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Rad Physics Exam 1
| Question | Answer |
|---|---|
| Electrons interact with the _______ to produce X-rays & heat. | Target |
| The study of stationary electric charges is | Electrostatics |
| The diameter of the input phosphor typically measures between | 15-30 cm |
| The cloud of electrons that forms before X-ray production is referred to as | Space charge |
| The unit of measurement of electrical charges is | Coulomb |
| Which primary exposure factor influences both the quantity and quality of xray photons? | kVp |
| Which of the following is NOT a correct law of electrostatics: A. Like charges repel B. Unlike charges attract C. Electric charges only reside on the internal surface of conductors D. All of the above | C. Electric charges only reside on the internal surface of conductors |
| Which of the following demonstrates the correct order of image recording components in a fluoroscopy system that uses a flat panel detector? A. CCD, ADC, Viewing monitor B. TFT, ADC, Computer, Viewing monitor C. ADC, CCD, Computer, Viewing monitor D. ADC, | B. TFT, ADC, Computer, Viewing monitor |
| The unit used to express tube current is_______. | mA |
| April is a potential difference that will maintain a current of _____ampere in a circuit with a resistance of ____ohm. | 1:1 |
| When operated in magnification mode, the electrostatic lenses have _____ of a negative charge fluoroscopy. | More |
| The intensity of the x-ray is greater on the________ | Cathode side of the tube |
| That changes direction in the conductor is | Alternating current |
| Which of the following is another name for the equivalent of automatic brightness control(ABC) within fluoroscopy? | Automatic Exposure Rate Control |
| When a conductor has a small cross-sectional area: A. Resistance decreases. B. Resistance increases. C. Resistance remains constant. D. None of the above. | B. Resistance increases. |
| What component of the x-ray tube is the source of free electrons? | Cathode |
| Which of the following situations will require the use of the large filament within a dual focus x-ray tube? A. Final imaging on a pediatric patient. B. Abdominal imaging on a bariatric patient. C. Chest imaging on a neonatal patient. D. Extremity imaging | B. Abdominal imaging on a bariatric patient. |
| Magnification of the fluoroscopic image results in improved | Spatial resolution |
| An adjustable form of a resistor is the | Rheostat |
| The anode heel effect is define as a variation in which of the following? | Beam quantity across the XR field |
| When a switch is turned on, the electric circuit A. Does not allow electrons to flow B. Is opened C. Is closed D. None of the above | C. Is closed |
| Which of the following components collects light photons from the output phosphor and converts them to electrons? A. Vidicon television pick up tube B. Charged coupled device C. Analog to digital converter D. Input phosphor | B. Charged coupled device |
| The device that regulates the amount of current flowing in the circuit is the | Resistor |
| As a result of the anode heel effect the anode side of the x-ray field demonstrates | Lower intensity |
| What is the anode heel effect caused by? | X-ray absorption within the anode |
| During fluoroscopy procedures, automatic brightness control is typically preferred over manual setting exposure factors because | ABC provides a constant signal intensity that compensates for changes in thickness and density |
| The purpose of grounding is to | Neutralize a charged object |
| The area of the x-ray beam projected towards the patient is described as the | Effective focal spot |
| Mutual induction involves electricity being induced into a | Secondary coil |
| The line focus principle describes the geometric relationship between which of the following factors within the x-ray tube | Anode angle and effective focal spot size |
| This part of the image intensifier is made of cesium iodide | Input phosphor |
| Which of the following anode angles with the same size actual focal spot can create a radiographic image demonstrating the highest spatial resolution? | 6° |
| In fluoroscopy, each capacitor in a CCD represents a | Pixel |
| When comparing a small anode angle to a large anode angle, a small anode angle with the same size focal spot will result in which of the following? | Increased spatial resolution and decreased anode heat capacity |
| The __________ absorbs electrons and emits light in florouscopy. | Output phosphor |
| A radiographer has the choice of multiple XR systems, where each is using a different anode angle. Which system should be used if maximum spiritual resolution is desired? | 7° |
| The electrostatic focusing lenses have a _______ charge in fluoroscopy. | Negative |
| The term “tube loading” refers to? | Heat energy created in the XR tube |
| A loss of brightness around the edge of the fluoroscopic image caused by the curve of the photocopy is | Vignetting |
| What is the wave form factor (W) for a 3 phase 12 pulse x-ray generator? | 1.41 |
| The________ is designed to set the electron stream in motion at constant velocity, and is located very close to the output phosphor in fluoroscopy. | Anode |
| The purpose of an Anode Cooling Chart is to determine the proper amount of | Time before taking another exposure |
| A step up transformer results in | Decreased current |
| The ratio of the number of light protons at the output phosphor as compared with the input phosphor is the | Flux gain |
| Rectifiers are found on the | Secondary circuit |
| The electronic vacuum tube that converts the remnant x-ray beam to light, then to electrons, then back to light increasing the light intensity in the process is the: | Image intensifier |
| _______ is measured in cd/m^2/mR/s. (Or 1%) | Conversion factor |
| In fluoroscopy, the purpose of the ______ is to convert the electronic signal from the camera tube or CCD into a visible image. | Television monitor |
| In an x-ray circuit, four rectifiers will produce | Full wave rectified current |
| Place the following events leading to the production of x-rays in order from first to last: 1. Alternating current is converted to direct current 2. Voltage is adjusted at the auto transformer 3. Voltage leaves the step up transform 4. Voltage goes to pri | 2, 4, 3, 1 |
| If a transformer has 5 turns in the primary, 20 turns in the secondary, and 150 Volts as the output, what is the primary voltage? | |
| How many heat units are created from a single x-ray exposure using a single phase x-ray machine with an exposure technique of 70 kVp and 25 mAs? | 70 x 25 x 1 = 1750 HU |
| If 100 x-ray photons reach a 30 cm input phosphor and 5000 light photons are produced at a 2.5 cm output phosphor, what is the brightness gain of the image intensifier? | |
| In a parallel circuit, three resistors (R1, R2, R3) have values of 8 ohms, 12 ohms, and 20 ohms, respectively. If a total voltage of 24 Volts is applied across the circuit, calculate the total current flowing through it. | |
| Calculate mAs for 50 mA and 10 milliseconds. | 50 x 0.01 = 0.5 mAs |
| What is defined as a measure of exposure in air, followed by a computation to estimate absorbed dose to the patient . | DAP/KAP |
| What is to defined as a light sensitive semiconducting device that generates an electrical charge when stimulated by light and stores this charge in a capacitor. | CCD |
| What is defined as the size of the area on the target that is exposed to electrons from the tube current? | Actual focal spot |
| What is defined as the electrons liberated from the filament during thermionic emission that form a cloud around the filament? | Space charge |
| What is defined as the phenomenon of inducing an electric current in that conductor by moving a conductor through a magnetic field? | Electromagnetic induction |
Created by:
Lanigober
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