Midterm I Flashcards
Name the body planes and what they divide.
Midsagittal plane divides left & right.
Midcoronal plane divides anterior & posterior Horizontal (transverse) plane divides superior & inferior
Define the terms position, projection and view.
Position = side of body nearest film; should be marked as such (ie RAO) Projection = path of the xray beam AP/PA/oblique View = side of anatomy best visualized, usually side nearest film.
Which body substance has the least subject density? The greatest? How
would they appear radiographically?
Air – least attenuation – looks dark
Bone – very attenuated – looks lighter
Metal – greatest attenuation looks white
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?
Disease process may affect the way tissue attenuates xrays.
o Additive Condition Increased Attenuation (blastic)
o Destructive Condition Decreased Attenuation (lytic)
o Less attenuation= greater radiographic blackness; mAs controls it (milliamps X
seconds = mAs)
Which body substance attenuates most? Least?
Air – least attenuation radiolucent
▪ Muscle.water – moderate attenuation
▪ Bone – very attenuated
▪ Metal – greatest attenuation radiopaque
What is radiographic density? What what xray factor controls it?
Radiographic Density = radiographic blackness = amount of blackness on film. mAs controls it (milliamps X seconds = mAs)
When you double or halve mA and leave everything else as is, what happens to your film? What happens to your patient?
mAs (mA x sec is primary controller of quantity of xray, radiographic blackness and is directly related to patient exposure.
o Doubling mAs doubles Radiographic Blackness and patient exposure.
When you double or halve exposure time and leave everything else as is, what happens to your film? What happens to your patient?
Cutting mAs by half makes half the blackness and halves patient exposure
Which will give greater density, 100 mA @ 1 second or 200 mA @ 1⁄2 second? Which is more likely to have motion blur?
100mA@1/10s=10mAs 100mA@1/2s=50mAs 200mA@1/4s=50mAs 300mA@1/6s=50mAs 500 mA @ 1/10s =50mAs o Greater mAs = greater radiographic blacknes, less blur so 10 mAs has motion 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 necessary for visible change in blackness.
What xray factor is primarily responsible for controlling contrast?
Radiographic Contrast = variety of gray shades from darkest to lightest.
Controlled by kVp; controls penetration.
Higher kVp lowers dosage, decreased mAs.
What is generally meant by improving contrast?
Improve contrast = increase number of shades of gray
Grids can improve contrast by reducing radiation fog by absorbing scatter radiation as it
exits patient’s body.
What is beam restriction? What is scatter? Scatter is BAd
Scatter is dependent on kVp, amount and type of irradiated tissue (soft tissue scatters more than bone)
Beam restriction reduces scatter, improves image quality and greatly reduces patient exposure. Beam must always be restricted.
oAperature diaphragm, cones/cylinders, collimaters
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?
Radiographic grid → absorb scatter radiation as it exits pts body.
Should be used with larger body parts, higher kVp
Placed b/n patient and film
Reduces radiation fog and improves contrast
What are two types of shape distortion?
How can shape distortions be minimized?
Elongation = occurs when tube or film improperly aligned
Foreshortening = occurs when body part is improperly aligned with film
What are the types of size distortion? How can they be minimized?
Size distortion occurs only in the form of magnification. Objects can’t be minified.
Magnification results from increased OID. Increased SID may compensate.
Are children more sensitive to radiation than adults? What are the most sensitive body cells to radiation? The least sensitive?
Age – young cells more sensitive
o Differentiation – simple cells more sensitive
o Mitotic rate – rapidly dividing more sensitive
o Metabolic rate – using energy rapidly, more sensitive
o Highest sensitivity cell: bone marrow, gonadal, eye lenses, GI
o 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.
o SI equivalent is gray (1Gray = 100 rad)
What is a REM?
Radiation Equivalent in Man (rem) Measurement of biological change; this is the
reading on monitoring devices.
What is the SI equivalent to REM? To RAD? To ROENTGEN? How many rem = 1 mSv?
REM: SI equivalent is sievert (1 rem=10mSv or 1 Sv=100rem or 1/10rem=1mSv)
RAD: SI equivalent is gray (1Gray = 100 rad)
hich is more dangerous, having a chest xray or being an unmarried male who eats Twinkies and drinks soda pop while driving his Ford Pinto?
The later. Alcohol use, being unmarried, smoking, MVA, pedestrian accident all greater risk than xray.
Which joint space(s) are seen well on routine shoulder (internal & external rotation) views? Which joint space is not seen well on those views?
Seen well? = proximal humerus, scapula, clavicle; acromion clearance
Not seen well? = glenohumeral joint → Need Grashy view
AC joint → axial projection
scapulothoracic → scapular “Y” view
When to order PA/lateral chest exam?
PA to see 1. lung fields, heart, great vessles, ribs, 2. soft tissues
o Lateral to see:
- (L) reduce cardiac magnifcation,
- localize mediastinum and lesions,
- lung fields, heart, great vessels, ribs o Exposed on 2nd full inspiration
When to order thoracic spine exam?
Thoracic spine (AP): suspect spine lesions; FYI lung and ribs will be overexposed
Rib exam?
Rib: 1. body structures, 2. rib fractures, 3. upright chest film to determine underlying lung/soft tissue injury
i. Oblique to see around angle of ribs
ii. Collimated down to rib in question
why include an upright chest film with a rib study?
upright chest film to determine underlying lung/soft tissue injury
What is a scaphoid view? Which side of the wrist is the scaphoid on?
Ulnar flexion during PA hand projection
How to image lumbar spine instability?
Flexion and extensions views lateral
What is a pars interarticularis fracture? What condition might it result in?
Pars interarticularis fracture → fracture of bone b/n pedicle and lamina o May indicated spondylolysis
Pars defect requires LAO and RAO of lumbar spine
i. eye – pedicle, nose – TVP, ear – superior articular process, foreleg – inferior articular process, neck – pars interarticularis, body – lamina
In addition to the routine threeview which cervical spine views are indicated when radicular symptoms are noted?
Routine 3 view = AP, AP open mouth, lateral
o Oblique view to visualize intervertebral foramina, osteophytes
The best view for sacroiliac joints and lumbosacral area?
AP spot view 2530 degrees
A common fracture sight in cases of inversion ankle sprain is the base of the 5th metatarsal. Which additional views demonstrate the area?
Minimum series: AP dorsoplanter projection, Med oblique, lateral o Fracture of 5th MT – Dancer’s fracture, Jone’s fracture
i. AP ankle or lateral ankle
What study demonstrates pneumoperitoneum and/or bowel obstruction?
Acute abdomen series =
i. Supine (AP) AKA KUB, Scout film; overview (bowel obs)
ii. Upright chest – captures free air b/n liver and diaphragm
(pneumoperitoneum) , lung base pathology
iii. Decubitus, esp. if pt can’t stand (bowel obstr)
What plain film study will be useful in determining whether a patient has a leglength inequality?
AP pelvis
Be able to identify xray views and basic radiographic anatomy when projected on the lecture hall screens.
Hand: PA
forearm: AP
Some useful info:
Ulnar flexion minimizes overlap of carpals on the lateral side of the proximal row of carpal bones. Good view for the scaphoid.
Some useful info:
If your patient has a respiratory complaint or fever a chest study is the appropriate exam. Rib exams don’t show lung conditions, but if your patient has rib trauma, you should request or perform a chest film in addition to the rib study. Thoracic spine films are for thoracic spine only and don’t have good diagnostic information for either of the above.
Some useful info:
inversion of the ankle is a common injury. It often involves a fracture (Jones) of the base of the 5th metatarsal. An AP and/or medial oblique foot view demonstrates the area well.
Some useful info:
Flexion and Extension studies of the lumbar spine in the lateral position are useful for evaluation of hyper mobility. A Neutral lateral lumbar film should be obtained prior to this study. CT would be the best advanced imaging.
Some useful info:
Pneumoperitoneum is imaged with the patient in the upright position. Free air is not seen in supine or prone films. Any free air that is present will be layered along the diaphragm. If a patient is unable to stand a viable alternative is the left lateral Decubitus abdomen. In this position free air is seen as it rises to the border of the liver.
Some useful info:
When a patient exhibits radicular symptoms cervical oblique views are useful in demonstrating intervertebral foramina.
Some useful info:
The glenohumeral joint isn’t seen well in routine AP projections of the shoulder. The Grashey view and axial projection demonstrate it well.
Some useful info:
The axillary portion of the ribs is not seen well in frontal projections. Oblique views are required. The oblique position that puts the axillary portion parallel to the plane of the film without superimposition of the vertebral column is the correct position.
Some useful info:
The AP axial lumbosacral joint spot film demonstrates L5/S1 joint space without overlap of L5 body. This joint is not seen well on AP lumbar projections. It also shows SI joints well.
Some useful info:
Always have at least two projections of an area. Optimally they are 90° from one another. Two obliques suffice in some cases.
Some useful info:
The best view for the sacroiliac joints is the AP or PA axial projection.
