LMRT Core Review Questions and Answers Rated A+

LMRT Core Review Questions and Answers Rated A+ As a professional radiographer, the practice of ALARA requires you to restrict the XR beam to the clinical area of interest The factors that affect XR emission under the direct control of the radiographer are called_ factors prime Milliamperage-second (mAs) directly affects all of the following EXCEPT beam quality The factors that directly affect XR quantity are mA & filtration The factors that directly affect XR quality are kVp & beam filtration If 1 coulomb is equal to 6.3 x 10(18) electron charges, how many electrons flow from cathode to anode 1 second 6.3 x 10(18) If 1 ampere equals a flow of 6.3 x 10(18) electrons per second, how many electrons flow from cathode to anode in 1 milliampere? 6.3 x 10(15) As the mA doubles, the number of electrons flowing from cathode to anode increase 2-fold The product of tube current 7 exposure time is equal to XR beam quantity In order to increase radiographic film density by 40% the radiographer would change the mAs from 15-21 mAs The relationship between mAs & exposure is directly proportional The reaction of a photographic film to light is equal to the product of the intensity of the light and the duration of the light exposure. the reciprocity law Increasing the kVp for an exposure will cause the electrons to travel faster from cathode to anode Increasing the energy of an incident electron will result in the production of an XR photon with greater energy Kilovoltage is the primary controlling factor of radiographic film density Adjustments in kVp should be used to control radiographic contrast XR beam penetrability is primarily controlled by kVp All factor remaining constant, which of the following set of exposure conditions would yield an image with GREATEST radiographic film density 400 mA, 200 ms, 40" SID The length of the exposure time (S) for a radiograph, is used to primarily control motion A radiograph is taken 400 mA, 55 ms, 95 kVp. A second image could be taken to improve contrast at 400 mA,0.110 sec, 80 kVp When an XR photon passes through matter, it undergoes a process called attenuation During the process of attenuation, XR photons in the beam reduce in number In which element are the inner-shell electrons more tightly bound to the nucleus? lead (Z=82) As the electron shells move farther from the nucleus, total electron energies_ and binding energies_. increase; decrease When XR photons interacts w/matter & change direction, the process is called scatter If a photon interacts w/matte & scatter, the photon exists w/less energy During photoelectric absorption, a/an_ shell electron is ejected inner During photoelectric absorption, the ejected electron is called a/an photoelectron When an electron from an outer shell fills a vacancy in an inner shell photon is released During the photoelectric interaction, as an electron transfer from an outer shell to a vacant inner shell energy is released in the form of a characteristic photon Secondary radiation energies are highest for which element barium Compton scattering occurs when an incident XR photon interacts w/a_ electron loosely bound outer-shell The electron dislodged during Compton scattering is called the recoil electron The photon that exits the atom after a Compton scattering is called the Compton scattered photon During Compton scattering, the incident photon energy is divided between the recoil electron & the scattered photon As the angle of deflection is increased from 0-180 degree greater energy is imparted to the recoil electron Unwanted radiographic image densities caused predominantly by scattered photons is called radiation fog In which process is matter converted back to energy? annihilation reaction Which of the following interactions has a significant impact on the XR image? photoelectric absorption In the human body,_ is the predominant interaction through most of the diagnostic XR range Compton Scattering In effort to decrease the mAs of an exposure, the15% rule of kVp change may be considered. Changing the original kVp of 84 using 15% rule will have what impact greater Compton scatter interactions The incidence of the photoelectric effect increase with increasing atomic # of the absorber Photons that pass though the body unaffected produce radiographic contrast The atomic interaction that produces scatter radiation is Compton The greatest source during a radiographic examination is the patient As a general rule, a radiographic grid is employed for part thickness above 10 cm Which statement about radiographic grids is incorrect? a grid is a series of lead strips that alternate w/radiopaque interspace strips the purpose of moving the grid during the radiographic exposure is to blur out the radiopaque strips The ratio of the height of the lead strips to the distance between the lead strips is the grid ratio Which grid would have the greatest distance between lead strips? 6:1 Which grids would most effectively reduce scatter? 15:1 The # of grids lines per inch is the grid frequency As the lead content of a grid increases the ability of the grid to remove scatter increases Angulation across the long axis of a linear grid causes grid cut-off A device that moves the grid during a radiographic exposure is called a Potter-Bucky diaphragm A potter-bucky diaphragm must move the grid in a direction that is_ to the direction of the grid lines perpendicular Digital radiography (DR) is characterized by the use of reusable receptors Computers operate using a_ language binary machine Each binary # is called a bit An eight-bit word is called a byte When the main power to the computer is turned off,_ is erased RAM Which computer device does not store memory? mouse Indirect DR uses_ as the detector material amorphous silicon CR systems acquire clinical information by laser scanning a PSP plate The window level controls brightness The window width controls image density Resolution is controlled by_ size pixel A common feature between indirect & direct DR technology is thin film technology (TFT) Computerized digital images consist of a_ of picture elements, each w/a video display value or gray shade matrix Each pixel in a digital display matrix is located according to its electronic address A matrix of size 2048 x 1536 would have_ pixels 3,145,728 If the digital FOV is 1024 & the display matrix is 256, the pixel size would be 4 In digital imaging, the limiting factor in spatial resolution is the pixel size A pixel that has an 8-bit depth displays_ shades of gray 256 Which of the choices below would produce the highest spatial frequency & contrast? 3 mm renal calculi (stone) All of the following are related except one? manual processing In digital imaging processing, the digital data set is arranged into a histo-graph distribution in order to determine the exposure index & values of interest (VOI) The purpose of a LUT is to Apply a predetermined scale of contrast to the digital data set The relationship b/w digital image resolution Is direct w/matrix size & indirect w/pixel size Of the many types if digital image procedures performed in a contemporary medical imaging dept, the largest file sizes are typically generated by MRI The deviation index (DI) Compares entrance dose to the detector to a reference industry-standard target dose An S value of 200 represents a/an Exposure to the IP of 1 mR When changing exposure technique from 9 mAs to 18 mAs using computed radiography, the radiographer An EI # increase from Grossly overexposed digital images will demonstrate A loss of contrast Of the choices below, the greatest ALARA violation would be Repeating an image w/an S # of 210 b/c of exposure technique An XR exposure taken at 80 kVp has an average energy of 35 keV In the technology of CR, the latent image is actually Electrons "holes" in Europium All of the following impact digital image spatial resolution EXCEPT Bits/pixel When using a Fuji CR system in the fixed-mode of operation The system will not correct for exposure inadequacies by the computer to adjust density & contrast, ypur exposure techniques must be accurate, similar to film/screen texhnology All of the following are true of the Moire effect EXCEPT It is most likely to occur w/DR technology , particularly amorphous selenium