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Physics Final
Physic's and imaging final
| Question | Answer |
|---|---|
| What unit of measure is used for the absorbed dose multiplied by the radiation weighting factor in the SI system: | SV |
| The maximum number of electrons found in any energy level (shell) at any point in time is: | 2n^2 |
| The number of protons in the nucleus is called the: | atomic number |
| All electromagnetic radiation travels at: | The speed of light |
| Isotopes have ________ number of protons and ________ number of neutrons compared to a stable atom of a material: | the same; different |
| The particles that distinguish one element from another are the: | protons |
| Background radiation accounts for 6 msv of exposure, man made sources account for ___ msv of that: | 3 |
| The theory that electrons circulate in discrete circular paths was proposed by: | Bohr |
| If an electron is gained or lost from an atom, the atom becomes: | Ionized |
| Which of the following describes a product of the absorbed dose, the radiation factor and the tissue sensitivity? | Effective dose |
| Which of the following units of measure are used for patient absorbed dose? | Gy |
| A gamma ray is created in a _______________ and an x-ray is created in a _______________: | nucleus of an atom; x-ray tube |
| Which of the following particles creates the most ionizations in air, and has a radiation weighting factor of 20? | Alpha particles |
| True/False: Stochastic effects of radiation require a threshold dose before they are detectable: | False |
| True/False: In diagnostic imaging, deterministic effects of radiation rarely occur: | True |
| True/False: Thomas Edison discovered x-rays | False |
| True/False: Time, distance, shielding are the cardinal rules of radiation safety: | True |
| True/False: Technologist wear a TDL type personal monitoring device: | True |
| True/False: Air kerma is an easily measured and comparable factor used for entrance skin exposure: | True |
| True/False: 0.05 Sv or 5 REM is the yearly occupational dose limit in the US: | True |
| Energy is measured in ________ | Electron volts |
| Atoms and molecules are the fundamental building blocks of __________ | Matter |
| Radio waves, light, and x-rays are all examples of _________ energy: | electromagnetic |
| What is the removal of an electron from an atom called: | Ionization |
| The energy of x-rays is _______________ | Electromagnetic |
| The biggest source of man-made radiation exposure to the public is ______________ | diagnostic x-rays |
| Absorbed dose is measured in units of ____________ | grays |
| ALARA= | As Low As Reasonably Achievable |
| The smallest particle that has all the properties of an element is a(n) : | Atom |
| The chemical element is determined by the number of __________ in an atom: | protons |
| An atom in a normal state has an electrical charge of ____________ | zero |
| The binding energies, or energy levels, of electrons are represented by their __________ | shells |
| When an atom has the same number of protons as another, but a different number of neutrons, it is called an: | isotope |
| True/False: KERMA is a measure only done in air: | False |
| An atom that loses or gains one or more electrons is a(n): | Ion |
| Which of the following measures current flowing in a circuit: | mA |
| The absorbed dose for the PA view of the chest is 1 mrad, the absorbed dose for the later view of the chest is 4 mrad. What is the integral dose for this chest exam: | 5 |
| The atomic number of an element is symbolized by the letter: | Z |
| Deterministic effects of radiation include all of the following except: | cancers |
| During beta emission, an atom releases: | electrons |
| The only difference between x-rays and gamma rays is their: | origin |
| The __________ is the least penetrating form of ionizing radiation: | alpha particle |
| The three properties of photons are _________, __________, and __________. | frequency; wavelength; and energy |
| The theory of ALARA for health care workers supports which of the following practices for pregnant technologist: | No modification to the work rotation |
| What is the velocity of ALL electromagnetic radiation: | 3 x 10^8 m/s |
| The rate of rise and fall of a sine wave is called it's: | Frequency |
| A hertz (Hz) is equal to _________ cycle(s) per second: | 1 |
| If the wavelength of a beam of electromagnetic radiation increases by a factor of 2, then it's frequency must: | decrease by half |
| The intensity of radiation __________ in __________ proportion to the square of the distance of the object from the source: | decrease; inverse |
| If the intensity of light from a flashlight is 4 millilumens (mlm) at a distance of 3 feet, what will the intensity be at 6 feet: | 1 millilumen |
| The energy of a photon is directly proportional to its: | frequency |
| Photons with the highest frequencies have the: | Shortest wavelengths |
| The smallest unit of electrical charge is the: | electron |
| Electrification occurs through the movement of: | electrons only |
| Like charges __________ and unlike charges __________: | repel; attract |
| The charges on an electrified object are distributed: | evenly on the surface of the object |
| On the surface of an electrified object, the charges concentrate on the: | Sharpest curvature |
| A __________ is a source of a direct current: | battery |
| What is the unit of electric potential: | Volt |
| An electric potential applied to a conductor produces an __________ and a __________: | electric current; magnetic field |
| An alternating (AC) current is represented by a __________ line: | sinusoidal |
| What is ohm's law: | I=V/R |
| Electrical power is measured in: | watts |
| When a group of anatomic dipoles are aligned, they create a: | magnetic domain (a magnet) |
| What is the SI unit of magnetic field strength: | Tesla |
| Methods of electrification are all of the following except: A) friction B) contact C) induction D) retention | D) retention |
| Radiation protection practices, for example, shielding all patients and applying ALARA principles are based on the theory of __________, which has a non-threshold relationship: | stochastic |
| Which of the following materials is strongly magnetic: | ferromagnetic |
| Which of the following describes the type of radiation used, the tissue exposed and the amount absorbed, in other words, which tells us the most information regarding an exposure to radiation: | Effective dose |
| True/False: Materials with an outer shell and conductive band that overlap are good conductors of electricity: | True |
| True/False: Occupational dose limits for a pregnant worker are 0.5 R for the whole gestation and 0.05 R for each month: | True |
| True/False: When DC is applied to the primary coil of a transformer, the secondary coil increases voltage: | False |
| True/False: A step down transformer is used when an increase in current is require: | True |
| The principle application for a transformer is to: | change voltage |
| 220 V are supplied to the primary coil and it has 800 turns. The secondary coil has 200 turns, what is the voltage in the secondary: | 55 |
| At what point in the x-ray circuit is the rectification circuit located: | Between the step-up transformer and the x-ray tube |
| Which of the following timer types provides exposure times as low as 1 mS: | electronic timer |
| Which of the following generator types has the most voltage ripple: A) 3 phase 6 pulse B) 3 phase 12 pulse C) single phase full-wave D) high frequency | C) Single phase full-wave |
| All of the following are radiographer operated controls except: A) kVp selection B) generator selection C) exposure switch D) mA selection | B) generator selection |
| The voltage in the x-ray circuit is adjusted or fine tuned in the __________ for ease and safety: | Autotransformer |
| The incoming power to a step up transformer is 100 V, 10A with a turns ration of 250:1 (secondary; primary): | 25,000 V |
| The most likely found incoming line current in a modern radiography system is: | 3 phase power |
| Nearly all hard wired equipment operates on incoming line voltage of: | 440 V |
| All of the following are principle parts of the x-ray system except: A) The tube B) High voltage generated C) Filament transformer D) Operating console | C) Filament transformer |
| A step down transformer has __________ windings in the secondary vs. primary side: | less |
| True/False: The basic x-ray circuit is divided into the main circuit and the anode circuit: | False |
| True/False: The mAs in a system controls the quality of the beam: | False |
| True/False: In single phase power systems, the potential never drops to zero: | False |
| Which of the following transformers has one winding: A) Filament transformer B) High voltage transformer C) Autotransformer | C) Autotransformer |
| True/False: The high voltage generator consist of high voltage transformer, rectifiers, and an autotransformer: | False |
| The filament in the x-ray tube requires__________ amperes to emit electrons, thermionic emission: | 3-5 |
| Which of the following waveforms has the highest efficiency: A) 3 phase 6 pulse B) 3 phase 12 pulse C) Single phase full wave D) All are equal | B) 3 phase 12 pulse |
| A single phase full wave rectifier system produces _______ pulses per cycle: | 2 |
| The three main parts of the x-ray imaging system are the x-ray tube, __________, and __________. | operating console; high voltage generator |
| The operating console contains circuits that are: | Low voltage only |
| Variations in power distribution to the x-ray machine are corrected by the: | Line voltage compensator |
| Which of the following components receives power first in the x-ray circuit: | Autotransformer |
| The autotransformer has ___________ solenoid(s): | One |
| The __________ circuit (transformer) provided electrons for the cathode within the x-ray tube: | filament |
| Thermionic emission at the filament determines the __________ across the x-ray tube during exposure: | milliamperage |
| A step-down transformer is located in the __________ circuit: | filament |
| The least accurate type of timer is the ________ time: | Mechanical |
| The automatic exposure control (AEC) terminated the exposure when: | Sufficient radiation reaches the image receptor |
| The mAs timer is usually set to give the ________ mA at the _______ time: | highest; shortest |
| A diode allows electrons to flow from | Cathode to anode |
| The high voltage generator contains the high voltage transform, the __________ , and the __________: | Filament transformer; rectifiers |
| The difference in the waveform between the primary and secondary sides of the high voltage transformer is: | Amplitude |
| With half-wave rectification, the current flows through the x-ray tube during the ________ part of the cycle: | Positive |
| Full-wave rectified, three-phase units provide an x-ray beam at __________ pulse(s) per second: | 360 |
| Voltage across the x-ray tube is most constant with: | High frequency generators |
| A single-phase waveform has __________ ripple: | 100% |
| The x-ray beam generated by the circuit with the __________ voltage ripple has the __________ quantity and quality: | lowest; highest |
| The external structure of the x-ray tube includes the support structure, the protective housing, and the: | Glass envelope |
| As an x-ray tube ages, the inside can become coated with tungsten, which can cause ___________ in the tube: | arcing |
| The negative side of the x-ray tube holds the: | filament |
| The filament is made out of: | Tungsten |
| Thermionic emission at the filament creates a: | Space charge |
| The rotating anode is turned by a: | magnetic field |
| When electrons bombard the target, ________% of their kinetic energy is converted to heat: | 99 |
| The __________ is the source of radiation in the x-ray tube: | Focal spot |
| Because of the line focus principle, the effective focal spot size decreases with decreasing: | Target angle |
| Low capacity x-ray tube rotors revolve at a minimum _______ rpm: | 3600 |
| The x-ray intensity is lower on the anode side of the tube because of the: | Heel effect |
| The anode side of the tube should be directed toward the __________ part of the patient: | Thinner |
| What is the formula for heat units for a 3-phase, 6-pulse x-ray machine: | 1.35 x kVp x mA x seconds |
| Tube failure can occur from: | Long exposure times |
| The filament in an x-ray tube is about __________ cm in length: | 1-2 |
| All of the following are inside the glass envelope, except: A) Stators B) Rotor C) Focal spot D) Filament | A) Stators |
| Extrafocal or off-focus radiation is produced from: | Non-focused electrons |
| The heel effect is caused by the: | Anode angle |
| The effective focal spot size is __________ the actual focal spot size: | smaller than |
| Cracking on the anode can occur from: | Single excessive exposure |
| Projectile electrons travel from: | Cathode to anode |
| At the target, the projectile electrons characteristically interact with __________ but are not usable radiation: | Outer shell excitation |
| The production of heat at the anode is directly proportional to: | mAs |
| The efficiency of x-ray production increases as ________ increases: | kVp |
| Electron interactions at the inner-shell of the target atom produce __________ radiation: | Characteristic |
| The useful characteristic x-rays from tungsten targets are __________ -shell x-rays: | K |
| Characteristic K-shell tungsten x-rays have an effective energy of __________ keV: | 69 |
| Most of the x-rays produced at the target are: | Bremsstrahlung |
| At 55 kVp, __________ of the useful 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 quantity of bremsstrahlung radiation increases proportionately with increased: | mAs |
| An exposure taken at 100 kVp would have continuous emission spectrum with an average energy of __________ keV: | 33 |
| The __________ of an x-ray beam is higher when the peak of the emission spectrum is further to the ___________: | quantity; left |
| An increase in mAs would __________ the __________ of the emission spectrum: | increase; amplitude alone |
| An increase in kVp would __________ the __________ of the emission spectrum: | Increase; amplitude and position (shift to right) |
| Changes in __________ & __________ result in directly proportional changes in the amplitude of the emission spectrum: | mA; time |
| True/False: Some of the x-ray photons may pass through matter and not interact with the matter at all: | True |
| During the photoelectric True/False: During the photoelectric interaction, the incident x-ray photon must be equal to or greater than the binding energy of the inner-shell electron: | True |
| True/False: A photoelectric interaction is more likely to occur when the x-ray photon energy and the the electron binding energy are farther from one another: | False |
| True/False: When a scattered photon is deflected back toward the source, it is traveling in the direction opposite to the incident photon and is called backscatter radiation: | True |
| True/False: During pair production, the positively charged electron is termed a negatron: | False |
| True/False: As kVp increases, the total number of photons transmitted without interaction increases: | True |
| When an x-ray passes through matter, it undergoes a process called: | Attenuation |
| During the process of attenuation, the x-ray photon may interact with: | The nucleus, the entire atoms, and orbital electron |
| In which element are the inner shell electrons more tightly bound to the nucleus: A) mercury (Z = 80) B) tungsten (Z = 74) C) lead (Z = 82) D) chromium (Z = 24) | C) Lead (Z=82) |
| Secondary radiation is created after a ___________ interaction: | photoelectric absorption |
| When x-ray photons interact with matter and change direction, the process is called: | Scatter |
| When an x-ray photon with a slightly greater energy than the binding energy of the inner-shell electron interacts with that inner-shell electron, the following interaction results: | photoelectric absorption |
| During the photoelectric interaction, as an electron transfers from an outer shell to a vacant inner shell, energy is released in the form of: | a characteristic photon |
| During coherent scattering, the scattered photon possesses _________ as the incident photon: | the same energy, the same frequency, and the same wavelength |
| Compton scattering occurs when an incident x-ray photon interacts with a __________ electron: | loosely bound outer-shell |
| The electron dislodged during Compton scatter is called the: | Recoil electron |
| During which interaction with matter is the x-ray photon converted to matter in the form of two sub-atomic particles: | Pair production |
| What is the total differential absorption in bone compared to fat: Bone Z# 13.8 and mass density 1900 kg/m^3 Fat Z# 6.8 and mass density 910 kg/m3 | 17.5 |
| Which of the following interaction has a significant impact on the x-ray image: | Photoelectric absorption |
| Which of the following interactions with matter results in a radiograph with a long scale of contrast (low contrast gray image): | Compton scattering |
| Which of the following interactions with matter results in a radiograph with a short scale of contrast (high contrast black and white image): | Photoelectric interactions |
| An outer-shell electron is ejected and the atom is ionized during: | Compton interactions |
| Which x-ray interaction involves the ejection of the K-shell electron: | Photoelectric absorption |
| The scattered x-ray from a Compton interaction usually retains ___________ of the energy of the incident photon: | Most |
| As kVp __________, the probability of photoelectric absorption ___________. | increases; decreases |
| In ___________, there is complete absorption of the incident x-ray photon, with no other photons created during that incident: | Photoelectric interaction |
| __________ occurs only at the very high energies used in radiation therapy and in nuclear medicine P. E. T. imaging: | Pair production |
| Only at energies above 10 MeV can __________ take place: | Pair production |
| When the mass density of the absorber is __________, it results in ___________ Compton scatter: | increases; increased |
| K-shell binding energy increases with increasing: | Atomic number |
| Which has the greatest mass density? | Bone |
| Differential absorption in diagnostic imaging is primarily caused by: | Photoelectric absorption |
| Differential absorption is dependent on (the): | - kVp of the exposure - atomic number of the absorber - mass density of the absorber |
| Barium is a good contrast agent because of its: | High atomic number |
| At energies below 40 keV, the predominant x-ray interaction in bone is | photoelectric absorption |
| If 5% of an incident beam is transmitted through a body part, then 95% of that beam was: | Attenuated |
| Compton interactions, photoelectric absorption, and transmitted x-rays all contribute to: | Differential absorption |
| X-rays transmitted without interaction contribute to: | The radiographic image |
| In the diagnostic range, rare earth scintillators are better absorbers than Calcium Tungstate. This is due to the phenomena known as: | k-edge effect or absorption |
| The main reason to use a scintillator or phosphor as a capture element is: | to decrease patient exposure (dose) vs. direct exposure systems |
| The light-emitting efficiency (speed) of the intensifying screen is improved by the: | reflective layer |
| Screen characteristics are determined by the: | - size of the phosphor crystals - thickness of the phosphor layer - phosphor concentration |
| A phosphorescent material emits light: | for a period of time after stimulation |
| A screen that emits light after an exposure terminates is exhibiting: | Screen lag |
| The intensification factor is a measurement of screen: | Speed |
| The ability of an intensifying screen to absorb x-ray is called: | detective quantum efficiency |
| Image noise is increased with increased: | conversion efficiency (CE) |
| Both the isotropic emission of light from screen phosphor crystals and the added reflective layer contribute to: | Image blur |
| As screen speed ______image detail _______: | Increases; decreases |
| A wrist x-ray required ________ detail and would be best imaged with a ______speed phosphor: | Higher; 100 |
| Adding a light absorbing dye to the tube side of a phosphor ___________ the screen speed compared to phosphors with a reflective layer: | Decreases |
| True/ False: The tube side of a cassette should have a high Z# material, to prevent excessive attenuation: | False |
| Nosie in an image negatively effects: | Contrast |
| True/ False: The best method of reducing noise when using a very fast speed system, would be to increase the mAs. | The best method of reducing noise when using a very fast speed system, would be to increase the mAs. |
| True/False: An image with very few gray shades, mostly black and white, is described as having a wide latitude: | False |
| True/ False: The law of reciprocity states that as long as the mAs is the same, no matter the combination of mA and time, the amount of exposure is the same. | True |
| Patient or part thickness has a direct effect on scatter in the resulting image. Which of the following parts would produce the most scatter? | Femur |
| The best way to minimize magnification is to use a: | - Long SID - Small OID |
| The distance at which a focused grid can be used is directly related to the: | focal range |
| The interspace material used in grids is said to be: | Radiolucent |
| The most commonly used beam restricting device is the: | variable collimator |
| If the grid ratio is increased, and no technical factors are changed, the radiograph would show an increase in: | Contrast |
| How can you improve image contrast with a heavy patient without increasing patient dose: | Use tight collimation |
| Which type of collimation (beam restrictor) is most effective? | Cylinder |
| Which of the following grids would be best used for portable imaging? | parallel, 10:1 |
| Which kVp selection would result in the most scattered x-rays in the image-forming beam? | 90 kVp |
| The prime factors include each of the following except: | filtration |
| Milliamperage-second directly affects each of the following except: | quality |
| If kVp is doubled, the amount of x-ray photons approximately: | increases fourfold |
| The 15% rule states that an increase in kVp is equivalent to a _______ increase in mAs, in terms of exposure to the IR: | 100% (doubling) |
| A factor that affects the amount of scatter produced is: | Kilovoltage |
| As the volume of irradiated tissue ___, the amount of scatter ___: | Increases; increases |
| Increasing the kVp from 60 to 80 increases the intensity of xray from 100mR to ____mR: | 178 |
| As patient size increases a ______in mAs is required for every 4cm increase in patient thickness: | Doubling |
| When imaging a barium filled stomach, which of the following kVp selections is most appropriate when a standard abdomen requires 75kVp for good image quality: | 110 |
| A radiograph taken at 80 kVp, 40 mAs, 10:1 grid (GCF 4) at 40 inches was of adequate quality. If the distance is changed to 80 inches what corresponding change would provide an image of equal contrast and density: | 160 mAs |
| Which of the following is the most commonly used technique chart in Radiography today: | AEC chart |
| True/ False: Using a fixed kVp chart provides for a longer scale of contrast when compared to a variable kVp chart: | True |
| True/False: Filtration of the x-ray beam causes an increase in quality and a decrease in quantity: | True |
| True/ False: HVL is a good measure of beam quantity: | False |
| True/False: The law of reciprocity states that no matter the mA and time combination, as long as the mAs is the same, exposure will be the same: | True |
| True/False: Detail in an image is controlled by kVp: | False |
| True/ False: Distortion in an image can be shape or size in nature: | True |
| All of the following pathologies would require an increase in kVp except? | COPD/emphysema |
| Magnification causes excessive blur in our images, to decrease magnification we would do all of the following except? | Decreased SID |
| True/ False: A patient presents for a shoulder radiograph, they are much more muscular than the average patient. Increasing the mAs is the best option to get proper image quality: | False |
| A high quality radiograph should always demonstrate: | minimum magnification |
| Spatial resolution improves with decreased ___ blur: | - Scintillator -Motion -Geometric |
| ___ is defined as the ability to image two separate objects of high contrast and visually detect one from the other: | Spatial resolution |
| Radiographic ___ is random fluctuation in the optical density of a radiograph: | Noise |
| What is the formula for the magnification factor: | MF = SID/SOD |
| The three primary geometric factors affecting image quality are _________: | size distortion, shape distortion, and focal spot blur |
| Large objects with large interspaces are described as__________: | having low spatial frequency |
| spot blur can be reduced by using: | a small focal spot |
| The best way to minimize magnification is to use a: | - Long SID - Small OID |
| Distortion can be reduced by: | placing the object plane parallel to the image plane |
| Patient (part) thickness affects image quality by affecting | - focal spot blur - radiographic contrast - Magnification |
| When reducing the field of view from 14 x 17 in to 10 x 12 in a decrease in scatter is realized. Which of the follwoing factors should be increased to maintain IR exposure or image density: | mAs |
| The small focal spot will provide a: | Finer detail of image |
| An average patient is imaged at 70 kVp 40 mAs for a lumbar spine exam. patient measuring 15 cm larger than average would require which of the following: | 320 mAs |
| Patient or part tthickness has a direct effect on scatter in the resulting image. Which of the following parts would produce the most scatter: | Femur |
| Which type of collimation (beam restrictor) reduces the blur seen in an image: | Cylinder |
| Subject contrast(how x-ray interacts in the body) is affected by: | patient thickness |
| The technologist primarily controls radiographic contrast by varying the: | Kilovoltage |
| Which kVp selection would result in the greatest percentage of scattered x-rays in the image-forming beam? | 90 kVp |
| The three primary factors influencing the amount of scatter in the exit beam are: | kVp, field size, and patient thickness |
| The most commonly used beam restricting device is the: | variable collimator |
| The use of a compression device will increase: | contrast |
| The use of ___ improves contrast and reduces patient dose: | collimation |
| Beam restriction with a(n) ___ is only accurate at a fixed SID: | aperture diaphragm |
| Patient thickness should be measured with the ___ in a variable kVp chart: | Caliper |
| In a fixed kVp system, a _______kVp and ____mAs are used compared to a variable kVp system: | Higher; Lower |
| In a variable kVp technique chart, the optimal mAs is set for each body part and there is a ___ kVp increase for each cm of thickness: | 2 |
| How can you improve image contrast with a heavy patient without increasing patient dose? | Use tight collimation |
| Decreasing the kVp while holding mAs constant will increase: | Image noise |
| What are the four primary exposure factors: | kVp, mA, time, and SID |
| Optical density or exposure to the IR is primarily controlled by changing the: | mAs |
| Changes in kVp affect: | - optical density - image contrast - patient exposure |
| An increase in mAs causes ___ in beam quality and ___ in beam quantity: | no change, an increase |
| The relationship between the quantity of x-rays and the ___ is directly proportional: | Milliamperage |
| If mAs is increased from 20 mAs to 40 mAs, the patient exposure will ____: | be doubled |
| Beam penetrability is increased if ___ is/are increased: | kVp |
| A ___% increases in kVp has the same effect on optical density as doubling the mAs: | 15 |
| If the distance from the source to the image (SID) is reduced by half, how is the x-ray intensity at the image affected: | it is increased 4 times |
| A 10% increase in kVp has ___ effect on x-ray intensity than/as a 10% increase in mAs: | Much greater |
| True/False: The best spatial resolution is created with a smaller matrix size: | False |
| True/ False: Larger pixel sizes provide better spatial resolution: | False |
| True/ False: Bit depth describes the number of gray shades that can be displayed by a pixel, the greater the number the better: | True |
| True/ False: An MTF of 0.8 is a higher quality image than an MTF of 0.3: | True |
| True/ False: A system that displays 8 lp/cm has greater detail than a system that displays 10lp/cm: | False |
| True/ False: Misalignment of the tube, part and receptor results in foreshortening/elongation of an object in our image: | True |
| True/ False: When imaging an object with a SID of 100cm and an OID of 20cm, the MF = 1.25: | True |
| True/False: A system with 5 lp/mm resolution, can show an object as small as 0.05mm: | False |
| True/ False: Focal spot blur is greater when we utilize short SIDs and large OIDs: | True |
| True/ False: Computed radiography cassettes may be used with the same imaging equipment as film/screen cassettes, with minor modification to techniques: | True |
| A photostimulable phosphor in a metastable state will emit light: | - Immediately - when stimulated by light - over time (after exposure but before processing) |
| The photostimulable phosphor screen is handled in a: | Reader |
| The computed radiography reader is made up of ___, ___, and ___ modules: | - Mechanical - optical (lend & mirror) - Computer |
| The four steps of creating an image with computed radiography are: | metastable state, stimulate, read, and erase |
| Following the laser stimulation of the photostimulable phosphor, the excited electrons are: | mostly (99%) stabilized |
| The laser is one of the ___ features of the computed radiography reader: | Optical |
| Optical filters are used to filter out the ___ light and allow the ___ light to reach the photodetector: | stimulating; emitted |
| The output signal from the photostimulable phosphor plate is converted from analog to digital by the: | Photodiode |
| True/ False: Spatial resolution, contrast resolution, are identical in screen-film imaging and computed radiography | False |
| The principal source of reduced contrast resolution in computed radiography is : | Scatter radiation |
| With computed radiography the contrast is: | constant(LINEAR) regardless of radiation exposure |
| The laser beam must be less than 100 nm in diameter in order to maintain: | high spatial resolution |
| __ is prevented by flooding the imaging plate with bright light after reading: | Ghosting |
| In CR as the display field of view is increased in size, spatial resolution (sharpness) in the image: | Decreases |
| In a 12-bit analog-to-digital converter, each pixel will have how many possible values: | 4096 |
| Mottle is likely to appear in the computerized image any time the: | exposure indicator is low in a positive system |
| Which of the following types of DR uses a fan beam and a detector array: | SPR |
| True/ False: An indirect DR system with CsI is preferred over GdOS, due to its better spatial resolution from needle-like phosphor crystals: | True |
| Which of the following DR systems has the best spatial resolution: | a-Se |
| Which of the following choices will require the least image exposure for the same image quality/noise level: | 5% dead space |
| True/ False: Indirect DR systems loss of detail is due to light spread in the scintillator: | True |
| True/ False: The space a TFT fills in a Direct DR system is considered the active area of the pixel: | False |
| Which of the following DR systems has the lowest spatial resolution or the widest Line spread function: | scintillator with a-Si |
| Scanned Projected Radiography was developed to complement: | CT |
| True/ False: In DR spatial resolution is improved with decreased FOV: | False |
| True/ False: Systems with high dead space require greater technical factors verses systems with lower dead space for equal image quality: | True |
| True/ False: In CR and DR selecting the exam and view prior to processing selects the VOI, algorithm and the Look up table: | True |
| True/ False: In CR and DR the acquired or raw data is very low contrast. The algorithm used during processing will correct the contrast and brightness of the image for viewing: | False |
| True/ False: In CR and DR, we have a wider exposure latitude, this requires technologist to be more accurate with their technical selection to avoid repeat examinations: | False |
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emilygarner22
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