Test 2 Flashcards
What dose response relationship is used for skin erythema and hematologic depression?
Linear, threshold
The model for ALARA has what type of dose-response relationship?
Linear, nonthreshold
What does response relationship is used for radiation therapy?
Nonlinear, threshold
When performing a portable x-ray, the patient’s skin should be at least ______ below the collimator/
30 cm
Studies consist of observations and statistical analysis of data, such as the incidence of disease within groups of people.
Epidemiology
Carcinogenesis is
the formation of cancer
Who reviews regulations formulated by the ICRP and decides to include those recommendations in US radiation protection criteria?
NCRP
There are ____ major organizations responsible for evaluating the relationship between radiation EqD and induced biologic effects.
Four
Every diagnostic imaging system must have a protective tube housing and
correctly functioning control panel
Who provides limits for occupational dose limits and public dose limits?
ICRP
_______ is the most significant late stochastic effects caused by exposure to ionizing radiation.
Cancer
Diagnostic x-rays are considered to have a
Linear, nothreshold
A lead-lined metal diagnostic-type protective tube housing is required to protect the patient and imaging personnel from
Off-focus
Which organization reviews studies of biologic effects of ionizing radiation and risk assessment?
NRC-BEIR
The housing enclosing the x-ray tube must be constructed so that the radiation leakage through any portion of the housing away from the useful beam, measured at a distance of ____m from the x-ray source, does not exceed ____ mGy/hr when the tube is operated at its highest voltage at the highest current that allows continuous operation.
1.0. 0.88
_______ means that below a certain radiation level or dose, no biologic effects are observed.
Threshold
Which organization mandates that every facility have a Radiation Safety Committee
NRC
Who develops the Radiation Safety Program?
Radiation Safety Officer
The radiographic examination table must be
As radiolucent as possible
Cancer and genetic defects are examples of?
Stochastic effects
When a prediction is made that the number of excess cancers will increase as the natural incidence of cancer increase with advancing age in the population, the risk sis considered to be?
Relative
______ indicates that a radiation absorbed dose of any magnitude has the capability of producing a biologic effect.
Nonthreshold
Biologic response is not directly related to radiation dose.
Nonlinear
Most types of cancer have this type of dose-response relationship.
Nonlinear
Most types of cancer have this type of dose-response relationship.
Linear, nonthreshold
______ is currently the predominant x-ray beam limitation device.
Collimator
Which type of radiation is not useful for imaging?
Compton
This portion helps prevent electric shock.
Protective tube housing
The protective tube housing helps prevent what from leaking.
Off-focus radiation
This portion helps prevent excess radiation form reaching the patient.
X-ray tube window
This radiation is emitted from the tube after passing through an aperture
Primary useful beam
The code of standards for diagnostic x-ray equipment states that a machine must have which of the following?
Beam limitation devices for spot films on fluoroscopy
T/F: The control panel or console must have visible mA and kVp digital readouts that permits the operator to assess exposure conditions.
True
To minimize skin exposure using a standard x-ray unit, a patients skin should be at least ______ form the collimator.
15cm
Alignment differences between x-ray light and light beams must not exceed _______ of the SID.
2%
“Indicates the ratio of the risk of stochastic effects attributable to irradiation of a given organ or tissue (T) to the total risk when the whole body is uniformly irradiated.”
Tissue weighting factor
___________ restricts the size and shape of the x-ray beam so it doesn’t exceed the size of the selected image receptor.
Positive beam limitation
Grids
increase the energy of the beam
Insulating oil surrounding the tube is an example of
inherent filtration
T/F: Embryologic effects is an example of late effect ionizing radiation.
True
The is a high probability that as single dose of approximately _____ will induce the formation of cataracts.
2.0 Gy
_______ is a late tissue reaction.
Organ atrophy
Radiation induced genetic abnormalities are caused by unrepaired damage to
DNA molecules on the sperm or ova of an adult
This is an example of a late tissue reaction to ionizing radiation.
Cataract formation
During Compton scattering, an incident x-ray photon strikes which type of electron?
Outer
During Compton, after an incident x-ray interacts with an atom the x-ray then
Continues in a different direction
In a collimator, one set of shutters are placed as close to the actual focal spot as possible reduction of?
Off-focus radiation
No conclusive proof exists that low-level ionizing radiation exposure below _______ causes a significant increase in the risk of malignancy.
0.1 GY
T/F: Any organ in the human body is vulnerable to damage from exposure to ionizing radiation.
True
T/F: All tissues and organs have the same sensitivity to ionizing radiation.
False
Radiation induced cataracts follow a _______ type of dose response.
Nonlinear, threshold
T/F: If an organ has a higher tissue weighting factor, it means that organ is less sensitive to radiation.
False
Inherent filtration provides the same amount of filtration as how many millimeters of aluminum?
0.5mm
The collimator mirror is equal to how many millimeters of aluminum?
1.0mm
T/F: Inherent and added filtration combine to meet required amount necessary, called total filtration.
True
A minimum of _____ aluminum equivalent total filtration is required for fixed radiographic units operating at above 70 kVp.
2.5mm
A mathematical equation is done to find the cumulative effective dose for a radiation worker, what is that equation?
Age x 10 mSv
The the embryo receives a high-dose of radiation during the first 12 weeks to equivalent doses above _____, fetal death or severe congenital abnormalities may occur.
200 mSv
What defines beam quality numerically?
Half value layer
Radiation induced cancer may take ______ or more years to develop in humans.
5
T/F: The physical appearance of cancer induced by ionizing radiation does not appear different than a cancer caused by other agents.
True
When using a compensating filter such as a wedge filter, do you put the thicker end of the filter towards the less dense or more dense portion of the part?
Less dense
Leukemia occurs approximately _____ years after exposure to ionizing radiation.
2
The ALARA concept adopts an extremely conservative middle concerning the relationship between
Ionizing radiation and potential risk
If a certain dose of radiation produces a skin burn, a higher dose of radiation will cause the skin to burn more severely, however; a dose below the threshold level for skin burn will
Not demonstrate the effect
Radiation workers annual occupational effective dose limit is ______ in any given year.
50 mSv
When looking at SI numbers, a low SI number out of range indicates?
The image is overexposed
In a fluoro unit, the input phosphor does what?
converts x-rays to light
In a fluoro unit, what receives electrons from the photocathode?
Output phosphor
In magnification mode on a fluoro unit the voltage on the electrostatic lens is _______.
Increased
________ is the ratio of input area to the output area of the image intensifier.
Minification gain
During a fluoro exam the radiologist uses pulsed fluoroscopy, this will of what to patient dose?
Decrease patient dose
What is the limit for nonoccupational exposed personnel per year?
5 mSv
Grids with higher ratios contain more lead strips, they also _____ patient dose and ______ scatter.
Increase; Decrease
For an 8:1 grid, the conversion factor used is?
4
What is the minimum SSD for a mobile radiography unit?
30 cm
Aliasing is an image artifact that
has a jagged or sawtooth appearance of curved or diagonal lines
This is made of amorphous silicon, converts x-ray energy into visible light.
Scintillator
T/F: When using a CR reader, the x-ray beam passes through the patient and deposited onto a PSP and then the absorbed energy produces a latent image composed of PSP molecules and excited electrons.
True
For non-digital fluoroscopic unit a HVL of 3 to 4.5 mm aluminum is considered acceptable when kVp ranges from _______.
80-100
Pregnant female radiation workers can not exceed ______ per month and no more than ______ throughout the entire pregnancy.
0.5 mSv, 5.0 mSv
During fluoro procedures with extended time, the FDA has recommended that a notation can be placed on the patient’s record if a skin dose in the range of _______ is received.
1-2 Gy
A Fluoro unit must have this type of switch
Deadman switch
For fluoroscopic units the current federal standard limit for entrance skin exposure rates have a maximum of _________.
88 mGy/min
According to the Health Effects article on Deterministic and Stochastic effects, deterministic effects occur after a _______ dose is reached, meaning that a dose below this are not expected to cause the particular effect.
Threshold
According to the Health Effects article on deterministic and stochastcis effects “the severity of the effect does not depend on the dose. It has an all-or-none response”
Stochastic
In 1929 a US Department of Labor study reported 33 cases of radium poisoning among this job. These worker put bristles in their mouths to bring the bristles to a point for painting.
Radium dial painters
