Image production
What is the longest field size dimension allowed by a 10" x 12" collimator at a 40 inch SID?
12.8 inches. Field size may be off by +\- 2% of the S ID, which in this case is .8 inches.
When technique produces a 2 mR exposure to an image receptor plate of 70 kVp at 25 mAs produces 1.6 mR? A) 70 KVP at 50 mAs B) 70 KVP at 27.5 mAs C) 70 KVP at 31.25 mAs D) 70 KVP at 35 mAs
70 KVP at 31.25 mAs 2 mR is 25% greater than 1.6 MR; so, a 25% increase in mass achieves this result. 25 mAs X 1.25 = 31.25
As the anode angle is decreased, what happens to the severity of the anode heel affect? A) increased heel effect B) decreased here effect C) no change in heel effect
A
What type of contrast would result from using high kVp values prior to image processing? A) Low scale of contrast B) high scale of contrast C) kVp has no effect on contrast
A
Which two of the following image receptor designs is/are used in direct radiography imaging equipment? (Select two) A) wired flat panel detector B) wireless flat panel detector C) cassette-based imaging plates D) Filmscreen cassettes
A and B. DR detectors must be connected in someway to the computer system. This can be done through a physical wire, or information from the detector can be sent wirelessly to the computer system. By definition, DR systems do not use a cassette.
Which two of the following will be affected by a change in the actual focal spot size? A) effective focal spot B) spatial resolution C) Image contrast D) Image receptor exposure
A and B. The actual focal spot is the area within the anode target where the x-ray photons are produced. The size of the actual focal spot is designated by the selection of the filament within the focusing cup. The selection of the small filament will result in a small actual focal spot, producing a smaller effective focal spot. Small actual focal spots result in a higher spatial resolution, due to decrease in blur. The effective focal spot does not have an impact on image contrast or image receptor exposure.
Which two of the following will be affected by a change in the actual focal spot size? A) effective focus spot B) special resolution C) Image contract D) Image receptor expose
A and B. The effective focal spot and spatial resolution will be affected by change in the actual focal spot size. The actual focal spot is the area within the Ano target where the x-ray photons are produced. The size of the actual focal spot is designated by the selection of the filament within the focusing cup. The selection of the small filament will result in a small actual focal spot, producing a smaller effective focal spot. Small actual focal spots result in a higher spatial resolution, due to the decrease in blur. The effective focal spot does not have an impact on image contrast or image receptor exposure.
A beam with more divergence can cause increase: (select two); A) penumbra B) IR exposure C) distortion D) production of scatter radiation
A and C. A more divergent beam can cause increased penumbra and increase distortion. Beam divergence describes the extent to which the x-ray photon spread out as they leave the x-ray to. For each example, a short SID has a high level of beam divergence. Image receptor exposure and scatter production are not affected by beam divergent.
Which two of the following variables would result in the smallest effective focal spot size? (Select two) A) anode angle of 5° B) anode angle of 20° C) filament size of 0.3 mm D) filament size of 2 mm
A and C. The effective focal spot size is affected by both the anode angle and the filament size. The smallest effective focal spot size can be accomplished by the smallest filament size and the smallest anode angle.
What do you mean is components are included in a digital imaging system that converts x-ray photons directly into electrical signal? A) TFT array B) scintillator C) photodiode D) amorphous selenium (a-Se)
A and D. A direct capture imaging system uses amorphous selenium to convert incident x-ray protons directly into electrical signal. This electrical signal is collected by the thin film transistor array. The scintillator Layer and photo diode are not included in a digital imaging system that converts x-ray photons directly into electrical signal
Which changes needed to compensate for a soft tissue mass in the abdomen? A) increase mAs B) reduce KVp C) reduce mAs D) increase SID
A)
If the generator you are using has 1000 mA capacity and your technique is 20 mAs at 74 kVp, what is the shortest exposure time possible? A) 0.02 seconds B) 0.2 C) 50 D) 5.0
A) 0.02 to find the exposure time, simply use the following formula: mAs/mA = exposure time 20 x 1000 = 0.02 seconds
A radiographs taken using 10 mAs with a 16:1 grid. A new radiograph is needed for the same patient, but using a 6:1 grid. What new mAs is needed to maintain the same image receptor exposure? A) 5 mAs B) 3 C) 22 D) 17
A) 5. Formula: mAs1 / mAs2 = GCF1/ GCF2 No grid = 1 5:1 grid = 2 6:1 grid = 3 8:1 grid = 4 12:1 grid = 5 16:1 grid =6 Equation: 10/x = 6/3
And radiograph is acquired using 12.5 mAs at 40 inch SID And results and excessive Magnification. If the S ID is changed to 80 inches, what new mAs should be used to maintain image receptor exposure? A) 50 mAs B) 25 C) 10 D) 3
A) 50 increasing the SID helps reduce Magnification, but the mAs needs to be increased, following the direct square law. mAs1/mAs2 = D1^2/D2^2 12.5/X = 1600/6400. => x =50 Also, anytime you double the distance the intensity decreases by four times (inverse square law). Therefore, that mAs needs to be increased by four. (12.5 x 4= 50)
Compared to the central axis of the x-ray beam, the anode side of the useful beam is what percentage of the central axis beam intensity A) 75% B) 95 C) 100 D) 120
A) 75 The cats outside has an intensity of approximately 120% of the central beam
What mA station would be used for an exposure with a 0.6 seconds and 50 mAs? A) 83 mA B) 30 C) 38 D) 156
A) 83.3 mA. To calculate mA, you should use the following formula: mAs/exposure time = mA 50/0.6 = 83.3 To check your answer, take the newly calculated mA of 83.3 and multiply it by 0.6 seconds. If your answer is 50 then you did the math correct.
A digital imaging system can often produce quality radiographs even when the patient status is much higher than desired. This is a result of what quality of radiographic system? A) large dynamic range B) large exposure range C) large bit depth D) large matrix size
A) A digital imaging system can often produce quality radiographs even when the patient dose is much higher than desired due to a larger dynamic range. Radiographers should always aim to use appropriate amount of radiation. Even if too much radiation is used, since the system has a large dynamic range, it will still be able to produce a quality image. This is because as long as the image receptor can capture exposure, the system will process the data and attempt to produce an image. In this case, an overexpose radiograph would be considered within the dynamic range, but outside of the desired range of acceptable exposures.
What type of contrast would result from using high KVP values prior to image processing? A) Low scale contrast B) high scale contrast C) kVp has no effect on contrast
A) A lower scale contrast would result from using high KVP values, but only before imaging processing. High kVp results in low contrast due to the relationship between kVp and Compton scatter. As kVp increases, Compton scatter increases that's decreasing contrast. However, during image processing, the look up table is applied. The LUT controls the visible contrast of a digital image by applying proper contrast regardless of the kVp used.
Which of the following is used to change the grayscale values in the recorded image to a new range of values in order to improve the displayed image? A) LUT B) quantization C) Values of interest VOI D) equalization
A) ALUT is applied to the data that has the standard contrast for that exam to provide the desired image contrast for display. Selecting a proper projection by informing the processing system of which projection it is to process ensures that the proper LUT will be applied when the image is processed. The proper LUT will provide the proper grayscale, regardless of variations in the technical factors, resulting in consistent images.
In what format must images be in so that they can be sent throughout the image viewing system? A) DICOM format B) PACD format C) FPD format D) PSP format
A) DICOM format. This makes it possible for equipment from different manufacturers to communicate with each other.
Which of the following includes direct patient care information, billing systems, and reporting systems? A) hospital information system (HIS) B) radiology information system (RIS) C) Picture archiving and communication system (PACS) D) Digital imaging and communication in medicine (DICOM)
A) HIS The RIS information system is used in the radiology department for ordering examinations and reporting results. PACS consist of digital acquisition, display workstations, and storage devices enter connected through a network. DICOM is a global information technology standard that allows network communication between a modality and a PACS
Which of the following is accurate regarding low pass filtering, or smoothing? A) smoothing is a local processing operation B) smoothing is a point processing operation C) smoothing is a geometric processing operation
A) Low past filtering, or smoothing, is a local processing operation, this operation initially blurs the image, reducing noise and the displayed brightness level of the pixel. This process also decreases image detail, which is not desirable. Therefore, low pass filtered image should also be viewed in a normal or high pass mode.
To evaluate the luminescence response of a digital display monitor, one would need to utilize a: A) Photometer B) densitometer C) sensitometer D) dosimeter
A) Photometer. If a photometer is not available,luminesce response can be a valuated visually using test patterns.
Which of the following factors does not influence image contrast? A) SID B) kVp C) part size D) scatter radiation
A) SID. Scatter radiation affects contrast by adding more exposure to the image receptor. KVp affects contrast by its influence on scatter production. Changes in part size also influence contrast. Remember the phrase; " more matter = more scatter". And of course, more scatter results in decreased image contract.
The spatial resolution of a radiograph system is expressed in units of; A) line pairs per millimeter (mm) B) Milligray (mGy) C) Milligray (mGy) -centimeters (cm)2 D) bits
A) Spatial resolution of a radiographs system is expressed in units of line pairs per millimeter, which can be written as lp/mm. The higher the measurement expressed the higher the special resolution. Milligray is a unit of absorbed dose, while bit is a binary number.
DR systems typically use TFT. This device functions to: A) correct the electrical charge B) convert x-ray photons into light C) collect light and convert it into electron D) convert the electrical signal into digital signal
A) TFTs functions to collect the total electrical charge from the DEL and deliver that electrical charge to the A/D converter for digital processing. The centiliter layer converts x-ray photons to light, while the analog to digital converter converts electrical charges to digital signal.
The brightness of the image on a viewing monitor as a result of: A) A monitor function B) Image receptor exposure C) tissue composition D) part thickness
A) The computer can easily change the brightness of the image using mathematical re-calculations.
How will the voltage of the secondary side be affected if there are more windings on the primary side of the transformer? A) The voltage will decrease B) The voltage will increase C) The voltage will remain the same
A) The secondary side voltage will decrease if there are more windings on the primary side of the transformer. This means that this is a step down transformer.
Compared to the central axis of the x-ray beam, the anode side of the useful beam is what percentage of the central axis beam intensity? A) 75% B) 95% C) 100% D) 120%
A) Think of the central axis of the x-ray beam as having 100% intensity. The anode side of the beam has decreased intensity, which is approximately 75% of the central axis beam intensity. The cathode side of the x-ray beam has increased intensity compared to the central axis. The cathode side has an intensity of approximately 120%, compared to the central beam. This is why it is so important to orientate the x-ray beam with the anode side over the thinnest portion of the patient and the cathode side over the thicker portion of the patient.
To reduce the severity of the anode heel effect, the SID can be: A) increase B) decrease C) changes in S ID have no impact on the heel effect
A) When shorter SID yes you, the image receptor is exposed to a greater amount of both high intensity photons produced on the cathode side of the x-ray tube, as well as low intensity -anode side photons.
Which of the following technical factor adjustments should be made when negative contrast media agents are used? A) decrease kVp B) increased kVp C) increased mAs D) decreased mAs
A) decrease kVp because negative contrast media agents have lower atomic numbers and, therefore, require less penetration.
Increasing the focal spot size has what effect on spatial resolution? A) decreasing spatial resolution B) increasing spatial resolution C) no change in spatial resolution
A) decrease. A large focal spot size allows for the use of a higher mAs, but it also decreases the spatial resolution. The focal spot size is a major controller of spatial resolution because it controls blur. The fact that the source of the x-ray photons is not a point source is what causes blur. As the focal spot decreases in size, blurred also decreases, thus increasing resolution. Vocal spots are usually not capable of imaging structure smaller than the focal spots in themselves.
Which pathologic condition requires a reduction in exposure factors to produce an acceptable image? A) emphysema B) atelectasis C) congestive heart failure D) Late stage pagets disease
A) emphysema is considered a destructive disease which requires a reduction in exposure factors.
Which technical factor should be used to control subject contract? A) kVp B) mAs C) SID D) FSS
A) kVp should we use to control subject contrast. As kVp increases, a wider range of photon energies is produced. The wider range of photon energies, the greater the ability of the photons to penetrate the body part. Excessive kVp Values reduce differential attenuation and consequently decreased subject contrast. SID, FSS, and mAs I have no effect on subject contrast.
Why must alternating current be used in the X-ray circuit? A) transformers cannot work without AC B) electrons cannot flow without AC C) x-ray to must have a C to produce x-rays D) AC is the only type of current available
A) rectifiers are used to convert alternating current to direct current before it reaches the X-ray tube.
Which of these changes are expected to decrease spatial resolution in the radiographic image? A) increased motion B) Increase kVp C) increase mA D) increased filtration
A) spatial resolution is affected by increased motion because the edges of objects are blurred on the radiograph. kVp, mAs, and filtration do NOT affect The sharpness of structural address, and, therefore, they do not affect spatial resolution.
What is the most common cause of an off level grid error; A) Grid misalignment due to uneven patient weight distribution B) Grid is placed upside down C) grid is not centered to the radiation beam D) Grade is used at the wrong source to image distance (SID)
A) this can occur when stationary grids are used for mobile procedures or decubitus views. Off level errors are like angling the beam across the lead strips, causing an undesirable absorption of primary radiation, which results in a radiograph with a decrease in exposure across the entire image. This occurs because the lead strips do not line up with the divergence of the primary beam.
To reduce the severity of the anode heel affect, the SID can be: A) increase B) decrease C) changes and SID have no impact on the heel effect
A) to reduce the severity of the anode Hill affect, as ID can be increased. When a shorter SID is used, the image receptor is exposed to a greater amount of both high intensity photons produce on the cathode side of the x-ray tube, as well as a low intensity anode side photons. When we begin to increase the SID, that is, move the x-ray tube farther away from the image receptor, the difference between photon intensities begins to also decrease, which decreases the divergence of the beam, and, therefore, decreases the severity of the anode heel affect .
As the matrix size increases, the pixel size decreases. A) True B) false
A) true, decreases. There is an inverse relationship between matrix size and pixel size. If the metric size is increased, the field of view will increase therefore the size of pixel must get smaller in order to fit into the same sized area. This increases spatial resolution because smaller structures are better visualized when the pixel size decreases.
Grid ratio has a significant influence on the radiographic contrast: A) true B) false
A) true. Grids remove scatter radiation that would otherwise reach the image receptor and decrease image contrast.
Radiographs that present with decrease exposure on the lateral edges of the image and normal exposure in the center may be caused by which focus grid error? A) upside down grid error B) off focus error C) off level error D) off center error
A) upside down. When an exposure is made with a grid placed upside down, radiation will pass through the grid along the central axle where the lead strips are most perpendicular and radiation will be increasingly absorbed away from the center. Therefore, the x-ray photons directed towards the center of the grid will be transmitted and result in normal exposure, but a significant number of protons on the lateral edge will be absorbed, resulting in a decreased exposure.
Which factors affect radiographic Image density (select the four that apply) A) mAs B) SID C) kVp D) Filmscreen system speed E) Digital imaging system speed
A, B, C, D. Ask AVP increases, density increases. As film screen imaging system speed increase, density increases. As mAs increases, density increases. As SID increases, density or brightness decrease. However, digital imaging system speed does not affect density, as the reconstruction program is set up to produce an acceptable density range for a variety of exposure conditions.
Which three of the following would be caused by increased diagnostic filtration? A) lower patient dose B) Higher patient dose C) lower contrast D) decreased exposure to the image receptor E) increased exposure to the image receptor
A, C, D. Lower patient does, lower contrast, and decrease exposure to the image receptor would be caused by increase diagnostic filtration. Increased filtration lowers the patient does by absorbing lower energy photons that would not otherwise have enough energy to penetrate the part of interest. Increase filtration decreases contrast by increasing the average energy of the beam, thereby increasing scatter production. Image receptor exposure is also decreased because some of the photons that would have added exposure or removed from the beam .
Image receptor exposure is affected by which three of the following? (Select three) A) kVp B) focal spot size C) collimation D) filtration
A, C, D. mAs is considered the controlling factor for image receptor exposure, due to her directly proportional relationship. Image receptor exposure is also affected by collimation (filed size), kVp, and filtration . For example Increasing collimation reduces the number of x-ray protons in the beam and decreases image receptor exposure. Increasing filtration also removes x-ray protons out of the beam and decreases image receptor exposure.
Which three of the following statements correctly describes the exposure indicator (EI)? Select all the apply A) reflects the amount of image receptor exposure to a digital image receptor B) have a direct relationship with image receptor exposure C) be useful in determining patient exposure D) do used to assess image quality
A, C, and D. Exposure indicators have an inverse relationship with image receptor exposure.
Which three of the following would be caused by increased diagnostic filtration? (Select three) A) lower patient does B) higher patient does C) lower contrast D) increased exposure to the image receptor E) decreased exposure to the image receptor
A, C, and E. Increasing filtration lowers the patient dose by absorbing low energy photons that would not otherwise have enough energy to penetrate the part of interest. Increase filtration decreases contrast by increasing the average energy of the beam, therefore increasing scatter production. Image receptor exposure is also decreased because some of the photons that will have added exposure are removed from the beam.
X-ray machines are designed to operate at a specific and continuous supply voltage. Which part of the imaging system is responsible for keeping incoming voltage adjusted to the proper value? A. Line compensator. B. Kilovolts peak (kVp) meter. C. Autotransformer. D. Milliampere (mA) meter.
A. Line compensator The line compensator adjusts the voltage supplied by the power company, which fluctuates due to variations in power distribution and consumption.
Which digital post-processing results in a black background surrounding the original collimated edges? A. Shuttering B. beam restriction C. Subtraction D. Collimation
A. Shuttering Shuttering is a post exposure processing technique that results in a black background surrounding the original collimated edges.
What do limiting spatial resolution (LSR) and modulation transfer function (MTF) have in common? A. They both measure spatial resolution in digital imaging. B. They measure how efficiently an image is moved to the picture archiving and communication system (PACS). C. They both affect brightness of the digital image. D. They are both indicators of exposure for digital receptors.
A. They both measure spatial resolution in digital imaging. LSR and MTF are measures of how accurately anatomy is reproduced in a digital image or measures of spatial resolution.
Which of the following factors have an impact on image contrast? ( select all that apply) A) grids B) kVp C) filtration D) collocation
All of the above. Grades improve contrast by removing scattered before it reaches the image receptor. kVp Will increase the amount of Compton scatter reaching the image receptor thus decreasing image contrast. Filtration increases the effect of KVP by changing the average photon energy of the beam. Collimation reduces the total number of photos available which reduces the amount of scatter radiation and therefore increases contrast.
A grid designed such that the angle of the lead strips align with the divergence of the beam is called a; A) cross hatched grid B) Focus grid C) linear grid D) inverted grid
B
The phosphor layer in a CR imaging plate is composed of? A) barium flourhalide B) amorphous selenium C) amorphous silicon D) cesium iodide
B
When using AEC, excessive image receptor exposure may result in an image with incorrect; A) mA setting B) radiation detector selection C) SID D) kV setting
B
How does the anode heel affect manifest itself on a radiographic image (select two) A) higher exposure on the anode side of the image B) higher exposure on the cathode side of the image C) increase detail on the anode side of the image D) increase detail on the cathode side of the image
B and C
What do changes will result when increasing the source to image distance (SID)? A) decrease spatial resolution B) increase spatial resolution C) decrease Magnification D) increase a Magnification
B and C
How does the anode heel affect manifest itself on a radiographic image? (Select two) A) higher exposure on the anode side of the image B) higher exposure on the cathode side of the image C) increase detail on the anode side of the image D) increase detail on the cathode side of them image.
B and C. The Anode heel effect causes x-ray photons to be absorbed in the heel of the anode. This results in a decrease in beam intensity (exposure) on the anode side and a higher intensity on the cathode side. The angle of the anode also causes an increase in photon alignment on the anode side, which results in more detail, and decreased alignment on the cathode side of the beam, resulting in less detail.
Which two in the following factors will result in improve spatial resolution? (Select two) A) increased SID B) increased OID C) decreased SID D) increased FSS E) decreased FSS
B and E
Which steps increase contrast in fluoroscopy? (Select the two that apply.) A. Increase kVp B. Use a smaller collimator field C. Use a larger collimator field D. Increase mA E. Reduce kVp
B and E. Using a smaller collimator field increases contrast, by reducing scatter and secondary radiation production, and thus reducing fog. Reducing KVP increases contrast, at the risk of lowered penetration. Changing MA does not impact contrast, assuming adequate exposure is used. The use of a larger collimator field will reduce contrast by increasing secondary and scattered radiation production increase in kVp increases penetration and reduces contrast.
Collimator misalignment must be within what percentage of the SID A) 1% B) 2 C) 5 D) 10
B) 2% The center of the Becky tray in the center of the x-ray beam must be a line to avoid clipping anatomical structures of interest and to avoid grid cut off
How many heat units are generated during an examination performed on a 40 year old man using 30 mA, A 0.125 second exposure, 60 kVp and a high frequency generator if the image had to be repeated? A) 6075 heat units B) 6525 heat units C) 2250 heat units D) 3150 heat units
B) 6525 mA x exposure time x kVp x rectification constant = heat units Note that there was two exposures so the formula must be multiplied by two. 300 x .125 x 60 x 1.45 x 2 = 6525 HU
Hey will you grab his produce using 4 mAs and 70 kVp. The resulting image receptor exposure is 0.001 mGy. If the technical factors are changed to 8 mAs with the new kVp, The next radiograph will have an image receptor exposure of; A) 0.0005 mGy B) 0.002 C) 0.004 D) 0.01
B) Exposure of 0.002 mGy. changes in the mAs results in proportional changes to the image receptor exposure. Therefore, when mAs doubled, image receptor exposure is also doubled.
A radiograph was few shades of gray exhibits; A) Low contrast B) high contrast C) medium contrast D) Long contrast
B) High contrast images have a wide histogram and can also be described as having a short scale contrast.
What is vignetting? A) automatic brightness control circuit B) decrease in light intensity at the periphery of a fluoroscopic image C) The ability of the eye to perceive fine detail D) increase in spatial resolution at the center of the fluoroscopic image
B) It is caused by light scatter within the active image area
The radiologist request an image of the splenic flexure and descending colon following a Floro portion of the lower gastrointestinal study. Which of the following projections would best demonstrate this anatomy? A) RAO abdomen B) LAO C) PA D) lateral
B) LAO would best demonstrate this anatomy. The best projections to demonstrate the splenic/left colic flexor and the descending colon are the LAO in the RPO projection.
Collimator misalignment must be within what percentage of the source to image distance? A) 1% B) 2% C) 5% D) 10%
B) The center of a Becky tray in the center of the x-ray beam must be a line to avoid clipping anatomical structures of interest and avoid grid cut off.
In a direct capture digital radiography system, a decrease detector element size results in: A) decrease spatial resolution B) increase spatial resolution C) increase contrast resolution D) decreased contrast resolution
B) TheDEL size refers to the physical measurement of the DEL, and the smaller the DEL, the higher the spatial resolution because this improves the ability of the system to demonstrate smaller structures. DEL size does not affect contrast resolution.
The side of the x-ray tube with a negative charge is the: A) anode B) cathode C) focusing cup D) rotor
B) cathode
Which of the following is produced by a digital image receptor? A) Digital matrix B) electronic signal C) Picture element D) detector size
B) electrical signal. This information has to be converted into a digital signal before it is processed. Detector elements are charge collecting elements used in flat panel detectors. They are also organized in the matrix.
A radiograph that has high image contrast will have: A) many shades of gray B) few shades of gray C) increased amount of blur D) decrease amount of blur
B) few shades of gray or a significant amount of black and white. Inversely, a low contrast image has very little black and white in numerous shades of gray. Contrast and blurred or not related, because a high contrast image may have a high amount of blur or a low amount of blur.
A grid design such that the angle of the lead strips aligns with the divergence of the beam is called a: A) cross hatch grid B) focused grid C) linear grid D) inverted grid
B) focused grid because the lead strips match the focus of the divergent x-ray beam. Crosshatch grids have grid lines running at right angles. Linear grids have lead strips that are running in only One Direction but do not align with the divergence of the beam. An inverted grid is not a grid type.
Which of the following changes will increase spatial resolution recorded in the radiographic image? A) decrease SID B) increase SID C) increase OID D) increase FSS
B) increase SID. A larger SID reduces the divergence of the x-ray photons and therefore decreases the appearance of blur. Increase spatial resolution can also be accomplished by decreasing the OID and decreasing the FSS.
How many heat units (HU) are generated during an examination performed on a 45 year old male using 300 mA, a 0.125 Second exposure, 60 kVp and a high frequency generator if the image had to be repeated? A) 6075 HU B) 6525 C) 2250 D) 3150
B) mA x exposure time x kVp x rectification constant = HU The rectification constant for a high frequency generator is 1.45. Also know that there was a repeat performed resulting in two exposures. Therefore, all the factors listed in the formula must be multiplied by two. Therefore, the equation would be set up as: 300 x .125 x 60 x 1.45 x 2 = 6,525 HU
What compound is used in flat panel image receptors to convert incoming x-ray photons directly into an electrical signal? A) cesium iodide B) amorphous selenium C) amorphous silicon D) gadolinium oxysulfide
B) none of the other compounds listed can be used in this way. Cesium iodide and gadolinium are scintillators, while amorphous silicone as a light detector and therefore cannot convert x-ray photons directly to an electrical signal.
Dynamic range is defined as the: A) range of exposures that produce quality images at an appropriate patient dose B) range of exposures that can be captured by a detector C) Number of x-ray photon striking the image receptor D) sharpness of structural lines recorded in the radiographic image
B) range of exposure that can be captured by a detector.
Prior to performing a PA Chess projection with AEC The radiographer discovers that the patient has had a right total pneumonectomy. Which technical consideration should be considered? A) selecting the center detector B) selecting only the detector on the right side C) selecting both outer detectors D) selecting only the detector on the right side
B) selecting the last to tactor in this scenario will result in proper exposure of the image and is the correct answer. If only the right detector is selected, the exposure will be too dark for an optimal image. If the radiograph are selects both outer detectors, the exposure will be too dark because the cell is detecting the increase density and the right hemothorax which has gradually filled with interstitial fluid following the surgery. Selecting the center detector places the T spine in the detector, which is more dense than the lung and will cause an over exposed image.
Focal spot size affects which of the following? A) Magnification B) spatial resolution C) Image receptor exposure D) Image contrast
B) spatial resolution
When using AEC, excessive damage receptor exposure may result in the image with incorrect: A) mA setting B) radiation detector selection C) SID D) KV setting
B) when using AEC, incorrect radiation detector selection may result in an image with excessive image receptor exposure. AEC is designed to maintain the same image receptor exposure regardless of changes in other variables, like KV, SID, or mA. Incorrect radiation detector selection can affect image receptor exposure because one of the radiation detectors may receive insufficient radiation and consequently terminate the exposure too late, resulting in excessive exposure to the image receptor. For example, if an automatic structure with increase tissue density is placed over a radiation detector, this will increase the exposure time and possibly result in over exposure to the receptor.
Which three of the following parts are used in making a transformer? A) transformer capacitor B) Core C) primary coil D) secondary coil
B, C and D.
Who judges radiographic images for quality? (Select the four that apply.) A. Lawyers B. Quality control technologists C. Radiologists D. Radiographers E. Ordering physicians
B, C, D, E. Lawyers depend upon hired expert radiologist to judge radiographs for them.
Why should a radiographer routinely use a small focal spot when imaging extremities? A. Decrease in contrast. B. Increase in recorded detail. C. Decrease in patient dose. D. Increase the life of the x-ray tube.
B. Increase in recorded detail. A smaller focal spot decreases unsharpness and increases recorded detail. This is important when imaging extremities.
How is signal maximized to a digital image receptor? A. Shorter exposure time B. Longer exposure time C. Higher source to image receptor distance (SID) value D. Lower milliamperage (mA) setting.
B. Longer exposure time The greatest signal strength is obtained with longer exposure time. The other responses reduce signal at the digital image receptor.
Which change should be made when performing an abdomen radiograph on a patient with ascites? A. Increase SID B. Raise exposure factors C. Choose a lower mA station D. Use an abdominal compression device
B. Raise exposure factors Ascites is the accumulation of fluid in the abdomen. Higher exposure factors are needed to penetrate the extra fluid content of the abdomen in such cases.
Which two of the following factors results in a brighter image being produced at the output phosphor of an image intensifier? (Select two) A) veil glare B) edge enhancement C) Flux gain D) Minification gain
C and D. Minification gain is simply an increase in brightness or intensity. Flux gain is a measurement of the increase in light photons due to the conversion efficiency of the output screen. Veil glare occurs when the intense light from a light source floods the eye directly. Edge enhancement is an image processing function.
Which of these digital radiography systems will have the highest contrast resolution? A) 8-bit system B) 2 C) 12 D) 4
C) 12 The system with the largest bit depth will have the highest contrast resolution. As a bit depth increases, the contrast resolution also increases. This means that increasing bit depth enables the system to capture more atomic information, even if the anatomy has very similar tissue densities.
What is the primary purpose of using AEC? A) provide the highest possible spatial resolution B) enable the use of different grid ratios C) provide an appropriate image receptor exposure D) Measure the entrance skin exposure rate
C) AEC controls mAs By adjusting the exposure time to provide appropriate exposure regardless of variations in tissue thickness.
As a source to image distance is doubled, the quantity of the photons reaching the image receptor is: A) doubled B) quadrupled C) reduced to 1/4 D) reduced to 1/2
C) For example, when SID is change from 40 inches to 80 inches, the quantity of the photons is reduced by a factor of four. If the distance was halved (changed from 80 to 40) the quantity of photons would be quadrupled. This is explained by the inverse square law.
Which action can improve recorded detail? A) select all larger kVp B) use the largest local spa C) increase the SID D) increase the OID
C) Increase the source-image receptor-distance (SID).
Which technique mimics The use of a grid? A) increase kVp B) decrease SID C) increase OID D) decrees mAs
C) Increased OID. (The air-gap technique, or increased OID, may be used to reduce scatter radiation and thus, increase image contrast.)
What is the unit for electrical current? A) watt B) hertz C) ampere D) volt
C) The ampere is the unit for electrical current. The electrical current flowing through the x-ray tube is very small, so it is commonly measured in mA.
In the CR imaging plate, the initial response of the phosphor layer when interacting with x-ray photons is to release; A) an electrical signal B) A Latent image C) light photons D) X-ray production
C) This luminescence occurs as soon as the phosphor layer is exposed to the incident x-ray photons. When the fluorohalides releases light photons, they do not release all the energy absorbed from the incident x-ray beam. Although some light is emitted, the phosphors Retain energy in the form of a latent image. It is this latent image that will be used to create a digital image for the computer to record and display. The phosphor layer releases light photons again when it is exposed to the lesser light within the plate reader .
How does the density log exposure curve appear for a digital imaging receptor? A) An S curve B) A shallow slope C) it's straight line at a 45° angle D) A steep slope
C) as an image is windowed, the data is moved up and down the 45° line.
Which conditions will require an increase in technical factors when performing a KUB? A) 1, 2 and 5 B) 3 and 5 C) 1 and 5 D) 2 and 4
C) asitus and soft tissue masses will require an increase in technical factors because sections of the abdomen that normally contain gas or fat are filled in with denser tissue/water. Diabetes will not affect the density of the abdomen. BalGas will require a decrease in technical factors because the extra gas in the admin requires less penetration of the beam. Pneumonia will affect densities in the thorax, not the abdomen.
The overall ability of an image intensifier to increase image illumination is called: A) Minification gain B) Flux gain C) brightness gain D) illumination gain
C) brightness gain is the product of multiplying the minification gain by the flex gain.
When SID is increased, which change must be made to maintain image receptor exposure? A) increase kVP B) decrease kVp C) increase mAs D) decrease mAs
C) increase SID = increase mAs. With increased SID, fewer photon strike the image receptor. Therefore, mAs Must be increased to maintain image receptor exposure. changing kVp does affect image receptor exposure but it is not usually adjusted when compensating for changing distances.
When SID is increased, which change must be made to maintain image receptor exposure? A) Increase kVp B) decrease kVp C) increase mAs D) decrease mAs
C) increase mAs. When S ID is increased, mAs Hass to be increased to to maintain image receptor exposure. With increased SID, if you were a photon strike the image receptor. Therefore mAs must be increased to maintain image receptor exposure.
Without changing any other factors, which affect is caused by decreasing the field size from 14x17 inches to 8 x 10"? A) decrease x-ray penetration of the part B) increase x-ray penetration of the part C) decrease in the amount of scatter radiation within the part D) increase in the amount of scattered radiation within the part
C) reducing the size of the field limits the amount of scatter produced. Increasing field size increase the amount of scatter, x-ray penetration is controlled by kVp.
Which of the following is needed to move electrons through a circuit? A) amperes B) ohms C) volts D) coulombs
C) volts. There needs to be a source of electric potential (voltage), which pushes electrons from a point of low potential energy to a higher potential energy.
Which device temporarily stores an electric charge? A. Rectifier B. Diode C. Capacitor D. Autotransformer
C. Capacitor A capacitor temporarily stores an electric charge. A diode only allows electrons to flow in one direction. A rectifier converts alternating current to direct current. An auto transformer is a transformer operating on the process of self induction.
A radiographer has made a good exposure of a lateral lumbar spine, and now must make a lateral spot L5S1 image using a 6€� x 6€� field. What parameter change is needed if manual exposure control is being used? A. No change B. 15% increase in kVp C. Double the mAs D. 15% reduction in kVp
C. Double the mAs Using manual exposure control, double the mAs will be needed to offset the loss of density due to loss of scatter density with the smaller field.
What information in the patient history should prompt the radiographer to decide against using automatic exposure control when taking a chest x-ray? A) pneumothorax B) chronic bronchitis C) oat cell carcinoma D) emphysema
D) A pathophysiologic change to lung tissue is emphysema results and easy penetration, so AEC should not be enabled for radiographic exams in these patients because the film will be too dense as a result of the control filling the shunt the exposure off quickly enough .
An increase in which factor will improve spatial resolution? A) focal spot side B) OID C) Grid ratio D) SID
D) An increase in SID decreases the amount of unsharpness and increases spatial resolution. As focal spot size increases, spatial resolution decreases. Increasing the OID decreases the spatial resolution. Grade ratio does not affect spatial resolution.
What is the function of a rectifier? A) change direct current to high frequency current B) convert direct current to alternating current C) increase 60 Hz alternating current to high frequency current D) convert alternating current to pulsating direct current
D) Convert alternating current to pulsating direct current
Modern x-ray tubes used today are known as: A) crooks B) roentgen C) electrode D) Coolidge
D) Coolidge tubes. They differ from crooks tubes as they have a heated cathode and are vacuum sealed
How does an increase in noise affect the quality of a digital image? A) density is decreased B) contrast is increased C) density is increased D) contrast is decreased
D) Digital image contrast is decreased by the presence of noise. Due to the ability of digital imaging systems to compensate for lack of density by adjusting the window level, image noise is not relevant to either increase or decrease in density. Because image noise has an inverse relationship with contrast, the increase noise does not increase contrast. And in spite of the ability of digital processing to increase image contrast, when this is done to a noisy image, it only makes the noise more visible. And then consequence, detail visibility (The function of contrast) is definitely inferior to an image not affected by noise.
SID refers to the distance from them A) collimator to the image receptor B) Target to the patient C) collimator to the patient D) focal spot target on the x-ray tube to the image receptor
D) SID refers to the distance from the focal spot target on the x-ray tube to the image receptor
You are performing a mobile chest x-ray on an aesthetic patient. The mAs and kVp are set as low as possible, but you still expect the image receptor exposure to be excessive for the patient's body habitus. Another way to decrease the image receptor exposure would be to: A) decrease the grade ratio B) decrease added filtration C) increase the anode angle D) increase the source to image distance (SID)
D) SID. This is because of the inverse square law, which states that the intensity of radiation at a given distance from the point source is inversely proportional to the square of the distance. Decreasing the grid ratio and added filtration would actually increase image receptor exposure. Finally, it is not actually possible to change the anode angle.
In an image intensifier, electronic intensification occurs when electrons are moved at high speed from there: A) cathode to Anode B) input phosphor to the output phosphor C) cathode to the output phosphor D) Photocathode to the output phosphor
D) The input phosphor converts the x-ray photons to light photons. The photocathode converts the light photons into electrons, which are moved at high speed to the output phosphor, where they are converted back to light. The output phosphor is thousands of times brighter than the input phosphor because of a smaller size and additional energy given to the electrons when they are accelerated through the image intensifier.
Electronic intensification in an image intensifier occurs when: A) The stream of electrons is forced towards the anode at high velocity B) The tungsten filament is heated and very high potential is applied between the cathode and the anode C) electrons are omitted from the cathode and accelerate towards the anode D) electrons are moved at high speed from the photo cathode to the outpatient phosphor
D) The input phosphor converts x-ray energy into light photons. The photo cathode converts the light photons into electrons, which are moved at high speed from the photo cathode to the output phosphor, where the energy is converted back to light. Electronic intensification occurs because of the additional energy given to the electrons when they are accelerated through the image intensifier.
The source of electrons in a traditional x-ray tube is the A) tungsten target B) pyrex vacuum envelope C) focusing cup D) cathode filament
D) The source of electrons in a traditional x-ray tube is the cathode filament. The filament is the negative charged portion of the x-ray tube that produces electrons from a process called thermionic emission.
When using an AEC which of the following changes will result in an increase image receptor exposure? A) decrease in the mA setting B) increase in grid ratio C) increase in the kV Setting D) increase in the exposure adjustment (density control)
D) an AEC System is designed to maintain image receptor exposure regardless of the tissue thickness. Because of this the only way to increase image receptor exposure when using AEC is to increase exposure adjustment/Density control. Other changes, like increase kilovoltage or decrease milliamperage, cannot be used to increase image receptor exposure because exposure time would be adjusted by the AEC system to maintain exposure. Increasing the grid ratio results in increased scatter absorption and therefore decreased image receptor exposure.
The intensity of the x-ray beam is expressed in units of: A) Bq B) Sv C) Gy D) c/kg
D) coulombs/kilogram. beam intensity refers to the number of x-ray photons in the beam. The intensity cannot be easily measured and essentially represents the number of ions created in the air by radiation exposure. Alternately, beam intensity can be measured as the air kerma in units of Milliegray. (MGy)
Which type of x-ray generator has the least amount of voltage ripple? A) three phase, 6 pulse B) Single phase, half wave C) Single phase, full wave D) three phase, 12 pulse
D) has the least amount of voltage ripple. The higher the number of phases and the higher the number of pulses, the lower the voltage ripple. This results in increased efficiency of x-ray production. Had a high frequency generator been included as an answer option, that would have been the best choice because these generators have the lowest voltage ripple.
Which set of technical factors will create the greatest image receptor exposure? A) 50 mA, 0.10 sec , 70 kVp B) 100 mA, 0.30 sec , 70 kVp C) 200 mA, 0.20 sec , 70 kVp D) 400 mA, 030 sec , 70 kVp
D) since mAs Who is the controlling factor for image receptor exposure, the mA/time combination that produces the largest mAs well produce the greatest image receptor exposure.
Which of the following chromosome breaks are the most easily repaired? A) none can be repaired B) double strand breaks C) Single strand brakes D) small base pair lesions
D) small base pair lesions are the most easily repaired. This is because these brakes require the least amount of damage compared to the other chromosome breaks.
If the x-ray tube is moved rapidly during a fluoroscopic exam, the image will appear to be blurry. This is a result of which of the following? A) low kVp B) low mA C) quantum mottle D) camera tube lag
D) this undesirable characteristic of most vidicon tubes Is what causes smearing of objects, which results in a blurry image.
When film-screen technology is used, which kilovolts-peak (kVp) setting produces the best scale of contrast for imaging ribs? A. 100 kVp B. 90 kVp C. 80 kVp D. 70 kVp
D. 70 kVp The lowest kVp of 70 provides the shortest scale of contrast.
Which part of the x-ray circuit is controlled by adjusting the milliamperage (mA) setting on the operating console for the purpose of producing the heat necessary for thermionic emission? A. Timer circuit B. Primary circuit C. Filament circuit D. Secondary circuit
D. Filament circuit The filament circuit controls the amount of heat applied to the filament that is required to boil off the desired number of electrons by the process of thermionic emission; the amount of current that is applied to the filament is under the control of the radiographer when the mA station is selected.
Which x-ray beam characteristic is reduced by adding aluminum filtration? A. Half-value layer B. X-ray beam quality C. Energy of the x-ray beam D. Quantity of x-rays
D. Quantity of x-rays Added aluminum filtration results in a reduction in the quantity of x-rays in the primary beam. HVL is a numerical value used to identify the quality of the beam, added filtration results in an increase in HVL, not a reduction. The quality of the x-ray beam refers to expenditure ability, which increases as a result of added filtration, not a reduction. Because most of the x-rays removed by the filter are of low energy, there is an increase in the average energy of the primary x-ray beam, not a reduction.
Which change in technical factors is most likely to result in decreased exposure to the image receptor (IR)? A. Increased focal spot size. B. Decreased source to image receptor distance (SID). C. Decreased beam restriction. D. Increased grid ratio.
D. increased grid ratio Grids with higher ratios are able to remove more photons from the x-ray beam. Because the grid reduces the number of photons reaching the image receptor, it also causes a decrease in exposure to the IR. Decreasing the SID results in greater x-rayed beam intensity and therefore greater IR exposure. A decrease in beam restriction results and more scattered radiation reaching the IR, which produces an increase in fog. Vocal spot size does not affect the exposure to the IR.
When using film-screen technology, how are the required milliampere-seconds (mAs), contrast, and patient dose affected as the grid ratio changes from 6:1 to 12:1? A. Decreased mAs, decreased contrast, and decreased patient dose. B. Decreased mAs, increased contrast, and decreased patient dose. C. Increased mAs, decreased contrast, and increased patient dose. D. Increased mAs, decreased contrast, and increased patient dose.
FLAG. D) the Increased mAs, decreased contrast, and increased patient dose. As grid ratio increases, an increase in mAs is needed to maintain density. Increased contrast and increased patient dose will also be noted.
How is gross exposure error demonstrated in a digital image? A) overall graininess B) missing data points C) increase contrast D) increase brightness
Missing data points. Over exposure creates a condition known as data drop. Data drop occurs when data elements in the detector are overwhelmed with photon energy and become in capable of recognizing their values. When the image is re-constructed, these saturated data points are dropped from the data set and excluded from the image reconstruction. Data drop can occur over an area of the detector, leading to detector saturation. Therefore, detector saturation can be described as a data drop that involves areas or regions of the detector. Data drop and detector saturation can present serious clinical issues for the interpreting physician and simulate a pathological process.
SID refers to the distance from the: A) collimator to the image receptor B) Target to the patient C) collimator to the patient D) focal spot target on the x-ray tube to the image receptor.
D)
When a 400 mA station is used, which of the following exposure times would be needed to produce 80 mAs? A) 0.6 seconds B) 0.4 C) 0.5 D) 0.2
D) 0.2 to get the necessary exposure time, 80 mAs divided by 400 mA to get 0.2 seconds.
An exposure is made using the following technical factors: 300 mA, 0.01 seconds, and 70 kVp. What new exposure time setting would produce the same total mAs if the mA is changed to 600? A) 0.001 seconds B) 0.002 C) 0.005 D) 0.008
c) this question is based on the reciprocal relationship between mA and exposer time. First, you should find the original mAs by multiplying 300 mA by 0.01 seconds to get 3 mAs. next, divide 3 mAs by the new mA setting of 600 to get The new exposure time, which is 0.005 seconds. Without doing any math, you can note that since you are doubling your mA from 300 to 600, you word, intern, have your time from 0.01 to 0.005 second.
