RADIOGRAPHER ONLINE EXAM PRACTICE KIT 13
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Attenuation:
These changes may include absorption and scatter radiation.Radiation that emerges from the patient is called exit radiation
Which photon tissue interaction makes radigraphy possible because of its creation of contrast?
Photoelectric interaction produces contrast as aresult of the incoming x-ray photons of the body ‘s tissues.Rays are completly absorbed in some areas of the patient.Choice A and b are types of scattering.Pair production does not occur in radiography.
Which photon tissue interaction produces radiation that may expose others in the room during fluroscopy?
Compton interaction produces scattered photons that emerge from the patient in divergent path and expose the radiographer of radiologist.The photoelectric effect is responsible for total absorption of the incoming x-ray photon during attenuation.Coherent scattering and pair production occur when x-ray energies are beyond the moderate rate used in radiograophy.
The traditional unit of absorbed dose is:
RAD stands for radiation absorbed dose.The gray in the SI ,not the traditional unit of absorbed dose.The Curie is the traditional unit of radioactivity. The coulombs/ kilogram is the SI unit of radiation exposure in the air.
The traditional unit of activity is
The Curie used primarily in nuclear medicine,is the traditional unit of radioactivity.Becquerel SI unit of radioactivity,gray SI unit of absorbed dose.The radiation weighting factor is a value used to adjust the absorbed dose amount to compensate for the greater damage caused by some ionizing radiation
Measurement of positive and negative particles created when ionizes atoms in the air helps define the:
The roentgen is the traditional measure of in-air exposure.Curie is a traditional unit of radioactivity.Becquerel measures radioactivity,gray measures absorbed dose
Linear energy transfer:
LET varies because of different level of ionization.It occurs with high ionization radiation such as neutrons & alpha particles ,as well asduring x-ray & gamma ray procedures.
The unit of curie would be used in what imaging modality?
The curie measures the quantity of radioactive material
Graph that shows the relationship between radiation received and the organism’s response are called:
This describes a dose -response curve, such as linear non- threshold.The H and D are characteristic curves represent the relationship between radiation exposure & optical density.
Medical x-rays are an example of:
Medical x-rays are an artificial source of ionizing radiation; diagnostic procedures account for the largest source of artificial radiation exposure to humans.Natural background radiation is contained in the environment
Cataractogenesis does not occur at low levels of radiation exposure,it is best expressed by which of the following dose-response relationships?
There is a ,definite safe, or threshold dose at which cataractogenesis does not occur.Occupational dose is the amount of radiation to which radiographer are exposed.
Increased dose equals increased probability of effects best describes which of the following?
Be sure to review stochastic and nonstochastic ,deterministic and probabalistic.The severity ,not the probabilty, of nonstochastic effects increases with increased dose. direct effect and indirect effect differentiate whether the inital ionizing event occurs on the most radiosensitive molecule or on another molecule.
The cumulative occupational exposure for a 22-year old radiographer is:
Occupational cumulative exposutre is determined by multiplying years of age times 1 rem
The annual effective dose limit for the general public,assuming frequency exposure is:
The limit is important to keep in mind when considering ALARA
The secondary productive barrier used in room shielding must be at least how thick?
Lead , not aluminium equivalent will absorb most of the scatter radiation energy. Because of the secondary barrier is located where only scatter or leakage occur ,1/32 inch lead equivalent is sufficient .Primary barrier requires 1/16 inch leaqd equivalent
The intensity of the scattered beam is 1/1000 the intensity of the primary beama at a …………… angle 1m from the patient
Photon lose considerable energy after scattering
If the radiation dose 6 feet from the x-ray table is 5R,what is the dose at a distance of 3 feet?
The dose is determined by inverse square law.The distance was halved ;therefore the dose went up 4 times
The minimum source to distance for fixed fluroscopes
The minimum source to skin distance for fixed fluroscopes is 15 inches; for portable fluroscopes, 12 inches.Be sure to review these required distances.
The use of gonadal shielding on female patients may reduce gonad dose by
Gonadal shielding is more effective for females,reducing the gonad dose by up to 95%.
Cells that are oxygenated are more susceptible to radiation damage;this describes:
Target theory states that for acell to die after radiation exposure , its master or target molecule DNA must be inactivated.The doubling dose is the dose of radiation necessary to produce twice the frequency of genetic mutations as would have occured in tha absence of the radiation
The blood count is depressed after a whole-body dose equivalent of at least how many rads?
The dose equivalent at which blood count is depressed is much higher than diagnostic levels but may occur during radiation therapy.
Highly reactive ions that have unpaired electrons in the outershell are called:
This is the definition of free radicals,which can cause biologic damage to the cell.Some free radicals may chemically combine to form hydrogen peroxide.Radiolysis results in an ion pair in the cell: a positively charged water molecule and a free electron.
The process of somatic cell division is called:
Cytogenesis refers to the origin and development of cells.Spermatogenesis is the development of spermatoza. Organogenesis refers to the formation and differentiation of organs during embryonic development.Germcell division is called meiosis.
The master molecule that directs cell activities is:
According to target theory, substantial research indicates that DNA,contained in the cellular nucleus, is the master molecule.Hydrogenperoxide is a poison that cause damage to the cell.A free radical is highly reactive ion with unpaired electrons in the outer shell. RNA transmits genetic instructions from the nucleus to the cytoplasm of the cell.
The most common effect from exposure to ionizing radiation is:
Although all of these effects may occur, the most common result of LET is no effect.However, ALARA must still be practiced
Most radiation -induced damage to cell occurs:
Adult nerve tissue and even immature cells, which are very radiosensitive,require doses of radiation higher than those used in medical diagnostic procedures,although ALARA must still be practiced
Radiation doses up to ………… are considered relatively low risk to the embryo and fetus
Doses lower than 50 to 20 still pose low risk to the embryo fetus, so ALARA must still be practiced
A concept of radiologic practice that encourages radiation users to adopt measures that keep the dose to the patient and themselves at minimum levels is called:
As low as reasonably achievable is a concept used in radiography to protect both the patient and the radiographer.
Which of the following is relatively insensitive of radiation?
Epithelialtissue and reproductive cells including immature sperm cells,are highly radiosensitive. On the other hand, adult nerve tissue requires very high dose to cause damage,although ALARA must still be practiced because once cells are damaged,repair may not take place.
Somatic effects of radiation:
In general these take large doses to manifest themselves
The best way to keep radiation dose to the patient low is:
Repeats double the dose to the patient for each exposure
X-rays may remove electrons from atom in the body by a process called:
This is what may cause harmful effects
Ionization may cause:
Ionization is multifacted.
Cell damage may be exhibited as:
Cell damage may be exhibited as loss of function or abnormal function
Damage to the cell being irradiated is called:
Damage from somatic effects is evident in the organism being irradiated.Most of the time these effects are benign.Genetic damage is passed to the next generation
Radiation effects that show up in the next generation are called:
Somatic effects are evident in the organisms being irradiated.
Radiation that is contained in the environment is called:
There is no control over natural background radiation, which has been present in the environment since the formation of the universe.Choice A.B and D all refer to artificially produced radiation ,that made by humans.
Background radiation is the source of what present of human exposure?
Natural background radiation ,which has been present since the formation of the universe ,accounts for 50% of human exposure.The greatest single source is radon.
The annual effective dose per person from natural background radiation is approximately:
You can assume the natural background radiation would below the annual recommended limits of exposure from diagnostic imaging.All choice are below this limit, choice B is correct. Background exposure is not high but is always present.
The greatest source of natural background radiation to human is:
radon which exists as a gas ,account for 50% of human exposure to natural background radiation
According to NCRP report #160, the increase in total exposure is primarily attributed to increase use of:
The huge increase in the use of CT since the 1980’s has primarily caused this increase.
According to NCRP report #160, interventional fluroscopy contributes approximately what amount to the annual dose to the population?
CT accounts for approximately what percent dose to the population?
Using data from NCRP Report #160, the typical dose for an upper GI is:
NCRP report #160 indicates the dose for an examination of the extremities is:
The smaller particle of an element that retains the characteristics of the element is a(n):
Atomic mass refers to:
X-ray travel as bundle of energy called:
X-ray exit the anode as burst of energy known as photons
The height of sine wave is called:
We usually focuse frequency and wavelength due to their relevance in imaging
The number of x-ray waves passing a given point per unit time is called:
Frequency is inverse to wavelength
The transformer that operates on principle of self induction is called:
Other transformers operates on principle of mutual induction
Electronic timers used in x-ray equipment allow for exposure times of:
One millisecond is the shortest time possible
To ensure consistency of radiographic quality from one exposure to the next, which device may be used?
Automatic exposure control is the only choice that has to do with consistency of radiographic quality.
What happens when a predetermined level of ionization is reached in the ionization chamber?
Choice A does not make sense because if a precedence level of ionization is reached, the unit could not be malfunctioning because it reached that predetermined level.
An x-ray machine that makes maximum use of heat loading potential uses:
A Falling load generator allows very short exposure times by taking advantage of adjusting to the shortest exposure time and highest mA allowed by high- voltage generator ,but it is not capable of long exposure times.
An x-ray machine that makes maximum use of heat loading potential uses a(n):
A Falling load generator allows very short exposure times by taking advantage of tube hear loading potential.When the tube ‘s maximum heat load has been reached for a set mA,the generator drops the mA to the next lower level that the tube can handle.
Devices in the x-ray circuit that operates on the principle of mutual induction are called:
Transformers operates on the principle of mutual induction.They are either step-up or step-down transformers
The high – voltage section of the x-ray circuit makes use of what type of transformer?
The step-up transformer, also called as high voltage transformer,increases or steps up the voltage to kilovoltage levels.
The device in the x-ray circuit that changes AC to DC is the:
DC is needed for the x-ray tube and a rectifier changes AC to DC.
What type of current is required for the proper operation of the x-ray tube?
The x-ray tube requires a DC to operate properly.The rectifier changes AC to DC. Choice B and D do not describe a type of current that can be eliminated immediately.
Modern rectifiers are made of:
If 2 two very similar choices are presented,one of them is usually the correct answer.silicon is the non metallic chemical element often used in the manufacture of rectifiers.Silicon based semiconductors are solid state diodes.
The result of thermionic emission is
Thermionic emission occurs when one filament is heated to a level that causes the electrons to be “boiled off” or emitted creating a cloud of electrons at the cathode.Therm refers to heat, ion refers to a chrged particle,and emit means “to giveoff”.
The focusing cup is located at the:
The focusing cup is part of cathode assembly it keep the electron stream narrow.
An interaction that produces x-rays at the anode as aresult of outer shell electrons filling holes in the K-shell is called:
This is a description of characteristic radiation.Although both characteristics and brems radiation produces x-ray at the anode, brems radiation occurs when a projectile electron misses the outer shell target electrons and moves close to the nucleus.brems radiation brems radiation brems radiation.Photoelectric effect does involves outershell electrons filling holes in the K- shell it does not produce x-rays at the anode. Both photoelectric effect and compton interaction which produces scatter radiation ,occur in the body.
When a quality control test is performed to ensure to ensure that adjacent mA stations are accurate,the result must be within the amount of one another:
Adjacent mA stations would be within 10 % of one another.
When a quality control test is performed to ensure that the same exposure factors produce x-ray output, succesive exposures must be within this amount of one another:
When exposure reproducibility is tested, variation is measured radiation intensity should not be more than 5%.
When a quality control test is performed to ensure that the collimator is providing appropriate radiation protection, the result must be within this amount?
The collimator must be accurate to within 2 % of SID
In digital fluroscopy ,the image should be viewed on what device to make advantage of the digital capabilities?
A primary advantage of digital fluroscopy is:
Post processing provides for manipulation of the image
The active portion of a CR imaging plate is:
Energy in a CR imaging plate is released after exposure to:
This occurs in reader unit
In digital fluroscopy and computed radiography ,the energy must be changed to digital form by a(n):
An algorithm is:
In computed radiography,each pixel corresponds to a shade of gray representing in area in the patient known as a(n):
A digital image is composed of rows and columns known as:
Image brightness in computed radiography may be adjusted by:
Window width adjust Contrast
The window level in computed radiography is the:
Radiographic contrast in computed radiography may be adjusted by changing the:
Window level adjust brightness
The amount of darkness on a radiograph is controlled primarily by
The visible image may alse be called the:
The quantity of x-rays produced is directly controlled by:
The rule or law that governs changing technique using kVp is the:
This is governed by 15% rule
Given an original technique of 10 mAs and 70 kVp,which of the following would produce a radiograph with double the density?
mAs has been doubled.
If SID is halved,what may be said about radiographic density?
This is governed by the Inverse square law.
The letter TFT stands for
Distortion that effects the size of the object as represented on the radiographic image is called:
There is no Minification
Shape distortion may take the form of:
These are 2 types of shape distortion.
A longer than usual OID may cause
An increase in OID will cause Magnification
CR cassettes should be erased:
This is a recommendation.They must be erased at least every 48 hours
The equation of H/D describes:
Height of the lead strips divided by the distance between them
If the exposure field is not accurately recognized,the histogram:
Noise increases with an increase in:
Fewer x-rays are required to produce an image .This cause an increase in noise or quantum mottle.
Edge enhancement provides:
Which of the following grid errors would result in an image that shows normal density in the middle but decreased density on the sides and may follow removal and replacement of the grid?
If the grid is placed in this position ,rays can only get through the middle of the grid.
Grid frequency is described as the:
When working with CR and DR , one must be aware that their response to scatter radiation is:
The images on radiologist’s monitors appear:
Generally, diagnostic stations have higher resolution monitors
A histogram analysis error may be caused by:
Smoothing provides:
The overall noise is evened out by this process.
Consistency of image appearence is achieved through the use of:
It is important that proper algorithms be used for each projection
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