Extra Review Flashcards
Which populations were used as sources of data on the incidence of radiation-induced cancer?
- Atomic bomb survivors
- Medically exposed patients
- Occupational exposed personnel
- Populations who received high natural background exposure
What are the limitations on epidemiologic studies?
- Failure to control experimental groups
- Insufficient observation periods
- Using improper control groups
- Deficient or Incorrect health records
Which of the following describes radiation damage that increases the probability of causing a late effect but will not increase the severity of the effect?
Stochastic
What’s the dose response relationship for Radiation-induced leukemia
linear-nonthreshold dose relationship
What’s the dose response relationship for Skin cancer
threshold
What’s the dose response relationship for Thyroid cancer
linear nonthreshold
What’s the dose response relationship for Osteosarcoma
linear-quadratic
What’s the dose response relationship for lung cancer
linear-nonthreshold
The function of a filter is to remove what from the x-ray beam?
Long wavelength radiation
To within what percent of the SID must the collimator light and actual irradiated area be accurate?
2%
The greatest beam limitation is accomplished when the cone/cylinder is _____, and the diameter opening is _____.
longer ; smaller
How much total filtration is required when using over 70 kVp?
2.5 mm of aluminum equivalent
The number of repeat radiographs can be reduced by
eliminating voluntary patient motion using immobilization devices
Using CR, it is estimated that overexposures of up to _____, and underexposures up to _____ are recoverable, thus eliminating the need for retakes.
500% ; 80%
An effective way of reducing patient dose is through
Accurate and effective positioning
Causes of repeat radiographs include the following:
- Dirty screens
- Incorrectly loaded cassettes
- Light leaks
- Chemical fog
- Processor artifacts
How tall must primary protective barriers be?
7 ft.
Leakage radiation from the x-ray tube housing shall not exceed _____ mR/hr at a distance of 1 meter from the tube.
100
Lead aprons worn during a mobile exam must have a lead equivalency of at least _____ mm.
0.5
The cardinal rules of radiation protection include:
- Time
- Distance
- Shielding
When wearing a lead apron, a pregnant radiographer is required to wear their fetal dosimeter
at the waist level on the inside of the apron
Factors which determine protective barrier thickness include:
- Time of occupancy
- Workload
- Use
Applying the inverse square law, if we double our distance from the source, the intensity at our new distance is _____ as much as the original intensity
1/4
The lethal dose required to kill 50% of the population in 30 days is the definition of
LD 50/30
The acute radiation syndrome includes the following:
- Bone marrow syndrome
- Gastrointestinal (GI)
- Central nervous system (CNS) syndrome
For the acute radiation syndrome, in the 100-1,000 R range, death is mostly the result of damage to the _____ system
hemopoietic (development of blood cells)
In the _____ stage, the person experiences nausea, vomiting, and diarrhea.
prodromal
In the _____ stage, the person appears to be symptom-free
latent
In the _____ stage, the person becomes noticeably ill and shows signs and symptoms of the specific syndrome reflecting the organ system which is damaged.
manifest
define chromatid aberration
- Occurs after DNA synthesis
- During the S-phase, a chromosome duplicates itself, creating sister chromatids
define chromosomal aberration
- Occurs before DNA synthesis
- Both daughter cells inherit a damaged chromatid
what are the 2 types of damage in chromosomal aberration?
- single break damage
- double break damage
define single-break damage
- Chromosome arm is broken off
- Deletion - arm does not reattach itself
- Inversion - inverts and reattaches itself
- Duplication - attaches itself to a different chromosome
define double-break damage
- Two portions of a chromosome are broken off
- interstitial deletion - both broken pieces do not reattach
- Inversion - if both pieces reattach themselves
- Duplication - if one or both arms attach to a different chromosome
- Translocation - two chromosomes exchange pieces
define Radiation cataractogenesis
formation of cataracts formed by radiation
define Alopecia
hair loss
define Erythema
redness of the skin
define Desquamation
peeling of the skin
define Inflammation
swelling and reddening of the skin
define Atrophy
shrinking of the tissue or organ
Personnel monitoring devices include all of the following except the ____ dosimeter.
scintillation
Which instrument detects the presence of radiation rather than measuring it?
Geiger muller
Diagnostic radiology personnel may receive an annual dose limit of:
5rem (50 mSv)
Dose limits are based on a ________________ dose-response relationship to radiation.
linear ; nonthreshold
The dose limit for the general public is _______ the dose limit for occupational exposure.
1/10
What factors can decrease the dose to the limited operator?
- time
- distance
- shielding
The unit of the SI system used to measure the equivalent dose is the:
sievert
The SI unit for measuring absorbed dose is the:
Gray
The unit commonly used to report the effective dose to occupational workers in the United States is:
mSv
What does ALARA stand for? Why is this concept the guiding principal to the field of radiology?
- As low as reasonably achievable
- this concept emphasizes the protection against radiation. To minimize the ionizing radiation exposure as much as possible to avoid occupational or patient dose.
What are the units of measurement for Exposure, Absorbed Dose and Equivalent/ Effective Dose? List both the conventional and SI units for each.
- Exposure =Roentgen (R) / 2.58 x 10-4 C/kg
- Absorbed Dose = Rad (rad) / 0.01 Gy
- Equivalent/ Effective Dose = Rem (rem) / 0.01 Sv
What are the types of dosimeters? Which is the most common and why?
Personnel Dosimeters:
- Film Badges
- TLD (Thermoluminescent dosimeter)
- OSR (optically stimulated luminescence)
- pocket dosimeters
> most common would-be film badges
> they’re inexpensive
> simple to use
Where should dosimeter badges be worn? Where should fetal dosimeter badges be worn?
- dosimeters should be worn at the collar level
- fetal dosimeters must be worn at the abdominal area
What is declaration of pregnancy? How is it executed?
- declaration of pregnancy is when the worker voluntarily reveals her pregnancy to the employer.
- The RSO (radiation safety officer) will then council with her to follow proper radiation protection
- can be limited to exams
- cannot be expelled from work
- minimizing the radiation exposure as much as possible
What is the effective annual dose limit for radiology personnel?
- The cumulative whole-body effective dose limit is calculated by multiplying one’s age in years by 1 rem (10 mSv).
- 5 rem (50 mSv)
Which dose-response relationship are dose limits and radiation protection based upon?
dose limits are based on linear nonthreshold relationships
Which governing body is responsible for establishing dose limits and protection guidelines?
nuclear regulatory commission (NRC)
What is a dosimetry report? Who is responsible for monitoring it?
- dosimetry report is film badges, TLD, OSL, and pocket dosimeters being collected every month
- The RSO (radiation safety officer) monitors the reports to retrieve and distribute to employees
What is the difference between a personnel monitor and a field-survey instrument?
- personnel monitors measure the radiation a worker is being exposed to
- field survey are devices used to detect and measure the radiation in an area
What is the dose limits for Whole-Body? Include both convention and SI units
5 rem (50mSv)
What is the dose limits for Lens of Eye? Include both convention and SI units
15 rem (150mSv)
What is the dose limits for Skin/ Extremities? Include both convention and SI units
50 rem (500 mSv)
What is the dose limits for Whole-body cumulative? Include both convention and SI units
Age x 1rem (Age x 10 mSv)
What is the dose limits for Fetus? Include both convention and SI units
- 10 months/280 days = 0.5 rem(5 mSv)
- 1 month/28 days = 0.05 rem (0.5 mSv)
What is the dose limits for Public Exposure? Include both convention and SI units
- Infrequent exposure = 0.5 rem (5 mSv)
- Frequent exposure = 0.1 rem (1 mSv)
What are the guiding principals of reducing the possibility of radiation exposure?
Cardinal principles
- time
- distance
- shielding
As LET ____________, the RBE ______________.
increases ; increases
Tissue is _______ radiosensitive under high oxygen conditions and _________ radiosensitive under hypoxic conditions.
more ; less
A _________ response to radiation is directly proportional to the dose received.
linear
If a response to radiation is expected, no matter how small the dose, then that dose-response is _________________.
nonthreshold
Radiation induced genetic damage follows a ___________________ dose-response relationship.
linear ; nonthreshold
define LET
- linear energy transfer
- rate of charged particles going through matter
define OER
- oxygen enhancement ratio
- OER = dose in rads bio. response in anoxic conditions / dose in rads bio. response in aerobic conditions
What are the two components of beam restriction? How are each of them important?
- kilovoltage
- irradiated material
What are the common beam-limiting devices?
- diaphragms
- cones
- collimator
What is the purpose of x-ray beam filtration?
- The purpose of x-ray beam filtration is to absorbed low energy photons from exiting the tube to reduce patient dose
- remove long wavelength radiation
Explain inherent filtration, added filtration and total filtration?
inherent - consists of the glass window of the X-ray tube and the cooling oil surrounding the tube housing
added - consists of aluminum or aluminum equivalent (Al eq.) of appropriate thick- ness inserted outside the glass window of the tube housing.
total - combination of inherent + added
What is the minimum Al/Eq for filtration above 70 kVp?
2.5 mm of Al EQ
What are the 3 types of gonad shields? When should they be employed?
- flat contact shield
- shadow shield
- shape contact shield
Describe how exposure techniques can be used to influence patient dose.
- With kVp, it is desired to have a low setting, as it deals with quantity. kVp also has a direct relationship with exposure.
- The higher the kVp, the higher the patient dose
- mAs deals with quality, having a direct relationship with density and exposure
- The minimum patient dose is a high kVp with a low mAs
- As long as the settings balance themselves out to maintain a radiographic balance, having a high kVp or vice versa is acceptable (technique settings also depends on the part being examined)
Why is patient positioning important in reducing patient dose?
- With the correct positioning, it will allow the radiographer to produce a high quality image.
- With all the correct angles, it can be observed once dealt with by the doctor.
- With correct positioning, there are no mistakes, thus reducing retakes and reducing patient dose
Why is it important for a technologist to always ask their female patients of child-bearing age whether they are pregnant?
- It is important to make sure the patient is not pregnant to avoid high exposure radiations during exams
- When pregnant, safety procedures need to be made to keep the fetus safe from radiation.
Give examples of some causes of repeat radiographs and how to avoid them.
- Incorrect positioning
- Processor artifacts
- Dirty screens
- Chemical fog
- Grid errors
