur
- NOF’S can affect the blood supply to the femoral head so need to be
classified correctly. - There are three types:
Subcapital (femoral head/neck junction)
Transcervical (mid-part of femoral neck)
Basicervical (base of femoral neck) - Most commonly occur:
Falls
High Speed Trauma
NOF (2)
- They are managed by different
surgical methods:
Arthroplasty (total hip replacement
or hemi arthroplasty) for patients
with a displaced intracapsular hip
fracture.
Dynamic Hip Screw (DHS) which
can only be used when the
fracture is non-displaced.
Cannulated screws also limited to
non-displaced fractures but can be
removed.
Anatomical relation of hip
fractures
Sub-capital
Transcervical
Basicervical
Inter-trochanteric
Sub-trochanteric
Post Cannulated Screw Removal
NOF
Comminuted intertrochanteric
fracture
Subtrochanteric fracture
Slipped Upper Femoral Epiphysis (SUFE)- Paeds
- Is a Type I Salter-Harris growth plate injury due to repeated trauma and hormonal factors
- During growth, there is a widening of the physis/ physeal plate which is pronounced during a growth spurt.
- The force across the growth plate can result in a fracture and as a result there is slippage.
Other Common Pelvic Fractures
Acetabular
Fracture
Pubic Rami
- Fracture
Iliac
wing
Fracture
Avulsion
Fracture
Other Common Pelvic Fractures
- Open Book Fracture
- It is a combination of
ligamentous rupture and/or
fractures to both the anterior
and posterior arch
Other Common Pelvic Fractures
Pathologies of the Pelvis
Avascular Necrosis of Hip (AVN)
It occurs when blood supply to the
head of the femur is interrupted. As
a result of this there is death of
marrow and osteocytes.
Paget’s Disease
- It is a chronic bone disorder which
causes abnormal bone re-modelling. It
is not understood entirely but we
understand that it occurs due to a
disease of osteoclasts - osteoclasts – cells that absorb old bone
- osteoblasts – cells that make new bone
- In Paget’s disease of bone, the
osteoclast cells start to absorb bone
at a faster rate - The osteoblasts then produce new
bone quicker, but the new bone is
larger and weaker than normal
OA
- It occurs when cartilage in the hip joint
gradually wears away over a period of
time. This results in the bone surfaces
rubbing against each other. To
compensate for the loss of cartilage
the bones start growing outwards
causing bone spurs (osteophytes). - Mainly caused by; Age, obesity and
family history
RA (Image also has underlaying OA)
- It is a chronic inflammatory disease that affects the
joints. - Auto-immune condition that mistakes the body’s cells for
foreign invaders and releases inflammatory chemicals
that attack the synovium. The inflamed synovium gets
thicker and makes the joint area feel painful and tender
and look red and swollen. - Joints become painful, swollen and stiff
- Usually occurs later in life, the age of 50 or so
It can begin as early as the 30’s - More prevalent in females
- Family history increases likelihood
Developmental Dysplasia of the hip (DDH)
- It results from an abnormal
relationship between the
femoral head and the
acetabulum - It occurs:* Mainly in females
- Due to Lax of ligaments and
abnormal position in utero
Perthes Disease
- Perthes is considered an
idiopathic condition, and there
are no clear predisposing
factors - Boys are five times more
likely to be affected than girls - Occurs generally between
ages of 3-12 - Presents as a flattened and
sclerotic femoral epiphysis
“Normal” FBs found in the pelvis
Intra-Uterine Contraceptive Device (IUCD)
Fallopian Tube Ligation
Neurostimulator (Nerve stimulator)
Insulin Pump with IUCD
