Review questions for x-ray equipment operation
55. what device is turned by a rotor?
A. ANODE b. mA meter c. ionization chamber d. step-up transformer pressing the rotor button activates a motor that turns the anode. It also begins thermionic emission at the cathode.
Neutrons
A neutron is a subatomic particle, symbol n or n^0, which has a neutral charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. A subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen. It has no electrical charge, it is neutral. They are extremely dense.
Photons
A particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass. A photon is an elementary particle that is quantum of the electromagnetic field, including electromagnetic radiation such as light and radiowaves, and the force carrier for the electromagnetic force. Photons are massless, so they always move at the speed of light in vacuum
Proton
A stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign. A subatomic particle found in the nucleus of every atom. The particle has a positive electrical charge, equal and opposite to that of the electron.
31. the electricity provided to the radiology department operates at:
A. 120 PULSES PER SECOND b. 60 pulses per seconds c. 110 pulses per second d. 220 pulses per second 60 cycles per second results in 120 pulses per second because it cycles back and forth 120 times per second
24. choose all of the following that are accurate(choose 6):
A. A MAGNETIC FIELD ALWAYS SURROUNDS AN ELECTRICAL CHARGE IN MOTION B. CURRENT FLOWS BACK AND FORTH IN AC C. LIKE CHARGES ATTRACT, AND UNLIKE CHARGES REPEL d. the volt is the unit of electrical current E. A CONDUCTOR ALLOWS THE FLOW OF ELECTRONS f. the ampere is the unit of electromotive force G. THE VOLT IS THE UNIT OF POTENTIAL DIFFERENCE H. THE PATH OF ELECTRICAL CURRENT IS CALLED THE CIRCUIT
51. what is the source of bremsstrahlung and characteristic rays?
A. ANODE b. mA meter c. falling load generator d. step-up transformer The anode is the component(piece of metal) of the x-ray tube where x-rays are produced. these are the x-rays produced by two types of interactions that occur between incident electrons from the cathode and the tungsten atoms of the anode. Bremsstrahlung "braking radiation" or "deceleration radiation" is electromagnetic radiation produced by the deceleration of a charged particle when deflected by another charged particle, typically an electron by an atomic nucleus Characteristic and bremsstrahlung are two unique mechanisms by which x-rays are produced. Brem x-rays produce a continuous x-ray spectrum, whereas characteristic x-rays are produced at specific narrow bands of energies.
49. what device spins at 10,000-12,000 rpm?
A. ANODE b. mA meter c. ionization chamber d. step-up transformer
65. x-rays are produced as incident electrons collide with inner shell electrons in target atoms by a process called:
A. CHARACTERISTIC b. photoelectric c. bremsstrahlung d. comptom as incident electrons dislodge K-shell electronis in the target material, outer shell electrons fall inward to fill the holes. This causes the release of energy in the form of x-rays, with energy characteristic of the difference in energy levels between the k-shell and l-shell.
9. what type of current is required for proper operation of the x-ray tube?
A. DIRECT b. falling load c. alternating d. fluctuating direct current is a representative of a flow of electrons in one direction only. e.g. a battery. It has a positive and a negative electrode, and, when placed in an electrical circuit, electrons flow from the negative terminal to the positive terminal(current flows in the opposite direction) alternating current is a current that changes direction in cycles as the electric potential of the source changes(the negative and positive "terminals" will alternate) x-ray tube consists of a source of electrons, the cathode, which is usually a heated filament, and a thermally rugged anode, usually of tungsten which is enclosed in an evacuated glass envelope. Its function is creating x-ray photons from electric energy supplied by the x-ray generator. this necessitates the use of a rectifier to change AC to DC.
81. three phase, 6-pulse full-wave rectification produces:
A. DIRECT CURRENT WITH 13% RIPPLE b. direct current with 4% ripple c. direct current with 100% ripple d. alternating current with 13% 13% ripple direct current, not alternating current. Three-phase, 12-pulse produces ripple as low as 4%. Single-phase ripple is 100%
23. choose all the of following statements are accurate regarding electrostatic charges.
A. ELECTROSTATICS IS THE STUDY OF ELECTRIC CHARGES AT REST b. the movement of electrons from one object to another is called ionization c. like charges attract, and unlike charges repel D. ELECTROSTATIC CHARGES CONCENTRATE ON A CONDUCTOR IN THE AREA OF GREATEST CURVATURE e. friction, contact, and induction are methods of ionization The rubbing of certain materials against one another can transfer negative charges, or electrons. For example if you rub your shoe on the carpet, your body collects extra electrons. The electrons cling to your body until they can be released. As you reach your cat, you get a shock. It is a deficiency or excess of electrons which occurs on ungrounded or insulating surfaces. Static electricity is a familiar electric phenomenon in which charged particles are transferred from one body to another. For example, if two objects are rubbed together, especially if the objects are insulators and the surround air is dry, the objects acquire equal and opposite charges and an attractive force develops between them. The object that loses electrons becomes positively charged, and the other becomes negatively charged. The force is simply the attraction between charges of opposite sign. It is the Coulomb's law. Electrostatics(part1):introdction to charge and Coulomb's law - Khan Academy
94. the test that measures the accuracy of successive exposures is:
A. EXPOSURE REPRODUCIBILITY b. spinning top test c. pinhole camera d. exposure linearity Exposures made at the same kVp and mA stations of the same phantom thickness should produce the same optical density on the resulting image. This is referred to as reproducibility. This speaks to the fact that the radiation intensity produced by the x-ray tube should be the same given the same technique setting. The ability of an exposure system ot duplicate an exposure, time after time. It is expressed as a log exposure or as a percent exposure change. The smaller the change, the more reproducible the system.
79. total brightness gain achieved using an image intensifier equals:
A. FLUX GAIN TIMES MINIFICATION GAIN b. diameter of input phosphor times diameter of output phosphor c. intensification factor-brightness without an image intensifier divided by brightness with an image intensifier d. total light emitted at the photocathode This is the equation used to calculate total brightness gain. The x-ray image intensifier converts the transmitted x-rays into a brightened, visible light image. Within an image intensifier, the input phosphor converts the x-ray photons to light photons, which are then converted to photoelectrons within the photocathode. The electrons are accelerated and focused by a series of electrodes striking the output phosphor, which vonerts the accelerated electrons into light photons that may be captured by various imaging devices. Brightness gain is an expression of the ability of an image intensifier tube to convert x-ray energy into light energy and increase the brightness of the image in the process. Brightness gain is the increase in the intensity of a fluoroscopic image by the use of an image intensifier.
12. electromagnetic radiation travels
A. IN WAVES ALONG A STRAIGHT PATH b. in circles c. back and forth d. as electrons in waves along a straight path a kind of radiation including visible light, radio waves, gamma rays, and x-rays, in which electric and magnetic fields vary. ER is produced whenever a charged particle, such as an electron, changes its velocity(whenever it is accelerated or decelerated) travels at speed of light because it has mass, particulate radiation may travel different paths.
76. the portion of the image-intensifier tube that converts electron energy to visible light is the:
A. OUTPUT PHOSPHOR b. photocathode c. input phosphor d. detector element this is where electronic image again becomes visible. a component of the image intensifier in fluoroscopic systems that converts the energy from the electrons into light photons.
97. AECs may be tested using:
A. PHANTOMS b. images of real patients c. analog meters d. fluoroscopic screens A phantom is a highly specialized object utilized in medical imaging for quality control, equipment calibration, dosimetry, and education. The use of the name is used interchangeably for each object despite their differences. A scientific device that is often used in the biomedical research community. A phantom is a specially designed object that is utilized as a "stand-in" for human tissue and can be scanned or imaged to evaluate, analyze, and fine-tunr the performance of an imaging device. Phantoms provide consistent results, ensure that the systems and methods for imaging the human body are operating correctly, and provide reliable and quantitative/measurable information. Mimics the photon properties of human tissue, which means the material will respond in a similar manner to how human tissues and organs would act under the specific imaging modality.
70. the primary purpose of filtration is:
A. RADIATION PROTECTION b. removal of short-wavelength(soft) rays c. hardening the beam for imaging d. removal of long-wavelength(hard) rays
15. waves of radiation are called
A. SINE WAVES b. strong waves c. signal waves d. current waves sine waves: when referring to a sine wave a cycle represents the path of the wave from the baseline then below the baseline and back to the baseline
57. the filament is kept warm by:
A. STANDBY CURRENT FROM THE TIME THE X-RAY MACHINE IS TURNED ON b. insulating oil c. lead housing d. current produced only during exposures the machine is keeps warm between exposures.
41. which device reduces voltage and provides current to produce an electron cloud or space charge at the filament?
A. STEP-DOWN TRANSFORMER b. rectifier c. cathode d. timer the step-down transformer is located in the filament circuit. Electron cloud is the region of negative charge surrounding an atomic nucleus that is associated with an atomic orbital; high probability of containing electron. A good visual example of an electron cloud is a simple atom, like hydrogen. In a hydrogen atom, the nucleus consists of one proton, and one electron orbits it. But the electron doesn't literally orbit it in a circular path. Electron cloud(space where electrons are likely to be found. Space charge is a collection of particles with a net electric charge occupying a region, either in free space or in a device. Space charge, electrical charge distributed through a 3-dimensional region. In an electron tube, for example, a negative charge results because electrons that are emitted from the cathode do not travel instantly to the plate(anode) but require a finite time for the trip.
35. a transformer that has more turns in the secondary coil than in the primary coil is called a:
A. STEP-UP TRANSFORMER b. solenoid c. step-down transformer d. filament transformer voltage is stepped up while current is stepped down in the same proportion. A transformer is named for what it does to voltage.
38. a step-down transformer:
A. STEPS DOWN VOLTAGE b. steps down current c. steps up voltage d. steps up resistance a transformer is named for what it does to voltage.
100. effective quality control and quality assurance programs are required for accreditation by:
A. THE JOINT COMMISSION b. joint review committee on education in radiologic technology c. american healthcare radiology administrators d. american registry of radiologic technologists
5. what is atomic mass?
A. THE NUMBER OF PROTONS PLUS THE NUMBER OF NEUTRONS b. the number of photons c. the number of electrons d. the number of photons plus the number of electrons atomic mass is the quantity of matter contained in an atom of an element photon is a piece of energy, has no mass, moves at the speed of light, acts like a particle, and has momentum. Because both protons and neutrons have an atomic mass of 1 amu, and electrons have masses of such little consequence, atomic mass can be calculate by adding up the total number of protons and neutrons in an atom. atomic number is the number of protons. Protons and neutrons are contained in the atomic nucleus.
Energy
Ability to do work
what is AC and DC?
Alternating current (AC) current flow changes between positive and negative because of electrons - electrical currents come from the flow of these electrons, which can move in either a positive(upward) or negative(downward) direction. This is known as the sinusoidal AC wave, and this wave is caused when alternators at power plants create AC power. Alternators create AC power by spinning a wire loop inside a magnetic field. Waves of alternating current are made when the wire moves into areas of different magnetic polarity—for example, the current changes direction when the wire spins from one of the magnetic field's poles to the other. This wave-like motion means that AC power can travel farther than DC power, a huge advantage when it comes to delivering power to consumers via power outlets. Direct current (DC) power, as you may suss from the name, is a linear electrical current—it moves in a straight line. Direct current can come from multiple sources, including batteries, solar cells, fuel cells, and some modified alternators. DC power can also be "made" from AC power by using a rectifier that converts AC to DC. DC power is far more consistent in terms of voltage delivery, meaning that most electronics rely on it and use DC power sources such as batteries. Electronic devices can also convert AC power from outlets to DC power by using a rectifier, often built into a device's power supply. A transformer will also be used to raise or lower the voltage to a level appropriate for the device in question. Not all electrical devices use DC power, though. Many devices, household appliances, especially, such as lamps, washing machines, and refrigerators, all use AC power, which is delivered directly from the power grid via power outlets.
Mass
Amount of matter in an object generally considered the same as weight.
Electrons
An electron is a negatively charged subatomic particle that can be either bound to an atom or free(not bound). An electron that is bound to an atom is one of the three primary types of particles within the atom -- the other two are protons and neutrons. Together, electrons, protons, and neutrons form an atom's nucleus. An electron is a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.
Structure of an atom.
Atoms are the basic building blocks of ordinary matter. Atoms can join togehter to form molecules, which in turn form most of the objects around you.
mAs and kVp (clover learning Youtube)
Cathode is negatively charged and anode is positively charged. Difference in charge is called tube potential. We measure the two potential in units of kilovolts. Increase kVp=increase beam intensity(quantity) Increase kVp=energy(quality) Only prime exposure varaible that can change energy of x-ray beam. The mA/time/SID does not change energy of x-ray beam. KvP is equal to maximum beam energy. If kVp is 100 the maximum energy photons in the beam is going to be 100 keV. KeV: kiloelectron volts: quantifying the energy of x-ray photons. Kvp affects other aspects of exposure. Increasing kVp increases dose to patient. More kVp creates more x-ray photons, more photons striking patient. Increase kVp it increases receptor exposure(amount of radiation strike in the image receptor). Opposite is true. KvP defined by 15% rule. If we increase kVp 15% this will double receptor exposure. Increased kVp decreases image contrast and the reverse is also true. Increasing kVp increases patient dose, receptor exposure but decreases image contrast. Changes to which of these technical factors will influence the receptor exposure? All of them. The tube current, exposure time, tube potential, distance.
Nucleus
Consists of electrically positive protons and electrically neutral neutrons. These are held together by the strongest known fundamental force, called the strong force. The nucleus makes up much less than .01% of the volume of the atom, but typically contains more than 99.9% of the mass of the atom.
Ionizing radiation
Electromagnetic radiation that is able to remove an electron from an atom
Kinetic energy
Energy of motion
Potential energy
Energy of position
Chemical energy
Energy resulting from a chemical reaction
Electrical energy
Energy resulting from movement of atoms or molecules
Nuclear energy
Energy resulting from the nucleus of an atom
Electromagentic energy
Energy that is emitted and transferred through matter
Matter
Has form or shape and occupies space.
Thermal energy
Heat energy resulting from movement of atoms or molecules
Fluoroscopy
Imaging technique that uses x-rays to obtain real-time moving images of the interior of an object Can be used for diagnosing a health problem such as heart or intestinal disease. It also can be used to guide treatments such as implants or injections, or in orthopedic surgery. It helps the healthcare provider look inside organs, joints, muscles, and bones. X-ray movie
What is output phosphor vs input phosphor
Input phosphors are 15 to 30cm and the output phosphor is usually 2.5 cm. The international commission on radiation units and measurements now recommeds the use of the conversion factor to quantify the increase in brightness created by an image intensifier. output phosphor: component of the image intensifier in fluorosopic systems that converts the energy from the electrons into light photons. In an II, the large number of light photons produced are subsequently captured by various imaging devices to produce a visible image. Input phosphor: component of the image intensifier in fluoroscopic systems that converts the energy from x-rays into light photons. It is composed of a fluoroscent material such as cesium iodide activated with sodium and coats the entrance surface of the image intensifier. The light produced by the entrance phosphor subsequently travels to a photocathode layer.
What is mAs and its significance?
Milliampere-seconds, also more commonly known as mAs, is a measure of radiation produced(milliamperage) over a set amount of time(seconds) via an x-ray tube. It directly influences the radiographic density, when all other factors are constant. Changes in mAs affect radiation dose, signal-to-noise ratio(SNR), and contrast. Increasing mAs produces more electrons in an x-ray tube and subsequently increases th amount of radiation exposure. High mAs will increase SNR but will decrease image contrast. It determines how many x-ray photons are produced(quantity). It has no effect on the strength(penetrating power) of the x-ray photons. mAs is a product of multiplying two factors together: time and milliamperage(mA). mA x time = mAs For example, a typical technique setting used for imaging an injured hand may be 60 kVp, 100 mA, and 1/100 of a second(0.01). In this example, 100mA multiplied by 0.01 seconds equals 1 mAs(or 1 milliampere-second).
Ripple
Refers to the fluctuation in voltage output of some x-ray generators. It is given a percentage value. Single-phase and two-phase generators have 100% ripple. Three-phase generators have ripple values between 5% and 15%. Modern x-ray generators use high-frequency inverters to create an approximate DC waveform, minimizing the ripple effect to less than 1%. Minimizing the ripple effect is desired to increase both the quantity and quality of the x-ray beam.
Ionization
Removal of an electron from an atom
Atomic number
The number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
87. the collimator must be accurate to a level of:
a. +-4% of SID b. +-5% of SID C. +-2% of SID d. +-10% of SID Collimation restricts the x-ray beam to the area of interest using lead shutters within the x-ray tube. Secondary beneficial effect is reduction of off focus radiation making it to the film. Because a smaller volume of tissue is being irradiated, less scatter radiation is produced. SID(source image receptor distance) is the distance of the tube from the image receptor, affecting magnification. The greater the SID, the less magnification the image will suffer. Guidelines set forth for patient protection state that the collimator light and actual irradiated area must be accurate to within 2% of the SID. There are many radiation protection devices and laws associated with today's x-ray equipment.
88. kVp must be accurate to within:
a. 1 of the amount on the control panel setting b. 5% of the control panel setting c. 2% of SID D. 10% OF THE CONTROL PANEL SETTING kVp stands for kilovoltage peak. This is the highest voltage(measured in thousands of volts) that will be produced by the x-ray machine during an exposure. For example, if 60 kVp is selected, 60 kilovolts(60,000 volts) is the maximum strength of x-rays produced in this exposure. kVp is the peak potential applied to the x-ray tube, which accelerates electrons from the cathode to the anode in radiography or computed tomography. kVp controls the penetrating strength of an x-ray beam(beam quality). Whenever an exposure is made, the x-rays must be energetic(strong enough) to adequately penetrate through the area of interest. The higher the kVp, the more liekly the x-ray beam will be able to penetrate through thicker or more dense material.
73. calculating heat units for three-phase, 12 pulse equipment requires the use of _____ as a constant; calculating heat units for single-phase equipment requires the use of _____ as a constant; calculating heat units for three-phase, 6-pulse equipment requires the use of _____ as a constant.
a. 1.0, 1.35, 1.41 b. 1.35, 1.0, 1.41 d. calculating heat units does not require the use of a constant because all x-rays possess the same ionizing potential D. 1.41, 1.0, 1.35
84. the increase in average photon energy when using three-phase, 12-pulse equipment compared with single-phase equipment is:
a. 1.35% B. 41% c. 1.41% d. 35% This is why the formula for calculating heat units for three-phase, 12-pulse equipment is multiplied by 1.41
83. the increase in average photon energy when using three-phase, 6-pulse equipment compared with single-phase equipment is:
a. 1.35% b. 41% c. 1.41% D. 35% This is why the formula for heat units for three-phase, six-pulse equipment is multiplied by 1.35 Youtube: HVDC concepts: section 3-6 pulse rectifier - TranspowerNZ
91. fluoroscopy exposure rate may not exceed:
a. 10 mGy(a) per minute B. 100 mGy(a) per minute c. 5 mGy(a) per minute d. 1 mGy(a) per minute It is measured in-air at the tabletop. Exposure rate is the amount of ionizing radiation per hour in a person's vicinity, whereas dose rate is the biological effect on the body from exposure to thatradiation.
95. the accuracy of the timer must be within:
a. 10% of the time chosen for exposures over 10ms B. 5% OF THE TIME CHOSEN FOR EXPOSURES OVER 10MS c. 5% of the time chosen for exposures under 10ms d. 10% of the time chosen for exposures under 10ms
30. the electricity provided to the radiology department is
a. 110Hz or 220Hz AC b. 110Hz or 220Hz DC C. 60HZ AC d. 60Hz DC 60 HZ means 60 cycles per second. The voltage may be 110 or 220 Hz(hertz) is the unit of frequency. 1 hertz is equal to 1 cycle per second. AC: alternating current DC: direct current
X 74. when a quality control test is performed to ensure that the penetrating ability of the x-ray beam is accurate, the result must be within what amount of the control panel setting?
a. 2% of SID b. 4% c. 10% D. 50% a control panel is a device which controls input power to the x-ray high-voltage generator and the x-ray tube. It includes equipment such as timers, phototimers, automatic brightness stabilizers, and similar devices, which control the technique factors of an x-ray exposure. SID: the source image receptor distance is the distance of the tube from the image receptor, affecting magnification. The greater the SID, the less magnification the image will suffer. https://brainly.com/question/27498469
98. the number of mAs used for analog fluoroscopy is:
a. 300 to 500 B. 3 TO 5 c. 10 to 12 d. 100 to 300
90. exposure reproducibility must be accurate to within:
a. 4 B. 5% c. 2% of SID d. 10% Exposures made at the same kVp and mA stations of the same phantom thickness should produce the same optical density on the resulting image. This is referred to as reproducibility. This speaks to the fact that the radiation intensity produced by the x-ray tube should be the same given the same technique setting. The ability of an exposure system to duplicate an exposure, time after time. It is expressed as a log exposure or as a percent exposure change. The smaller the change, the more reproducible the system.
89. exposure linearity must be accurate to within:
a. 4 b. 5% c. 2% of SID D. 10% Exposure linearity refers to a consistency in output radiation intensity at any select kVp settings when generator settings are changed from one mA and time combination to another Linearity in radiography is the production of a constant amount of radiation for different combinations of mA and exposure times. it is essential that all general x-ray units produce a proportional change in exposure as mA varies. The assumption is that an increase in mAs, should produce proportional increases in radiation exposure. Linearity tests are performed to monitor patient dose and image quality. Variation in output intensity during diagnostic exposures can result in unnecessary dose to the patient due to repeats from poor quality images.
66. what percentage of energy in the x-ray tube is converted to x-rays?
a. 99% b. 75% C. 1% d. 100% more than 99% of energy is converted to heat.
92. the feature that automatically adjusts kVp and mA during fluoroscopy is called:
a. AEC B. ABC c. DQE d. SNR Automatic brightness control is a device incorporated into the fluorocopic unit. Its function is to maintain a consistent overall appearance of the image by automatically adjusting the kVp and/or mAs. Analagous to the AEC systems Used to ensure that the brightness of the image at the monitor is constant. This is accomplished with automatic adjustment of tube voltage and current to accommodate the varying attenuation of the patient.
58. activating the rotor:
a. accelerates a procedure B. REDUCES TUBE LIFE c. keeps it oiled d. keeps the cooling fan activated each time the rotor is activated, thermionic emission begins to occur at the filament. This heating of the filament causes tungsten to evaporate, thus slowly deteriorating the filament. The rotor(made of copper) is rigidly connected to the target through the anode stem, causing the target to rotate rapidly during x-ray production. High strength ball bearings in the rotor allow it to rotate smoothly at high speeds.
48. which of the following measures tube current?
a. anode B. mA METER c. ionization chamber d. falling load generator current is the flow of electrons, as measured in mA. Hence the mA meter provides the reading. mA is a unit representing the amount of current passed through the x-ray tube. mA is a measure of radiation produced over a set amount of times(seconds) via an x-ray tube. It directly influences the radiographic density, when all other factors are constant.
56. which of the following is located between the patient and the image receptor?
a. anode b. mA meter C. IONIZATION CHAMBER d. falling load generator the ionization chamber is a wafer-thin chamber containing gas that is ionized by the x-rays passing through it. At a predetermined level of ionization, the exposure is terminated. two types of AEC systems have been used: phototimers and ionization chambers.
54. what device always delivers the shortest exposure time possible?
a. anode b. mA meter c. ionization chamber D. FALLING LOAD GENERATOR coupled with an electronic timer, this results in times as short as 1/1000 second.
50. what device uses maximum heat storage ability of the tube to deliver mAs?
a. anode b. mA meter c. ionization chamber D. FALLING LOAD GENERATOR this type of generator allows extremely short exposure times. design in which exposure factors are adjusted automatically to the highest mA at the shortest exposure time allowed by the high voltage generator.
52. what device increases voltage approximately 500 times?
a. anode b. mA meter c. ionization chamber D. STEP-UP TRANSFORMER this is where voltage is boosted to kilovoltage levels. A step-up transformer is a transformer that increases the voltage from the primary coil to the secondary coil while managing the same power at the rated frequency in both coils. It converts low voltage and high current from the primary side to the high voltage and low current on the secondary side of the transformer.
26. the two types of electomagnetic induction are:
a. autoinduction and mutual induction B. SELF-INDUCTION AND MUTUAL INDUCTION c. generated induction and self-introduction d. current induction and voltage induction Electromagnetic induction is a current procuded because of voltage production(electromotive force) due to a changing magnetic field. This either happens when a conductor is placed in a moving magnetic field(when using an AC power source) or when a conductor is constantly moving in a stationary magnetic field. https://simply.science/images/content/physics/Electromagnetism/EM_induction/Concept_map/Types_of_Induction.html#:~:text=There%20are%20two%20types%20of,and%20(2)%20Self%20Induction. self induction occurs in the auto Transformer; Mutual induction occurs in the step Up and step down Transformers
37. voltage coming to the x-ray machine is kept constant through the used of a(n):
a. autotransformer b. step-down transformer C. RECTIFIER d. line voltage compensator older x-ray machines require that the line voltage compensator be adjusted manually, whereas newer equipment lets the machine do the adjustment itself. this process of converting an AC supply into a constant unidirectional supply, or a pulsating unidirectional supply, is called rectification. Rectfier is an electrical component that converts alternating current to direct current. The process of converting AC to DC is called rectification. Purpose: if we had alternating current, we'd have electrons alternating back and forth between cathode and anode. We want electrons going in one direction. Reason we change AC to DC
36. what is the transformer used to boost voltage to kilo-voltage levels called?
a. autotransformer b. step-down transformer C. STEP-UP TRANSFORMER d. low-voltage transformer the voltage is varied at the autotransformer, then boosted to kilovoltage levels by the step-up transformer.
69. the x-ray emission spectrum consists of:
a. brems and characteristic rays b. discrete spectrum(produced by brem rays) and continuous spectrum(produced by characteristic rays) C. DISCRETE SPECTRUM(PRODUCED BY CHARACTERISTIC RAYS) AND CONTINUOUS SPECTRUM(PRODUCED BY BREMS RAYS) d. x-rays and electrons, both part of the electromagnetic spectrum Because x-rays are produced by brems and characteristic interactions at the anode, the resultant x-ray beam contains many different energies. An x-ray beam containing many different energies is called heterogeneous. The collection of all different energies(wavelengths) of x-rays is called the x-ray emission spectrum. Discrete x-ray spectrum: produced by characteristic x-rays because energies involved are specific to the target atom and are predictable. Continuous x-ray spectrum: produced by brems radiation because these energies all are different(from the peak electron energy down to zero energy)
64. x-rays are produced as incident electrons are slowed going past the nuclei of target atoms by a process called:
a. classical b. photoelectric C. BREMSSTRAHLUNG d. comptom as incident electrons fly past the atomic nuclei, they are slowed, causing the production of heat and x-rays by bremsstrahlung. x-rays are also produced by the characteristic interaction.
28. the strength of the magnetic fields in a transformer is increased by:
a. coiling the wires and placing the them in adjoining machines B. COILING THE WIRES AND LETTING THEIR MAGNETIC FIELDS OVERLAP c. keeping the wires very straight, increasing their effectiveness d. replacing the wires with diodes this intensifies the magnetic fields making the Transformers more efficient
75. the primary type of grid used in diagnostic imaging is:
a. crosshatch b. parallel c. rhombic D. FOCUSED focused grids have lead strips that are oriented parallel at the center(along the x-ray central axis) and progressively slanted to the periphery to match the beam divergence from the focal spot to the detector at a specific source to detector distance. It is used to reduce scattered noise and increase contrast in x-ray images. Primary radiation passing through an object gets scattered caused by the various density of different materials. Scatter radiation produces noise(radiographic fog) on the film or detector, which degrades the diagnostic quality.
61. the force with which the electron stream passes from cathode to anode is a result of _______ passing through the x-ray tube.
a. current B. KILOVOLTAGE c. tungsten d. heat voltage is the force behind the movement of electrons in a circuit
3. in digital fluoroscopy, the image must be turned into digital form by what device?
a. digital-to-analog converter b. flux capacitor C. ANALOG-TO-DIGITAL CONVERTER d. dvd-rom ADC is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal ADC is a device that converts analog signals into digital signals. The signals are turned back into digital form(demodulated) at the receiving end so that the computer can process the data in its digital format. analog: frequency/voltage/wave
80. single-phase, full-wave rectifier produces:
a. direct current b. pulsating direct current c. pulsating direct current with 120 pulses per second D. PULSATING DIRECT CURRENT WITH 120 PULSES PER SECOND AND 100% RIPPLE
82. three-phase, 12-pulse full-wave rectification produces:
a. direct current with 13% ripple B. DIRECT CURRENT WITH 4% RIPPLE c. direct current with 100% ripple d. alternating current with 13% ripple Three-phase, six-pulse produces ripple as low as 13%. Single-phase ripple is 100%.
19. wavelength and frequency are
a. directly proportional to each other B. INVERSELY PROPORTIONAL TO EACH OTHER c. inversely proportional to the square of their distance d. unrelated to each other if one quantity increases, the other decreases the wave with the greatest frequency has the shortest wavelength. Twice the frequency means one-half the wavelength. For this reason, the wavelength ratio is the inverse of the frequency ratio.
67. choose all that are properties of x-rays(choose 6)
a. electrically negative B. AFFECT FILM EMULSION(2 or more liquid that are unmixable) C. SCATTER AND PRODUCE SECONDARY RADIATION(scattered or leaked radiation) D. INVISIBLE TO THE HUMAN EYE e. travel at the speed of light(186,000 miles per hour) f. possess wavelengths between 1 A and 5 A G. TRAVEL IN BUNDLES OF ENERGY CALLED PHOTONS H. CAN IONIZE MATTER AND GASES i. can be focused by collimators J. CAUSE PHOSPHORS TO FLUORESCE
78. the input phosphor of the image-intensifier tube converts:
a. electron energy to x-ray energy b. x-rays and heat to visible light C. X-RAY ENERGY TO VISIBLE LIGHT d. x-ray energy to an electronic image this is the point where the rays exiting the patient strike the input phosphor and it glows with visible light, releasing electrons from the photocathode.
6. what device may be used to ensure consistency of radiographic quality from one exposure to the next?
a. electronic timer b. step-up transformer C. AUTOMATIC EXPOSURE CONTROL d. high-frequency generator AEC is an x-ray exposure termination device. It is always initiated by a human but an AEC detector system may be used to terminate the exposure when a predetermined amount of radiation has been received. It is a system designed to adjust the kV, mA, or exposure time in order to obtain an image of diagnostic quality AEC is calibrated to provide the images most preferred by the radiologists
62. heat is produced in the x-ray tube as:
a. electrons break apart while striking the anode B. ELECTRONS INTERACT WITH THE TARGET MATERIAL c. the anode stops spinning d. the rectifier operates this is primarily a result of bremsstrahlung interactions at the anode. bremsstrahlung/braking x-ray generation: when an electron passes near the nucleus it is slowed and its path is deflected. Energy lost is emitted as a Bremsstrahlung x-ray photon. Approximately 80% of the population of x-rays within the x-ray beam consists of x-rays generated in this way.
60. the process of thermionic emission causes:
a. electrons to boil off the anode b. the anode to spin c. the cathode to cool quickly D. ELECTRONS TO BOIL OFF THE FILAMENT this causes a space charge or electron cloud to form around the filament thermionic emission is the emission of electrons from a heated metal(cathode). when metal is heated in excess amount the electron in the atom gets enough energy to move out from the atom.
4. x-rays travel as bundles of energy called
a. energy waves b. phasers c. electromagnetic bursts D. PHOTONS photons are the smallest amount of any type of electromagnetic radiation; also considered a bundle of energy called a quantum; travels at the speed of light; travels in waves in a straight path. a quantum of light or other electromagnetic radiation(visible light, radio waves, gamma rays, and x-rays, in which electric and magnetic fields vary simultaneously) photons a.k.a light
10. the law stating that the outer shell of an atom can contain no more than eight electrons is called
a. ohm's rule B. OCTECT RULE c. octogan rule d. electron binding energy ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. ohm's law: voltage in the circuit is equal to the current x resistance the octet rule states that no more than eight electrons can be in the outer shell. It does not stipulate that there must be eight electrons in the outer shells
93. the test that measures the accuracy of adjacent mA stations is:
a. exposure reproducibility b. spinning top test c. pinhole D. EXPOSURE LINEARITY Exposure linearity refers to a consistency in output radiation intensity at any select kVp settings when generator settings are changed from one mA and time combination to another Linearity in radiography is the production of a constant amount of radiation for different combinations of mA and exposure times. it is essential that all general x-ray units produce a proportional change in exposure as mA varies. The assumption is that an increase in mAs, should produce proportional increases in radiation exposure. Linearity tests are performed to monitor patient dose and image quality. Variation in output intensity during diagnostic exposures can result in unnecessary dose to the patient due to repeats from poor quality images.
20. the x-ray beam changes as it travels through the patient by a process called
a. filtration B. ATTENUATION c. electrification d. annihilation attenuation is the reduction of the intensity of an x-ray beam as it traverses matter. The reduction may be caused by absorption or by deflection(scatter) of photons from the beam and can be affected by different factors such as beam energy and atomic number of the absorber. Radiation is emitted through. Medical imaging equipmnt and the energy is. Attenuated by a patient's bones and internal structures to create an image. The use of x-ray energy allows doctors to see inside a patient without having to create an incision. Attenuation is the measurement of energy absorbed and deflected as it passes through a medium. Essentially how much stopping power a material has on energy. Consider how energy travels; most energy forms, whether sound, heat, light or radiation, travel in waves. The wavelength and amount of force propelling the energy affects how that energy reacts to any objects in its path. The atoms of the object will absorb some energy, deflect some energy or allow some. Energy to flow through. The measurement of the absorbed and deflected energy provides us with an attenuation rate for any given material.
71. the amount of material needed to reduce the intensity of the beam by 1/10 is called:
a. half-value layer B. TENTH-VALUE LAYER c. total filtration d. inherent filtration we more commonly discuss beam quality using the term half-value layer. Regardless of the fraction, it is always the amount of material needed to reduce beam intensity to that level. TVL means the thickness of a specified material which attenuates x-radiation or gamma radiation to an extent such that the air kerma(number of individual x-ray photons per unit area), exposure rate or absorbed dose rate is reduced to one-tenth of the value measured without the material at the same point.
68. the x-ray beam is:
a. heterogeneous-all rays possess the same energy b. homogeneous-all rays possess the same energy c. monoenergetic-all energies correspond to the kVp D. HETEROGENEOUS OR POLYENERGETIC-CONSISTING OF MANY DIFFERENT ENERGIES(WAVELENGTHS) heterogeneous: diverse in character of content poly-energetic: composed of photons or other particles that have a range of energies. x-ray beams are heterogenous because photons can be found with different energies. This phenomenon happens because, in the interaction of the electrons with the anode, both characteristic and Bremmstahlung radiation may occur.
59. when making an exposure, the radiographer should:
a. hold the rotor for several seconds before pressing "expose" B. ACTIVATE THE ROTOR AND EXPOSURE SWITCH IN ONE CONTINUOUS MOTION c. begin the rotor while a student is still positioning the patient d. activate the rotor while estimating how fast the anode is spinning
8. what type of x-ray machine uses a continually decreasing mA for the shortest times possible?
a. ionization chamber b. portable c. c-arm D. FALLING LOAD GENERATOR FLG is a design in which exposure factors are adjusted automatically to the highest mA at the shortest exposure time allowed by the high voltage generator it delivers the desired amount of radiation to the image receptor in the shortest possible exposure delivers the maximum possible mA for the selected kVp by considering the instantaneous heat load characteristics of the x-ray tube FLG makes use of the maximum heat storage capacity at every mA and time combination. This allows for the shortest exposure time possible.
32. high frequency power:
a. is less effective than single-phase power B. HAS ALMOST NO RIPPLE c. has more ripple than three-phase power d. is yet unproved such a low ripple means higher average photon energy. High frequency is very efficient. a ripple is defined as the fluctuating AC component in the rectified DC output
18. the speed of x-rays is based on
a. mAs b. kVp c. size of the patient D. THE FACT THAT THEY ARE A FORM OF ELECTROMAGNETIC RADIATION the speed of x-rays is based on the speed of light the speed of x-ray travel is constant, regardless of the factors used to produce them. electromagnetic radiation if a form of energy that includes radio waves, microwaves, x-rays, and gamma rays, as well as visible light. the speed of X-ray travel is constant regardless of the factor used to produce them
99. marks on the focal track of the anode resulting from bombardment of electrons are called:
a. melts b. bullet marks C. PITTING d. cracks Pitting corrosion occurs when the cathode(damaged coating) is large and the anode(exposed metal) is small. Typically the surface protection later or film becomes the cathode when it is damaged and cracked. A small area of metal is then exposed and becomes the anodic.
2. what is the smallest particle of an element that retains the characteristics of the element?
a. mole B. ATOM c. molecule d. quark a quark is an elementary particle which makes up hadrons(any of the subatomic particles such as protons and neutrons that are made up of quarks and are subject to the strong force), the most stable of which are protons and neutrons. Atoms are made of protons, neutrons, and electrons. atoms may be broken down into subatomic particles but they would not have the characteristics of the element
29. electricity is supplied to the imaging department by a:
a. motor b. rectifier C. GENERATOR d. voltmeter a generator at the power company converts mechanical energy to electrical energy. A motor converts electrical energy to mechanical energy.
13. the latest digital fluoroscopic units are
a. nonionizing radiation b. cr cassettes c. conventional image intensifiers D. FLAT PANEL PLATES SIMILAR TO DIGITAL RADIOGRAPHY a class of solid-state x-ray digital radiography devices similar in principle to the image sensors used in digital photography and video. flat-panel detectors allow direct digital imaging of larger areas of the body, including the head
77. the portion of the image-intensifier tube that converts visible light to electrons is the:
a. output phosphor B. PHOTOCATHODE c. input phosphor d. anode the electrons are then accelerated towards the output phosphor. a surface engineered to convert light(photons) into electrons using the photoelectric effect. Photocathodes are important in accelerator physics where they are utilised in a photoinjector to generate high brightness electron beams.
53. what is the most commonly used AEC?
a. phototimer b. mA meter C. IONIZATION CHAMBER d. falling load generator the ionization chamber is located between the patient and the image receptor. Phototimers are seldom used. Ionization chamber is a radiation detector used for detecting and measuring charge from the number of ion pairs created within a gas caused by incident radiation. It consists of a gas-filled chamber with two electrodes; anode and cathode, in which a voltage is applied to maintain an electrical field. The anode is positively charged with respect to the cathode, and in most cases the outer chamber serves as the cathode.
85. programs that deal with the safe and reliable operation of equipment and programs that address all aspects of the delivery of radiology services are called, respectively:
a. quality assurance and quality control b. total quality improvement C. QUALITY CONTROL AND QUALITY ASSURANCE d. total quality management
21. the intensity of radiation is inversely proportional to the sqaure of the distance between the source of radiation and the person receiving it. This describes the:
a. square law b. reciprocity C. INVERSE SQUARE LAW d. octet law be certain to review the inverse Square law. Always remember the inverse Square relationship. The resulting answer cannot be double or half it will be 1/4 or four times In simpler terms, the inverse square law states that any energy or force will have a drastic dropoff in strength as it travels further away from the point source. Any source which spreads out in all directions without getting lost obeys the inverse square law. This source can be applied to sound, gravity, electrostatics, light, radiation.
40. which of the following devices is prereading?
a. step down transformer b. rectifier c. timer D. kVp METER the kVp meter indicates what the voltage will be after being stepped up. Hence it is prereading a kVp meter provides a convenient and fast method of measuring the effective kVp and exposure time of diagnostic x-ray machine.
47. what is located in the x-ray circuit between the high-voltage transformer and the x-ray tube?
a. step-down transformer B. RECTIFIER c. cathode d. timer
43. what changes AC to DC?
a. step-down transformer B. RECTIFIER c. cathode d. timer the production of x-rays is dependent on the current flowing in one direction across the x-ray tube. the rectifier changes incoming alternating current from the power company into direct current for use by the x-ray tube.
45. which of the following is composed of solid-state silicon-based diodes?
a. step-down transformer B. RECTIFIER c. cathode d. timer the rectifier changes AC to DC
39. where does thermionic emission occur?
a. step-down transformer b. rectifier C. CATHODE d. timer Thermionic emission is the emission of electrons from a heated metal(cathode). The cathode has its filament circuit that supplies it with necessary filament current to heat it up. As temperature increases, the surface electrons gain energy. The energy acquired by the surface electrons allows them to move a short distance off the surface thus resulting in emission. Thermionic emission is the liberation of electrons from an electrode by virtue of its temperature(releasing of energy supplied by heat).
44. which of the following is surrounded by a negatively charged focusing cup?
a. step-down transformer b. rectifier C. FILAMENT d. timer the filament and focusing cup are part of the cathode assembly. The focusing cup has a negative charge at the moment of exposure so as to repel the electrons from the cathode. a focusing cup is a negatively charged, shallow depression on the surface of the cathode of an x-ray tube, which concentrates the electron beam towards the focal spot of the anode. this narrows the stream as it goes to the anode. The filament is the cathode of the tube. What is the filament made of in x-ray? Tungsten. The electrons are produced by heating the filament(joule heating effect) i.e. a coil of wire made from tungsten, placed within a cup-shaped structure, a highly polished nickel focusing cup, providing electrostatic focusing of the beam on the anode.
46. what regulates the duration of x-ray production?
a. step-down transformer b. rectifier c. cathode D. TIMER
42. which device is electronic, with a setting as low as 0.001?
a. step-down transformer b. rectifier c. cathode D. TIMER the timer is accurate as low as 1/1000 of a second(which is 1ms or 0.001 second)
27. self-induction is used in the operation of what device?
a. step-up transformer B. AUTOTRANSFORMER c. step-down transformer d. electronic timer autotransformer is a transformer that contains an iron core and a single winding of wire; an autotransformer is used in the x-ray circuit to provide a small increase in voltage before the step-up transformer; the kVp settings are made at the autotransformer. It selects the major/minor kVp and steps the voltage up to kilovolts.
34. A varible transformer that is used to select kVp for the x-ray circuit is the:
a. step-up transformer B. AUTOTRANSFORMER c. step-down transformer d. rectifier the autotransformer is a variable transformer that operates on the principle of self-induction. Autotransformer selects the major or minor kVp and steps the voltage up to kilovolts. Purpose of autotransformer is to regulate the voltage of transmission lines and can be used to transform voltges. What to know about autotransformers: - incoming current to the autotransformer is 220V AC - only has one coil with two "side" - primary and secondary - used when only a small step-up or step-down in voltage is required - operates on the principle of self-induction - provides specific voltage to the high voltage transformer - provides specific amperage to the filament transformer
17. frequency is defined as
a. synonomous to wavelengths B. THE NUMBER OF WAVES PASSING A POINT PER UNIT TIME c. the number of waves striking the patient d. the number of exposures needed during an exam frequency is the number of vibration cycles that occur in 1s. Lower frequencies have larger wavelengths, higher have smaller. frequency and wavelengths are inversely related. The higher the frequency the smaller the wavelength.
22. as radiation strikes matter:
a. the energy of the rays is destroyed b. the energy of the rays is increased as they acquire the energy of the atoms C. THE ENERGY IS TRANSFERRED TO THE ATOMS ACCORDING TO THE LAW OF CONSERVATION OF ENERGY d. the energy is converted to matter according to Einstein's theory the law of energy states that the amount of energy is neither created nor destroyed. For example, when you roll a toy car down a ramp and it hits a wall the energy is transferred from kinetic energy to potential energy. It can only be converted from one form of energy to another.
86. an image intensifier's conversion factor is expressed as the ratio of:
a. the flux gain to the minification gain B. THE LUMINANCE OF THE OUTPUT PHOSPHOR TO THE EXPOSURE RATE AT THE INPUT PHOSPHOR c. the exposure rate at the output phosphor to the exposure rate at the input phosphor d. the size of the input phosphor to the size of the output phosphor It is a measure of the efficacy of the image intensifier.
1. in many cases, digital fluoroscopy eliminates which of the following?
a. the need for a radiographer B. POSTPROCEDURE "OVERHEAD" IMAGES c. image acquisition d. accurate positioning most views required by the radiologist are acquired digitally during fluoroscopy
14. at what speed do x-rays travel?
a. the speed of light - 186,000 miles per hour b. the speed of the incident electrons - 93,000 miles per second C. THE SPEED OF LIGHT - 186,000 MILES PER SECOND d. infinite speed
7. when a predetermined level of ionization is reached in the ionization chamber, what does the machine do?
a. the unit shuts off as a result of a malfunction b. the maximum allowable time has been reached c. the highest allowable dose to the patient has been reached D. THE EXPOSURE IS TERMINATED ionization is the removal of an electron from an atom ionization chamber is a type of gas-filled radiation detector used to determine the intensity of a beam of radiation or for counting individual charged particles. hence, exposure time when using an AEC is very dependent on the kVp.
16. wavelength is defined as the distance from
a. the x-ray tube to the patient b. the cathode to the anode c. the bottom of a wave to the top D. PEAK TO PEAK OF THE WAVE distance covered by one complete cycle of the electromagnetic wave. The distance from one peak to another peak or from trough to trough in one wave. The longer the wavelength of the radiation, the lower its energy.
72. which of the following statements regarding filtration is true?
a. total filtration must not be less than 2-mm aluminum equivalent b. total filtration must be removed all soft rays from the beam c. total filtration(added+compensating) must not be less than 2.5-mm aluminum equivalent D. TOTAL FILTRATION(NOT LESS THAN 2.5-MM ALUMINUM EQUIVALENT) = INHERENT FILTRATION(GLASS ENVELOPE, TUBE HOUSING, OIL) + ADDED FILTRATION(ALUMINUM) the added filtration component is customized(filter thickness, type of metal) for individual examinations and procedures(e.g. fluoroscopy) and takes advantage of specific metals filtration characteristics(e.g. absorption edges) to improve image quality and constrast. Filters are metal sheets placed in the x-ray beam between the window and the patient that are used to attenuate the low-energy(soft) x-ray photons from the spectrum. Filtering is the removal of these low energy x-rays from the beam spectrum which would otherwise not contribute to image quality but would add to patient dose and scatter. Inherent filtration from components in the x-ray tube, i.e. window, housing, cooling oil(equivalent to 0.5-1.0 mm AI) Added filtration from interchangeable metal sheets(AI, Cu, etc.)
33. the primary advantage of three-phase power is that:
a. voltage drops to zero only 6 times per second b. voltage drops to zero only 12 times per second C. VOLTAGE NEVER DROPS TO ZERO d. voltage is always at peak value three-phase power produces higher average photon energy than single-phase power. three-phase alternating current(AC) power is commonly used to deliver electricity to data centers as well as commercial and industrial buildings that house power-hungry machinery. 3 phase power can deliver more power with great efficiency, as opposed to single-phase AC power. Youtube: three phase electricity basics and calculations - The Engineering Mindset
25. electromagnetic induction is the process of causing an electrical current to flow in a conductor:
a. when it is placed in contact with another conductor b. when it is placed in contact with an insulator c. when it is placed in contact with a superconductor D. WHEN IT IS PLACED IN THE MAGNETIC FIELD OF ANOTHER CONDUCTOR Electromagnetic induction is the creation of an electro-motive force(EMF) by way of moving magnetic field around an electric conductor and conversely, the creation of current by moving an electric conductor through a static magnetic field. electromagnetic induction does not require that two conductors touch each other EMI is the process of generating electric current with a magnetic field. It occurs whenever a magnetic field and an electric conductor move relative to one another so the conductor crosses lines of force in the magnetic field. Youtube: electromagnetic induction - Bozeman Science
96. resolution of the television system may be measured using the following tool(s):
a. wire mesh test b. line pairs/millimeter resolution tool along with a kVp meter C. RESOLUTION TEST PATTERN d. resolution test pattern, wire mesh test, or line pairs/millimeter resolution tool
63. most of the energy conversion in the x-ray tube produces:
a. x-rays b. light C. HEAT d. current X-rays and heat are produced at the anode. This is the result of a massive energy conversion in which more than 99% of the incident electron kinetic energy is converted to heat energy while less than 1% is converted to x-ray energy. This is a clear example of the law of conservation of energy. No light is produced in the X-ray tube
11. examples of particulate radiation are
a. x-rays, gamma rays, and cosmic rays B. HELIUM NUCLEI AND BETA PARTICLES c. electrons, protons, and meteorites d. x-rays and quarks particle radiation is made up of any subatomic particles, such as protons, neutrons, and high-speed electrons, capable of causing ionization. Alpha and beta particles are two of the more common types of particle radiation. alpha particles(helium nucleus-two protons and two neutrons); beta particles(electronlike particles emitted from the nucleus of a radioactive atom) particulate radiations are highly ionizing. Helium nucleus is made of two protons and two neutrons. Beta particles are high energy, high speed electrons or positrons that are ejected from the nucleus by ome radionuclides during a form of radioactive decay called beta-decay. Beta particles have a mass which is half of one thousandth of the mass of a proton and carry either a single negative(electron) or positive(positron) charges. As they have small mass and can be released with high energy, they can reach relativistic speeds(close to the speed of light)
Characteristic vs. Bremsstrahlung radiation
discrete spectrum(brems ray): a projectile electron misses outer shell electrons in the target and moves in close to the nucleus. Because nucleus is positive and the electron is negative, it is slowed or braked. The reduction in kinectic energy causes the electron to slow and release energy as an x-ray photon. The resultant x-rays are called bremsstrahlung(braking) x-rays because they are produced by the slowing of projectile electrons. Most x-rays produced are from brems interaction. continuous spectrum(characteristic): a projectile electron collides with an inner shell electron of a target atom. It removes the inner shell electron from orbit and ionizes the atom. A hole exists in the inner shell from the vacated electron. An electron from an outer shell falls in to fill the hole. As the electron falls in, energy is given off in the form of an x-ray photon. This creates a hole in its shell of origin, and an electron from the next outer shell falls in to fill this vacancy; this continues until the atom is stable again. Each time an electron falls in to a hole, an x-ray photon is given off. Each x-ray photon has a specific energy, equal to the difference in the binding energies of the two shells involved. Only x-rays produced at the k-shell are of sufficient energy to be used in diagnostic radiography. Because the x-rays possess energy characteristic of the specific binding energies of the atom involved, they are called characteristic x-rays. Characteristic x-rays are produced at kVp levels greater than 70 but only in small numbers.
What is kVp and its significance?
kVp stands for kilovoltage peak. This is the highest voltage(measured in thousands of volts) that will be produced by the x-ray machine during an exposure. For example, if 60 kVp is selected, 60 kilovolts(60,000 volts) is the maximum strength of x-rays produced in this exposure. kVp is the peak potential applied to the x-ray tube, which accelerates electrons from the cathode to the anode in radiography or computed tomography. kVp controls the penetrating strength of an x-ray beam(beam quality). Whenever an exposure is made, the x-rays must be energetic(strong enough) to adequately penetrate through the area of interest. The higher the kVp, the more likely the x-ray beam will be able to penetrate through thicker or more dense material. kVp: the power or strength of the x-ray beam(quality of the x-rays) mAs: the number of x-ray photons produced by the x-ray tube at the setting selected(quantity of x-rays) For example, if an acceptable image of a body part that measured 10 centimeters was obtained using 60 kVp, an increase of 2 kVp would be needed to penetrate a body part that measured 11 cm (a 2 kVp increase for every additional cm of thickness, or 62 kVp). What kVp should be selected if a body part measures 12 cm? We should use 64 kVp because we have added another cm in thicknes
