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A161 Final
| Question | Answer |
|---|---|
| What type of X-Rays result from the interaction between a projectile electron and a target nucleus | Bremsstrahlung |
| In the diagnostic range, most x-rays are | Bremsstrahlung |
| A change in kVp affects both the ________ and the position of the x-ray emission spectrum. | Amplitude |
| Adding filtration is sometimes called ________ the x-ray beam because of the relative increase in average energy. | Hardening |
| Kinetic energy is the energy of______. | motion |
| In the diagnostic range, a _____increase in kVp is equivalent to doubling the mAs. | 15% |
| When electrons are accelerated from the cathode to the target what three things take place? | (1) Heat is produced (2) Characteristic x-rays are produced (3) Bremsstrahlung x-rays are produced |
| X-ray that results from interaction of the projectile electron with a target nucleus; braking radiation,, is the definition of | Bremsstrahlung x-rays |
| What are the influencing factors that affect the shape of an x-ray spectrum | 1.Projectile electrons accelerated from cathode 2/anode dont all have peak kinetic energy. 2.Thickness of the target in the x-ray tube. 3.Low-energy x-rays are more likely 2/be absorbed in the target. 4.Added external filtration 2/the x-ray tube assembly |
| Only approximately _____ of projectile electron kinetic energy is used for the production of x-radiation; the other _____ is converted into __________ . | 1%, 99%, heat |
| What are projectile electrons? | the electron’s that are traveling from the cathode to the target. They make up the tube current. |
| When the projectile electron interacts with an inner-shell electron violently enough to remove that electron, what type of x-ray is produced? | Characteristic X-ray |
| What type of characteristic x-ray is useful in imaging | those created from the K-shell of the Tungsten atom |
| Bremsstrahlung x-rays have a ____________ spectrum | Continuous |
| What is the main difference between characteristic and bremsstrahlung interactions? | If a projectile electron interacts with an inner shell electron then it is a characteristic interaction. If a projectile electron interacts with an outer shell electron then it is a bremsstrahlung interaction |
| What causes the most heat during x-ray production | The constant excitation and return of outer shell electrons |
| Doubling the x-ray tube current also doubles what | heat production |
| What types of x-rays are emitted when an outer-shell electron fills an inner-shell void? | Characteristic x-rays |
| A change in _______affects both the amplitude and the position of the x-ray emission spectrum. | kVp |
| Adding filtration to the useful x-ray beam reduces x-ray beam ___ while increasing the average __. | Intensity, energy |
| When kVp is increased by 15%, what should be done with mAs | mAs should be halved |
| What kind of relationship does heat production in the anode and the x-ray tube current have? | Direct relationship. As one increase the other increases |
| What role does mA have with the efficiency of x-ray production | It does not play a role. X-ray production is independent of the tube current |
| Except for K-shell x-rays, all characteristic x-rays have what level of energy | They have very low energy |
| Why is there an electrostatic force of attraction between the electron and the nucleus during a Bremsstrahlung interaction? | Since the electron is negative and the nucleus is positive it cause the electrostatic force |
| The larger the area under the curve of an emission spectrum it causes the intensity to be? | Higher |
| require at least 69 kVp | characteristic x-rays |
| Protective housing guards against excessive _____________ and electric shock | Radiation exposure page |
| The x-rays emitted through the window are called the | Useful beam page |
| The cathode is the ________ side of the x-ray tube; it has two primary parts, a __________ and a ___________. | Negative, filament, focusing cup |
| The outer-shell electrons of the filament atoms are boiled off and ejected from the filament is known as ____________. | Thermionic emission |
| Electrons carry a negative charge and repel one another. They tend to form a cloud around the filament called ______________? | Space charge |
| What is the most common cause of x-ray tube failure? | Tungsten vaporization creating deposits on the inside of the glass enclosure |
| What is the anode heel affect? | Because of the angled anode target, the radiation intensity is greater on the cathode side of the x-ray field than the anode side |
| What are the 2 main internal structures of the x-ray tube | The anode and cathode |
| What is the line-focus principle | Angling of x-ray target that allows a large area for heating (actual area) while maintaining a small focal spot (effective area). |
| What three components make up the external structure of the x-ray tube? | The support structure, the protective housing, and the glass or metal enclosure |
| Which side of the x-ray tube is the negative side? | Cathode |
| What are some of the reasons the filaments made of tungsten? | High melting point, does not vaporize easily, higher thermionic emission, high atomic number |
| The x-ray tube current is adjusted by controlling the | Filament Current |
| Name the two parts of an electromagnetic induction motor. | 1. stator 2. rotor |
| What happens to the effective focal spot size when the angle of the target is made smaller? | it is also made smaller |
| What is the importance of the focusing cup’s negative charge | to condense the electron beam and direct it to the target |
| When produced, x-rays are emitted _________, which means they travel in equal intensity in all directions. | Isotropically |
| What is the purpose of the glass or metal tube enclosure? | The enclosure maintains a vacuum inside the tube |
| The induction motor rotates what side of the x-ray tube? | Andoe |
| As the target angle _____ , so does the effective focal spot size | decreases |
| The heel effect states that the cathode has _______ x-ray intensity on the cathode side. | increased |
| What changes the x-ray tube current when adjusted? | Filament current |
| The _________ _________ focuses the flow of electrons from the Cathode to the Anode target. | Focusing Cup |
| Further heat capacity can be achieved by doing what to the rotation of the Anode? | Increasing the rotation speed. |
| What is the material desired for the manufacturing of the Anode Target in X-Ray systems? | Tungsten |
| How is the Anode rotation inside the tube housing powered? | An induction motor. |
| The ________ focal spot is the flow of electrons hitting the Anode while the _______ focal spot is the flow of electrons leaving the target. | Actual ; Effective |
| When the x-ray tube is centered above the examination table at the standard SID, the x-ray tube is in what position? | preferred detent |
| How does having a smaller focal spot affect spatial resolution? | It increases the spatial resolution or makes it better |
| What are x-rays called that escape through the protective housing? | Leakage Radiation |
| Which type of enclosure is least likely to fail and why? Metal or glass? | Metal because as glass enclosures age, tungsten vaporizes and coats the enclosure and causes the tube current to stray and interact with the enclosure. This results in arcing and tube failure. |
| The smaller the anode angle, the heel effect | Larger |
| What is the Center of the x-ray beam that interacts with the image receptor? | Central Ray |
| What can cause the anode to crack? | If the temperature of the anode heats up to rapidly |
| The x-ray __________ is adjusted by controlling the filament current. | tube current |
| Name the two types of anodes | stationary and rotating |
| By angling the ____________ one makes the effective area of the target much smaller than the actual area of electron interaction. | target |
| What kind of charge does the anode have? | positive |
| Explain the line focus principal. | 1. Results from angled targets. Allows a large area for heating while a small focal spot is maintained. It is preferred to use a small focal spot on some extremities because of better spatial resolution. |
| An x-ray tube _______ emits electrons when it is heated. When the current through the _______is sufficiently high, the outer-shell electrons of the ________ atoms are “boiled off” and ejected from the __________. This is also known as thermionic emission. | Filament, filament, filament, filament |
| What is the heel effect? | Absorption of x-rays in the heel of the target, resulting in reduced x-ray intensity |
| What are the electrodes called in the diode | What are the electrodes called in the diode |
| What are the parts of the rotating anode? | the target and the electromagnetic induction motor. |
| 1. THE X-RAY tube is a component of the x-ray imaging system rarely seen by radiologic technologists. It is contained in a protective housing and therefore is ____________? | Inaccessible |
| Tungsten provides for higher _______________ than other metals. | thermionic emission |
| What part of the X-Ray tube conducts electricity and radiates heat and contains the target? | The anode |
| The smaller the focal spot, the better the _______________ of the image | spatial resolution |
| X-ray quantity is ________________ to the mAs. | Directly proportional |
| X-ray quantity is ________________ to the square of the distance from the source. | Inversely proportional |
| What is the reduction in x-ray intensity that results from absorption and scattering? | Attenuation |
| Increasing ________ increases the quality of an x-ray beam | kVp |
| X-ray quantity varies ____________ with distance from the source. | Inversely |
| As the energy of an x-ray beam is increased, the penetrability is ______________. | Increased |
| What is the main purpose of adding filtration to an x-ray beam? | To remove selectively low-energy x-rays from the useful beam |
| What are the two types of filtration and how are the different? | Inherent filtration – glass or metal enclosure of beam Added filtration – an additional filter, usually in the form of a thin sheet of aluminum between the protective x-ray and tube housing, provides more filtration |
| Adding filtration the useful beam ______________ patient dose. | Reduces |
| The inverse square law demonstrates what relationship? | The x-ray intensity vs. distance. The x-ray intensity varies inversely with the square of the distance from the x-ray tube target |
| What is x-ray quantity? | The number of x-rays in the useful beam |
| An increase in mAs and kVp has what effect on x-ray quantity? | It increases it |
| What is the inverse square law formula | I1 = (d2)^2 ___ ____ I2 = (d1)^2 |
| What is the square law formula | mAs1 = (SID1)^2 _____ ______ mAs2 = (SID2)^2 |
| What is the ability of an x-ray beam to pass through tissue called? | Penetrability |
| Of mAs and kVp, x-ray quantity is affected by _____, and x-ray quality is affected by ____? | mAs and kVp / kVp |
| What word is synonymous with x-ray quality | penetrability |
| The total number of electrons that travel from cathode to anode to produce x-rays can be referred to as ________. | x-ray quality / radiation exposure / x-ray intensity |
| Although x-ray beams are considered polyenergetic, ideal filtration would create a _________ beam, therefore increasing the x-ray quality | monoenergetic |
| What is attenuation? | Attenuation is the reduction in x-ray intensity that results from absorption and scattering |
| An increase in distance has what effect on X-ray quality | None |
| What happens to the patient’s dose of you increase kVp and reduce mAs? | The patient dose is reduced significantly |
| If you increase the filtration of the x-ray beam what happens to the x-ray quantity | The x-ray quantity is reduced |
| Filters reduce patient dose by removing _______ before they are absorbed in superficial tissues. | Low energy photons |
| When SID is increased, mAs must be increased by ____ to maintain constant exposure to the image receptor. | SID^2 this is called the square law |
| If kVp is doubled, intensity increases by a factor of | 4 |
| You want to keep a constant exposure to your IR, but increase SID. Which law will help get the right result? | Use the Square Law- if SID is increased, mAs is increased by the square of SID. |
| What happens when mAs is doubled? | the number of electrons striking the tube target is doubled, and therefore the number of x-rays emitted is doubled. |
| This occurs when an incident x-ray is totally absorbed during the ionization of an inner-shell electron. | The photoelectric effect |
| What type of scattering is of little importance to diagnostic radiology? | Coherent scattering |
| In Compton scattering, the incident x-ray interacts with an _______ electron and ejects it from the atom. | outer-shell |
| During the photoelectric effect what is the ejected electron called? | photoelectron |
| For higher atomic number target atoms, electron binding energies are ______? | higher |
| X-rays throughout the diagnostic range can undergo an interaction with outer-shell electrons that not only scatters the x-ray but reduces its energy and ionizes the atom as well. This interaction is called_______. | Compton scattering |
| X-rays scattered back in the direction of the incident x-ray beam are called _______ | backscatter radiation |
| Compton scattering reduces _____ ______ | image contrast |
| What is the definition of differential absorption? | Different degrees of absorption in different tissues that result in image contrast and formation of the x-ray image. |
| Different degrees of absorption in different tissues that result in image contrast and formation of the x-ray image. | Differential absorption increases as the kVp is reduced |
| Differential absorption and attenuation depend on what 3 factors? | (1) The atomic number (Z) of the atoms in tissue (2) The mass density of the atoms in tissue (3)The x-ray energy |
| (1) The atomic number (Z) of the atoms in tissue (2) The mass density of the atoms in tissue (3)The x-ray energy | Positive, negative |
| X-rays interact with matter in 5 ways, but only 2 are important for making an x-ray image, which are they | Compton scattering and the Photoelectric effect. |
| What is the main difference in Compton radiation and the Photoelectric effect | Compton’s incident x-ray interacts with an outer-shell electron, Photoelectric’s incident x-ray interacts with an inner-shell electron. |
| Bone has an atomic number of 13.8; soft tissue has an atomic number of 7.4. Which will absorb more x-ray? | Bone will absorb more x-ray because of its higher atomic number. |
| The wavelength of the scattered x-ray is ____________ than the wavelength of the incident x-ray in Compton scattering | Greater |
| What type of effect results in total x-ray absorption? | Photoelectric effect |
| What causes differential absorption? | Compton scattering, photoelectric effect, and x-ray transmission through the patien |
| What important controlling factor must be changed (in what way) in order to show small differences in soft tissue? | Lowering the kVp |
| Are clinical x-rays considered monoenergetic or polyenergetic | polyenergetic |
| The higher the energy of an x-ray, the shorter is its ___________? | Wavelength |
| X-ray interaction that not only scatters the x-ray but reduces its energy and ionizes the atom as well are known as what type of interaction? | Compton interactions or Compton scatter |
| Compton interactions or Compton scatter | It reduces overall image contrast |
| What is the term used to describe an anatomical structure with high x-ray absorption characteristics? | Radiopaque |
| Anatomical structures that x-rays pass through are said to be ____. | Radiolucent |
| The energy of the Compton-scattered x-ray is equal to the difference between what? | The energy of the incident x-ray and the energy of the ejected electron |
| How is the atomic number of tissue related to Compton scattering? | It is not related, they are independent of each other. |
| The photoelectric absorption of x-rays produces what color area on the radiograph? | The light areas; radiopaque |
| What is scatter radiation called when x-rays are bounced back towards to the incident beam? | Backscatter radiation |
| X-rays that pass thru the body without interacting do what to the image? | Create black areas |
| What is the most common source of radiation exposure during fluoroscopy | scatter from the patient |
| What kind of human tissue has the highest atomic number and how does this affect the way x-rays react with the patient? | bone / more x-rays absorbed photoelectrically as compared to soft tissue |
| What three types of x-rays are important in the creation of a radiograph | 1. Compton-scattered 2. those absorbed by the photoelectric effect 3. those transmitted without interaction |
| At low energies, most x-ray interactions with tissue are _______. At high energies, ___________ predominates. | photoelectric / Compton scattering |
| ____________ is the ability to image small objects that have high subject contrast. | Spatial resolution |
| ____________ is the ability to distinguish anatomical structures of similar subject contrast. | Contrast resolution |
| ___________ is determined by the size, shape, and x-ray-attenuating characteristics of the anatomy that is being examined and the energy of the x-ray beam. | Subject contrast |
| Radiographic contrast is produced by 2 factors: ______________contrast and ____________ contrast. | Image receptor(contrast), Subject (contrast) |
| What are 2 things you can do to minimize magnification? | Large SID: use as large of a source-to image receptor distance as possible. Small OID: place the object as close to the image receptor as possible. |
| A low kVp results in a ________ subject contrast, or __________ scale contrast. While a high kVp results in a ________ subject contrast, or __________ scale contrast. | High, Short, Low, Long. |
| All images on the radiograph are larger than the objects they represent is a condition called _____________? | Magnification |
| Unequal magnification of different portions of the same object is called ___________? | Shape Distortion |
| What are the 3 principle geometric factors that affect radiographic quality? | 1. magnification 2. distortion 3. focal-spot blur |
| What are 6 subject factors that affect radiographic quality? | 1. subject contrast 2. patient thickness 3. tissue mass density 4. effective atomic number 5. object shape 6. kVp |
| What 3 conditions contribute to image distortion? | 1. object thickness 2. object position 3. object shape |
| On which side is the focal spot blur largest | Cathode |
| What is the greatest factor of spatial resolution? | Focal spot size |
| If there is a small difference between the OD of the radiograph, what kind of contrast does it have? | Low contrast |
| 2.The elbow of the humerus should be placed under which part of the the x-ray tube to take advantage of the heel effect and minimize the focal spot blur? | The anode side. Shoulder under the cathode side. |
| What factor has the most important influence on subject contrast? | kVp has the most important influence |
| An increase in patient thickness results in a/an ____________ in attenuation | Increase |
| Movement of the patient or the x-ray tube during exposure results in ______________. | Motion blur |
| 1. Keeping exposure time as short as possible, controlling contrast (kVp) and optimal density (mAs) are all techniques to create __________ quality images | High |
| Image quality is improved by _____________ that cause reduced motion blur. | Short exposure times |
| kVp is the primary control of x-ray beam quality and therefore controls ____________. | beam penetrability |
| The degree of blackening of the finished radiograph is called | Optical density |
| List the four prime exposure factors | kVp ,mA , S, SID |
| What controls film screen radiographic contrast | kVp |
| What exposure Factor determines the patient radiation dose | mA |
| What improvements are seen if you increase your SID | less magnification, less focal- spot blur, and improved spatial resolution |
| Name 3 patient factors that will determine the technique you choose | part thickness, body composition, and pathology |
| What are the 2 main factors that control the optical density, or the degree of blackening of the finished image? | mAs and SID |
| How will positioning the part of interest parallel with the image receptor affect your image? | This will decrease distortion. |
| Destructive pathology on a radiograph appears ______________. | Radiolucent |
| The use of a high kV results in a ________ scale, _________ contrast. | Long, low |
| With an increase in kilovolt peak does the quantity and quality increase or decrease? | increase |
| With an increase of milliampere what happens to the quality? | No Change |
| With an increase in milliampere what happens to the quantity? | increase |
| When filtration is added (increased) what happens to the quality? | increase |
| When filtration is added (increased) what happens to the quantity? | decreased |
| What is the 15% rule? | A 15% increase in kVp accompanied by a half reduction in mAs results in the same OD. |
| What prime exposure factor has no effect on x-ray quality? | SID (distance) |
| The number of x-rays produced, or x-ray quantity is controlled by ________? | mA |
| The factors that influence and determine the quantity and quality of x-radiation to which the patient is exposed is called ____________. | Exposure factors page |
| _______ is the primary control of the x-ray beam quality. | kVp |
| ________ controls OD | 3. mAs |
| A radiographic technique calls for 400 mA, 1/20 seconds. What is the mAs? | 20 mAs |
| A radiographic technique calls for 600 mA and 50 milliseconds. What is the mAs? | 30 mAs |
| mA is a unit of electric current, and mAs is a unit of | electric charge |
| T/F - The heel effect is caused by the angle of the anode. | True |
| T/F - The intensity of the x-ray beam varies along the cathode-anode axis, with the maximum intensity being on the anode side, and the minimum intensity on the cathode side. | False |
| The mechanism on the x-ray tube crane that provides "stops" in a specific location is the | detent |
| A line that is perpendicular to the long axis of the x-ray tube and is the center of the primary x-ray beam is the | central ray |
| Surrounding the x-ray tube and line with lead is the | tube housing |
| Mechanical energy can be classified as either kinetic or | potential energy |
| X-rays consist of _______ energy | electromagnetic energy |
| X-rays with greater energy have a shorter ________ and are more penetrating. | wavelength |
| Which of the following are accurate statements regarding the characteristics of x-rays? 1. they are highly penetrating and invisible 2. they cause certain crystals to fluoresce 3. they travel in straight lines at the speed of light | 1, 2, 3 |
| The smallest possible unit of electromagnetic energy is the | photon |
| The common unit of measure for the potential difference across the x-ray tube is the | kilovolt |
| The negative side of an x-ray tube is commonly called the | filament |
| The filaments in most modern x-ray tubes are surrounded by a focusing cup which serves to | compress the electron stream |
| A modern dual focus x-ray tube contains 1. one anode 2. two anodes 3. one filament 4. two filaments | 1 & 4 |
| In a modern diagnostic x-ray tube, the majority of the energy of the electron stream is converted into _________ upon striking the anode | heat |
| he amount of space charge created at the cathode is primarily controlled by the | tube current |
| The heating of the filament in a x-ray tube results in the liberation of electrons by a process termed | thermionic emission |
| Which of the following will effect focal spot size? 1. anode angle 2. filament size 3. rotational speed 4. prep time | 1 & 2 |
| In a modern rotating anode, the rotator motion is accomplished by the use of a/an | induction motor |
| The principle method by which the space charge can increase in a modern tube is by employing a higher | mA |
| The primary purpose of the glass envelope of an x-ray tube is to | provide a vacuum |
| he protective housing of an x-ray tube is designed to | reduce hazard of leakage radiation |
| The heel effect occurs because of | x-ray absorption in the anode |
| Small target angles result in which of the following? | small focal spot size |
| Tungsten is the choice of material for x-ray anodes because of its | high atomic number |
| The effective focal spot is | smaller than the actual focal spot |
| Which of the following is a component of an electromagnetic induction motor? | stator |
| Necessary property of x-ray target material | high melting point |
| The anode angle of an x-ray tube is increased to give which of the following? | higher heat capacity |
| Based on this illustration of the bremsstrahlung emission spectrum , what was the kVp selected? | arch came down at 95 |
| How does the radiographer use the operating console to control the quality of x-ray photons produced? | By setting kVp |
| If a filament electron enters an atom with 100 keV, passes the nucleus, and exits with no kinetic energy, what is produced? (the electron is influenced by the nucleus and loses all of its energy) | 100-keV brems |
| To find the energy of a characteristic photon, the outer shell binding energy is subtracted from the ________ binding energy of the shells involved. | inner shell |
| On a total x-ray emission spectrum, the discrete line is placed at: | 69 keV |
| Which are causes of x-ray tube failure? (1) Excessive leakage radiation (2) Excessive and prolonged anode heating (3) A high exposure on a cold anode | 2 and 3 only |
| Which support structure is the most common? | Ceiling support system |
| All are functions of the anode except: 1. electrical conductor, 2.mechanical support, 3.thermal dissipater 4.heat insulator | Heat insulator |
| The intensity of radiation at a location is inversely proportional to the square of its distance from the source of radiation is a statement of the: | Inverse square law |
| The average energy is represented by the _____ of the bell curve of a continuous spectrum | peak |
| Which material is added to the filament to increase the efficiency of thermionic emission and prolong the life of the x-ray tube? | Thorium |
| Which may happen to projectile electrons when they encounter target atoms? (1) Create heat energy (2) Produce bremsstrahlung x-rays (3) Produce gamma rays | 1 and 2 only |
| Which type of x-rays is produced with the filling of each shell vacancy in the tungsten atom? | Characteristic |
| T/F - In the diagnostic range, bremsstrahlung radiation constitutes most of the x-ray beam. | True |
| T/F - Penetrability is an expression of x-ray quality and conveys the ability of x-rays to pass through tissues. | True |
| The efficiency of x-ray production is _______ the tube current. | not affected |
| Most of the heat generated at the target is due to | outer shell excitation |
| At 55 kVp, _______ of the x-rays produced are bremsstrahlung. | 100% |
| Bremsstrahlung x-rays are produced by ________ at the target. | slowing electrons |
| Characteristic x-rays are produced by _______. | released binding energy |
| The _____ is the source of radiation in the x-ray tube. | focal spot |
| The mAs is usually set to give the _______ mA at the _____ time for protection of the patient. | highest shortest |
| A PA chest examination (120 kVp/3 mAs) is taken at a SID of 300 cm. Calculate the new mAs needed if the same image is obtained using a SID of 100 cm? | 0.3 |
| T/F - Filtration of the x-ray beam increases x-ray quantity. | False |
| T/F - Penetrability is an expression of x-ray quality and conveys the ability of x-rays to pass through tissues. | True |
| Which factors affect both x-ray quality and x-ray quantity? (1) Distance (2) Filtration (3) kVp | 2 and 3 only |
| Which factors affect x-ray quantity? (1) kVp (2) Filtration (3) mAs | 1, 2, and 3 |
| Which term is used interchangeably with x-ray quantity? | Radiation exposure |
| T/F - X-ray quality decreases as kVp increases | False |
| T/F - The hell effect is a subject factor that affects radiographic image quality. | False |
| Large differences in the effective atomic number of adjacent tissues result in: | High subject contrast |
| Movement of the patient or x-ray tube causes: | Motion blur |
| The blurred region on the radiograph over which the technologist has little control is: | Focal-spot blur |
| The factors that affect magnification are: | OID and SID |
| The formula SID ÷ SOD is used to calculate: | Magnification factor |
| he only factor that affects subject contrast that is under radiographer control is: | kVp |
| The shape, position, and thickness of an object affect the: | Distortion |
| The type of distortion caused by elongation or foreshortening is: | Shape distortion |
| What is the effect on radiographic image quality if focal-spot size is increased? | Increased focal-spot blur |
| Which affect the quality of a radiographic image? (1) Patient positioning (2) Selection of technique factors | 1 and 2 |
| an Increase in OID will have an increase on | magnification |
| when these increases, the radiographic image quality will increase | (1) Spatial resolution (2) Contrast resolution |
| Factors used to describe radiographic image quality include: | (1) Optical density (2) Contrast (3) Detail |
| If an x-ray image is underexposed, which technique change would be best to obtain optimal OD on the repeated image? | Double mAs |
| In order to minimize distortion in a radiographic image, the: | Part is positioned parallel to the image receptor |
| T/F - Using a large focal spot increases x-ray beam quality as compared to using a small focal spot. | False |
| What is the effect of decreasing kVp on the x-ray beam? | Decreased quality and penetrability |
| Which exposure factor controls image contrast? | kVp |
| Which image quality factor is controlled by mAs? | OD - optical density |
| Which patient factors must be considering when setting radiographic technique? | (1) Patient/part thickness (2) Pathology (3) Tissue composition |
| Which prime exposure factor affects the intensity of the x-ray beam at the IR? | SID |
| Which term might be used to describe an x-ray image that has a few shades of gray with marked visible differences between the ODs? | Short-scale contrast |
| Which would provide the greatest detail in an x-ray image? | (1) Small focal spot (2) Longer SID |
| To apply the inverse square law, one must know | two distances and one intensity |
| When mAs is increased, x-ray quantity | increases proportionately |
| To maintain a constant optical density, what percentage of increase in kVp should be accompanied by a reduction of one half the mAs? | 15% |
| As filtration is added to an x-ray beam | Low energy x-rays are removed more readily than high energy x-rays |
| X-rays of higher energy can be obtained by increasing | kVp |
| To obtain minimum magnification, one should do which of the following | position the anatomy close to the IR |
| A thin object at a long SID contributes least to image ____________? | distortion |
| What results from an inclined object | A foreshortened image |
| A radiograph that shows a relative lack of focal spot blur would be | sharp in detail |
| Another term for focal spot blur is | penumbra |
| Spatial resolution is principally affected by ______ _______ size. | focal spot size |
| Short exposure times are recommended for radiography of the stomach to minimize what? | minimize motion blur |
| The chest represents high contrast anatomy (high subject contrast). Therefore, what is most appropriate? | high kVp |
| A function of optimizing contrast is to make | detail visible |
| A shorter gray scale on a radiograph would be obtained by doing what when all other factors remain the same | reducing kVp |
| Staring @ 60kVp, what new kVp would result in an optical density that is one half of the original? | 51 |
| When a radiographic technique is changed from 22.5 mAs @ 100 cm SID to 200 cm SID, what is the new mAs? | 90 |
| T/F - Radiographic density is the degree of blackening of an area of film. | True |
| What primarily determines the variation in density on the finished radiograph | Absorption characteristics of the body |
| 80 kVp at 20 mAs is a set of factors that would produce | greatest density |
| What happens to density with decreases in tissue thickness? | Increases |
| The greater the OID, the greater the chance of scatter photons missing the image receptor, thereby _________ contrast. | increasing |
| An abdomen image exhibits motion when using 70 kVp, 100mA and 0.40 sec. Which of the following is the proper correction? | 70 kVp, 400 mA and 0.1 sec |
| grayer overall with less difference between each shade of gray is considered | low contrast |
| Which set of factors will provide the lowest contrast - 60 kVp @ 40 mAs or 90 kVp @ 5 mAs | 90 kVp @ 5 mAs |
| The higher the kVp, the ________ the scale of contrast | lower |
| The longer the SID (within reason), the _________ the image. | sharper |
| The inverse square law applies to which of the following sources? a. Gamma Ray b. Plane c. Point d. Ultrasound e. X-ray | Point |
| The inverse square law is a result of ______. | Divergence |
| The control of exposure time is always: a. Automatically set b. Determined by kVp c. On the primary side of the auto-transformer d. On the primary side of the the high-voltage transformer | d. On the primary side of the the high-voltage transformer |
| The 3 principle parts of an x-ray imaging system are: | X-ray tube, control console,& high voltage generator |
| The large filament is used during radiography when the heat load is _______ and visibility of is ________ important. | High, Less |
| Why are there 2 filaments in a x-ray tube? | To provide 2 focal spots |
| The main reason for using the line focus principle is to? | Reduce focal spot size |
| What is the advantage of the rotating anode over the stationary anode tube? | Higher heat capacity |
| Useful characteristic x-rays are produced in tungsten by the | removal of K-shell electrons |
| What is produced when an projectile electron excites an outer-shell electron? | Heat |
| Bremsstrahlung radiation is produced by conversion of _________ __________ kinetic energy to ___________ energy. | projectile electron, electromagnetic |
| When a bremsstrahlung x-ray is produced a projectile electron _______ _____. | loses energy |
| When distance is increased, x-ray quantity at that distance decreases in proportion to the ______ _______. | distance squared |
| Another meaning of x-ray quantity is x-ray _________. | intensity |
| When filtration is added to the x-ray tube which of the following increases? a. Radiation output b. Radiation quality c. Radiation quantity d. SID | Radiation quality |
| Higher effective energy of the x-ray beam is created when: | filtration is added |
| The purpose of a wedge filter is to produce a uniform x-ray beam __________ at the ____ . | intensity, IR |
| What scattering contributes to image noise? | Compton scattering |
| Which of the following occurs in a Compton interaction? a. An atom is excited b. An atom is ionized c. An photon has increased wavelength d. Kinetic energy is doubled. | b. An atom is ionized |
| After Compton scattering the scattered x-rays have: | longer wavelength |
| The probability that an x-ray will undergo Compton interactions decreases with increasing | x-ray energy |
| Compton-scatter x-rays have _______ energy than the incident x-ray. | lower |
| Which of the following has the lowest effective atomic number? a. Air b. Bone c. Fat d. Lung e. Muscle | c. Fat |
| During a photoelectric interaction an ______ is emitted from the atom. | electron |
| The radiographic image is formed primarily by | photoelectric interactions |
| Differential absorption is the difference between the x-rays that are _____ and those that are ________. | absorbed, transmitted |
| As kVp increases, the relative number of x-rays that interact with tissue ________. | decreases |
| Differential absorption between lung and soft tissue occurs principally because of the difference in | mass density |
| When proper radiographic detail cannot be obtained because of large OID, what can be changed in technique will improve detail? | Increasing SID |
| What is the primary thing that will reduce motion blur? | Proper patient instructions |
| Longer gray-scale on an image can be obtained by doing what? | Increasing kVp |
| What features does long gray-scale contract have? | Many shades of gray that have minimal differences. |
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