Week 6: Radiographic Distortion

what is radiographic distortion

difference between actual object and its recorded image, radiographs are 30% larger

what is shape distortion

unequal magnification of structure, the more included the greater distortion

3 examples of size distortion

enlargement, elongation, shortening

causes of distortion

beam source, patient, film, alignment, position of central ray

what is superimposition

anatomic structures are stacked/superimposed on one another so that xray beam may penetrate multiple structures before arriving at film plate

what may superimposition cause

lines, shapes, forms that are unrecognizable, 2d representation of a 3d structure

5 steps for evaluating plain film radiographs (ABCDS)

alignment, bone density, cartilage space, disc space, soft tissue

what to look for in alignment

general architecture, contour of bone, alignment relative to others

abnormal findings for general skeletal architecture

absent bones, supernumary bones, congenital abnormalities

abnormal findings for contour of bone

cortical fractures, avulsion fractures, impaction fractures, spurs

abnormal findings fo alignment of bone to those adjacent

joint sublux/dislocations

what to evaluate for bone density

general bone density, texture abnormality, local bone density changes (osteophytes, trabecular lines)

what to evaluate for cartilage space

joint space width, subchondral bone, epiphyseal plates

abnormal findings for joint space width

decreased joint spaces, excessive sclerosis

abnormal findings for subchondral bone

erosions

abnormal findings for epiphyseal plates

compare bilaterally for changes in thickness

what to look at for disc space

looking at cervical/thoracic/lumbar spine

what to evaluate for soft tissues

muscles, fat pads, joint capsules, periosteum, miscellaneous findings

abnormal findings for soft tissue

gross wasting, gross swelling, displacement of fat pads, elevation of fat pads, calcifications, foreign bodies

contrast-enhanced radiographs

contrast medium injected/ingested into body to improve visualization of areas with low contast

radiolucent uses

air

radiopaque uses

barium sulfate and iodine

what is duel contrast radiograph

GI dual contrast exam