Midterm Flashcards
What does the mid-sagittal plan divide?
Left and right sides of body
What does the mid-coronal plane divide?
Anterior and posterior sides of body
What does the horizontal or transverse plane divide?
Superior and inferior parts of body
Define the term “position”
side of the body nearest film; should be marked as such. ie: RAO
Define the term “projection”
path of the x-ray beam: AP/PA/oblique
Define the term “view”
side of anatomy best visuallized, usually side nearest film
Which body substance has the least subject density? the greatest? And how would they appear radiologically?
Least attenuation: Air, looks DARK = “radiolucent
Very attenuated: Bone, looks LIGHTER
Most attenuated: Metal, looks WHITE = “radiopaque”
What is “attenuation”?
Attenuation: a quantity that characterizes how easily a material or medium can be penetrated by a beam of light, sound, particles or other energy or matter
How does pathology affect attenuation? Specifics?
Disease process may affect the way tissue attenuates x-rays. Additive condition (blastic): Increased attenuation (LIGHTER) Destructive condition (lytic): Decreased attenuation (DARKER)
What body parts attenuate most and least?
look up
How are attenuation and radiographic blackness related?
Less attenuation = greater radiographic blackness; mAs controls it (milliamps x seconds = mAs)
What is radiographic density?
radiographic density = radiographic blackness (amount of blackness on film) Controlled by mAs
When you double or halve mA and leave everything else as is, what happens to your film? To your patient?
Doubling mAs doubles Radiographic Blackness and patient exposure. Cutting mAs by half makes half the blackness and halves patient exposure
What happens to your film when you double or halve exposure time and leave everything else as is?
??
What reduces blur?
Greater mAs = greater radiographic blackness, which results in less blur
What is the minimum change that can be made to mAs in order to see a visible change in radiographic density?
25-30% change in mAs is necessary for a visible change in blackness
What x-ray factor is primarily responsible for controlling contrast (variety of gray shades from darkest to lightest)?
kVp which controls penetration. Higher kVp lowers dosage, decreased mAs (?)
What is generally meant by improving contrast?
Increasing the number of shades of gray
How might you improve contrast?
Grids absorb scatter radiation as it exits, which reduces radiation fog = improved contrast
What is beam restriction?
Beam restriction reduces scatter, improves image quality and greatly reduces patient exposure. Beam must always be restricted
What is scatter? Good or bad?
Scatter is dependent on kVp, amount and type of irradiated tissue (soft tissue scatters more than bone). Scatter is bad.
How is scatter minimized?
Aperture diaphragm, cones/cylinders, collimaters (double check this)
What is the purpose of a radiographic grid? When should it be used?
Where is the grid placed?
What is the visible effect of using a grid?
Purpose: It absorbs scatter radiation as it exits patient’s body
When: With larger body parts, higher kVp
Where: between patient and film
Effect: Reduces radiation fog and improves contrast
What are two types of distortion?
Elongation: occurs when tube or film is improperly aligned
Foreshortening: occurs when body part is improperly aligned with film
What types of size distortion are there?
Size distortion: only in the form of magnification. Objects can’t be minified.
What does magnification result from?
Increased OID (?). Increased SID may compensate ??
Are children more sensitive to radiation than adults?
Young cells are more sensitive
What are the most sensitive cells to radiation?
Sensitive Cells:
- Differentiation: simple cells
- Mitotic Rate: rapidly dividing cells
- Metabolic rate; using energy rapidly
Highest Sensitivity cells: bone marrow, gonadal, eye lenses, GI
What are the least sensitive cells to radiation?
Lowest Sensitivity cells: muscle, nerve, chondrocyte
What is a ROENTGEN?
Roentgen (R): symbolizes amount of ionization produced by a specific amount of radiation in air only
What is a RAD?
Radiation Absorbed Dose (rad): measurement of energy absorbed and can be applied to any absorbing material
What is the SI equivalent to REM? To RAD? To ROENTGEN?
SI equivalent is gray: 1 Gray = 100 rad…???
How many rem = 1 mSv?
1 rem = 10 mSv or 1 Sv= 100 rem or 1/10 rem = 1 mSv
Which is more dangerous, having a chest x-ray or being an unmarried male who eats Twinkies and drinks soda pop while driving his Ford Pinto?
The later
Which joint spaces are seen well on routine shoulder (internal and external rotation) views?
Proximal humerus, scapula, clavicle, acromion clearance
Which joint spaces are not seen well on routine shoulder views? And what would be a better view?
- Glenohumeral joint. Use Grashy view instead
- AC join. Use axial projection instead
- Scapulothoracic. Use scapular “Y” view instead
When would you order a PA chest exam?
To see 1. lung fields, heart, great vessels, ribs, or 2. soft tissues
When would you order a lateral chest exam
To see 1. (L) reduce cardiac magnification,
- localize mediastinum and lesions,
- lung fields, heart, great vessels, ribs (??)(exposed on 2nd full inspiration)
When would you order a thoracic spine exam?
When you expect spine lesions (lung and ribs will be over exposed)
When would you order a rib exam? And what views?
- body structures
- rib fractures
- upright chest film to determine underlying lung/soft tissue injury
Oblique to see around angle of ribs
Collimated down to rib in question
What is a scaphoid view?
Ulnar flexion during PA hand projection
Which side of the wrist is the scaphoid on?
??
How do do you image lumbar spine instability?
Flexion and extensions views - lateral (???)
What is a pars interarticularis fracture? What condition might it result in?
Fracture of bone between pedicle and lamina. May indicate spondylolysis
What is the Routine 3 view of the cervical spine that is indicated when radicular symptoms are noted?
Routine 3 view = AP, AP open mouth, lateral
In addition to the routine 3 view, what other cervical spine views are indicated when radicular symptoms are noted? Why?
Oblique view, to visualize intervertebral foramina, osteophytes.
What is the best view for sacroiliac joints and lumbosacral area?
AP spot view 25-30 degrees
Fracture of the base of the 5th metatarsal is common in inversion ankle sprains Jones’/Dancer’s fracture): what views demonstrate this area well?
Minimum series: AP dorsoplantar projection, med oblique, lateral
Additional: ankle or lateral ankle.
What study/acute abdomen series demonstrates pneumoperitoneum and/or bowel obstruction?
Acute abdomen series:
- Supine (AP), AKA KUB, Scout film; overview (bowel obs)
- Upright chest: captures free air b/w liver and diaphragm (pneumoperitoneum), lung base pathology
- Left Lateral Decubitus Abdomen, esp if pt. can’t stand (free air is seen as it rises to the border of the liver)
What plain film study will be useful in determining whether a patient has a leg length inequality?
AP pelvis
What action minimizes overlap of carpals on the lateral side of the proximal row of carpal bones, allowing for a good view of the scaphoid?
Ulnar Flexion
What is the best view to demonstrate L5/S1 joint space without overlap of L5 body?
AP axial lumbosacral joint spot radiograph. (The joint is not shown well on AP lumbar projections)
True or False: The axillary portion of the ribs is not seen well in frontal projections.
True. Oblique views are req’d. The oblique position that puts the axillary portion parallel to the plane of the radiograph without superimposition of the vertebral column is the correct position.
How many projections must you always have of an area?
Always have at least two. Optimally 90 degrees from one another (two obliques work in some cases)
kVp facts:
- Killivolt peak
- Effects QUALITY and CONTRAST
- Controls penetration
- Distance does not affect it
- Scatter is dependent on it (along with amt/type of tissue)
- Lower kVp = more contrast, Higher kVp = less contrast (higher kVp gives a more refined image - more shades of gray)
mAs facts:
- Controls blackness, density (quantity)
2. Can up mA or time for the same effect. Upping mA for fewer seconds results in less blur
