Misc Flashcards
A hand exam was performed using 55kVp & 0.63mAs. What type of radiation was used; Photoelectric Effect or Compton Scattering?
Photoelectric effect
What is the maximum dose pregnant women can receive?
4mSv
What is the Acute Radiation Syndrome 4 response stages?
- Prodromal ~ initial symptoms, severity increases as dose increases
- Latent~ no visible symptoms, recovery or lethal effects
- Manifest Illness~ symptoms return more severe
- Recovery or Death
Skull Morphology:
What is the angle of the petrous ridges for a Mesocephalic skull? Brachycephalic? Dolichocephalic?
Which is considered normal?
Mesocaphalic ~ 47 degrees (normal)
Brachycephalic ~ 54 degrees
Dolichocephalic ~40 degrees
What is seen on a Caldwell Projection of the skull?
Frontal Sinuses & Anterior Ethmoid Sinuses
CR Perpendicular~ petrous ridges fill orbits
CR Angle ~ petrous ridges in 1/3 of orbits
What is seen on Townes Projection of the skull?
occiptal and parietal bone
foramen Magnum with Dorsum sellae
What is seen on Waters projections of the skull?
petrous ridges below maxillary sinuses
orbits, maxillae & zygomatic arches
An exam was ordered for a mobile chest, the resulting image shows grid lines, how did this occur, what type, & how would this be corrected?
Parallel grid cutoff, along one edge of the image,
Correction: make sure the grid isn’t titled and lined up to the beam.
What classification of drugs would be used in a cardiovascular emergency, and which would be found on the crash cart?
Adrenergic ~ constrict blood vessels & stimulate heart
Dopamine(Intropin)
Epinephrine (Adrenalin)
Isoproternol (Isuprel)
Antimuscarinic ~ increase cardiac output, constrict blood vessels
Atropine Sulfate(Atropine)
Cardiotonics ~ increase force of heart contractions
What would be the path of aPort -a -Cath to its resting point?
Right subclavian – Brachiocephalic – Superior Vena Cava
What is a Nephrostomy tube?
catheter with multiple side holes, placed in the kidney perculatneously,
used to drain the kidney and administer drugs
What does TIPS stand for and what is its purpose?
Transjugular Intrahepatic Portosystemic Shunt
Originating from the jugular vein, purpose is to relieve portal hypertension, & reduce the risk of variceal bleeding
What are the CT#’s for Bone, Air, Lungs, Water, Fat?
Bone ~ +1000 Air~ -1000 Lungs ~ -250- (-)800 Water ~ 0 Fat ~ -100
How do the CT detectors work?
measure transmitted x-ray values(linear coefficent attenuation), convert them to electrical signals and relay thm to the computer.
What is Pitch? What is the ideal pitch?
Pitch is the ratio of the movement thru grantry/ slice thickness
Ideal pitch ~1
decreased pitch, slices closer together, increased pt does
increased pitch, slices farther apart, decreased pt dose
For angio what is the catherization technique?
modified Seldinger:
puncture anterior wall of artery
sterile
What is Hemopoitic Syndrome? What dose does it occur at?
Depression of the hemopoitic system, recovery is possible, occurs at 0.5-10Gy
more the 8Gy = Fatal
Which blood cell is most radiosensitive?
Lymphocytes
What is linear energy transfer?
Average energy deposited per unit length of track by ionizing radiation as it passes through and interacts witha medium
Low LET causes indirect damage (sparse interactions along long path)
High LET causes direct damage (dense interactions along short path)
When are cells the most radiosensitive?
not mature or specialized, greatest reproductive activity and longest mitotic phases
What is the difference between Deterministic effects & Stochatic effects?
Deterministic ~ threshold, directly related to dose, can have early effects and late effects, (Erythemia, epilation, desquamation, blood disorders, Acute Radiation Syndrome, etc)
Stochastic ~ all or nothing, non-threshold, not dose related, based of probabilities, “no safe dose”
What is the lethal dose for humans?
50/60 (50%of people in 60 days)
What are the acceptable whole body annual dose limits for occupational workers, public and students?
occupational workers ~ 20msv
public ~ 1 msv
in MB students fall under public members
How often should the protectibe apparel by tested?
Yearly
What is the max radiation dose for a stored loaded film?
0.5 mircogrey
What is the max dose for the lends of the eye for members of the public? Radiation workers?
15mSv
150mSv
WHat is the max dose for skin, hands, all other organs for members of the public? Radiation workers?
50 mSv
500mSv
What are early deterministic effects?
Nausea fatique erythema epilation blood disorders intestinal disorders fever dry and moist desquamation
What is the min threshold for deterministic effects?
2 Gy
What kind of somatic effects are DI exams most significant?
Stochastic effects
What is the gonadal dose the delays or supresses?
0.1 Gy
In terms of gonadal dose, 2 Gy can cause what?
temporary sterility
The tech is using the following info as the original manually selected technical factors.
600mA 100cm SID 1.5mm Focal spot
0.05 seconds 5.0 OID 35cm X 43 cm field size
70kv 8:1 grid ratio CR system
Which new set of tehnical factors will achieve the same exposure rate (intensity)?
a) 60 kV, 300mA,0.2 seconds
b) 60 kV, 600 mA, 0.2 seconds
c) 80 kV, 300 mA, 0.1 seconds
d) 80 kV,600 mA, 0.1 Seconds
a)
15% decrease in kV, the mAs must be doubled in order to maintain the density
The AP chest image is underexposed but has sufficient contrast. How should the tech alter the mAs or kV to n produce a minimal change in OD?
A. 4% change in kV
B. 15% change in kV
C. 15% change in mAs
D. 30% change in mAs
D.
a 30% change in mAs will show a visible change in OD
