XR Flashcards
What is the standard radiographic view for the hips and what are the technical factors and positioning?
AP pelvis - supine
Normal angle between femoral neck and shaft - 125-135 degrees
75-85 kVp range
mAs 12 (at 80 kVp)
Position: Supine, arms at side or on chest. Feet 15 to 20 degrees medial rotation. Heels 8 to 10 inches apart
Suspend breathing on expiration
Coverage: entire pelvis (girdle and L5) , sacrum and coccyx with proximal femoral neck. Greater trochanter in profile. Optimal exposure - L5, sacral area and margins of femoral head and acetabula
Central ray - midway between level of ASIS and pubis symphysis
What is the purpose of an AP unilateral hip and what is the position and central ray (CR)?
Post op or follow up to demonstrate acetabulum, femoral head and neck and greater trochinae
CR - perpendicular to the femoral neck in question 2.5 inches distal on a line drawn perpendicular to the to the midpoint of a line between ASIS and pubic symphysis (1.2 inches distal to mid femoral neck)
What is the purpose of an AP oblique, its position and were is the CR placed ?
DDH or non- trauma hip unlike AP
What are some special projections of the pelvis and proximal femur ?
Requested in trauma after routine shows pathology or post-surgery for follow up
- AP axial pelvic outlet and inlet
- Oblique projections of acetabulum
- Axiolateral of hip and proximal femur
- Oblique for SI joints
What is the advantage of a PA L spine vs an AP and state one advantage ?
Because the patient is prone for PA, the natural L spine is placed in a way that the intervertebral discs are parallel to the diverging beam. Allowing better visualization of the disc spaces
Probe is also more comfortable for patients with back pain
Lower radiation dose for females by 25-30%
Disadvantage - large abdomen - increased object to image distance of the lumbar vertebrae which distorts the image
What is the central ray for an AP L spine?
CR at iliac crest level (L4/L5 space) - L spine and sacrum with 14 x 17 inch(30x35 cm) casette
CR at 1.5 inches above the iliac crests(L3) - 11 x 14 inch (20x35 cm) casette - L spine only
What is the central ray for a lateral L spine ?
Perpendicular to the long axis of the spine
14 x 17 inch casette center at level of iliac crest
11 x 14 - center 1.5 above iliac crest
CR for oblique L spine ?
Perpendicular to midpoint of casette entering 2 inches medial to ASIS and 1.5 inches above iliac crest
CR for lateral c spine ?
Perpendicular to casette directed horizontally to C4 (upper margin of thyroid cartilage)
CR for swimmer’s view?
Centered to T1 and directed perpendicular to the shoulder is shoulder well depressed. If not a 5 degree angle needed to separate 2 shoulders
CR for swimmer’s view?
Centered to T1 and directed perpendicular to the shoulder is shoulder well depressed. If not a 5 degree angle needed to separate 2 shoulders
CR for AP axial c spine
Directed through C4 at 15 to 20 degree cephalad angle ( chin extended to avoid superimposed mandible on upper vertebrae). Should enter at lower level of thyroid cartilage
Purpose and CR for oblique c spine
C4 at or just above the level of the hyoid bone
15° cranial tilt of the central ray
CR for open mouth c spine view
Through the center of the open mouth, perpendicular to center of casette
CR for AP humerus
Perpendicular to the mid portion of the humerus and center of the casette
CR for lateral humerus
Perpendicular to the mid portion of the humerus and the center of the cassette
CR for AP clavicle
Perpendicular to the mid-clavicle
CR for AP AC joint
Midpoint between AC joints (bilateral)
CR for AP shoulder joint
Perpendicular to a point 1 inch inferior to the coracoid process
A - external rotation
B - neutral
C - internal rotation
CR for an AP oblique projection of shoulder joint (Grashey projection) and purpose
Eliminates overlap of the humeral head with the glenoid
Perpendicular to the glenoid cavity at a point 2 inches inferior to the superolateral border of the shoulder
CR for Y (transcapular projection of shoulder
Perpendicular to glenohumeral joint
CR for transthoracic lateral projection of the shoulder joint - purpose ?
Suspected trauma in proximal humerus - true lateral view
CR Directed below the axilla, slightly above the level of the nipple
CR for axillary (axial) projection of shoulder
(Superior inferior view)
Angled 5 to 15 degree through the joint and toward the elbow
(Arm abducted to 90 degrees
Compare axial, Y view and apical oblique view of the shoulder
CR for apical oblique view (Garth view) of shoulder
45° caudal angle of the x-ray tube
2.5 cm inferior to the coracoid process, or 2 cm inferior to the lateral clavicle at the level of the glenohumeral joint
The view is best for evaluating the glenohumeral joint for dislocations and trauma to the glenoid of the scapula; this projection can be used as a replacement to the lateral scapula view in trauma, however, interpretation is difficult. The angle of the beam means it is tangential to the anterior-inferior glenoid rim (great for Bankart fractures) and gives a better view of the posterior humeral head (ideal for Hill-Sachs defect)
CR for AP forearm
Perpendicular to midpoint of forearm
CR for lateral forearm
Perpendicular to the midpoint of the forearm
CR for AP and lateral elbow
Perpendicular to elbow joint