Safety: Radiation Physics and Radiobiology Flashcards
- What occurs as electrons decelerate upon encountering the tungsten anode?
A. The anode converts the electrons to protons
B. Electron kinetic energy increases
C. An electromagnetic wave is produced
D. X-rays are produced
D. X-rays are produced
The anode is the X-ray tube component involved in the production of X-rays. X-rays are generated when high-energy electrons encounter the anode. The anode target material is comprised of tungsten, which has a high anatomic number and melting point. Tungsten’s high atomic number (Z=74) contributes to bremsstrahlung X-ray production.
- A source of free electrons are produced by heating the x-ray tube filament to incandescence. This is termed:
A. Photoelectric effect
B. Thermionic emission
C. Piezoelectricity
D. Electromagnetic effect
B. Thermionic emission
Thermionic emission involves the heating of the x-ray tube filament, which is achieved when the rotor is activated, increasing the filament current. The filament circuit generates current and voltage which heats the filament to incandescence, producing valence electrons from filament atoms.
- Which of the following contributes to the acceleration of electrons?
A. Rotating anode component
B. Magnetic properties of the target material
C. Stationary anode component
D. High potential difference between the cathode and anode
D. High potential difference between the cathode and anode
A focused electron beam travels from the cathode toward the anode. Electrons accelerate toward the anode end of the tube as a result of the high potential difference between the cathode and the anode. A rotating versus stationary anode would not contribute to the acceleration of electrons, but rather, the dissipation of heat.
- Which X-ray tube component serves to guide electrons toward the anode?
A. Induction motor
B. Envelope
C. Focusing cup
D. Stator
C. Focusing cup
The focusing cup, which is manufactured from molybdenum (Mo) or nickel (Ni), functions to guide electrons toward the anode’s focal track.
- Which of the following is necessary for production of X-rays?
A. Rotating anode
B. Insulating oil
C. Deceleration of electrons
D. Acceleration of neutrons
C. Deceleration of electrons
X-rays are produced when electrons decelerate upon encountering the tungsten anode. Insulating oil and a rotating anode aid in dissipation of heat but are not necessary for X-ray production.
- Most target interactions involve:
A. Incident electrons
B. Outer-shell tungsten electrons
C. Inner-shell tungsten electrons
D. A and C
E. A and B
E. A and B
Most incident electrons interact with outer-shell tungsten electrons. This results in the transformation of kinetic energy into heat energy, rather than the production of ionizing radiation.
- A projectile electron interaction with the electrostatic charge of the tungsten nucleus generates:
A. K-shell X-rays
B. Bremsstrahlung radiation
C. L-shell X-rays
D. Characteristic radiation
B. Bremsstrahlung radiation
When an electron with great kinetic energy interacts with the electrostatic charge of the target nucleus, the projectile electron slows, changes direction, and loses kinetic energy. This results in Bremsstrahlung X-ray photon emission.
- A projectile electron interacts with a tungsten atom. An inner shell electron is ejected, and the atom is ionized. When the K-shell vacancy is filled by an outer orbital shell, what is the result?
A. Photodisintegration
B. Creation of a positron and negatron
C. Emission of a characteristic X-ray photon
D. Bremsstrahlung radiation
C. Emission of a characteristic X-ray photon
When a high-speed electron interacts with a tungsten target atom by way of ejecting an inner (i.e., K-shell) electron, the atom is ionized. Outer orbital shells (i.e., L, M, N) fill the K-shell vacancy, which releases a characteristic X-ray photon. These photons are only diagnostically useful when they are produced from the filling of the K-shell or an inner orbital shell.
- Which of the following is true regarding an increase in kilovoltage?
A. Increasing the voltage difference increases electron speed
B. Increasing kilovoltage is the best method of altering the quantity of electrons generated from the filament
C. High-energy electrons produce long-wavelength X-rays
D. High-energy electrons produce low-energy X-rays
A. Increasing the voltage difference increases electron speed
As kilovoltage is increased, the speed of electrons increases. High-energy electrons generate high-energy, short-wavelength X-rays. X-rays are a form of electromagnetic energy on the electromagnetic spectrum which exhibit high frequency and very short wavelength (i.e., compared to light and radio waves) characteristics.
The quantity of electrons that are generated from the filament is optimally controlled by altering mAs.
- The rate of electromagnetic photon oscillation is termed:
A. Frequency
B. Wave-particle duality
C. Particulate radiation
D. Wavelength
A. Frequency
Oscillation of an electromagnetic photon is called frequency (Hz). The distance from crest-to-crest or trough-to-trough between two adjacent electromagnetic photons describes wavelength. Frequency and wavelength exhibit an inverse relationship, the higher the frequency the shorter the wavelength. The height of a wave’s crest or trough is termed amplitude, measured in a unit of angstroms.
- The quality of an X-ray photon generated at the target is relative to kilovoltage and describes the photon’s:
A. Energy
B. Penetration
C. Wavelength
D. A and B
E. A, B, and C
E. A, B, and C
Kilovoltage is relative to the quality of the X-ray photon and determines photon characteristics including the photon’s energy, penetration, and wavelength. Kilovoltage alters exposure because kilovoltage plays a role in the quantity of high-energy X-ray photons which are generated at the anode.
- The penetrating ability of the X-ray beam is described as:
A. mAs
B. Beam quality
C. Beam quantity
D. Beam filtration
B. Beam quality
Beam quality describes the penetration of the X-ray beam, or how “hard” the X-ray beam is. Beam quality can be adjusted by modifying kVp which determines the energy level of the X-ray beam.
- All of the following are true regarding primary radiation, except:
A. The primary X-ray beam is heterogeneous
B. Directed through the X-ray tube window port
C. Produced at the tungsten target
D. Image-forming portion of the beam
E. Consists of the X-ray beam prior to interaction with a medium
D. Image-forming portion of the beam
The primary X-ray beam is produced at the tungsten target and is then directed through the X-ray tube window port. The primary beam involves the incident beam prior to interaction with a medium (i.e., the patient). This portion of the beam is heterogeneous; filtration is utilized to reduce low-energy photons which are not strong enough to reach the IR and contribute to patient dose.
- The remnant X-ray beam is also called:
A. Exit radiation
B. The image-forming beam
C. Primary radiation
D. A and B
E. B and C
D. A and B
Remnant radiation is also called exit radiation and involves the portion of the X-ray beam which leaves the medium and interacts with the IR to produce the diagnostic image.
- Which law describes why a decrease in distance between the radiation source and IR increases the exposure rate?
A. Inverse-square
B. Line-focus principle
C. Density-maintenance
D. Reciprocity
A. Inverse-square
The inverse square law states that radiation intensity is inversely proportional to the square of the distance from the source and exposure rate increases as the distance between the IR and source of radiation decreases. For this reason, an adjustment of technical factors is necessary, and the appropriate mAs value with a change in distance can be determined using the density-maintenance formula.
- Which is a fundamental property of X-ray photons?
A. X-rays travel in a straight line
B. X-rays can be focused
C. X-rays travel slower than the speed of light
D. X-rays are nonfluorescent
A. X-rays travel in a straight line
Radiographers should understand the properties of X-ray photons, including that X-rays travel in a straight line and at the speed of light, are ionizing, cannot be focused, are comprised of a spectrum of energies, are not affected by a magnetic field, and are not perceivable by the senses.
- When primary X-ray photons interact with matter and endure a change in direction, this best describes:
A. Scatter radiation
B. Attenuation
C. Absorption
D. Exit radiation
A. Scatter radiation
Leakage and scatter radiation are secondary sources of radiation which occur when the primary X-ray photon interacts with matter and endures a change in direction. The tube housing serves to decrease the extent of leakage radiation.
- An incident X-ray photon interacts with a K-shell electron of a target atom. The X-ray photon is entirely absorbed, and the electron is removed. This describes:
A. Photoelectric effect
B. Compton effect
C. Thompson scattering
D. Classical scattering
A. Photoelectric effect
The photoelectric effect is also called photoelectric absorption. The photoelectric effect comprises the primary source of radiation exposure to the patient and there is total absorption of the X-ray photon. The mechanism involves interaction between the incident X-ray photon and an inner K-shell electron, in which the incident photon has an energy greater than or equal to the K-shell binding energy causing removal of this electron. Any remaining energy of the incident X-ray photon transfers to the removed electron, which is called a photoelectron. Outer orbital shell electrons fill the inner-shell vacancy, which results in emission of characteristic X-ray photons.
- What determines the amount of energy which is transferred to a Compton electron?
A. Binding energy of an X-ray photon
B. Direction of the scattered photon
C. Energy of the photoelectron
D. Angle of deflection
The mechanism of Compton scatter involves an incident X-ray photon which interacts with an outer shell electron of a target atom. Energy of the X-ray photon must exceed the energy of the orbital electron to eject it from its shell. Some of this energy transfers to the ejected electron, called the Compton electron, while the remaining energy exhibits a change in direction and a scattered photon is produced. The angle of deflection, or the amount of directional change by the scattered photon, determines the energy of the scattered photon and the amount of energy transmitted to the Compton electron. The angle of deflection increases with the amount of energy imparted to the Compton electron.
- Which form of scattering occurs at very low X-ray photon energy levels, where the incident X-ray photon interacts with and excites the target atom but does not eject an orbital electron?
A. Classical scattering
B. Coherent scattering
C. Thompson scattering
D. Compton scattering
E. A, B, and C
E. A, B, and C
Unmodified, coherent, or Thompson scattering are other names for classical scattering. This type of scattering happens when an incident X-ray photon interacts with and excites the target atom without ejecting an orbital electron, and it happens at very low X-ray photon energy levels. There is no ionization or energy transfer between the incoming photon and the target atom since no orbital electrons are expelled from orbit. The incident photon changes direction but does not lose any energy in the process. Classical scattering results in decreased image quality and increased skin exposure for the patient.
- An x-ray beam’s decrease in intensity as it travels through a medium is referred to as:
A. Attenuation
B. Absorption
C. Divergence
D. Half-value layer
A. Attenuation
Attenuation is the term used to describe the decrease in the amount or intensity of an X-ray beam as it travels through a medium. Absorption and scattering of the X-ray beam contribute to attenuation.
- Atoms with the same mass number and atomic number are called:
A. Isotones
B. Isobars
C. Isomers
D. Isotopes
C. Isomers
Isomers are atoms that have the same mass and atomic number. Atoms with the same atomic number, or number of protons, but distinct mass numbers are called isotopes. As a result, the number of neutrons in them varies. Isobars are groups of atoms with the same mass number but distinct atomic numbers. Isotones are atoms with distinct atomic numbers but the same neutron number
- Biological effects of radiation increase as:
A. Quality of the X-ray beam increases
B. Absorbed dose increases
C. Area of exposure increases
D. B and C
E. A, B, and C
E. A, B, and C
The degree of penetration and the extent of energy delivered to the irradiated tissue (LET) are determined by the radiation quality. The effect increases with the amount of radiation that is absorbed. The larger the irradiation area, the greater the biologic effect.
- What is the annual whole-body EfD limit advised by the NCRP for those who are occupationally exposed?
A. 0.5 mSv
B. 50 mSv
C. 5 mSv
D. 120 mSv
B. 50 mSv
Effective dose is calculated for the entire body and is expressed in millisieverts (mSv). The NCRP recommends 50 mSv (5 rem) as the yearly whole-body effective dose (EfD) limit for individuals who are occupationally exposed to radiation.
- Which unit is used to express the absorbed dose?
A. Roentgen
B. rem
C. rad
D. Sv
C. rad
Radiation absorbed dose (rad) is the unit of measure for absorbed dose installed on a medium. Gray (Gy) is the SI unit of absorbed dose.
- The SI unit for absorbed dose equivalent is:
A. Roentgen
B. Becquerel
C. Coulomb
D. Sievert
D. Sievert
The SI unit of absorbed dose equivalent is the Sievert. 1 cSv is equivalent to 1 rem, and 1 Sv is equivalent to 100 rems. Sievert is a measurement which describes the capacity of radiation to elicit a certain biological reaction in a medium.
- What is the unit for dose equivalent, calculated by multiplying the absorbed dose (in gray) by a quality factor (QF)?
A. Sievert
B. Gray
C. rad
D. rem
A. Sievert
The sievert (Sv) is the International System of Units (SI) measure for dose equivalent, representing the biological impact of ionizing radiation. It is determined by multiplying the absorbed dose in gray (Gy) by a quality factor (QF), which adjusts for the varying biological effects of different radiation types. Historically, the unit “rem” (radiation equivalent man) was used, where 1 Sv equals 100 rem. However, the sievert has become the standard unit in contemporary practice.
Reference:
U.S. Nuclear Regulatory Commission. (n.d.). § 20.1004 Units of radiation dose. Retrieved from [source link].
This reference provides information on radiation dose units, confirming that the gray (Gy) is the SI unit for absorbed dose and the sievert (Sv) is the SI unit for dose equivalent.
- The unit of radiation exposure which will produce 2.58 × 10⁻⁴ coulombs per kilogram of air is:
A. Becquerel
B. Roentgen
C. Curie
D. Sievert
B. Roentgen
The Roentgen is the exposure unit that will produce 2.58 × 10⁻⁴ C/kg. As an indicator of exposure, within the diagnostic range, the roentgen is unaffected by field size or area.
- To ensure ongoing awareness of patient exposure during fluoroscopic procedures, in compliance with CFR, Title 21, cumulative air kerma is shown in what unit of measure?
A. Sievert
B. rem
C. mGy
D. C/kg
C. mGy
The United States Food and Drug Administration (FDA) Code of Federal Regulations (CFR), Title 21, Volume 8 states, “cumulative air kerma means the total air kerma accrued from the beginning of an examination or procedure and includes all contributions from fluoroscopic and radiographic irradiation” and that “fluoroscopic air kerma display device means a device, subsystem, or component that provides the display of AKR and cumulative air kerma required by § 1020.32(k), which includes radiation detectors, if any, electronic and computer components, associated software, and data displays.” In compliance with the FDA CFR, Title 21, cumulative air kerma is displayed in a unit of mGy (milligray in air).
- Which cell type exhibits the lowest radiosensitivity?
A. Muscle cells
B. Lymphocytes
C. Adult nerve cells
D. Fetal nerve cells
C. Adult nerve cells
Nerve cells are the least radiosensitive in the body; in fetal life, however, nerve cells are extremely radiosensitive. Muscle cells have a relatively low level of radiosensitivity. The most radiosensitive of all bodily cells are lymphocytes, a subset of white blood cells that are involved in the immune system.
- Which is true of a linear dose-response curve?
A. Exhibits no threshold
B. Does not allow for plotting of somatic effects
C. A and B
D. Used to plot genetic effects of radiation
D. Used to plot genetic effects of radiation
A linear dose-response curve is used to illustrate the genetic consequences of radiation and some somatic effects. With the linear non-threshold (LNT) model, there is no threshold for the linear dose-response curve, meaning that radiation is never completely safe below a certain level. There are also linear-threshold dose-response models, which have a known threshold below which no effects are observed.
- Damage to biologic tissue increases as:
A. Density of interactions at cellular level decreases
B. Linear energy transfer increases
C. Relative biologic effectiveness decreases
D. The kVp (kilovoltage peak) settings are decreased
B. Linear energy transfer increases
Biologic effect and damage will rise in proportion to the linear energy transfer, or transferred energy (LET), which is a result of interactions between radiation and a biologic medium. Depending on the radiation type and the properties of the absorber, LET describes the rate at which photon or particle energy is transferred to (absorbed by) biologic material (via ionization processes).
- A patient is exposed to low levels of radiation over an extended length of time. Malignancy caused by radiation manifests itself years later. This delayed consequence of radiation exposure exemplifies:
A. Deterministic effects
B. Compton effects
C. Nonstochastic effects
D. Probabilistic effects
D. Probabilistic effects
A late reaction to low-dose exposure characterizes a dose-response type relationship known as probabilistic effects, also called stochastic effects. Genetic effects and radiation-induced cancer are the late (or stochastic) consequences of radiation exposure. These can happen years after surviving an acute radiation dose or during prolonged exposure to low radiation levels. Personnel who are exposed to low doses of radiation over extended periods of time must be particularly mindful of the late effects of radiation. Guidelines for occupational radiation protection are consequently founded on the late effects of radiation as determined by a non-threshold, linear dose-response curve.
- Among the following, which tissue would be most radiation-sensitive?
A. Hypoxic tissue
B. Anoxic tissue
C. Avascular tissue
D. Oxygenated tissue
D. Oxygenated tissue
The oxygen enhancement ratio (OER) defines aerobic conditions’ capacity to increase radiation efficiency. A cell’s sensitivity to radiation rises with increased oxygenation; a cell which is oxygen-free is less sensitive. Tissue without oxygen is referred to as anoxic, and tissue with little oxygen is referred to as hypoxic. Because anoxic and hypoxic lesions often have little to no blood flow, they are more radioresistant.
- Which of the following presents when the whole body receives a large dose of radiation at one time?
A. Somatic effects
B. Stochastic effects
C. Chronic radiation syndrome
D. Probabilistic effects
A. Somatic effects
Short-term early somatic effects may manifest if a significant dose of radiation is applied to the entire body at once. For example, acute radiation syndrome results from bodily exposure to 600 rad (6 Gy) at one time. Leukopenia, exhaustion, nausea, vomiting, diarrhea, and other symptoms are early indicators of acute radiation syndrome and appear during the prodromal phase of the condition.
- After a very high dosage of ionizing radiation, early somatic symptoms appear within:
A. Minutes or hours after exposure
B. Days after exposure
C. Weeks after exposure
D. A and B
E. A, B, and C
E. A, B, and C
Early somatic effects require a very high dosage of radiation administered to the entire body in a little amount of time. Consequently, doses derived from proper use of diagnostic radiologic procedures cannot cause early somatic effects. Though, technologists still need to be aware of early somatic effects. Certain high dose CT scans or fluoroscopy procedures may have early somatic repercussions, such as erythema or epilation, if they are not performed carefully. Following radiation exposure, early somatic symptoms may appear minutes, hours, days, or weeks later. Depending on which system or systems are affected and what symptoms occur, whole body reactions can be classified as either hematologic, gastrointestinal, or central nervous system responses.
- When individuals are chronically subjected to radiation, cataracts can form on their orbital lenses. This is an example of a(n):
A. Nonstochastic effect
B. Probabilistic effect
C. Late somatic effect
D. Early somatic effect
C. Late somatic effect
The long-term repercussions of radiation exposure are a concern for individuals who are employed in environments where radiation is present. Low, prolonged doses might result in late somatic consequences, which can manifest years after initial exposure. Radiation can cause cancerous somatic consequences, such as skin cancer, leukemia, thyroid tumors, and malignancies of the bones. A further example of the late somatic consequences of radiation is the development of cataracts on an individual’s orbital lenses following chronic radiation exposure.
- In which of the following region(s) is delayed cancer presentation most likely to arise as a result of long-term occupational exposure to radiation?
A. Thyroid tissue
B. Breast tissue
C. Nerve cells
D. Muscle cells
E. A and B
E. A and B
In addition to local effects like skin erythema, infertility, and cataracts, occupationally exposed individuals are primarily concerned with late effects of ionizing radiation, such as radiation-induced leukemia, genetic effects, and cancers, like bone, thyroid, breast, and lung malignancies; these effects can manifest years after initial exposure to low levels of ionizing radiation. The radiosensitivity of a cell is directly related to its rate of reproduction and is inversely proportionate to its degree of differentiation, according to the law of Bergonie and Tribondeau.
- The effects of radiation that a person is directly exposed to are referred to as somatic effects. What is an illustration of a local somatic effect among the following?
A. Leukemia
B. Non-small cell lung cancer (NSCLC)
C. Skin erythema
D. Papillary thyroid carcinoma
C. Skin erythema
Infertility, skin erythema, and cataracts are examples of delayed local effects of radiation exposure, following a linear, threshold, dose-response curve. The linear, non-threshold dose response curve signifies long-term (delayed) somatic effects.
- The effects of radiation that manifest on the irradiated tissue are known as somatic effects. Which of the following somatic conditions can result from prolonged radiation exposure to the gonads?
A. Temporary infertility
B. Permanent infertility
C. Genetic mutations
D. A and B
E. A, B, and C
D. A and B
The effects of radiation on the irradiated tissue(s) are known as somatic effects. The timing of somatic effects (i.e., early, late) is determined by the amount of time that passes between radiation exposure and the onset of symptoms. The reproductive organs of humans are very radiosensitive. The germ cells that are generated in the ovaries (oogonia) and testes (spermatogonia) have a significant impact on inheritance and fertility. Genetic alterations and/or temporary or permanent infertility can result from excessive radiation exposure to the gonads. While genetic changes have an impact on future generations, infertility is a somatic condition because it affects the exposed individual.
- Radiation sensitivity is higher in highly mitotic undifferentiated stem cells. Excessive radiation exposure to which structure(s) can lead to development of leukemia?
A. Blood-forming organs
B. Crypt cells of Lieberkühn
C. Bone marrow
D. A and B
E. A and C
E. A and C
Leukemia, which is a cancer of the body’s blood-forming tissues, or a reduction in life expectancy can result from excessive radiation exposure to the bone marrow or other blood-forming organs. Erythroblasts are young, immature, highly radiosensitive embryonic cells, and lymphocytes are the body’s most radiosensitive cells.
- What is the NCRP’s recommended total gestational dosage-equivalent limit for the embryo or fetus?
A. 5.0 mrem
B. 50 mrem
C. 50 mSv
D. 5 mSv
D. 5 mSv
The NCRP suggests a 5 mSv maximum total equivalent dosage for the embryo or fetus. This can also be expressed as 500 mrem or 0.5 rem. For the duration of the gestational period, this dosage limit applies. For each month during pregnancy, the maximum allowable dose is 0.5 mSv, also expressed as 50 mrem or 0.05 rem.
- Late consequences of ionizing radiation exposure include all of the following, except:
A. Carcinogenesis
B. Cataractogenesis
C. Acute radiation dermatitis
D. Shortened lifespan
E. Embryologic effects
C. Acute radiation dermatitis
Carcinogenesis, cataractogenesis, embryological effect, and a reduction in longevity are four categories of late radiation exposure
- Which of the following is not an immediate local somatic effect?
A. Dermal erythema
B. Erythropenia
C. Dermal epilation
D. Temporary infertility
B. Erythropenia
The gonads may have transient sterility, and the skin may experience erythema and epilation as an immediate localized consequence of excessive radiation exposure. Erythropenia refers to an atypical reduction in the quantity of red blood cells circulating throughout the body and would be considered a hematologic somatic effect.
- An early reaction to a high-dose exposure is indicative of what kind of dose-response relationship?
A. Deterministic
B. Stochastic
C. Nonstochastic
D. Probabilistic
E. A and C
E. A and C
Effects that are nonstochastic, or deterministic, have a threshold dose that needs to be exceeded in order for them to manifest. Greater doses cause nonstochastic effects to become more severe. Erythema, cataracts, and infertility are a few instances of nonstochastic effects. To prevent nonstochastic effects, dose limits have been defined.
- A stochastic effect can be characterized as which of the following?
A. A late effect of radiation exposure which exhibits no threshold dose
B. An acute effect of radiation exposure which, at a given dose, becomes more severe and won’t happen below a certain threshold
C. A late effect of radiation exposure which exhibits a threshold and manifests in subsequent generations
D. An immediate consequence of radiation exposure that displays a threshold
A. A late effect of radiation exposure which exhibits no threshold dose
Stochastic effects are defined as those which happen by chance, without a dose threshold, whose severity is dose-independent and whose probability is dose-proportional. Cancer and genetic impacts are the two main stochastic consequences in the context of radiation protection.
- There are several models available to predict the stochastic effects of radiation. Which model does the International Commission on Radiological Protection currently support?
A. Bystander effect model of radiobiological damage
B. Linear-quadratic model
C. Linear no-threshold model
D. Adaptive-dose response model
C. Linear no-threshold model
Experts contend that radiation exposure causes cancer to develop in a stochastic way, meaning that there is no threshold, and the risk rises proportionately with dose. According to the linear-no threshold model, the risk of inducing cancer increases linearly and does not have a threshold. The International Commission on Radiological Protection presently recognizes this concept.
- Which of the following is not an early sign of acute radiation syndrome?
A. Cataractogenesis
B. Leukopenia
C. Gastrointestinal symptoms (i.e., vomiting, diarrhea)
D. Fatigue
A. Cataractogenesis
Short-term, early somatic effects of acute radiation syndrome may occur if a significant dose of radiation is applied to the entire body at once (i.e., whole body dose of 600 rad [6 Gy]). Severe nausea, vomiting, diarrhea, leukopenia, and fatigue are early symptoms of acute radiation syndrome that appear in the prodromal stage of the condition. Cataractogenesis is a chronic somatic effect relative to radiation exposure.
- The occurrence of acute radiation syndrome is a result of whole-body exposure to a large dose of penetrating radiation. Which syndrome requires the greatest radiation exposure before radiation sickness symptoms become apparent?
A. Central nervous system syndrome
B. Hematopoietic syndrome
C. Bone marrow syndrome
D. Gastrointestinal syndrome
A. Central nervous system syndrome
Although certain symptoms can appear after a dose as low as 20 Gy, or 2000 rads, central nervous system syndrome usually manifests with a dose larger than about 50 Gy, or 5000 rads. After such a significant exposure, death typically results within three days. An increase in pressure in the constraining cranial vault because of an elevation in fluid content from edema, vasculitis, and meningitis, along with expected collapse of the circulatory system, are the primary causes of death. Gastrointestinal (GI) syndrome generally results from an exposure between 6 and 10 Gy. Bone marrow syndrome, which is also called hematopoietic syndrome, results following a dose of between 0.7 and 10 Gy.
- What is seen in the picture with the letter A?
A. Quantum mottle
A. Tube arcing
B. Grid cutoff
C. Moiré pattern
D. Motion artifactE
E. Quantum mottle
The image designated “A” was acquired using 2 mAs and the image labeled “B” was reacquired at 160 mAs. The primary observation is the significant rise in quantum mottle associated with the low exposure in the image labeled “A” (observe pixel value variation in the circled area).
- What adjustments did the radiographer make in order to enhance image “A”?
A. Decrease mAs
B. Increase SID
C. Increase kVp
D. Increase mAs
E. Decrease OID
D. Increase mAs
The image designated “A” was acquired using 2 mAs and the image labeled “B” was reacquired at 160 mAs. The primary observation is the significant rise in quantum mottle associated with the low exposure in the image labeled “A” (observe pixel value variation in the circled area).
- Given the grid artifact displayed in this image, what was the most likely cause?
A. The grid is upside down
B. There is misalignment of the X-ray tube with respect to the grid focal distance
C. The computed radiography sample frequency and the line frequency per cm in the grid are nearly equal
D. The patient moved during exposure
The computed radiography sample frequency and the line frequency
“To stop scattered x-ray photons from lowering the quality of images, antiscatter grids are frequently utilized. Lead strips and aluminum strips, which are x-ray absorbing and transmitting materials, respectively, make up these grids. A grid artifact may arise if the frequency of these lines per centimeter in the grid is near the computed radiography sample frequency.”
- What artifact is apparent on this radiograph
A. Static artifact
B. Quantum mottle artifact
C. Double exposure artifact
D. Fog artifact
An electrical discharge that causes lightning-like black densities on the radiograph is the source of static artifact.
- What is the purpose of the technique being demonstrated in this illustration?
A. Reduce patient dose
B. Reduce scatter
C. Increase beam penetration
D. Reduce image contrast
B. Reduce scatter
This diagram illustrates the usage of an air gap technique to minimize scatter.
There are less scattered photons that come into contact with the detector in image B because there is a larger air gap between the patient and the detector in comparison to image A.
Due to the patient’s closer proximity to the source of photons, the patient will receive a higher dose of radiation
- Given the artifact displayed in this image, what was the most likely cause?
A. Dead pixel artifact
B. Abdominal piercing
C. Metallic implanted device
D. Static artifact
A. Dead pixel artifact
“Even when the patient’s position changes, there is a spherical artifact that remains in the same place on all radiographic images. A burned-out or dead pixel caused this artifact.”
1543: How can this lateral swimmers cervical spine radiograph be improved?
A. Use of a filter
B. Reduce mAs
C. Increase mAs
D. Increase kVp
E. A and B
E. A and B
In this instance, an exposure of 80 kVp over 80 mAs (EI 2611) has produced an oversaturated (unduly dark) ‘burnt out image.’ A swimmer’s lateral cervical spine radiograph frequently needs high exposures to penetrate through substantial amounts of soft tissue. Overexposure should be suspected if the radiographer is unable to window the soft tissue and bony features into an ideal image. A filter helps prevent lower density areas from being overexposed in a swimmer’s lateral cervical spine radiograph. Alternatively, decreased mAs may be necessary.
- What artifact is apparent from this illustration?
A. Grid cutoff
B. Moiré pattern
C. Quantum mottle
D. Detector calibration limitation
B. Moiré pattern
A moiré pattern on a digital radiograph appears as an interference pattern, typically resulting from the misalignment of the grid used during image acquisition and the pixel array of the digital detector. This misalignment creates an optical illusion, manifesting as alternating light and dark bands or patterns superimposed on the radiographic image, potentially obscuring diagnostic information. Adjusting the alignment of the grid or employing software corrections can help mitigate or eliminate moiré artifacts.
