Intro to Imaging Pt. 1 (9/6a) Flashcards
Conventional radiograph
x-rays or plain films
image made by x-rays passing through the body onto film, ionizing silver emulsion on the film
Attenuation
degree to which the tissue absorbs/scatters x-rays before they hit the recording medium
Amount of attenuation depends on
thickness, atomic number, and density of tissue
Greater attenuation
Structure is more radiodense
appears whiter
Less attenuation
Structure is more radiolucent
appears blacker
Radiodense
structure absorbs and scatters x-rays to the largest degree in the body
highest attenuation
EX: bone
Radiolucent
x-rays pass right through the structure and aren’t absorbed
lowest attenuation
EX: gas in lungs
Radiopaque
not naturally occurring in the body
will be bright white because of high atomic numbers
highest in the radiodensity scale
EX: metal
Most radiodense bone
Cortical bone
in relation to inner spongy bone
Radiodensity Scale
(least → most radiodense)
1) air - black
2) fat - charcoal
3) water - gray
4) bone - light gray
5) metal - white
Contrast
relative shade difference between adjacent structures
Density vs Contrast relationship
greater difference in density/thickness → greater contrast
Standard A to P
X-rays pass through the tissue next to the film plate, which is located behind the patient in the anterior (A) to posterior (P) direction
Exceptions to A→P rule
Chest - done P to A because lungs and heart are more anterior
Hands/Feet - done P to A with palm or sole down on film plate
How to hold radiograph for standard A→P
hold it as if the person faced you in anatomical position
Put the R on the right side, if it is an L marker hold it so L is on the left
How to hold radiograph for chest
Viewed in anatomical position
How to hold radiograph for hand/foot
Viewed as taken
Position (radiograph)
Refers to:
1) patient’s general body position (EX: supine, erect)
2) specific body position or which body part is closest to image receptor
Projection (radiograph)
describes the path the x-ray through the patient and onto the recording medium
How many projections are needed (radiograph)
Need at least 2 projections as close to 90 deg to each other to view a structure in all 3 planes
Routine series (radiograph)
Typically done A→P, but each joint has a “routine series” (aka projections) deemed necessary to get comprehensive view
ABC’S of Radiographs
A - Alignment
B - Bone density
C- Cartilage
S - Soft tissue
Alignment (radiograph)
Size, number, shape and contour
Bone and joint position
Most common cause of malalignment is trauma
(can cause more radiodensity of muscle)
Bone density (radiograph)
Cortical bone should be a bright white tube that is more radiodense than the adjacent
Trabeculae (normal stress on the bone) indicate healthy bone
Sclerosis
Osteopenia
