Positioning appendicular/axial skeleton basics Flashcards
Elbow AP and Lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
Elbow AP
Centering
* 2.5cm to the point midway of the medical and lateral epicondyles of the humerus
Collimation
* The image should demonstrate the distal third of humerus and the proximal third of the radius and ulna.
Positioning in relation to IR
* The arm is adjusted such that the medial and lateral epicondyles are equidistant from the cassette.
Patient gross position
* The arm is then extended fully, such that the posterior aspect of the entire limb is in contact with the tabletop and the palm of the hand is facing upwards.
Lateral
Centering
* The vertical central ray is centred over the lateral epicondyle of the humerus.
* The central ray must pass through the joint space at 90 degrees to the humerus, i.e. the epicondyles should be superimposed.
Collimation
* The image should demonstrate the distal third of humerus and the proximal third of the radius and ulna.
Positioning in relation to IR
* The patient is seated alongside the table, with the affected side nearest to the table.
* The elbow is flexed to 90 degrees and the palm of the hand is rotated so that it is at 90 degrees to the tabletop.
Patient gross position
* The shoulder is lowered so that it is at the same height as the elbow and wrist, such that the medial aspect of the entire arm is in contact with the tabletop.
Exposure factors
*
Wrist AP and lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
* The vertical central ray is centred to a point midway between the radial and ulnar styloid processes.
Collimation
* The image should demonstrate the proximal two-thirds of the metacarpals, the carpal bones, and the distal third of the radius and ulna. (head of metacarpals)
Positioning in relation to IR
* The wrist joint is adjusted to ensure that the radial and ulnar styloid processes are equidistant from the cassette.
Patient gross position
* The elbow joint is flexed to 90 degrees and the arm is abducted, such that the anterior aspect of the forearm and the palm of the hand rest on the cassette.
Lateral
Centering
* The vertical central ray is centred over the styloid process of the radius.
Collimation
* The image should demonstrate the proximal two-thirds of the metacarpals, the carpal bones and the distal third of the radius and ulna.
Positioning in relation to IR
* The radial and ulnar styloid processes should be superimposed
Patient gross position
* The elbow joint is extended to bring the medial aspect of the forearm, wrist and hand into contact with the table.
*The hand is rotated externally slightly further to ensure that the radial and styloid processes are superimposed.
Exposure factors
*
Shoulder AP and Axial
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
* The horizontal central ray is directed to the palpable coracoid process of the scapula. The beam can then be directed
caudally and collimated. 2.5cm below
* The central ray passes through the upper glenoid space to separate the articular surface of the humerus from the acromion process.
Collimation
* The image should demonstrate the head and proximal end of the humerus, the inferior angle of the scapula and the whole of the clavicle.
* The head of the humerus should be seen slightly overlapping the glenoid cavity but separate from the acromion process.
Positioning in relation to IR
* The medial and lateral epicondyles of the distal humerus
should be parallel to the cassette.
Patient gross position
* The arm is supinated and slightly abducted away from the
body.
*patient is erect (in trauma settings, the patient may be sitting in a bed etc)
Axial
Centering
* The vertical central ray is directed through the proximal aspect head of the humeral head. Some tube angulation, towards the palm of the hand, may be necessary to coincide with the plane of the glenoid cavity.
*If there is a large OFD, it may be necessary to increase the overall focus-to-film distance (FFD) to reduce magnification.
Collimation
* The image should demonstrate the head of the humerus, the acromion process, the coracoid process and the glenoid cavity of the scapula.
* The lesser tuberosity will be in profile, and the acromion process and the superior aspect of the glenoid will be seen superimposed on the head of humerus.
Positioning in relation to IR
* The elbow can remain flexed, but the arm should be abducted to a minimum of 45 degrees,
Patient gross position
* The patient is seated at the side of the table, which is lowered to waist level.
*The cassette is placed on the tabletop, and the arm under examination is abducted over the cassette.
*The patient leans towards the table to reduce the object-tofilm distance (OFD) and to ensure that the glenoid cavity is included in the image.
Exposure factors
*
Hand PA (DP) and oblique
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
PA (DP)
Centering
*The vertical central ray is centred over the head of the third metacarpal.
Collimation
*The image should demonstrate all the phalanges, including the soft-tissue fingertips, the carpal and metacarpal bones, and the distal end of the radius and ulna
Positioning in relation to IR
* The wrist is adjusted so that the radial and ulna styloid processes are equidistant from the cassette.
Patient gross position
* The forearm is pronated and placed on the table with the palmer surface of the hand in contact with the cassette.
* The fingers are separated and extended but relaxed to ensure that they remain in contact with the cassette.
Oblique
Centering
*The vertical central ray is centred over the head of the fifth
metacarpal.
Collimation
* The image should demonstrate all the phalanges, including the
soft-tissue of the fingertips, the carpal and metacarpal bones,
and the distal end of the radius and ulna
Positioning in relation to IR
*The correct degree of rotation has been achieved when the
heads of the first and second metacarpals are seen separated
whilst those of the fourth and fifth are just superimposed.
Patient gross position
*From the basic postero-anterior position, the hand is externally rotated 45 degrees with the fingers extended
Patient gross position
Exposure factors
*
consider lateral
Forearm AP and lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
*The vertical central ray is centred in the midline of the forearm to a point midway between the wrist and elbow joints.
Collimation
*Both the elbow and the wrist joint must be demonstrated on the cassette.
* Both joints should be seen in the true antero-posterior position, with the radial and ulnar styloid processes and the epicondyles of the humerus equidistant from the cassette.
Positioning in relation to IR
*The arm is adjusted such that the radial and ulnar styloid processes and the medial and lateral epicondyles are equidistant from the cassette.
Patient gross position
*The arm is abducted and the elbow joint is fully extended, with the supinated forearm resting on the table.
*The shoulder is lowered to the same level as the elbow joint.
Lateral
Centering
*The vertical central ray is centred in the midline of the forearm to a point midway between the wrist and elbow joints.
Collimation
*Both the elbow and the wrist joint must be demonstrated on the image.
Positioning in relation to IR
*The arm is adjusted such that the radial and ulnar styloid processes and the medial and lateral epicondyles are superimposed.
Patient gross position
*From the antero-posterior position, the elbow is flexed to 90 degrees
*The humerus is internally rotated to 90 degrees to bring the medial aspect of the upper arm, elbow, forearm, wrist and hand into contact with the table.
Exposure factors
*
consider horizonal lateral beam
Humerus AP and Lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
*The central ray is directed at right-angles to the shaft of the humerus and centred midway between the shoulder and elbow joints.
Collimation
*Both joints should be seen on the image
Positioning in relation to IR
*The position of the patient is adjusted to ensure that the medial and lateral epicondyles of the humerus are equidistant from the cassette.
Patient gross position
*The patient sits or stands with their back in contact with the cassette.
*The patient is rotated towards the affected side to bring the posterior aspect of the shoulder, upper arm and elbow into contact with the cassette.
Lateral
Centering
*The horizontal central ray is directed at right-angles to the shaft of the humerus and centred midway between the shoulder and elbow joint.
Collimation
*Both joints should be seen on the image.
Positioning in relation to IR
*The humerus is adjusted to ensure that the medial and lateral epicondyles of the humerus are superimposed.
Patient gross position
*From the anterior position, the patient is rotated through 90 degrees until the lateral aspect of the injured arm is in contact with the cassette.
* The patient is now rotated further until the arm is just clear of the rib cage but still in contact with the cassette
Exposure factors
*
Foot AP and oblique
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
*The central ray is directed over the cuboid-navicular joint,
midway between the palpable navicular tuberosity and the
tuberosity of the fifth metatarsal.
Collimation
*The tarsal and tarso-metatarsal joints should be demonstrated when the whole foot is examined.
(in trauma cases you may want to include the malleoli)
Positioning in relation to IR
*The plantar aspect of the affected foot is placed on the cassette and the lower leg is supported in the vertical position by the other knee.
Patient gross position
*The patient is seated on the X-ray table, supported if necessary, with the affected hip and knee flexed.
Oblique
Centering
*The vertical central ray is directed over the cuboid-navicular joint.
Collimation
*The dorsi-plantar oblique should demonstrate the inter-tarsal and tarso-metatarsal joints.
Positioning in relation to IR
*From the basic dorsi-plantar position, the affected limb is allowed to lean medially to bring the plantar surface of the foot approximately 30–45 degrees to the cassette.
Patient gross position
*The patient is seated on the X-ray table, supported if necessary, with the affected hip and knee flexed.
Exposure factors
*
consider lateral
Ankle AP and lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
*Centre midway between the malleoli with the vertical central ray at 90 degrees to an imaginary line joining the malleoli.
Collimation
*The lower third of the tibia and fibula should be included.
* A clear joint space between the tibia, fibula and talus should
be demonstrated (commonly called the Mortice view).
Positioning in relation to IR
*The limb is rotated medially (approximately 20 degrees) until the medial and lateral malleoli are equidistant from the cassette.
(Insufficient medial rotation causes overshadowing of the tibiofibular joint with the result that the joint space between the fibula and talus is not demonstrated clearly.)
Patient gross position
*The affected ankle is supported in dorsiflexion by a firm 90-degree pad placed against the plantar aspect of the foot.
(Insufficient dorsiflexion results in the calcaneum being superimposed on the lateral malleolus.)
Lateral
Centering
*Centre over the medial malleolus, with the central ray at right-angles to the axis of the tibia.
Collimation
*The lower third of the tibia and fibula should be included.
*The base of the fifth metatarsal and the navicular bone should be included on the image to exclude fracture.
Positioning in relation to IR
*The medial and lateral borders of the trochlear articular surface of the talus should be superimposed on the image.
Patient gross position
*With the ankle dorsiflexed, the patient turns on to the affected side until the malleoli are superimposed vertically and the tibia is parallel to the cassette.
Exposure factors
Tibia and Fibula AP and lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
*Centre to the middle of the cassette, with the central ray at right-angles to both the long axis of the tibia and an imaginary line joining the malleoli.
Collimation
*The knee and ankle joints must be included, since the proximal end of the fibula may also be fractured when there is a fracture of the distal fibula.
Positioning in relation to IR
*The ankle is supported in dorsiflexion by a firm 90-degree pad placed against the plantar aspect of the foot. The limb is rotated medially until the medial and lateral malleoli are equidistant from the cassette.
Patient gross position
* The patient is either supine or seated on the X-ray table, with both legs extended.
Lateral
Centering
*Centre to the middle of the cassette, with the central ray at right-angles to the long axis of the tibia and parallel to an imaginary line joining the malleoli.
Collimation
*The knee and ankle joints must be included, since the proximal end of the fibula may also be fractured when there is a fracture of the distal fibula.
Positioning in relation to IR
*The leg is rotated further until the malleoli are superimposed vertically
Patient gross position
*From the supine/seated position, the patient rotates on to the affected side.
Exposure factors
*
Knee AP and lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
*Centre 2.5 cm below the apex of the patella through the joint space, with the central ray at 90 degrees to the long axis of the tibia. (1cm)
Collimation
*Proximal third of the tibia and fibula and distal third of the femur
Positioning in relation to IR
*To enable correct assessment of the joint space, the central ray must be at 90 degrees to the long axis of the tibia
*posterior aspect in contact with the image receptor
Patient gross position
*The affected limb is rotated to centralize the patella between the femoral condyles,
Supine or erect (weight bearing)
Lateral
Centering
*Centre to the middle of the superior border of the medial tibial condyle, with the central ray at 90 degrees to the long axis of the tibia.
Collimation
*Proximal third of the tibia and fibula and distal third of the femur
Positioning in relation to IR
*The patella should be projected clear of the femur.
* The femoral condyles should be superimposed.
* The proximal tibio-fibular joint is not clearly visible.
Patient gross position
*The patient lies on the side to be examined, with the knee flexed at 45
* A sandbag is placed under the ankle of the affected side to bring the long axis of the tibia parallel to the cassette.
(my personal way of achieving this is to rest the affected side calcaneus on the other leg)
consider horizonal beam lateral
Exposure factors
60kV 3mAs
Femur AP and lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
*Centre to the middle of the cassette, with the vertical central ray at 90 degrees to an imaginary line joining both femoral condyles.
Collimation
*preferably with both the knee and hip joints included on the image
Positioning in relation to IR
Posterior aspect in contact with IR
Patient gross position
*The affected limb is rotated to centralize the patella over the femur.
*supine
Lateral
Centering
*Centre to the middle of the cassette, with the vertical central ray parallel to the imaginary line joining the femoral condyles.
Collimation
*preferably with both the knee and hip joints included on the image
Positioning in relation to IR
*The position of the limb is then adjusted to vertically superimpose the femoral condyles.
Patient gross position
*From the antero-posterior position, the patient rotates on to the affected side, and the knee is slightly flexed.
* The pelvis is rotated backwards to separate the thighs.
Exposure factors
*
Pelvis and hip lateral (HBL)
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
Pelvis
Centering
*Midline midway between the upper border of the symphysis pubis and anterior superior iliac spines. (basically just above the symp pubis)
Collimation
*For the basic pelvis projection, both iliac crests and proximal femora, including the lesser trochanters, should be visible on the image
Positioning in relation to IR
*To avoid pelvic rotation, the anterior superior iliac spines must be equidistant from the tabletop. A non-opaque pad placed under a buttock can be used to make the pelvis level. The coronal plane should now be parallel to the tabletop
Patient gross position
*The limbs are slightly abducted and internally rotated to bring the femoral necks parallel to the cassette.
Hip lateral (HBL)
Centering
*Centre through the affected groin, midway between the femoral pulse and the palpable prominence of the greater trochanter, with the central ray directed horizontally and at right-angles to the cassette. (perpendicular with the IR)
Collimation
To include the acetabulum, femoral neck, Trochanters, upper third of the femur (collimated closely to improve image contrast so no need for soft tissues)
Positioning in relation to IR
*The grid cassette is positioned vertically, with the shorter edge pressed firmly against the waist, just above the iliac crest.
*The longitudinal axis of the cassette should be parallel to the neck of femur. This can be approximated by placing a 45-degree foam pad between the front of the cassette and the lateral aspect of the pelvis.
Patient gross position
*The unaffected limb is then raised until the thigh is vertical, with the knee flexed.
Exposure factors
*
Chest PA erect
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
Chest
Centering
*The surface marking of T7 spinous process can be assessed by using the inferior angle of the scapula before the shoulders are pushed forward.
Collimation
*Full lung fields with the scapulae projected laterally away
from the lung fields.
* The clavicles symmetrical and equidistant from the spinous
processes and not obscuring the lung apices.
* The lungs well inflated, i.e. it should be possible to visualize
either six ribs anteriorly or ten ribs posteriorly.
* The costophrenic angles and diaphragm outlined clearly.
* The mediastinum and heart central and defined sharply.
* The fine demarcation of the lung tissues shown from the
hilum to the periphery.
Positioning in relation to IR
* The median sagittal plane is adjusted at right-angles to the middle of the cassette
*Clavicles are equidistant to the IR as they are to each other (no rotation)
Patient gross position
*The patient is positioned facing the cassette, with the chin extended and centred to the middle of the top of the cassette
*The shoulders are rotated forward and pressed downward in contact with the cassette.
Exposure factors
Abdomen supine AP
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
Abdomen
Centering
*Midway between iliac crests
Collimation
*To include the symphysis pubis, lateral margins (soft tissues), hemidiaphragms
Positioning in relation to IR
* The pelvis is adjusted so that the anterior superior iliac spines are equidistant from the tabletop.
Patient gross position
*The patient lies supine on the imaging table, with the median sagittal plane at right-angles and coincident with the midline of the table.
Exposure factors
*
C spine AP and lateral
Centering
Collimation
Positioning in relation to IR
Patient gross position
Exposure factors
AP
Centering
* A 5–15-degree cranial angulation is employed, such that the inferior border of the symphysis menti is superimposed over the occipital bone.
* The beam is centred in the midline towards a point just below the prominence of the thyroid cartilage through the fifth cervical vertebra.
Collimation
*C1 to T1, soft tissues included
Positioning in relation to IR
* posterior aspect of the head and shoulders against the vertical Bucky.
* The median sagittal plane is adjusted to be at right-angles to the cassette and to coincide with the midline of the table or Bucky
Patient gross position
*The neck is extended (if the patient’s condition will allow) so that the lower part of the jaw is cleared from the upper cervical vertebra
Lateral
Centering
*The horizontal central ray is centred to a point vertically below the mastoid process at the level of the prominence of the thyroid cartilage.
Collimation
*The whole of the cervical spine should be included, from the atlanto-occipital joints to the top of the first thoracic vertebra.
Positioning in relation to IR
*The patient stands or sits with either shoulder against the IR.
* The median sagittal plane should be adjusted such that it is parallel with the cassette.
Patient gross position
*The head should be flexed or extended such that the angle of the mandible is not superimposed over the upper anterior cervical vertebra or the occipital bone does not obscure the posterior arch of the atlas
Exposure factors
*
consider peg view
