Computed Tomography for Technologists 2nd Edition Exam Newest With complete solution Updated 2024/25

Computed Tomography for Technologists 2nd Edition Exam Newest With complete solution Updated 2024/25 Which is NOT a synonym for the preliminary/localizer image taken at the start of a CT examination? A. Topogram B. Scout C. Scanogram D. Spiral - D. Spiral The ability of a system to differentiate, on the image, objects with similar densities is known as: A. High contrast resolution B. Low contrast resolution C. Spatial resolution D. Temporal resolution - B. Low contrast resolution Each two dimensional square of data that make up the CT image is called a: A. Pixel B. Voxel C. Matrix D. Fragment - A. Pixel How many pixels are contained in a 1,024 matrix image? A. 1,024 B. 2,048 C. 262,144 D. 1,048,576 - D. 1,048,576 Beam attenuation can be defined as: A. The phenomenon by which artifacts result when lower energy photons are preferentially absorbed, leaving only higher-intensity photons to strike the detector array. B. Xray energy that is produced from bombarding a substance with fast moving electrons. C. The ability of the detector to capture transmitted photons and change them to electronic signals. D. The phenomenon by which an xray beam passing through a structure is decreased in intensity or amount because of absorption and interaction with matter. - D. The phenomenon by which an xray beam passing through a structure is decreased in intensity or amount because of absorption and interaction with matter.Which of the following is a low attenuation structure: A. Iodine filled aorta B. Rib C. Trachea D. Calcified arteries - C. Trachea An object is slightly less dense than water. What is the expected hounsfield measurement? A. -940 B. -10 C. 50 D. 850 - B. -10 Why does the administration of iodinated contrast media result in an enhanced image? A. Iodinated contrast material increases the ability of the enhanced structure to attenuate the xray beam. B. Iodinated contrast material decreases the average photon energy of the xray beam; therefore more photons are absorbed by the patient. C. The administration of contrast material results in a smaller pixel, thereby increasing spatial resolution, which results in an enhanced image. D. - A. Iodinated contrast material increases the ability of the enhanced structure to attenuate the xray beam. The xray beam sources for CT produce xray energy that is polychromatic. This means: A. When viewed by the naked eye, the beam exhibits many different colors. B. It produce, as a byproduct, a substance known as polychlorinated biphenyl. C. Photons contained in the beam are all of the same wavelength. D. The beam comprises photons with varying energies. - D. The beam comprises photons with varying energies. An object that appears on the image but is not present in the object scanned is called a/n: A. Artifact B. Anomaly C. Shadow D. Ghost - A. Artifact Which is an advantage of filtering the xray beam? A. Filtering reduces the anode heat load B. A filtered beam produces images with substantially less quantum mottle C. Filtering the beam prevents energy from being converted to heat, therefore 100% of the energy is converted to xrays. D. Filtering reduces the radiation dose to the patient. - D. Filtering reduces the radiation dose to the patient Scan thickness is primarily important for the part it plays in:A. Noise reduction B. The contrast scale C. Detector aperture opening D. Volume averaging - D. Volume averaging You are working with the radiologist to establish examination protocols for your department. Which of the following is a logical consideration when determining an appropriate slice thickness for studies of the internal auditory canal? A. Because the auditory ossicles are quite small, a thin slice will be necessary to reduce the chance that volume averaging will obscure their appearance on the image. B. The appropriate slice thickness will vary considerably from patient to patient. Therefore, each technologist should be free to adjust the slice thickness as he or she deems necessary for the particular patient. C. A slice thickness of 5 to 7mm is adequate because the structures of interest are not particularly small and the examination is most often ordered as a screening study for asymptomatic patients. D. The thickest slice available should be used to reduce the radiation dose to the corneas. - A. Because the auditory ossicles are quite small, a thin slice will be necessary to reduce the chance that volume averaging will obscure their appearance on the image. How many CT numbers are assigned to each pixel in the image matrix? A. One half the number of all values recorded from the detector array B. One C. The number of HU per pixel is one tenth the display field of view D. Two values for a 256 matrix; 4 values for a 512 matrix - B. One Which is another name for raw data? A. Image data B. Scan data C. Reconstructed data D. Displayed data - B. Scan data When in the anatomic position, the arms are: A. raised above the head, palms backwards B. crossed over the chest, palms on opposite shoulders C. down by the sides, palms forward D. by the sides, elbows bent, palms backward and resting on hips - C. down by the sides, palms forward Which of the following components is NOT housed within the gantry? A. Three phase generator B. High-frequency generator C. Slip rings D. Xenon gas detectors - A. Three phase generatorThe power capacity of the generator is listed in: A. milliamperes (mA) B. thousand heat units (KHU) C. million heat units (MHU) D. kilowatts (kW) - D. kilowatts (kW) Which of the following describes a slip ring device? A. A recoiling system cable used to rotate the gantry frame B. A brushlike apparatus that provides continuous electrical power and electronic communication across a rotating surface C. A device used to shape the xray beam, thereby reducing the radiation dose to the patient and reducing image artifact D. A device that restricts the xray beam emerging from the gantry to thin ribbons - B. A brushlike apparatus that provides continuous electrical power and electronic communication across a rotating surface Which is a disadvantage of a small focal spot size? A. Reduced spatial resolution B. Reduced detector efficiency C. Increased penumbra D. Reduced heat capacity - D. Reduced heat capacity The ability of the tube to withstand by product heat is called: A. heat capacity B. heat dissipation C. thermal potential D. thermal transference - A. Heat capacity Regarding the detectors in the CT system, geometric efficiency is controlled primarily by: A. detector material B. type of photodiode used C. filtration D. detector spacing and aperture - D. Detector spacing and aperture Which of the following is a characteristic of xenon gas detectors? A. Low efficiency B. Sensitive to temperature and moisture C. May exhibit afterglow D. Also called scintillators - A. Low efficiency Which component of the CT system converts the electric signal supplied by the detectors into a digital format? A. Photodiode B. Array processor C. Display processor D. Analog to digital converter - D. Analog to digital converter"A precise set of steps to be performed in a specific order to solve a problem" describes: A. an algorithm B. beam attenuation C. the mean of a random variable D. the binomial probability formula - A. an algorithm What is interpolation? A. A technique for expressing waveform as a weighted sum of sines and cosines B. An efficient algorithm used to compute DFT and its inverse C. the difference between the first quartile and the third quartile. This is one way to describe the spread of a set of data. D. A mathematical method of estimating an unknown value using the known values on either side of the unknown - D. a mathematical method of estimating an unknown value using the known values on either side of the unknown Which is an example of a computer input device? A. Microprocessor B. Primary memory C. CT detector mechanisms D. Laser camera - C. CT detector mechanisms The central processing unit performs what function? A. dissipates excessive heat that builds up on the target material B. interprets computer program instructions and sequences tasks C. samples the detectors D. restricts the xray beam into thin ribbons - B. interprets computer program instructions and sequences tasks All the thousands of bits of data acquired by the CT system with each scan are called? A. Image data B. Calibration vectors C. Raw data D. Ray sums - C. raw data The DAS reads each arriving ray and measures how much of the beam has been attenuated. This is: A. a ray sum B. a view C. back projection D. a sample - A. a ray sum In CT image creation using a third generation design, a complete set of ray sums is known as: A. convolution equation B. algorithmC. spatial frequency filter D. view - D. view The process of converting the data from the attenuation profile to a matrix is known as: A. reformation B. archiving C. back projection D. referencing - C. back projection The process of applying a filter function to an attenuation profile is known as: A. data processing B. convolution C. archiving D. reformation - B. convolution Increasing the scan field of view: A. increases the number of detector cells collecting data B. increases the range of HU displayed on the image C. decreases the pixel size D. decreases the display field of view - A. increases the number of detector cells collecting data What is the function of the digital to analog converters? A. converts the data into shades of gray to be displayed B. converts the digital signal from the computer into an analog signal for the display monitor C. converts the light emitted from crystal detectors into an electric current D. converts the analog signal from the detectors to a digital signal for the computers - B. converts the digital signal from the computer into an analog signal for the display monitor Why is it necessary to convert the digitized data from the reconstruction processor to shades of gray? A. to allow an HU to be assigned to each structure B. to remove streak artifacts from the final image C. to enhance the desirable aspects of the image and suppress the undesirable aspects D. so that an image can be displayed on the monitor - D. so that an image can be displayed on the monitor What hounsfield values are in the naturally occurring range (not manmade): A. -1,000 to 1,000 B. -600 to 0 C. 0 to 1200 D. -2,000 to 4,000 - A. -1,000 to 1,000 Decreasing the window width in a CT image decreases: A. Slice thicknessB. mAs C. the appearance of quantum mottle D. the anatomic diversity displayed - D. the anatomic diversity displayed The window width of a specific CT image is set at 300 and the level is set at 100. How is a structure with a measurement of 280 HU displayed? A. it is white B. it is a light shade of gray C. it is a dark shade of gray D. it is black - A. it is white If the main tissue of interest is liver, which of the following is the best approximate window level setting? A. -600 B. 0 C. 50 D. 600 - C. 50 On a CT image an ROI is placed within a structure and measured. Its standard deviation is 0. What can be determined about this structure? A. it is composed of water or something with the same density as water. B. it is composed of fat C. it is very homogenous D. it is very heterogeneous - C. it is very homogenous For which application are the raw data necessary? A. to magnify the image B. to decrease the display field size C. to create a histogram D. to obtain a hounsfield measurement of a specific structure - B. to decrease the display field size A magnification factor of 1.5 is used to enlarge the image data, resulting in: A. a decrease in the pixel size B. an increase in the pixel size C. an inaccuracy in any subsequent distance measurement D. an image that is larger and may allow a more accurate cursor placement for measurements - D. an image that is larger and may allow a more accurate cursor placement for measurements Compared with conventional radiographic images, CT localizer images: A. do not superimpose anatomic structures B. are of slightly poorer image quality c. result in a much higher radiation dose to the patient d. result in a much lower radiation dose to the patient - B. are of slightly poorer image qualityWhich are key aspects of the axial method of data acquisition? A. the table remains stationary while the xray tube rotates within the gantry, collecting data B. multiple parallel rows of detectors are needed C. the table moves continuously throughout the data acquisition D. each slice is created from data acquired during a 180 degree rotation of the tube - A. the table remains stationary while the xray tube rotates within the gantry, collecting data The interscan delay inherent in an axial scan method is caused by which factor? A. tube cooling B. detector realignment C. table movement between data acquisitions D. serial image reconstruction algorithms that must reconstruct data from each slice before data for the next slice can be acquired - C. table movement between data acquisitions The practice of grouping more than one axial scan in a single breath hold is often referred to as: A. reformatting B. clustering C. dynamic scanning D. volumetric scanning - B. clustering Compared with helical scanning, what are the primary dis-advantages to the axial method of scanning? A. low contrast resolution is inferior B. spatial resolution is inferior C. radiation dose is much higher; noise is more pronounced D. total examination time is longer; data reconstruction is more limited - D. total examination time is longer, data reconstruction is more limited What is it called when a patient breathes differently with each data acquisition and areas of anatomy seem to be misplaced in the z-axis? A. mis-registration B. retrospective reconstruction C. slice thickness blooming D. slice sensitivity profile degradation - A. mis-registration Basic ingredients defining a helical scan include all of the following except: A. a continually rotating xray tube B. multiple parallel rows of detectors C. constant xray output D. uninterrupted table movement - B. multiple parallel rows of detectors All of the following are synonyms for helical scanning except:A. volumetric scanning B. spiral scanning C. continuous acquisition scanning D. dynamic scanning - D. dynamic scanning All of the following were improvements necessary to make helical scanning possible except: A. fourth generation scanner design B. gantries with slip ring design C. software the adjusts for table motion D. improved raw data management - A. fourth generation scanner design The goal of helical interpolation methods is to: A. calculate the appropriate mAs for a given patient size B. take the slant and the blur out of the helical image so that they closely resemble images taken from the axial methods C. automatically assign the optimal window width and level to each reconstructed image D. eliminate artifacts from voluntary and involuntary patient motion - B. take the slant and the blur out of the helical image so that they closely resemble images taken from the axial methods What is the pitch in the following scenario: 16 slice scanner, .5mm slice thickness, table movement of 12mm per rotation. A. 1 B. 1.25 C. 1.5 D. 2 - C. 1.5 How much anatomy (lengthwise) will be covered in a helical scan when the following parameters are selected: 15 seconds total acquisition time, .5 seconds gantry rotation time, 2mm slice thickness, 4 slices per rotation , pitch of 1.5? A. 40mm B. 90mm C. 160mm D. 360mm - D. 360mm Which of the following is NOT a reconstruction possibility when an MDCT system produces four 1mm slices with each gantry rotation? A. slices can be combined to create two/2mm slices B. slices can be combined to create one/4mm slice C. slices can be divided to produce 16/.25mm slices D. slices can be reconstructed to create images that overlap by .5mm - C. slices can be divided to produce 16/.25 mm slices All of the following are scan parameters EXCEPT: A. mAsB. slice thickness C. matrix D. pitch - C. Matrix Which of the following combinations of mA and scan time will result in 350 mAs and be the best choice for a cardiac scan? A. mA=300, scan time=.50 seconds B. mA=200, scan time=2 seconds C. mA=350, scan time=1 second D. mA=700, scan time=.50 seconds - D. mA=700, scan time=.50 seconds Which can be attributed to the uncoupling effect? A. Even when the mAs or kVp are too high, a good image results B. When mAs or kVp settings are too high or too low, quantum mottle results C. mA and scan time have no relationship to the quantity of xray produced D. Normal xray physics are reversed; mAs controls the quality of the xray beam, whereas the kVp controls the quantity of the xray beam - A. Even when the mAs or kVp are too high, a good image results Which is a disadvantage of a bone algorithm? A. it reduces spatial resolution B. it smooths data, reducing the difference between adjacent pixels C. it accentuates the difference between neighboring pixels D. it reduces the visibility of soft tissue structures - D. it reduces the visibility of soft tissue structures What is a partial scan? A. A scan that collects two matching samples taken 180degrees apart B. A scan that collects data from a 360 degree tube arc C. A scan that collects data from a 360 degree tube arc plus the width of the field of view D. A scan that collects data from 180 degrees tube arc plus the degree of arc of the fan angle - D. A scan that collects data from 180 degrees tube arc plus the degree of arc of the fan angle What is the true test of the quality of a specific image? A. Whether it serves the purpose for which it was acquired B. Whether it has a limiting resolution of 71lp/mm or greater C. Whether is has an MTF of greater than 1 D. Whether pixel size is .5mm or smaller - A. whether it serves the purpose for which it was acquired What two main features are assessed to measure image quality? A. mAs and kVp B. spatial resolution and contrast resolution C. temporal resolution and the degree of motion artifact D. focal spot size and DFOV - B. spatial resolution and contrast resolutionWhich of the following is an imaging challenge that depends on contrast resolution? A. A calcified nodule in the lung B. Tiny contrast filled arteries that are just 1mm apart C. Bony erosion in the ossicles of the internal auditory canal D. Distinguishing between white matter and gray matter of the brain - D. distinguishing between white matter and gray matter of the brain What is spatial frequency? A. the number of line pairs visible per unit length B. the ratio of the accuracy of the image compared with the actual object scanned C. the ratio of pixel size to slice thickness D. the number of xray photons detected per pixel - A. the number of line pairs visible per unit length A graphical representation of the CT system's capability of passing information through it to the observer is called: A. interpolation B. modulation transfer function (MTF) C. receiver operator characteristics D. contrast detail response - B. modulation transfer function (mtf) Using a standard 512 matrix for all studies, which contains the smallest pixel? A. A scan of the internal auditory canals in which DFOV is 16cm B. A scan of the brain in which the DFOV is 25cm C. A scan of the chest in which DFOV is 35cm D. A scan of the abdomen in which DFOV is 42cm - A. a scan of the internal auditory canals in which DFOV is 16cm Which term describes an isotropic voxel? A. A rectangular solid B. A square C. A cube D. A slab - C. a cube The ability to differentiate a structure that varies only slightly in density from its surrounding is referred to as: A. spatial resolution B. high contrast resolution C. detail resolution D. low contrast resolution - D. low contrast resolution An image of a water phantom displays a range of pixel values. What can be said about this image? A. it was reconstructed with a "soft" algorithm B. it is "noisy"C. the mAs setting used ot produce the image was too high D. a thick slice was used - B. it is "noisy" When discussing the quality of a CT image, what is meant by temporal resolution? A. the internal auditory canal is often used to evaluate a system's overall quality. because the internal auditory canals are located in the temporal bone, this is called its temporal resolution B. the ability of a system to display an object that has a density that is similar to its background. C. how rapidly data are acquired ; it is controlled by gantry rotation speed, the number of detector channels in the system, and the speed with which the system can record changing signals. D. the ability to resolve, as separate objects, small, high contrast objects - C. how rapidly data are acquired; it is controlled by gantry rotation speed, the number of detector channels in the system, and the speed with which the system can record changing signals All of the following are key aspects of a quality assurance program EXCEPT: A. the tests that make up the program must be performed on a regular basis B. all tests must be completed by a medical physicist C. the results from all tests must be recorded using a consistent format D. documentation should indicate whether the tested parameter is within specified guidelines - B. all tests must be completed by a medical physicist How often is the accuracy of a scanner's slice thickness tested? A. Daily B. Weekly C. Monthly D. Semi-annually - D. semi-annually A water phantom is scanned and several ROI's are placed in the resulting image. The ROI's placed at the perimeter of the image measure differently from the ROI's near the center. This indicates a problem with: A. linearity B. cross field uniformity C. noise D. low contrast resolution - B. cross field uniformity A water phantom is scanned and several ROI's are placed in the resulting image. The standard deviation measurements from the ROI's range from 15-25. What can be said about the image? A. it is noisy B. the spatial resolution is 15 to 25lp/cm C. the low contrast resolution is within normal limits D. the radiation dose is unnecessarily high - A. it is noisyWhat can be done to improve linearity of a CT system? A. daily calibrations B. increasing mAs C. decreasing kVp D. widening the window width when viewing the images - A. daily calibrations What quality control test must be performed by a medical physicist? A. cross field uniformity B. spatial resolution C. radiation dose measurements D. laser light accuracy - C. radiation dose measurements Which is the true statement regarding beam hardening? A. the beam is hardened more by bone and less by fat B. the beam is hardened more by air and less by bone C. nothing can be done to minimize beam hardening artifacts D. lowering the kVp is the best method of reducing beam hardening artifacts - A. the beam is hardened more by bone and less by fat Artifacts that result from undersampling are called: A. out of field artifacts B. metallic artifacts C. cone beam artifacts D. aliasing artifacts - D. aliasing artifacts Raw data that results from an MDCT scan acquisition is used so that the 1mm slices are combined to produce thicker slices for reviewing. This is called: A. 3D reformation B. image reconstruction C. segmentation D. multiplanar reformation - B. image reconstruction In what situation would overlapping reconstructions for subsequent image rendering no be indicated? A. slice thickness=.5mm, DFOV 25 B. slice thickness=2mm, DFOV 35 C. slice thickness=5mm, DFOV 42 D. slice thickness=7mm, DFOV 45 - A. slice thickness = .5mm, DFOV 25 Assume the raw data are still available. In what scenario would it be impossible to create an MPR? A. source images vary in slice thickness B. source images vary in gantry tilt C. source images vary in image center D. source images vary in DFOV - B. source images may vary in gantry tiltWhich of the following statements is true regarding MPR's? A. they are created from raw data B. they are 3D in nature C. all MPR images have the same image quality as the source image D. they can be created either at the operator's console or at a separate workstation - D. they can be created either at the operator's console or at a separate workstation A limitation of scanner created MPR's is: A. only one examination protocol per scanner can be programmed to automatically create MPR's B. they take more time to create than manually produced MPR's C. in most cases, only straight sagittal and coronal planes can be automatically generated D. they are not consistently produced, so techs must remember to check to see whether they were created - C. in most cases, only straight sagittal and coronal planes can be automatically generated Which is a disadvantage to workstation created MPR's? A. they require that the raw data be sent to the workstation, which is difficult to transmit via PACS B. to produce the highest quality MPR's the thinnest slices must be sent to the workstation. This amount of data can slow down the PACS C. most radiologists have not been trained to create MPR's D. workstations are only able to create MPR's in the sagittal and coronal planes - B. to produce the highest quality MPR's the thinnest slices must be sent to the workstation. This amount of data can slow down the PACS. Another name for surface rendering is: A. volume rendering B. segmentation C. projection display D. shaded-surface display - D. shaded-surface display In creating a surface rendered image, what can happen if the threshold is set too narrow? A. actual protruding structures can be imperceptible B. non tissue materials, such as fluids, can be displayed as if they were tissues and can obscure protruding structures C. too much data are included so that less powerful computers may not be able to generate a display D. the SR image generated cannot be rotated - A actual protruding structures can be imperceptible A MIP is a good method to display all of the following EXCEPT? A. pulmonary nodules B. fracture extentC. contrast filled coronary arteries D. bronchial tree - D. bronchial tree Which has become the favored 3D imaging technique in CT? A. volume rendering B. surface rendering C. MIP D. MinIP - A.volume rendering VR techniques assign each voxel an opacity value based on its . This value determines the degree the voxel will contribute to the final image. A. location B. Hounsfield units C. depth D. width - B. Hounsfield units The process of selectively removing or isolating information from the 3D data set is referred to as: A. clipping B. cutting C. segmentation D. dissociation - C. segmentation Which electronic system allows clinicians to input an electronic device order for a CT examination and transmits that order to the CT department? A. RIS B. PACS C. HIS D. CPOE - D. CPOE What two electronic elements form the radiology information infrastructure? A. RIS and PACS B. HIS and CIS C. CPOE and EMR D. LAN and SSL - A. RIS and PACS Which of the following is NOT a true statement regarding PACS? A. vast amounts of data pass through any PACS B. PACS technology has a huge impact on the workflow of radiologists and technologists C. to be included in a PACS system, images must be in a digital form D. once the hardware for the PACS is installed, the system runs virtually maintenance free - D. once the hardware for the PACS is installed, the system runs virtually maintenance free Computers that act on requests from other networked computers, rather than from a person inputting directly into it, are called:A. LANS B. star topologies C. servers D. P2P - C. servers The computers that are integral to the functioning of the PACS are referred to as: A. archival devices B. core servers C. routers D. bridges - B. core servers The amount of data that can be transmitted between two points in the network in a set period of time is known as: A. bandwidth B. pixel volume C. memory capacity D. frequency - A. bandwidth A scheme that compresses an image without any loss of information when the image is decompressed is called: A. lossy B. fractional coding C. scalar and vector quantization D. lossless - D. lossless DICOM refers to a: A. specific geometric arrangement of computers in a network B. universally adopted standard for medical image interchange C. type of magnetic tape used to store data D. peer to peer computer network such as the Usenet news server - B. universally adopted standard for medical image interchange Which is NOT true of an LCD monitor? A. the purchase price of an LCD is approximately half that of a CRT monitor B. LCD monitors have a longer life span compared with CRT monitors C. Assuring the continued quality of the LCD is much simpler than that of the CRT monitor D. LCD monitors maintain their luminosity better than do CRT monitors - A. the purchase price of an LCD is approximately half that of a CRT monitor A device that is used to automatically load an unload optical discs is called a/n: A. ethernet B. tape drive C. media vending machine D. optical jukebox - D. optical jukeboxRegarding an order for a CT examination, all of the following statements are true EXCEPT: A. CT examinations can only be ordered by a physician B. before beginning any examination the technologist must verify that the correct examination is planned by checking the clinician's order C. In many facilities clinicians orders for CT exams are transcribed by clerks, this process introduces the potential for transcription errors D. Ideally, some patient screening should occur at the time the examination is scheduled - A. CT exams can only be ordered by a physician Which of the following is NOT an acceptable method of verifying a patient's identity? A. Call the patient by his full name and then ask to recite his birth date and year, so that it can be checked against the CT order B. Use the patient's armband to check the patient's name and medical record number C. Ask family members who accompany the patient to verify the patient's name and address and check that against the CT order D. Use the sign on the door of the patient's room or ask the patient what hospital room they are assigned to - D. Use the sign on the door of the patient's room or ask the patient what hospital room they are assigned to Why is a patient questioned regarding whether they have a history of an overactive thyroid? A. to select the right protocol B. to determine whether iodinated contrast agent can be administered intravenously C. to help the radiologist diagnose a goiter D. to determine whether a female patient could be unknowingly pregnant - B. to determine whether iodinated contrast agent can be administered intravenously BUN and serum creatinine provide information about a pt's: A. thyroid function B. kidney function C. risk of allergy to contrast dye D. cardiac function - B. kidney function For which of the following examinations is it common to check laboratory results for prothombin time (PT), partial thromboplastin time (PTT), and platelet count: A. coronary CT angiography B. postmyelography CT studies C. CT guided biopsy D. CT abdomen and pelvis - C. CT guided biopsy Which of the following is a TRUE statement regarding signed consent forms? A. in most states, a signed consent form is required before any CT examination B. once a patient signs a consent form they can no longer file a malpractice claim C. if written consent is required it must be signed by the patient before the administration of any medication for pain relief or sedationD. A signed consent form is not necessary for any CT examinations - C. if written consent is required it must be signed by the patient before the administration of any medication for pain relief or sedation All of the following are true statements regarding patient restraints EXCEPT: A. the immobilizer must be easy to remove quickly if necessary B. patients are restrained primarily as a convenience for the technologist C. if leg immobilizers are necessary, wrist immobilizers must also be applied D. a Dr's order is necessary when a pt is to be restrained against his will - B. patients are restrained primarily as a convenience for the technologist Why is it important for the technologist to note the patient's breathing, skin color, and overall health before the examination begins? A. the technologist can accurately chart each of these factors to the patient's chart B. it will help determine whether the patient is healthy enough to proceed with a study C. if a pt has even a small problem with any of these areas they will not be given IV contrast material D. it will help the technologist notice signs should adverse effects occur during the scan process - D. it will help the technologist notice signs, should adverse effects occur during the scan process Which of the following is NOT considered one of the vital signs? A. weight B. pulse C. respiration D. blood pressure - A. weight Where is a pedal pulse felt? A. behind the knee B. along the dorsal aspect of the greater toe or arch of the foot C. anterior ankle D. posterior ankle or top of foot - D. posterior ankle or top of foot What is the normal range for the respiratory rate of an adult? A. 14-20 B. 21-26 C. 26-30 D. 30-34 - A. 14-20 The normal range of blood pressure in children is: A. lower than adults B. about the same as adults C. about the same as the elderly D. is twice that of either adults or the elderly - A. lower than adults To distinguish adjacent tissues on a CT image, the tissues must:A. have different densities B. have different functions C. have sharply defined edges D. be abnormal - A. have different densities A contrast material that is of a substantially higher density than that of the surrounding structures can be referred to as a agent: A. low attenuation B. positive C. negative D. gastrointestinal - B. positive The structural property of a contrast agent regarding the number of particles in solution compared with blood is known as: A. ionicity B. osmolality C. valence D. viscosity - B. osmolality The intravenous infusion of HOCM may result in: A. a sharp drop in blood sugar B. severe fetal abnormalities if given to a pregnant women C. dehydration D. a sensitivity to seafood - C. dehydration Which factors affect the viscosity of an intravenous iodinated contrast agent? 1. iodine concentration 2. lipid solubility 3. total volume delivered 4. temperature of the agent A. 1 and 2 B. 2 and 3 C. 1 and 4 D. 1, 3 and 4 - C. 1 and 4 An imaging center's protocol for a routine body CT on an adult pt calls for the administration of 100ml of an LOCM with a concentration of 320mgl/ml. A pt has poor veins, which results in a smaller IV catheter to be used for venipunture. Concerns about the precarious venous access have resulted in the decision to use a lower concentration contrast agent. What volume of LOCM with a concentration of 240mgl/ml will deliver an equivalent amount of iodine to that of the dose called for in the protocol? A. 84ml B. 100ml C. 125ml D. 133ml - D. 133mlWhy is there such a wide variation in literature among quoted incidences of adverse reactions to contrast media? A. there is no standard definition of adverse reactions or standard system to classify their severity B. Adverse reactions are not reported because of fears about possible litigation C. Adverse reactions are so rare that statistics are difficult to collect D. The pharmaceutical companies that produce contrast agents do not allow statistics regarding the incidence of adverse reactions to be published - A. there is no standard definition of adverse reactions or standard system to classify their severity Which is an example of a chemotoxic reaction to intravascular contrast media? A. hives B. contrast induced nephropathy C. coughing D. nasal stuffiness - B. contrast induced nephropathy Contrast reactions that are accompanied by a temporary drop in blood pressure, bronchospasms, facial edema, urticaria, and laryngeal edema are generally classified as: A. side effects B. minor reactions C. moderate reactions D. severe reactions - C. moderate reactions Comparing the reported rate of adverse reaction, A. LOCM are somewhat lower than HOCM, by a factor of approx two times B. LOCM are much lower than HOCM, by a factor of approx 4-5 times C. LOCM and HOCM have similar reaction rates, but LOCM reactions are less severe D. some data suggests a lower mortality rate with HOCM - B. LOCM are much lower than HOCM, by a factor of 4-5 times When a patient who previously reacted to HOCM is given an LOCM for a subsequent study, the risk of repeat reaction is approx: A. 5% B. 40% C. 80% D. 95% - A. 5% What is the single best method of reducing the risk of idiosyncratic contrast medium reaction? A. premedicate the patient with steroids B. use LOCM C. reduce the dose D. perform a test injection - B. use LOCM The basic functioning unit of the kidney id the:A. cortex B. nephron C. medulla D. collecting tubule - B. nephron Which statement is true concerning the use of serum creatinine to assess renal function? A. serum creatinine is a highly accurate measure of renal function B. serum creatinine uniformly over-estimates the glomerular filtration rate; therefore the values can be easily adjusted for an accurate measure of renal function C. measuring serum creatinine is a fast and inexpensive way to estimate renal function D. serum creatinine values are not affected by patient demographics - C. measuring serum creatinine is a fast and inexpensive way to estimate renal function Which of the following are considered at high risk for developing CIN? A. patients older than 65 years of age B. male patients with a history of atheroscerlotic disease C. patients with diabetes mellitus and pre-existing renal insufficiency D. patients with a history of renal calculi - C. patients with diabetes mellitus and preexisting renal insufficiency Which is a true statement regarding the risks posed by intravascular contrast media in combination with the drug metformin? A. Iodinated contrast media can cause lactic acidosis, which is only dangerous if the patient is also taking metformin B. Metformin causes renal impairment, exacerbating the risk of CIN C. Iodinated contrast media in combination with metformin will result in acute (and in some instances, chronic) renal failure requiring dialysis D. When renal dysfunction occurs in patients taking metformin, the drug can accumulate and result in lactic acidosis - D. when renal dysfunction occurs in patients taking metformin, the drug can accumulate and result in lactic acidosis After the injection of an iodinated contrast medium, patients with brain metastasis have increased risk of: A. seizures B. dehydration C. anaphylactoid reaction D. renal failure - A. seizures What is the most common type of delayed reaction to intravascular contrast medium? A. fever B. headache C. skin reaction D. salivary gland swelling - C. skin reaction Barium leaking into the peritoneal cavity is referred to as:A. barium peritonitis B. barium impaction C. aspiration pneumonitis D. barium obstruction - A. barium peritonitis Given orally, compare LOCM with HOCM. A. LOCM offers no advantage and is much more expensive B. LOCM offers a clear advantage in all patients C. LOCM has not been approved for oral administration D. In some instances, particularly with infants, LOCM may provide significant advantages over the HOCM agents - D. in some instances, particularly with infants, LOCM may provide significant advantages over the HOCM agents Which is NOT a true statement regarding the placement of a peripheral IV line for the administration of an iodinated contrast agent for a scan of the abdomen? A. standard precaution must be adhered to B. sterile technique must be followed C. an indwelling catheter, butterfly infusion set, or straight needle can be used, depending on the preference of the technologist D. basic consent must be obtained from the patient - C. an indwelling catheter, butterfly infusion set, or straight needle can be used, depending on the preference of the technologist What type of catheter do most manufacturers recommend be flushed with a heparinized saline solution after their use? A. open ended CVAD catheters B. closed ended CVAD catheters C. standard peripheral indwelling catheters D. PICCs that contain a luer activated device - A. open ended CVAD catheters Which is a true statement regarding implantable ports? A. implanted ports are typically used for short term injections that require high flow rates such as blood transfusion or contrast media administration B. Among CVAD's, ports have the lowest incidence of infection because they are completely buried under the skin and there is no site for micro-organisms to enter C. the port can be easily accessed using standard straight needles, no special training in required D. the port is placed so that only the face of the device shows through an opening in the skin - B. among CVAD's, ports have the lowest incidence of infection because they are completely buried under the skin and there is no site for micro-organisms to enter The difference between the bolus phase, the non-equilibrium phase and the equilibrium phase of contrast enhancement is primarily determined by: A. brand of iodine contrast used B. injection rate and scan delay C. type of pathology presentD. film processing time - B. injection rate and scan delay The arteriovenous iodine difference is calculated by: A. taking an HU measurement of the liver before and after the contrast injection B. comparing an HU measurement of the pancreas to that of the liver C. comparing an HU measurement of the aorta to that of the inferior vena cava D. dividing the concentration of iodine by the volume used - C. comparing an HU measurement of the aorta to that of the inferior vena cava Another name for the bolus phase of contrast enhancement is the: A. arterial phase B. venous phase C. portal vein phase D. delayed phase - A. arterial phase Iodinated contrast is administered at a rate of 3ml/s for a routine abdominal scan in which the protocol calls for a delay of 60seconds between the start of the injection and the start of scanning. Soon after the start of the contrast injection, the pt begins to feel an intense warm feeling and being surprised by this calls for the technologist. How long beyond the 60seconds can the technologist delay the scan acquisition (to comfort the pt) without risk of degrading the diagnostic utility of the scan? A. 5-10 seconds B. 30-40 seconds C. 5-8 minutes D. 12-15 mintues - B. 30-40 seconds The general rule of contrast media injection regarding injection rate and scan delay do not apply to: A. routine brain imaging B. coronary angiography C. routine abdominal scanning D. thoracic scanning - A. routine brain imaging When can a drip infusion technique for contrast media administration be used? A. for a study of the chest when the clinical indication is suspicious for pulmonary emboli B. for an angiographic study of the brain performed to demonstrate a suspected middle cerebral artery occlusion C. for a study of the brain when the clinical indication is suspicious of tumor D. a drip infusion technique can never be used for contrast enhanced CT studies - C. for a study of the brain when the clinical indication is suspicious of tumor All the following are disadvantages of the hand bolus technique of contrast administration EXCEPT? A. Flow rate is variable B. Scan delay cannot be precisely controlled C. It requires two operatorsD.it cannot be used for injecting into standard PICC lines - D. it cannot be used for injecting into standard PICC lines The volume of contrast administered is increased from 100ml to 150ml. The flow rate is unchanged at 3ml/s. What can be expected? A. The time to reach peak aortic enhancement is decreased B. the magnitude of the peak enhancement is decreased C. the duration of the contrast injection is increased D. the duration of the scan acquisition is increased - C. the duration of the contrast injection is increased Because of the pt's IV access, the flow rate of a contrast injection is reduced from the protocol of 4ml/s to 2ml/s. What other adjustment is likely to be made? A. The scan delay is increased B. The scan delay is decreased C. The volume of contrast is decreased D. The volume of contrast is increased - A. the scan delay is increased What injection technique is used for most clinical applications? A. a drip infusion technique B. a uniphasic injection with a constant flow rate C. a biphasic injection in which the initial 50ml bolus is delivered at a higher flow rate D. a multiphasic injection with two or more contrast flow rates, followed by a saline flush - B. a uniphasic injection with a constant flow rate What effect does a pt's cardiac output have on contrast enhancement? A. as cardiac output is reduced the magnitude of the peak aortic enhancement is diminished B. as cardiac output is reduced, the magnitude of the peak aortic enhancement is increased C. as cardiac output is reduced, there is progressively longer delay in the time required for the contrast bolus to reach peak aortic enhancement D. as cardiac output is reduced, there is a progressively shorter delay in the time required for the contrast bolus to reach peak aortic enhancement - C. as cardiac output is reduced, there is progressively long delay in time required for the contrast bolus to reach peak aortic enhancement The test bolus method is used to determine the scan delay for a CT angiography study. Ten trial images are taken at 2second intervals beginning 12 seconds after the start of the test injection. Maximum enhancement in the selected region of interest is seen on the fourth image. What scan delay range is optimal? A. 5 to 8 seconds B. 20-23 seconds C. 32-35 seconds D. 100-120 seconds - B. 20-23 secondsThe rational use of CT involves which two key components? A. halving the mAs and doubling the kVp B. eliminating most pediatric examinations and requiring a second physician's opinion to order adult examinations C. reducing the use of helical scanning and increasing the frequency of visits by physicists to assess radiation dose delivered D. appropriate selection of patients and the minimization of the radiation dose without compromising diagnostic quality - D. appropriate selection of patients and the minimizing of the radiation dose without compromising diagnostic quality Which unit universally expresses dose? A. effective dose B. organ dose C. absorbed dose D. there is no consensus regarding an expression of dose, and many units have been used - D. the is no consensus regarding an expression of dose, and many units have been used The unit of ionizing radiation exposure in air is the: A. roentgen (R) B. radiation absorbed dose (rad) C. gray (Gy) D. sievert (Sv) - A. roentgen (R) The unit of absorbed dose is the: A. roentgen (R) B. radiation absorbed dose (rad) or Gray (Gy) C. computed tomography dose index (CTDI) D. multiple scan average dose (MSAD) - B. radiation absorbed dose (rad) or Gray (Gy) The Systeme International d'Unites (SI) units for ionizing radiation: 1. Is used internationally 2. replaces the unit known as the rad 3. replaces the unit known as the rem A. 1 only B. 1 and 2 C. 1 and 3 D. 1, 2, and 3 - D. 1, 2, and 3 The quality factor (Q) is used to: A. account for different health effects produced from different types of ionizing radiation B. account for the pitch in helical CT C. describe exposure from scatter radiation D. convert older units to SI units - A. account for different health effect produced from different types of ionizing radiationWhich of the following statements is TRUE concerning the measurement referred to as effective dose? A. It is measured in rad or Gy B. It is a weighted average of organ doses C. There is no agreement on the weighting factors to be applied to each radiosensitive organ D. It is relatively easy to calculate accurately and is therefore used universally - B. it is a weighted average of organ doses The areas of scatter into adjacent tissues are sometimes called: A. tails B. overflow C. excess D. collimation - A. tails The dose to the central slice plus the dose from the scatter into nearby slices equals the: A. MSAD B. Sv C. mAs setting D. R - A. MSAD Which is now the preferred expression of radiation dose in CT dosimetry? A. R B. CTDI vol C. DLP D. MSAD - B. CTDI vol The relationship between mAs and dose is: A. inversely proportional: the higher the mAs the lower the dose B. linear; the higher the mAs the higher the dose C. represented by the equation: dose = 1/ sq route (mAs) D. highly variable and impossible to quantify - B. linear, the higher the mAs, the higher the dose When looking at the overall radiation dose from radiologic sources, CT contributes: A. a very low percentage of the total B. a proportional amount - that is, CT examinations represent approximately 11% of all diagnostic procedures and account for approximately 11% of the total dose C. a disproportionately high percentage of the total D. nearly 90% of the total - C. a disproportionately high percentage of the total Keeping in mind how a parent will perceive risk to their child, guidelines have been outlined for CT examinations of pediatric patients. Which of the following is NOT one of the recommendations?A. the parent should be told that the CT examination of a child is associated with a small risk B. the parent should sign a consent form acknowledging that out of every 100 children who undergo CT examination, 1 will develop a fatal cancer later in life C. the examination should be restricted to cases in which it is specifically indicated and cannot reasonably be substituted for with a diagnostic examination that does not use ionizing radiation D. scan parameters must be customized according to the size of the child being scanned - B. the parent should sign a consent form acknowledging that out of every 100 children who undergo CT examination, 1 will develop a fatal cancer later in life The latency time for cancer induction in the dose ranges used in CT is estimated to be between: A. 10-30 days B. 1-5 years C.10-30 years D. 40-60 years - C. 10-30 years Children are more radiosensitive than adults for all of the following reasons EXCEPT: A. children will have more time to express a cancer than do adults B. in children the latency time for cancer induction is only a few months C. radiation exposure is cumulative, and children may undergo more than one CT examination in their lifetimes D. children have more dividing cells, and adverse effects of radiation act on dividing cells - B. in children the latency time for cancer induction is only a few months Which of the following are strategies that may reduce the radiation dose to the patient? 1. adjusting mAs to suit individual patient dose 2. avoid increasing kVp beyond 120 3. increasing pitch 4. performing multiphase studies only when clinical indications exist A. 1 and 2 B. 1 and 3 C. 2 and 4 D. 1, 2, 3 and 4 - D. 1, 2, 3 and 4 A patient is being positioned for a routine scan of the brain. Why is he asked to tuck his chin down toward his chest? A. so that the scan time can be reduced B. to allow immobilization sponges to be used C. to reduce radiation exposure to the lens of the eye D. to eliminate the need to tilt the gantry so that the axial scan mode can be used - C. to reduce radiation exposure to the lens of the eye What is the expected HU value of a measurement taken in a lateral ventricle? A. -70 to -60B. 4 to 8 C. 20 to 30 D. 40 to 50 - B. 4-8 Which is a typical injection protocol for a routine examination of the brain? A. 100 mL delivered at 1ml/second, scan delay of 5 minutes B. 150 mL delivered at 2ml/second, scan begins when injection is complete C. Split bolus, 50ml delivered at 1.5ml/s, wait 2 minutes, 50 ml delivered at 1.5ml/second, scan begins when second injection is complete D. 60ml (concentration 370), delivered at 4ml/s, scan delay from timing bolus using the carotid artery as the reference vessel - A. 100 ml delivered at 1ml/second, scan delay of 5 minutes Compared with a cerebral CTA, what parameter must be changed for a cerebral CTV? A. slice thickness is reduced B. delay from the start of injection to the start of scanning is increased C. scans are performed in the axial mode, rather than the helical mode D. kVp is increased - B. delay from the start of injection to the start of scanning is increased Which is a true statement regarding an emergency department patient who is suspected of suffering from acute stroke? A. A CT scan of the head is only done if the patient has a previous history of stroke B. an MRI of the head is the first choice of imaging procedures, a CT of the head is only done if an MRI cannot be done within 24 hrs C. A CT scan of the head must be done as soon as possible because it is a necessary examination in determining whether a pt can receive t-PA treatment D. an unenhanced CT scan will provide no useful information in the diagnosis and treatment of acute stroke. Only CTA and CT perfusion studies are indicated - C. A CT scan of the head must be done as soon as possible because it is a necessary examination in determining whether a pt can receive t-PA treatment What is the goal in performing perfusion studies for patients with acute stroke? A. to determine whether the stroke is hemorrhagic or ischemic B. to determine the onset time of the stroke C. to depict the spatial relationship of complex vascular lesions to the surrounding structures D. to distinguish infarcted tissue from the penumbra - D. to distinguish infarcted tissue from the penumbra For what study might data be acquired while the patient is lying prone on the CT table? A. routine chest B. CT angiography for suspected pulmonary embolism C. Cardiac scoring D. High resolution chest CT - D. high resolution chest CTA volumetric HRCT study refers to a protocol that includes which of the following? A. Thin sections, taken at an interval of 20mm or more between slices, during inspiration, with the patient in supine position B. A sampling technique that is intended to provide representative areas of the lung C. Thins sections, in a helical mode, taken contiguously so as to cover the entire lung, during inspiration with the patient in a supine position D. three series of thin sections, in helical mode, taken contiguously so as to cover the entire lung; series one is supine inspiratory; series two is supine expiratory; and series three is prone inspiratory - C. thin sections, helical mode, taken contiguously so as to cover the entire lung, during inspiration with the patient in a supine position Why do many protocols for the evaluation of PE scan in the caudal to cranial directions? A. to chase the contrast bolus through pulmonary circulation B. to reduce radiation exposure C. to reduce artifacts attributable to patient motion D. to eliminate to need for the patient to hold his or her breath - C. to reduce artifacts attributable to patient motion What must happen to a thrombus for it to be referred to as en embolus? A. it must detach from its original site B. it must be formed in the right side of the heart C. it must be formed from clotted blood D. it must lodge in a pulmonary vessel - A. it must detach from its original location At a particular institution the PE protocol includes a second scan series, performed 180 seconds after the iv contrast injection, that extends from the iliac crests to the knees. What is the purpose of this second series? A. to check for ureteral obstruction B. to check the pelvis and lower extremities for deep vein thrombosis C. to check that the patient is excreting the iodinated contrast D. to assess the patient's cardiac output - B. to check the pelvis and lower extremities for deep vein thrombosis What heart valve is located between the right atrium and right ventricle? A. Mitral B. Pulmonary C. Aortic D. Tricuspid - D. Tricuspid Beta blockers are likely used as part of a cardiac CT protocol when the: A. patient has a history of iodine allergy B. patient has asthma and is being treated with an albuterol inhaler C. patient's heart rate is higher than 65 bpm D. patient's heart rate is less than 60 bpm - C. patient's heart rate is higher than 65bpmAn imaging technique that attempts to acquire data only during cardiac segments with the lowest cardiac motion is called: A. a split bolus B. prospective ECG triggering C. retrospective ECG gating D. electron beam CT - B. prospective ECG triggering A patient who is scheduled for a CT study has an irregular heartbeat with a rate approximately 85bpm. For which clinical indication is this the most problematic? A. coronary artery disease B. assessment of ventricular function C. possible thoracic aortic dissection D. evaluation of congenital aortic arch anomaly - A. coronary artery disease Why is it recommended that cardiac CT calcium scoring be restricted to patients with risk factors for coronary artery disease, rather than using it as a screening tool for all patient's? A. it has not proven to be an accurate measure of coronary artery calcifications B. a correlation has not been proven between a positive calcium score and a future risk of developing heart disease C. the examination is uncomfortable for the patient D. risks related to the radiation dose are a concern; for asymptomatic patients with no cardiac risk factors, it is not certain that the benefit of the examination outweighs the risk from the radiation exposure - D. risks related to the radiation dose are a concern; for asymptomatic patients with no cardiac risk factors, it is not certain that the benefit of the examination outweighs the risk from the radiation exposure Although patient compliance can sometimes be a factor, what volume of oral contrast is typically considered the minimum amount needed for a routine CT study of the abdomen and pelvis? A. 100ml B. 400ml C. 600ml D. 1500ml - C. 600ml Which is a window level used to visualize subtle liver lesions? A. 150ww;70wl B. 350ww;50wl C. 1500ww;-600wl D. 2000ww;600wl - A. 150ww; 70wl A noncontrast CT of the abdomen is ordered on Mr. Smith. The primary indication is a 15year history of alcoholism. What can the technologist do to help the radiologist determine whether the patient has a fatty liver? A. Administer IV contrast and repeat series B. Administer additional oral contrast and repeat seriesC. continue scanning through pelvis, even though a pelvic exam was not ordered D. Place a region of interest HU measurement within the liver and spleen before filming - D. place a region of interest HU measurement within the liver and spleen before filming The phase of liver enhancement that occurs 60-70 seconds after an IV bolus contrast injection is called the: A. early arterial phase B. late arterial phase C. portal venous phase D. equilibrium phase - C. portal venous phase For what clinical indication might a dual phase (late arterial and portal venous) CT of the abdomen be requested? A. to assess possible liver metastasis from a primary thyroid tumor B. detection of suspected liver abscess C. characterization of fatty infiltration of the liver D. acute cholecystitis - A. to assess possible liver metastasis from a primary thyroid tumor The nephrogram phase is seen approximately after IV contrast injection? A. 30 seconds B. 70 seconds C. 110 seconds D. 5 minutes - C. 110 seconds An adrenal mass that measures less than or equal to 10HU on unenhanced CT: A. is an adenoma B. is most likely malignant C. can be either an adenoma or a malignant mass D. is lipid poor - A. is an adenoma What explains the diversity in clinical presentation of acute appendicitis? A. The variable position of the appendix B. The skill of the examiner C. The varying ability of patients to accurately describe their symptoms D. The underlying cause of the obstruction - A. the variable position of the appendix A focused appendiceal CT refers to a scan protocol that: A. limits the scan area to the lower abdomen and upper pelvis B. uses a rectal contrast agent C. does not include any type of contrast media D. scans the entire abdomen and pelvis with IV and oral contrast material - A. limits the scan area to the lower abdomen and upper pelvis What percentage of urinary tract calculi will be seen on non-contrast helical computed tomography?A. 40% B. 60% C. 85% D. 99% - D. 99% Which is NOT a synonym for the preliminary/localizer image taken at the start of a CT examination? E. Topogram F. Scout G. Scanogram H. Spiral - D. Spiral The ability of a system to differentiate, on the image, objects with similar densities is known as: E. High contrast resolution F. Low contrast resolution G. Spatial resolution H. Temporal resolution - B. Low contrast resolution Each two dimensional square of data that make up the CT image is called a: E. Pixel F. Voxel G. Matrix H. Fragment - A. Pixel How many pixels are contained in a 1,024 matrix image? A. 1,024 B. 2,048 C. 262,144 D. 1,048,576 - D. 1,048,576 Beam attenuation can be defined as: E. The phenomenon by which artifacts result when lower energy photons are preferentially absorbed, leaving only higher-intensity photons to strike the detector array. F. Xray energy that is produced from bombarding a substance with fast moving electrons. G. The ability of the detector to capture transmitted photons and change them to electronic signals. H. The phenomenon by which an xray beam passing through a structure is decreased in intensity or amount because of absorption and interaction with matter. - D. The phenomenon by which an xray beam passing through a structure is decreased in intensity or amount because of absorption and interaction with matter. Computed Tomography for Technologists 2nd Edition Exam Newest | With complete solution Updated 2024/25Which of the following is a low attenuation structure: E. Iodine filled aorta F. Rib G. Trachea H. Calcified arteries - C. Trachea An object is slightly less dense than water. What is the expected hounsfield measurement? A. -940 B. -10 C. 50 D. 850 - B. -10 Why does the administration of iodinated contrast media result in an enhanced image? E. Iodinated contrast material increases the ability of the enhanced structure to attenuate the xray beam. F. Iodinated contrast material decreases the average photon energy of the xray beam; therefore more photons are absorbed by the patient. G. The administration of contrast material results in a smaller pixel, thereby increasing spatial resolution, which results in an enhanced image. H. - A. Iodinated contrast material increases the ability of the enhanced structure to attenuate the xray beam. The xray beam sources for CT produce xray energy that is polychromatic. This means: E. When viewed by the naked eye, the beam exhibits many different colors. F. It produce, as a byproduct, a substance known as polychlorinated biphenyl. G. Photons contained in the beam are all of the same wavelength. H. The beam comprises photons with varying energies. - D. The beam comprises photons with varying energies. An object that appears on the image but is not present in the object scanned is called a/n: E. Artifact F. Anomaly G. Shadow H. Ghost - A. Artifact Which is an advantage of filtering the xray beam? E. Filtering reduces the anode heat load F. A filtered beam produces images with substantially less quantum mottle G. Filtering the beam prevents energy from being converted to heat, therefore 100% of the energy is converted to xrays. H. Filtering reduces the radiation dose to the patient. - D. Filtering reduces the radiation dose to the patient Scan thickness is primarily important for the part it plays in:E. Noise reduction F. The contrast scale G. Detector aperture opening H. Volume averaging - D. Volume averaging You are working with the radiologist to establish examination protocols for your department. Which of the following is a logical consideration when determining an appropriate slice