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130 mAs A radiograph is made using 40 mAs at a 40-inch SID. If the image must be repeated at a 72-inch SID, a value of 130 mAs is necessary to maintain the same exposure. This is determined by the exposure maintenance formula. An mAs of 12, 13, or 120 would not be enough to maintain the same exposure.
A radiograph is made using 40 milliampere seconds (mAs) at a 40-inch SID. If the image must be repeated at a 72-inch SID, what mAs value is necessary to maintain the same exposure? 13 mAs 12 mAs 120 mAs 130 mAs
15 mAs Per the mathematic expression for the exposure maintenance formula: mAs1/mAs2 = D12/D22 Where, mAs1 = original mAs value, mAs2 = new mAs value, D 1= original distance, and D 2= new distance. 60/x = (80) 2/(40) 2 60/x = (2) 2/(1) 2 60/x - 4/1 4X = 60 × 1 4X = 60 × 1 X = 15 mAs Therefore, the new mAs setting are 15 mAs. Per the calculation, 20 mAs, 35 mAs, and 45 mAs are incorrect.
A radiograph is produced at 80 inches source-to-image distance using 60 mAs. If the same procedure is repeated at 40 inches source-to-image distance, what is the new mAs setting required to maintain the same image receptor exposure? 15 mAs 20 mAs 35 mAs 45 mAs
The image receptor was underexposed. The exposure indicator displays a value that indicates insufficient technical factors were used to obtain the image. The image must be repeated to correct the image. mAs should be increased for the repeat exposure. -Quantum mottle or noise is an indication of insufficient receptor exposure. There are no display adjustments that can correct image noise, so a repeat image is required. The most appropriate technical factor correction is to increase the mAs (milliampere-seconds) to increase the beam intensity. Only adjusting the window level will not decrease the noise. In this situation, the patient was not overexposed.
A radiographic image displays with obvious quantum noise (mottle). Which is true? Select all that apply. The image only needs to have the window level adjusted to remove the noise. The patient was overexposed. The image receptor was underexposed. The exposure indicator displays a value that indicates insufficient technical factors were used to obtain the image. The image must be repeated to correct the image. mAs should be increased for the repeat exposure.
Increase in grid ratio Image contrast is affected by several technical factors. One of those factors is grid ratio. To increase contrast, the radiologic technologist will increase the grid ratio. An increase in grid ratio absorbs more scatter radiation, reducing image fog, resulting in an increase in image contrast.
A radiologic technologist is adjusting an image for optimum viewing. The technologist makes which adjustment to increase the image's contrast? Increase in grid ratio Increase in kilovoltage Decrease in kilovoltage Decrease in milliamperage
Quantum mottle Quantum mottle makes the radiographic image look grainy and occurs due to the limited number of x-rays cast on the image receptor. Debris in the IR leads to white spots on the image. Double exposures are seen when the same IR is exposed twice. Scatter radiation occurs when the x-rays are scattered due to any object. Scatter radiation reduces the image contrast.
Compare and contrast both images. Which effect is depicted in the first x-ray image? Quantum mottle Scatter radiation Double exposure Debris in the image receptor (IR)
80 kVp Measurement of the body part is not critical because part size is grouped as small, medium, or large. For most x-ray examinations of the spine and trunk of the body, the optimal kVp is approximately 80 kVp. Lower kVp may be used in extremity studies. 90 kVp may be used in barium studies.
For most x-ray examinations of the spine and trunk of the body, the optimal kilovolts peak (kVp) is approximately what value on the technique charts? 60 kVp 70 kVp 80 kVp 90 kVp
It results in higher energy. High kilovolt peak results in higher average energy of the beams. The primary interaction is by the Compton Effect, which produces more scatter radiation and thus results in reduced image contrast (long scale). Short exposure time, not high kilovolt peak, minimizes motion blur. High kilovolt peak does not affect exposure time or increase spatial resolution.
How does high kilovolt peak affect the x-ray beam? It minimizes motion blur. It results in higher energy. It increases exposure time. It increases spatial resolution.
C Exposure linearity is assessed by evaluating the radiation output of the x-ray tube at the adjacent milliampere (mA) stations. The radiation output of the adjacent mA stations should be within 10%. Thus, case 3 is said to have passed the test as the percent difference is equal to 6.25%, which is within 10%. The percentage difference at stations 1, 2, and 4 is not within the desired percentage difference of 10%.
In order to evaluate the exposure linearity of the x-ray tube, the exposure time is kept constant and the radiation output is evaluated at adjacent mA stations, as shown in the table. In which of the given cases has the equipment passed the test? A B C D
Filtration of the x-ray beam Because it is normally not possible to measure filtration directly, one resorts to measurement of the half-value layer (HVL) of the x-ray beam. The measured HVL must meet or exceed the value for the total filtration to be considered adequate. Focal spot size can be tested with a pinhole camera. A kVp meter can measure kVp. Positive beam limitation accuracy can be tested by the nine penny test.
One resorts to measurement of the half-value layer (HVL) of the x-ray beam because it is normally not possible to measure what parameter directly? Focal-spot size Kilovolt peak calibration Filtration of the x-ray beam Positive beam-limiting collimation
The patient was overexposed. The image receptor was saturated. -Excessive radiation exposure causes image receptor saturation, which in turn results in a loss of image contrast. The display or procedure (processing) parameters cannot be adjusted to correct this error in overexposure. The patient received too much radiation when the image was obtained. Adjusting the window width will not correct the patient's radiation dose. Similarly, selecting a different procedure will not necessarily correct these errors.
The exposure indicator displays a value that shows an excessive amount of radiation was used to produce a radiographic image using computed radiography. The displayed image has a loss of contrast. Considering these factors, which is true? Select all that apply. The image only needs to have the window width corrected for proper display contrast. The patient was overexposed. The image receptor was saturated. The exposure indicator and image can be corrected by choosing a different procedure. The patient was not overexposed.
It increases the contrast of the image. It avoids appearance of grid lines on the image. It decreases the amount of scatter radiation reaching the image receptor. The Bucky mechanism is a grid that is an integral part of an X-ray table; it is located above a cassette tray, below the tabletop. It increases the contrast of the image by decreasing the amount of scatter radiation reaching the image receptor. It avoids the appearance of grid lines on the image because of its movement during exposure. A flat panel detector is used for digital image creation and amplification. A collimator helps define the directions and dimensions of a radiation beam.
What are the functions of a Bucky mechanism in an imaging system? Select all that apply. It increases the contrast of the image. It avoids appearance of grid lines on the image. It helps in digital image creation and amplification. It defines the directions and dimensions of a beam. It decreases the amount of scatter radiation reaching the image receptor.
Anode and cathode The anode and cathode are the primary components of the x-ray tube. The x-ray tube is a diode - because it has two electrodes, the anode and cathode. The triode is not a component of the x-ray tube. The anode bearings and rotor are located inside the x-ray tube, but they are not primary components. The high-voltage cables and tube support mechanism are not components of the x-ray tube.
What are the primary components of the x-ray tube? Diode and triode Anode and cathode Anode bearings and rotor The high-voltage cables and tube support mechanism
The x-ray production falls. A Coolidge tube is a modern vacuum tube. If the Coolidge tube becomes gassy, x-ray production is reduced and may ultimately lead to failure of the x-ray tube. The microswitch is activated when the oil in the tube expands due to excessive heat. Excessive exposure may lead to pitting and cracking of the anode. Vaporization of the filament allows the tube current to stray and alters the electrical properties of the tube.
What happens if the Coolidge tube becomes gassy? The x-ray production falls. The microswitch is activated. The anode gets cracked or pitted. The electrical properties of the tube are altered.
It is a plot between frequencies of occurrence versus the digital value of each pixel. A histogram is a plot between frequencies of occurrence versus the digital value of each pixel. It is a characteristic feature of each anatomical projection and is very useful in digital radiography. It is not a plot between the digital values of each pixel versus the number of blank pixels. It is not a plot between the number of blank rows and the number of blank columns. It is not a plot between the digital values of each pixel versus the number of blank columns.
What is a histogram? It is a plot between the number of blank rows and the number of blank columns. It is a plot between frequencies of occurrence versus the digital value of each pixel. It is a plot between the digital values of each pixel versus the number of blank pixels. It is a plot between the digital values of each pixel versus the number of blank columns.
Preprocessing function equalizing each pixel response Flat fielding is a preprocessing function that adjusts pixel response to the x-ray beam. Compensation for dead pixels is known as interpolation. Monitor contrast and brightness is controlled by window width and window level. Recognition of collimated borders is a preprocessing function that is done on every digital image taken.
What is flat fielding used for? Recognition of collimated borders Changes contrast and brightness on the monitor Preprocessing function equalizing each pixel response Compensation for a dead pixel by assigning an estimated value to the area
Increases radiation dose of the patient The grid is a device that removes scattered photons exiting the patient before they reach the image receptor. Additional lead in the grid requires increased exposure factor settings, which increases the patient's dose. The grid removes scattered photons and reduces fog. Window level controls image brightness. Kilovolt peak controls the penetrating ability of the x-ray beam.
What is the consequence of using additional lead in the grid? Increases fog in x-ray film Controls image brightness Increases radiation dose of the patient Controls the penetrating ability of the x-ray beam
N s/N p The turns ratio of a transformer is the ratio of the number of windings on the secondary coil (N s) to the number of turns on the primary coil (N p), that is, N s/N p. According to transformer law, I s/I p= V p/V s= N p/N s. These values represent the inverse of the turns ratio.
What is the formula for the turns ratio of a transformer used in an x-ray imaging system? I s/I p V p/V s N s/N p N p/N s
It decreases the amount of scatter radiation. The part indicated with the red arrow in the figure is a radiographic grid. It decreases the amount of scatter radiation reaching the image receptor. The thin-film transistor (TFT) array isolates each pixel element. The window level changes the image brightness. A collimator controls the size and shape of the x-ray field.
What is the function of the part indicated with the red arrow in the figure? It isolates each pixel element. It changes the image brightness. It decreases the amount of scatter radiation. It controls the size and shape of the x-ray field.
Controlling contrast Window width is an image manipulation parameter that controls the contrast on the display monitor and controls the ratio between black and white. Scattering of radiation causes fog. Beam collimation controls the scattering of radiation and prevents fog. Penumbra is decreased by placing the object close to the image receptor. Window level controls the image brightness.
What is the function of window width? Decreasing fog Controlling contrast Decreasing penumbra Controlling image brightness
Some correct answers were not selected The x-ray beam quality increases. The x-ray beam penetrability increases. Added filtration delivers more uniform exposure to the image receptor. Therefore, it decreases patient dose, increases x-ray beam quality, and enhances x-ray beam penetrability. Added filtration has a negligible impact on image contrast and scatter radiation.
What is the result if the added filtration is increased? Select all that apply. Some correct answers were not selected The patient dose decreases. The image contrast increases. The scatter radiation decreases. The x-ray beam quality increases. The x-ray beam penetrability increases.
To ensure the x-ray exposure field is no larger than the receptor size PBL is a form of x-ray beam collimation of field size that ensures that the x-ray exposure field is no larger than the receptor size. An x-ray tube produces x-rays during radiography. A grid permits primary radiation to pass, while reducing scatter radiation by absorption. Spot film permits the acquisition of static images in a dynamic fluoroscopic examination.
What is the role of positive beam limitation (PBL)? To produce x-rays during radiography To permit primary radiation to pass by reducing scatter radiation To ensure the x-ray exposure field is no larger than the receptor size To permit the acquisition of static images in a fluoroscopic examination
Ask the patient not to move. Artifacts like blur and shadow are the unwanted blemishes on an image. The patient's movement during the capture of the radiographic film leads to blurs on the film. Thus, the radiologic technologist should ask the patient to not move during the procedure. The radiologic technologist uses a new image receptor to avoid double exposure. Focal spot size does not affect motion on an image. The patient should be advised prior to the examination to remove accessories to avoid unwanted artifacts on the radiograph.
What should the radiologic technologist do to correct motion in a radiograph? Adjust the focal spot size. Use a new image receptor. Ask the patient not to move. Ask the patient to remove accessories.
Upon overexposure to a digital image receptor The radiographer should set proper exposure factors for obtaining good-quality images. Overexposure to a digital image receptor results in a loss of contrast. Use of the highest grid ratio increases contrast. The presence of additional lead in the grid reduces the scatter and also increases contrast. Reduced source-to-image receptor distance increases magnification and causes distortion but does not affect contrast.
When does a radiographer observe loss of contrast in a radiographic image? Upon use of the highest grid ratio Upon overexposure to a digital image receptor Upon the presence of additional lead in the grid Upon reducing the source-to-image receptor distance
Decreasing the distance between the beam and the object When the x-ray tube is placed closer to the object, penumbra is increased. Smaller pixel size improves image resolution. Decreasing the amount of scatter enhances radiographic contrast. Increasing source-to-image distance decreases the magnification.
When is penumbra increased? Selecting a smaller pixel size Enhancing radiographic contrast Increasing source-to-image distance Decreasing the distance between the beam and the object
Scatter radiation decreased CNR is improved when scatter radiation is reduced, not increased. Increasing or decreasing focal spot size will not impact CNR.
Which adjustment will have an impact on contrast to noise ratio (CNR) in digital radiography? Focal spot size increased Focal spot size decreased Scatter radiation increased Scatter radiation decreased
Intensity of exit radiation AEC measures the radiation intensity after it passes through the patient, which is exit radiation. Beam intensity is an expression of x-ray quantity. The focal spot size and the half value layer are not related to AEC.
Which factor is measured by automatic exposure control (AEC)? Focal spot size Half value layer Intensity of exit radiation Intensity of the primary beam
Grid ratio Scatter radiation Quantum mottle Beam restriction The factors that affect scatter radiation and signal to noise ratio (SNR) also affect contrast to noise ratio (CNR). Factors that affect scatter radiation are grid ratio and beam restriction. The presence of quantum mottle also affects CNR. CNR is improved when scatter radiation is reduced. SID and focal spot size do not affect CNR.
Which factors affect contrast to noise ratio (CNR) in digital radiography? Select all that apply. Some correct answers were not selected SID Grid ratio Focal spot size Scatter radiation Quantum mottle Beam restriction
Use of faster image receptors Use of minimum peak kilovoltage setting X-ray tube life can be extended with proper handling and maintenance. Use of minimum peak kilovoltage (kVp) settings and faster image receptors extend the life of an x-ray tube. Using short exposure times extends x-ray tube life. Using gassy Coolidge tubes may damage the x-ray tube. Heat causes expansion of the oil in the x-ray tube, which has a negative effect on tube life.
Which factors can extend x-ray tube life? Select all that apply. Use of long exposure time Use of a gassy Coolidge tube Use of faster image receptors Use of minimum peak kilovoltage setting Expansion of oil in the x-ray tube housing
It permits "real-time" imaging of dynamic patient functions Digital fluoroscopy systems record images electronically rather than using cassettes Dose-reduction features such as last image hold (LIH), pulsed fluoroscopy, and electronic shuttering are essential -Fluoroscopy permits "real-time" imaging of dynamic patient functions. Digital fluoroscopy systems record images electronically rather than using cassettes. In fluoroscopy, dose-reduction features such as LIH, pulsed fluoroscopy, and electronic shuttering are essential. The lead protective apron attached to the fluoroscopic carriage is of great value in reducing operator dose.
Which is (are) true of fluoroscopy? Select all that apply. It permits "real-time" imaging of dynamic patient functions Digital fluoroscopy systems record images electronically rather than using cassettes The lead protective apron attached to the fluoroscopic carriage is of little value in reducing operator dose Dose-reduction features such as last image hold (LIH), pulsed fluoroscopy, and electronic shuttering are essential
Modulation transfer function (MTF) The basic definition of MTF is the ability of a system to record available spatial frequencies. The dynamic range refers to the ratio of the largest and smallest values within a specific quantity. Nyquist frequency refers to the minimum rate of which a frequency can be sampled without errors being introduced. DQE relates to the measure of combined effects of signal and noise, not spatial frequencies.
Which is the ability of a system to record available spatial frequencies? Dynamic range Nyquist frequency Modulation transfer function (MTF) Detective quantum efficiency (DQE)
Interpolation Digital radiographic images must be manipulated before processing them. Manipulation involves assigning values to dead pixels and dead rows or columns in the image, based on adjacent pixels. This method is called interpolation. Image compression helps compress the file size for teleradiography. Analysis of the image histogram is important for image production, not for the elimination of dead pixels. A characteristic curve gives a relationship between optical density and radiation exposure. It does not help eliminate the dead pixels in the output of image receptors.
Which method is used to eliminate dead pixels in the output of a digital image receptor? Interpolation Image compression Image histogram analysis Characteristic curve preparation
Smoothing Smoothing is used to reduce the display of noise in an image. Subtraction is used to remove background anatomy and allow visualization of contrast media-filled vessels. Window width is used to control the contrast of the image. Image reversal is used to reverse the dark and light pixel values of an image.
Which post-processing option is used to reduce the display of noise in an image? Smoothing Subtraction Window width Image reversal
Flatfielding Flatfielding is a software correction that equalizes the response of each pixel to a uniform x-ray beam, thus helping reduce the heel effect observed in digital radiographs exposed to a raw x-ray beam. Collimation does not reduce the heel effect; it helps focus the x-ray beam. Interpolation helps give a value to dead pixels and makes the images more interpretable. Screen-film technology is not used in digital imaging.
Which process helps reduce the heel effect on digital radiographic images? Flatfielding Collimation Interpolation Proper screen-film contact
Variable kilovoltage chart The variable-kVp radiographic technique chart uses a fixed mAs value and a kVp that varies according to the thickness of the anatomical part. In general, exposures made with this method provide radiographs of shorter contrast scale because of the use of lower kVp. High kilovoltage charts, fixed-kVp charts, and automatic exposure control charts all use higher kVp.
Which radiographic technique chart generally uses lower kilovolts peak (kVp)? High kilovoltage chart Fixed kilovoltage chart Variable kilovoltage chart Automatic exposure chart
Heel effect The image depicts the heel effect, which occurs due to the difference in exposure on the image. Some parts of the image may look bright, and other parts may look dark due to the heel effect. Pixel shift is a technique used to correct the image misregistrations that occur during the subtraction serial image acquisition. Image lag occurs when there is a time lag of the input signal to display the image. Line noise results in the appearance of linear artifacts on the radiographic image.
Which term describes the variation in intensity seen on this image? Pixel shift Image lag Line noise Heel effect
Half-wave-rectified circuit The circuit represents a half-wave-rectified circuit, which contains one or more diodes. A circuit with a high-frequency generator produces a nearly constant potential voltage waveform. The unrectified voltage circuit shows the unrectified voltage at the secondary side of the high-voltage step-up transformer. A full-wave-rectified circuit contains a minimum of four diodes.
Which type of circuit does the figure represent? High-frequency circuit Full-wave-rectified circuit Half-wave-rectified circuit Unrectified voltage circuit
High frequency A high frequency generator has the least percentage ripple, less than 1. A full wave generator has a percentage ripple of 100. A half wave generator has a percentage ripple of 100. A 3 phase, 6 pulse generator has a percentage ripple of 4.
Which type of generator has a percentage ripple of less than 1? Full wave Half wave High frequency 3 phase, 6 pulse
Increase in beam restriction Contrast resolution is increased when scatter is reduced. An increase in beam restriction will increase contrast resolution. Increase in kilovolt peak (kVp), milliamperage-seconds (mAs), and source to image distance (SID) will not increase contrast resolution.
Which will increase contrast resolution in a digital image? Increase in kVp Increase in mAs Increase in SID Increase in beam restriction
To lower the patient's dose To improve image resolution Using cesium iodide as a detector material reduces exposure and lowers the patient's dose. It also helps improve image resolution. Avoiding the use of high temperature chemical solutions for image processing prevents chemical fog. A sufficient amount of light emitted from the phosphor crystals prevents quantum mottle. Beam modification during radiography controls the scattering of radiation.
Why is cesium iodide used as a detector material in fluoroscopy? Select all that apply. Some correct answers were not selected To prevent chemical fog To reduce quantum mottle To lower the patient's dose To improve image resolution To control scattering of radiation
To control image brightness Window level is the postprocessing option that adjusts the brightness of the image. Window width adjusts the contrast of the image. Magnification is used to magnify all or part of an image. Equalization is used to alter the pixel values across the image.
Why is the window level adjusted during postprocessing of an image? To control image contrast To control image brightness To magnify all the parts of the image To alter the pixel value of the image