Intro to Radiology Flashcards
What amount of radiation results in sickness and death within a few weeks?
a) 1 sV
b) 2 sV
c) 10 sV
d) 15 msV
10 sV = 10,000 msV
1 sV radiation produces a ____% chance of eventually developing cancer
5.5%
What is the lowest dose of radiation at which cancer may occur in adults?
a) 10 sV
b) 15 msV
c) 50 msV
d) 1 sV
c) 50 msV
How much radiation is given by a CT abd/pelvis
a) 10 sV
b) 15 msV
c) 50 msV
d) 1 sV
b) 15 msV
Exposure of radiation is additive up until how long of a time period
a) 1 week
b) 1 month
c) 1 year
d) 10 years
e) unknown
e) unknown
In an x-ray, the farther the object is from the screen/detector the ______ it appears
larger
True/False: With increased photon energy, you have increased absorption
False
True/False: With increased photon energy, you have increased penetration
True
True/False: With increased photon energy, you have increased dose of radiation to patient
False
Why is PA more common than AP for chest x-rays?
Because PA gives more accurate size of heart (closer to heart)
In which situation would you order an AP CXR over a PA CXR?
a) to view cardiomegaly
b) to view right sided rib fractures
c) to view right sided pneumothorax
d) more than two of the above
d) more than two (b+c)
What causes structures to appear black on XR?
a) increased density
b) decreased density
c) increased thickness
b)
What type of contrast is best for those with impaired kidney function
a) LOSM
b) IOSM
c) HOSM
b) isoelectric
Rank the following from most radiolucent (black) to least radiolucent (white): fat, spongy bone, compact bone, water and most tissues, air
air, fat, water and most tissues, spongy bone, compact bone
What four things determine the contrast produced when an x-ray beam passes through the body? Which can be manipulated?
atomic number, thickness of object, density of object, penetrating characteristics of beam
latter can be manipulated
Why is barium useful for radiology of GI tract?
It provides better mucosal structure detail
Why does barium give better contrast than air?
Barium is much more dense (3.5 vs 0.00129) and has a higher atomic number (56 vs 7.64)
Other than barium, what organs do contrast media for ionizing radiography pose a risk of toxicity to? (3)
kidneys, heart, neural tissue
What XR view of the abdomen would be shot if the person was laying on their side with the beams going from front to back?
lateral decubitus
Air liquid interfaces give information on structures and ____ of patient
position
What do air liquid interfaces look like in pneumothorax?
Normally straight line, but in pneumothorax will be curved. Lung pulling away from chest wall
Air liquid interfaces inside abdominal cavity would signal…
pneumoperitoneum
With increasing photon energy, there is: \_\_\_\_\_\_\_\_\_\_ penetration \_\_\_\_\_\_\_\_\_\_ absorption \_\_\_\_\_\_\_\_\_\_ radiation dose to patient \_\_\_\_\_\_\_\_\_\_ contrast \_\_\_\_\_\_\_\_\_\_ dark color in film
increasing penetration, decreasing absorption, decreasing dose to patient, decreasing contrast, increasing dark color
With decreasing photon energy, there is: \_\_\_\_\_\_\_\_\_\_ penetration \_\_\_\_\_\_\_\_\_\_ absorption \_\_\_\_\_\_\_\_\_\_ radiation dose to patient \_\_\_\_\_\_\_\_\_\_ contrast \_\_\_\_\_\_\_\_\_\_ dark color in film
decreasing penetration, increasing absorption, increasing dose to patient, increasing contrast, decreasing dark color (lighter)
Whiteness in film can be due to all of the following EXCEPT:
a) thickness of object
c) decreased density of object
d) too low of penetration
c) decreased density
What are four phases of timing in CT scan
1) pre-IV contrast
2) arterial dominant phase of iodinated IV contrast
c) portal venous phase
d) excretory phase
In an under penetrated CXR, what structures are less clear (2)?
vertebra behind heart shadow, edges of hemidiaphragm
In an over penetrated CXR, what structures are less clear?
Heart shadow (spine is way too visible)
Why were mammograms invented?
In order to see calcifications in breast - required lower kEV to see but normally not enough to pass through denser obstructing materials
What is the drawback of a mammogram?
Due to lower kEV, increases radiation dose
What are the four types of breast composition?
a) predominantly fat
b) scattered fibroglandular densities
c) heterogeneously dense
d) dense
What is the challenge with dense breast tissue?
Since its more dense, need more kEV to see breast structures (more penetration) but higher kEV means higher penetration so structures won’t be as visible. Why US is used in conjunction with mammogram
What are the two mammogram types and how is the breast viewed?
CC = craniocaudal (from above looking down) MLO = mediolateral oblique (looking from side to side)
What position information does a CC give you?
a) horizontal
b) vertical
a) horizontal, from top looking down
What position information does an MLO give you?
a) horizontal
b) vertical
b) vertical, looking from side to side
On PA XR with right shoulder rotation towards the plate, would the heart appear bigger or smaller?
Bigger because its further away
What two structures should you use to check for rotation on an x-ray?
Strenoclavicular joints
Spinous process
If you turn your left shoulder towards the plate on a PA XR, would the distance between the strenoclavicular joints and spinous process increase or decrease?
Decrease
Which of the following are CT scans not good for?
a) tumors
b) soft tissues
c) masses of blood and bones
d) quick emergencies
b) soft tissues
What is the orientation of a patient in CT scans?
Pt laying down with feet towards you
What two types of reconstructions are relatively new to CT scans, which previously only used axial reconstructions?
coronal and sagittal
If you were looking to see the vasculature of the lungs, which CT window would you use?
a) tissue window
b) vein window
c) lung window
c) lung window
tissue window shows lungs as black
____ uses a giant steady state magnetic field on order of 0.5-3.0 Tesla
MRI
What is 1 tesla equal to in gauss
10 k gauss
What types of frequencies are applied to tissues in MRIs causing protons to change their conformation?
Radio
What type of contrast do MRIs use?
Gadolinium based
How does the contrast used by MRIs work?
It changes the spin relaxation time
What are the cons of using Gadolinium based contrast? What disease does it cause?
It can be dangerous to kidneys. Causative agent in rare d/o nephrogenic systemic fibrosis
Which of these shows cartilage and bone?
a) MRI
b) CT
MRI
Describe the 5 steps that produce MRI images
1) Atoms spin in random directions
2) MRI produces magnetic field, atoms rearranged as either north or south (some unmatched)
3) Radio frequency pulse applied –> unmatched atoms spin other way
4) Radio frequency turned off –> extra atoms returned to normal position and emit energy
5) energy sends signal to computer that converts to images
If you wanted to see joints, would you order a
a) CT scan
b) Xray
c) MRI
c) MRI
What are three cons of using an MRI?
a) too long for emergencies
b) expensive due to super cooled magnetic field
c) does not show air (not as good as bowel)
What is the “double” in double contrast barium?
1) barium adherent to colonic mucosa (high + density contrast)
2) outlined by air throughout lumen (low density - contrast)
