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
CR for AP oblique elbow - internal (clears coronoid process of radial head) and external rotation
Perpendicular to elbow joint
Why is PA used for hand more than AP ?
PA - best to check malalignment, joint narrowing, soft tissue issues in early RA. AP oblique (ball-catcher) - early evidence of RA 2nd to 5th prox phalanges and MP joints
Compare PA, PA oblique and AP oblique hand views
Compare lateral hand views?
CR for AP wrist
Perpendicular to midcarpal area
CR for AP oblique wrist
Perpendicular to midcarpal area - just distal to radius
CR for lateral wrist
Perpendicular to wrist joint
What bones are seen better on AP oblique wrist projection?
CR for PA wrist scaphoid carnal bone
Perpendicular to the table and directed to enter the scaphoid
CR for thumb all views
Perpendicular to the MCP joint
CR for 2nd to 5th digits PA and lateral
Perpendicular to the PIP joint
Lateral views of 2nd to 5th digits, how oriented?
CR for AP large intestine XR/FL study
Directed 30 to 40 degrees cephalad to enter midline 2 inches below level of iliac crest
What is the view to include if want to see colon to rectum for large bowel study
CR for AP large intestine right lateral decubitus
CR for AP oblique large intestine LAO position
Perpendicular to cassette entering 1-2 inches lateral to the midline of the body at he level of the iliac crest
CR for LPO for stomach and duodenum imaging
CR for Right lateral stomach and duodenum
CR for RAO stomach and duodenum
CR for AP of stomach and duodenum
CR for PA prone stomach, duodenum and proximal jejunum
CR from PA oblique oesophagus (RAO position)
CR for lateral abdomen dorsal decubitus
Horizontal and perpendicular to center of cassette and directed to mid coronal plane 2 inches above iliac crests
CR for left lateral decubitus AP abdominal exam
Directed to perpendicular to film at midpoint of mid sagittal plane at level of iliac crest (some patients a slightly higher CR 2 inches above crest needed to include diaphragm.
CR for AP lateral decubitus chest
Horizontal and perpendicular to center of casette - horizontal beam impt to view air fluid levels, pneumothorax - primary goal for this projection
CR for RAO
Perpendicular to center of casette at level of T7
CR for AP chest
Perpendicular to long axis of sternum and center of cassette. Landmark is jugular notch - center of lung field - T7
CR for left lateral chest
CR for PA chest
What is hand spread method
What view is also known as cross table lateral chest
What is Towne’s view of the skull?
An angled AP view
centring point
midway between the external auditory meatuses and exits the foramen magnum
What are the baselines used in skull radiography?
Baselines Used in Skull Radiography
The orbitomeatal line (OML) runs from the nasion through the outer canthus of the eye to the center of the external auditory meatus.
The infraorbitomeatal line (IOML) runs from the inferior orbital margin to the upper border of the external auditory meatus.
The meatomental line (MML) runs from the external auditory meatus to the mental point (tip of chin).
Other lines used in skull radiography include the glabellomeatal (GML), acanthomeatal (AML), and lipsmeatal (LML).
What are the common normal sutures present in all infants?
How is a mortice view of the ankle obtained ?
Slight 20 degree internal rotation so the fibula apes not overlap the talus
CR for calcaneus axial view
centring point
the central ray is angled 40° cephalad from the long axis of the foot centred at the base of the 3rd metatarsal (midfoot)
What are the remaining CR for the lower limb bones?
AP and lateral femur:
for one image: mid femur region or for two images:
proximal femur: place detector to include anatomy from ASIS to mid-femoral shaft
distal femur: place detector to include anatomy from mid-femoral shaft to knee joint
to ensure overlap of anatomy, a physical side marker can be positioned at mid-femur region
Knee: AP AND lateral - knee joint 1.5-2.0 cm distal. to the apex of the patella or at the tibial tuberosity FOR LATERAL if the patella is affected by certain injury
Leg: AP - mid of tibia, lateral - mid between ankle and knee
Ankle: AP midpoint of malleoli, lateral - bony prominence of the medial malleolus of the distal tibia
Dorsoplantar foot: x-ray beam centred to the base of the 3rd metatarsal
the beam must be angled approximately 10° posteriorly towards the calcaneum to mimic the arch of the foot, this may change if the arch is high or flat, lateral - base of metatarsals or mid foot
AP toes - x-ray beam centred to the metatarsophalangeal joint in question
the beam is perpendicular to the detector , lateral - interphalangeal joint of 1st digit and proximal interphalangeal joint of 2nd to 5th digit
CR for T spine
AP - the level of the 7th thoracic vertebra at the mid sagittal plane
the central ray is perpendicular to the image receptor
Lateral - the level of the 7th thoracic vertebra, which correlates to the inferior border of the scapula, centred directly over the thoracic spine (most commonly equates to the posterior third of the thorax)
the central ray is perpendicular to the image receptor
Name artifacts common to all forms of radiography
motion artifact
due to patient movement resulting in a distorted image
radiopaque objects on/external to the patient (e.g. jewellery (e.g. necklaces, piercings), clothing (e.g. buttons), hair (e.g. ponytail, hair braids etc.)
image compositing (or twin/double exposure)
superimposition of two structures from different locations due to double exposure of same film/plate
only in film and computed radiography
similar appearance to detector lag/ ghosting artifact in direct digital radiography (see below)
grid cut-off
debris in the housing 4
debris in the housing caused by the collimator tube can cause small trapezoidal regions, indicative of lead shavings
parallax effect: whenever the object is off-centre or tilted in relation to the central beam, the projected image might get distorted, inducing incorrect measurements5. An example of this effect would be the apparent narrowed disc spaces in the low thoracic region in lumbar radiographs (i.e., the object off-centre, with diverging beams in relation to the focal point
Film radiography artifacts
finger marks
improper handling with hands
clear film
malfunction of the machine or placing the film in the fixer before developer solution
static electricity
black “lightning” marks resulting from films forcibly unwrapped or excessive flexing of the film
crescent-shaped black lines
due to fingernail pressure on the film
crescent-shaped white lines
due to cracked intensifying screen
black film
complete exposure to light.
clear spots
air bubbles sticking to film during processing
fixer splashed on film prior to developing
dirt on the intensifying screen
Artifacts common to CR and DR
stitching artifacts
occur when two separate CR or DR images are merged into a single image
over exposure
CR artifacts
incorrect detector orientation i.e. upside-down cassette
spoke like radiopaque lines
Direct DR artifacts
detector image lag or ghosting
latent image from previous exposure present on current exposure
backscatter
electronics are visible on the exposed image
increased radiation exposure required for portable DR (digital radiography) examinations
dead pixel artifact
signal dropout 4
large areas of signal loss, due to detector drop
speckled radiopaque spots 4
due to detector drop
detector calibration limitation 4
faint radiopaque striping (often vertical) in the background of an image, yet not evident on the anatomy
this artifact should be carefully examined, if it does not interfere with the anatomy, it is not a detector failure/grid cut off, rather a limitation of the detector calibration
often seen as lower exposure
failure of detector offset correction 4
similar to ghosting, however, the digital detector not being calibrated when promoted is the cause
electronic shutter failure 4
the digital image often will have obscurely shaped, tight collimation that defies logic
often a computer error often fixed with recollimation post exam (this should be explored before re-examination)
values of interest misread 4
image appears washed out and underexposed
this is often due to a largely collimated area of smaller anatomy i.e. a patella protection
tighter digital collimation in conjunction with reprocessing will correctly assign the correct values of interest
mid grey clipping 4
loss of contrast in areas of different pixel density yet not change in density can be seen i.e. the metal on a knee replacement
due to poor contrast enhancement
grid-line suppression failure 4
faint grid lines present on an image, with no grid cut off
Describe where Lisfranc and Chopart joints are
Lisfranc separates cuneiforms and cuboid from metatarsals
Chopart separates talus and calcaneus from navicular and cuboid
