FINAL TQ Flashcards
- What causes silver-halide crystals to remain crystalline and inactive?
No exposure to radiation
- When determining the amount of time to submerge film in a fixing bath, remember, the total fix time = …
2x clearing time
- “tree branches” on film is caused by…
Static electricity
- T/F: radiographs can’t be weight-bearing
False, most radiographs are weight-bearing
- a latent image is made when ____% of PSP retains energy
50%
- How many tones of gray are available in film imaging?
30-35
- How many tones of gray are available in computed radiography?
10,000
- T/F: You are not allowed to process in the same room while you are shooting x-rays?
True!…if the x-ray and processor are in the same room, the exposure will interfere with laser scanning
- Digital radiography _____ patient dose because it increases the kVp and decreases the mAs
reduces
- Does film have a higher or lower spatial resolution (line pairs per millimeter) than digital imaging?
Higher
- What is the spatial frequency of film?
8.0 lp/mm
- A film image degrades about ___% in 8 hours.
25%
- What is the ability to image 2 separate objects as being distinct?
Resolution
- What is the ability to distinguish anatomic
structures of similar subject contrast?
Contrast resolution
- What is the ability to image small objects that have high subject contrast?
Spatial resolution
- The _____ the speed of the film, the _____ the contrast
Faster, higher
- Every ____ increase in optical film density
doubles the exposure
0.3 (log2.0=0.3)
- The shoulder region of the characteristic film
curve tells us….
At a particular amount of time, the amount of radiation makes no difference.
- In regards to anatomic part thickness, if we increase the contrast (reduce the amount of gray tones), then we ______ magnitude of difference
Increase (there is a greater difference between the thick and thin anatomical parts on film)
- If we lower the radiation quality (kVp), we create _______ contrast
Higher
- T/F: Changing mAs affects the subject contrast
False
- When evaluating pediatric patients, exposure time
must be _______, due to thinner parts
Faster
- Source image distance is _____ for stationary units
Fixed
- To control optical density, you change ______.
mAs
- To control contrast, you change ______.
kVp
- To control distortion, you change _______.
Patient position
- when you have a high subject contrast, such as a chest, the safest way to create a lower image contrast
is to use _____kVp and _______mAs
High kVp, low mAs
- In order to produce a visible change in optical density, mAs must be changed by at least _____%
30%
- In order to produce a visible change in optical density, kVp must be changed by at least _____%
4%
- For the most part, the principle action of radiation on humans is ________.
Indirect (due to radiolysis of water)
- Radiosensitivity increases as….
(all of the above)
- age of tissue decreases
- metabolic activity increases
- cell proliferation rate increases
- tissue growth rate increases
- According to the Law of Bergonie and Tribondeau, stem cells are radiosensitive. The 1st type of stem cells
to be affected are…
Hematologic System cells (first system to affected is the blood, and you go into
hematologic depression)
- …(continued from 32) the second type of cells to be affected are…
GI gut lining cells
- …(continued from 32) the last type of cells to be affected are…
CNS cells
- What part of the body is the least radiosensitive?
The foot!!!
- Because skin is nonlinear, what is its threshold dose?
200 rads
- What type of chromosomal aberrations are
considered to be the most significant in terms of latent human damage?
Multi-hit aberrations
- T/F: Gonadal dysfunction requires a high minimum dose.
False
gonadal damage can happen with only a 10rad exposure, a very low minimum dose
- The absolute risk is…
The number of cases of a given effect per rad per year
- The excess risk is…
The number of observed cases minus the expected cases
- the relative risk is…
The number of observed cases divided by the number
of expected cases
- The acute threshold of Cataract formation is….
2 Gy
- Females are ___ times more susceptible to thyroid
carcinoma
3 times
- Doubling dose is…
The amount of radiation needed to double the mutation
rate.
- In order to reduce exposure, we ____ time, _____
distance, and _____ shielding.
Minimize time, maximize distance, employ shielding
- T/F: Grids do not improve patient or doctor safety
True
- What determines barrier thickness?
The highest energy level employed by the x-ray unit (changes from machine to machine)
