CT Registry Review (MIC) Questions and Answers Rated 100%

CT Registry Review (MIC) Questions and Answers Rated 100% In order for an x-ray photon to be measured it must: 1. enter the detector chamber 2. be absorbed by the detector material 3. be converted to a measurable event *ANS* 1,2,3 Which system component converts the projection attenuation data into the proper digital form for the array processor? *ANS* analog-to-digital converter Which of the following is NOT a function of a PACS system? a. reconstruction of the image from the raw data b. long term data storage c. digital distribution of images d. image display for the radiologist *ANS* reconstruction of the image from raw data Which of the following is not part of the CT tube? a. tungsten target b. collimator c. rotating anode d. filament *ANS* collimator Which of the following is FALSE regarding CT systems? 1. they are limited to nonoblique transverse scanning 2. they cannot generate a straight coronal or sagittal image 3. hey have no moving parts *ANS* 1,2,3 Xrays are used in CT because: a. they are easily produced by the high frequency generator b. they are less harmful than the heating effects of microwave radiation c. they penetrate the body according to specific attenuation characteristics of each tissue d. the FDA imposes no limit on the dose to the patient *ANS* C Most of the commands from the technologists are received by the: *ANS* operators console Xrays are produced whenever fast moving electrons collide with any form of matter because: *ANS* The electron loses kinetic energy which is converted into the emission of an x-ray photon The mA determines the: *ANS* quantity of x-ray photons Which of the following is a component NOT normally located in the gantry of a modern CT system? *ANS* array processor Tube interscan delay time refers to: *ANS* the time between the end of one scan and the start of the next scan during which the tube will cool Increased _______ will increase the likelihood that a given x-ray will penetrate a material 1. kV 2. mA 3. exposure time *ANS* 1 Which of the following are NOT commonly used on today's commercially available CT scanners? 1. xenon detectors 2. fourth-generation technology 3. continous rotation technology *ANS* 1,2 Which of the following statements is FALSE regarding occurrences after an x-ray photon penetrates the detector aperture? 1. the photon can pass through the detector unmeasured 2. the photon is converted completely into a electron 3. the measured signal in enhanced by an amplifier *ANS* 2 Scatter radiation is caused by: *ANS* deflections from the original trajectory of an x-ray photon through the patient What control does the operator have over the x-rays in a CT exam? *ANS* the energy level and the quantity of x-rays can be selected Which of the following is the standard that's used to achieve compatibility for image transfer between various imaging modalities, viewing stations, and printers in a hospital? *ANS* DICOM The enormous heat that builds up in the CT tube is caused by what? *ANS* Collision of the electron beam with the tungsten target on the tube anode _________________ made helical imaging possible *ANS* Continuous rotation scanners The patient table: a. may move continuously during the scan b. can never be positioned automatically by software due to safety precautions c. remains stationary through the exam once it is initially positioned d. only moves after each slice is completed *ANS* A The main purpose of the detector is to: *ANS* capture x-ray photons and convert them to a measurable signal The cathode filament: *ANS* helps determine the size of the focal spot Which of the statements in TRUE: 1. kV is the voltage potential between the tube cathode and anode while mA ultimately controls the filament temp of the cathode filament 2. kV controls the energy level of the x-ray photons and mA controls the number of x-ray photons emitted from the tube 3. although kV and the mA affect the operation of the CT x-ray tube, the two parameters have no bearing on the image quality *ANS* 1,2 The number of electrons that flow from the cathode to the anode is controlled by the: *ANS* mA Which of the following is TRUE regarding solid state detectors: 1. x-ray photons cause the detectors to generate a flash of light 2. they are the detector type used on most CT scanners 3. they can be used in both third-generation and fourth-generation CT systems *ANS* 1,2,3 The slip ring on continous rotation CT scanners: 1. prevent the high voltage cable from winding up 2. allows the exam to commence more rapidly 3. eliminates the need for the reversal of gantry frame rotation *ANS* 1,2,3 CT is commonly referred to as all of the following except: 1. computerized axial tomography 2. digital subtraction angiography 3. CAT-scan 4. computed tomography *ANS* 2 Which of the following CT scanner designs does NOT use an x-ray tube? 1. first generation 2. PET/CT 3. electron beam CT 4. MDCT *ANS* 3 __________ allows remote authorized individuals to connect to a server in a secure fashion using the routing infrastructure provided on a public network, such as the internet. *ANS* VPNs (virtual private networks) Which technology do multi-row detector scanners employ? *ANS* third-generation Which of the following statements is FALSE regarding the collection of CT data? 1. long scan times are more desirable because they average out motion artifacts 2. reconstruction process used to create the image occurs in the array processor 3. to collect the complete st of CT data, x-rays must be passed through the body at many different angles 4. the detectors measure the x-rays which completely penetrate the patient *ANS* 1 On a single-row detector scanner, collimation: 1. controls the slice thickness 2. minimizes the x-ray dose to the patient 3. reduces the detection of scatter radiation *ANS* 1,2,3 In a radiology department, a ________________ is a example of a "client" on the network: a. CT scanner b. viewing console in the physicians reading room c. printer for diagnostic images *ANS* a,b,c Which of the following is TRUE regarding multi-row detector for CT scanners? 1. size of the detector arrays along the z-direction may be different 2. the attenuation information from adjacent detector arrays may be added together to generate thicker slices 3. all of the detectors arrays may or may not be used *ANS* 1,2,3 The CT x-ray tube rotates around the patient to: 1. keep the tube cool 2. generate projection views at different angles 3. minimize the x-ray dose administered to the patient *ANS* 2 Collimation: 1. accomplished by electrically blocking x-rays 2. affects scan time 3. limits low every x-ray photons and passed high energy photons 4. is accomplished by physically blocking x-rays *ANS* 4 Tungsten is used as the target material on the tubes anode because it has a _________ atomic number and a _________ melting point 1. low, high 2. high, low 3. low, low 4. high,high *ANS* 4 CT images can be directly scanned in planes other than transverse by: 1. orienting the patient's body part so that it is not perpendicular to the x-ray beam 2. tilting the gantry 3. changing the angle that the x-ray beam leaves the tube *ANS* 1,2 Which of the following does NOT affect the quantity of x-rays that completely penetrates the patient? 1. the distance that the x-ray photons must travel on their course through the body 2. the molecular composition of the tissues through which the x-ray photons pass 3. the type of detector material used *ANS* 3 The operators console may include 1. monitor 2. keyboard 3. graphic input device *ANS* 1,2,3 ___________ is the mathematical process used by single-row detector scanner to reconstruct CT images from raw data *ANS* Filtered back projection MDCT scanners capable of collecting 64 slices in a single rotation do NOT: a. perform conventional CT scans b. perform helical CT scans c. use filtered back projection as their method of image reconstruction d. perform localizer scans *ANS* C The x-ray beam used in CT scanning is ___________ the patients tissues. 1. reflected off of 2. attenuated by 3. generated by *ANS* 2 A retrospective reconstruction, in which the reconstruction field-of-view is varied, uses: a. reconstructed image in the sagittal plane b. CT raw data c. more photons d. CT image data *ANS* C CTA images come from a _____ scan. 1. conventional, or serial 2. helical 3. localizer *ANS* 2 The actual attenuation data measured by the detectors from all projections during a scan is contained in CT ___________ data *ANS* raw Using _______ reconstruction filter would decrease the appearance of noise in a CT image. 1. no 2. a sharp 3. a smooth *ANS* 3 A kernel is a: a. component in the x-ray tube b. post processing filter applied to image data c. type of detector d. filter applied to the CT raw data *ANS* D Iterative reconstruction is: a. type of image reconstruction method used in CT before multi-row detector scanners were available b. complex cycle of correction calculations applied during image reconstruction in order to reduce noise in the image c. second reconstruction process performed after initial reconstruction in which a set of modified parameters is used d. typically performed on helical image data, to generate images in orientations other than those that can easily be directly acquired with CT *ANS* B From which of the following can the most diagnostic multi-planar reconstructions be generated? 1. stacked transverse images from helical scan 2. stacked transverse images from conventional, serial scan 3. stacked localizer images *ANS* 1 A pixel is a: *ANS* single 2D picture element within the image plane In a ______, the highest pixel values from a stack of CTA images are projected along many "rays" *ANS* MIP If an image matrix has 360 rows and 360 columns, how many pixels are there in the image? a. 21,600 b.129,600 c. 259,200 d.379,800 *ANS* B Important clinical benefits of iterative reconstruction include: 1. ability to reduce radiation dose without compromising image quality 2. no longer needing to perform multi-planar reconstructions 3. reduction in noise seen in the image *ANS* 1,3 Which statement is FALSE regarding 3D SSD? a. helical image data is well suited for 3D SSD because there is minimal misregistration or gaps b. the volume data, form which the 3D SSD is generated, is created by combing transverse, sagittal, and coronal recons. c. the tissue surface may be selected by using a threshold vaule equal to the tissue's CT number d. patient motion during the scan is detrimental to the quality of the 3D images *ANS* B What is 3D SSD? *ANS* 3D (Shaded surface display) Reconstructed images of the surfaces of anatomical structures A helical scan performed on a 64 slice MDCT scanner is reconstructed with: *ANS* Cone beam recons A CT manufacturer has a scanner in which the focal spot of the x-ray beam can move to two, slightly separated, distinct locations. What benefit does the dual focal spot provide compared to an identical scanner possessing a single focal spot? *ANS* The number of projections is doubled A __________ scan uses only a single projection *ANS* Localizer What does convolutin do to the image quality when it is added to the back projection reconstruction process? a. normalizes the attenuation coefficients to ensure tissues are displayed with correct CT numbers b. increases the number of projection thereby reducing streaking artifacts. c. improves contrast resolution by reducing scatter radiation d. enhances important characteristics of attenuation profiles thus reducing streak and star artifact *ANS* D The ______moves during a helical scan on a third generation scanner 1. x-ray tube 2. patient table 3. detector elements *ANS* 1,2,3 Which of the following is a reconstruction technique applied to the raw data after the primary reconstruction has already been accomplished? *ANS* Retrospective recontruction A smooth, or low pass, reconstruction filter is typically NOT selected for a(n) _____ exam. a. pituitary b. kidneys c. liver d. IAC (internal auditory canals) *ANS* D Which is NOT an advantage of a helical study compared to a conventional serial CT study? 1. minimal anatomical misregistration sometimes caused by inconsistent breath-holding 2. shorter total exam time 3. can retrospectively reconstruct a slice at any arbitrary position 4. offers the best image quality for a brain exam *ANS* 4 An increase in ___________ does NOT occur in the resulting images when applying a sharp, or high-pass reconstruction filter during the image reconstruction of CT raw data. 1. contrast resolution 2. edge enhancement 3. appearance of noise *ANS* 1 Which of the following utilizes convolution? 1. 3D SSD 2. Fourier tranform 3. filtered back projection *ANS* 3 _____________ yields an image that appears 3D but also shows anatomical details above and below 3D surfaces *ANS* VR (volume rendering) Which type of storage media may hold CT image data? 1. internal hard disk 2. CD 3. re-writable optical disk *ANS* 1,2,3 ____________ may have to be edited from the data set to get a diagnostic MIP of a CTA exam *ANS* Bones In which technique are tissues other than the surface of a structure excluded by setting a threshold value and eliminating pixels above or below that threshold? *ANS* 3D shaded surface display Which statement is TRUE: 1. amplified electrical signal obtained from detectors must be digitized 2. digital CT images are numerical representations of cross-sectional anatomy 3. digital signals may be formed by sampling analog signals at discrete time intervals *ANS* 1,2,3 Muti-planar reconstructions are performed on which of the following: a. image data b. raw data c. attenuation profiles *ANS* A ____________ allows helical data to be converted into planar raw data *ANS* Interpolation Which of the following may occur during the interscan delay of a conventional or serial CT scan, performed on a continuous rotation scanner? a. table position is incremented b. tube continues to rotate in same direction as during scan c. tube assembly makes a 360 degree rotation *ANS* a,b,c On a third generation single row detector scanner, if there are 750 detectors and there are 900 projections in a full rotation, how many samples of attenuation data are collected for the raw data of a single slice if the scan call for an overscan of 400 degree rotation. *ANS* 715,000 The _______________ determines the intensity of the laser beam in a laser camera 1. intensifying grid 2. pixel values in the image data 3. magnifying power of the lens *ANS* 2 The pencil thin section of the x-ray fan beam that strikes a single detector is called a : a. line b. projection c. view d. ray *ANS* D 3D shaded surface displays are performed on CT: 1. image data 2. raw data 3. attenuation profiles *ANS* 1 Which of the following is TRUE regarding the slice thickness of an image reconstructed from a helical scan a. on a multi-row detector scanner the thickness is equal to the beam collimation b. on a single-row detector scanner, the thickness is equal to the beam collimation c. on a multi-row detector scanner the thickness is always equal to the detector size *ANS* B MIP images: a. are most frequently used for visualizing air filled spaces b. can NOT be run in a cine loop c. are most accurate when a large volume of interest is selected d. do NOT demonstrate detail beneath the brightest pixel *ANS* D Which of the following determinants of CT image quality is responsible for how grainy or speckled a CT image appears *ANS* Noise An increase in ________ will result in hardening of an x-ray beam 1. tissue density 2. tissue thickness 3. kVp *ANS* 1,2,3 Which of the following are possible results of partial voluming 1. decreased sharpness 2. misleading CT numbers 3. improvement in resolution *ANS* 1,2 Which of the following is FALSE about the spatial resolution of an image a. resolution is dependent on matrix size b. resolution is dependent on reconstruction OB c. resolution is dependent on scanned FOV *ANS* 3 Which of the following is NOT directly proportional to mAs 1. the mean energy of the x-ray photon leaving the tube 2. number of x-ray photons leaving the tube 3. x-ray tube heating 4. dose to patient *ANS* 1 Which of the following has the highest patient dose assuming all other parameters are the same 1. mA=200, rotation time=2 seconds 2. mA=200, rotation time=1 second 3. mA= 150, rotation time= 3 seconds 4. mA=400, rotation time=1 second *ANS* 3 What will result in a increased voxel size? *ANS* increased slice thickness What is the conversion equation from CT number to Hounsfield unit? *ANS* CT number= Hounsfield unit If the radiologist requires 2 mm thick contiguous slices through the pituitary, and 2.4 cm of coverage, ___ slices are necessary? a. 8 b. 10 c. 12 d. 13 *ANS* C CT number ____________ would appear black if a window width of 400 and a window level of -100 are used. *ANS* Below -300 If a reconstruction FOV of 32 cm and a 512x512 matrix are used, the pixel size is ________mm. *ANS* 0.625 x 0.625 Which of the following is a reason to increase pitch? a. greater volume of anatomy can be covered in a given time b. given volume of anatomy can be covered faster c. radiation dose to the patient can be increased *ANS* a,b Which of these would be used to better visualize low contrast resolution: 1. decreased mAs 2. sharp reconstruction filter 3. narrow window width *ANS* 3 Increasing ___________ results in lowering the patient dose 1. pitch 2. mAs 3. table increment *ANS* 1,3 If a thin slice is used, which of the following would help reduce the apparent image noise? a. reduced reconstruction field of view b. increased matrix c. increased mAs d. increased kVp *ANS* C A set of images is reconstructed with a 150 mm reconstruction FOV. Keeping all other parameters constant, a second set of images is reconstructed with a 300 mm reconstruction FOV, and then magnified so that the anatomical structures in the first and second set appear the same size. Which of the following statements is FALSE? 1. the resolution of the second set of image is better then the first set 2. the apparent noise in the second set of images is more pronounced than the first set 3. the patient dose of the first set of images is higher than the second set *ANS* 1,2,3 The ___________determines how penetrating the x-ray beam will be *ANS* kVp The smallest object that can be resolved if a reconstruction FOV of 24 cm and a 512 x 512 matrix are used is ____________mm. *ANS* .47 Which of the following parameters affects the contrast of a CT image? *ANS* kVp Which of the following values for pitch would stretch the x-ray helix the most? a. 1.5 b. 1.0 c. .8 d. 05 *ANS* A There are __________ total pixels in a 1024 x 1024 matrix 1. 2048 2. 524,288 3. more than 1 million 4. more than 2 million *ANS* 3 For a given distance for coverage, which of the following is TRUE? 1. as reconstruction FOV increases, patient dose increases 2. as pitch increases, patient dose decreases 3. as slice thickness increases, patient dose decreases *ANS* 2,3 Which statement is FALSE 1. magnification requires the raw data 2. increasing magnification increases resolution 3. magnification decreases the size of displayed anatomy *ANS* 1,2,3 Compared to a CT scan protocol without iterative reconstruction applied, when using iterative reconstruction the scan parameter most likely to be reduced is: a. mAs b. matrix c. pitch d. scan field of view *ANS* A A CT Number Calibration Test should be performed how often? *ANS* Daily If the slice thickness is changed form 5 mm to 7 mm and all other parameters are held constant, ___ % more photons will be used in making the slice. a. 30 b. 40 c. 60 d. 80 *ANS* B ___________ the window ___________will make the image appear darker so that the bony structures can be evaluated 1. increasing, width 2. decreasing, level 3. decreasing, width 4. increasing, level *ANS* 4 Which of the following is the expected result of a CT number Calibration test performed on a water phantom? *ANS* 0+-3 ____________ affects the number of water *ANS* No imaging parameter Which of the following parameters allows adjacent slices to be overlapped without increasing the dose to patient *ANS* reconstruction interval Which of the following can be changed retrospectively 1. the slice thickness form an MDCT helical scan 2. slice overlap from a single-row detector scanner helical scan 3. pitch of a helical scan *ANS* 1,2 Which of the following would be used in a high resolution study of the temporal bones 1. reduced slice thickness 2. reduced reconstruction FOV 3. sharp reconstruction filter *ANS* 1,2,3 The ability to scan a moving organ without seeing motion artifacts on the images is an example of an exam performed with high: a. temporal resolution b. spatial resolution c. contrast resolution d. noise *ANS* A On a conventional, or serial, CT scan, if we want 5mm slices with 1mm of overlap, the table increment should be ___mm. *ANS* 4 On MDCT the final reconstructed slice thickness is determined by the *ANS* number of rows of detectors and the size of the detectors whose attenuation data gets combined Which of the following parameters is responsible for partial volume averaging a. matrix size b. kvp c. slice thickness d. patient dose *ANS* C The distance that the table travels between slices is called: a. table increment b. collimation c. rotation d. reconstruction interval *ANS* A Which of the following parameters cause helical slices to be reconstructed so they overlap? a. table increment b. reconstruction interval c. pitch d. collimation *ANS* B Which of the following does NOT occur when reconstruction FOV is decreased? a. spatial resolution is increased b. pixel size is increased c. noise in the image increases *ANS* B If a calcification with a CT number of 300 appears pure white on an image, which of the following could be the window width and window level selected? 1. wl = 0, ww = 500 2. wl = 300, ww = 500 3. wl = 100, ww = 1000 *ANS* 1 A blood urea nitrogen level of _________ mg/dl is considered outside normal range a. 10 b. 18 c. 32 *ANS* C A 25 year old female is scheduled for a CT scan of the sinuses. She is absolutely certain she is not pregnant and it has been three weeks since her last menstrual period. Which is the best course of actions a. perform the exam immediately while she is experiencing sinus problems b. postpone procedure until she is more certain c. cancel procedure indefinitely d. suggest she get a MRI instead *ANS* B To modify a standard CT protocol so that it is appropriate for children, which should be decrease? 1. pitch 2. kvp 3. mas *ANS* 2,3 Which does NOT minimize the radiation dose to the patient a. decreasing distance from the x-ray tube to the patient b. filtration of the low energy photons from the beam c. increasing pitch d. pre-patient collimation *ANS* A Air in the plural space causes the lung to collapse, this condition is known as *ANS* pneumothorax Which medical device is used most often to the delivery oxygen therapy? *ANS* nasal cannula Which if FALSE about oximetry? a. pulse oximeter works by passing a beam of red and infrared light through a capillary bed b. oximetry is a procedure for measuring the concentration of oxygen in the blood c. oximetry is used for patient monitoring d. normal oxygen saturation is 85% to 90% *ANS* D Which test is NOT and indication of renal funcition 1. BUN 2. creatinine 3. PTT *ANS* 3 The human embryo/fetus is most sensitive to radiation when? *ANS* First trimester Platelets are small: a. implants b. detector elements responsible for capturing attenuated photons c. cell fragments necessary for blood coagulation d. catheters used for administering contrast media. *ANS* C A creatinine level of 3.1 mg/dl indicates the: 1. kidneys are not removing waste products from the urine 2. patient is not a good candidate to receive IV contrast 3. value is below the normal range *ANS* 2 Which statement is TRUE? 1. respirators are not allowed in CT 2. Pulse ox are allowed in CT 3. patient should be removed from CT to treat cardiac arrest *ANS* 2 Which of the following values for prothrombin time are considered outside normal range? a. 12 sec b. 20 sec c. 30 sec *ANS* b,c What is the range for prothrombin time? *ANS* 10-14 sec Which of the following statements in TRUE if the patient history was taken at the time of scheduling? 1. a claustrophobic patient can arrive for the scan prepared with a prescription sedative 2. time can be saved the day of the exam by skipping the screening process 3. if it has been determined that the patient has no prior illness or conditions monitoring is unnecessary *ANS* 1 If the mA of a 2 second brain scan is doubled and all other parameters are not changed, the dose is: A. doubled B. unaffected C. halved D. quadrupled *ANS* A Renal function refers to which organs? *ANS* Kidneys Which of the following reduced patient dose at the expense of increasing the apparent noise in the image? a. kVp b. pitch c. table increment d. mAs *ANS* D During a CT scan, the patient must be monitored: a. visually and verbally b. occasionally c. by a nurse d. by a pulse oximeter *ANS* A ____________ offers standardized lab values indicating the blood's ability to coagulate for patients who are taking anticoagulant medications *ANS* INR (international normalized ratio) Chest tubes 1. are used to remove air or fluid from pleural cavity 2. may be looped so that they don't get in the way during the CT scan 3. are attached to a drainage system that needs frequent emptying *ANS* 1 When reviewing the images from a helical CT scan, a subtle, suspicious area of possible pathology is noticed. What could be done to better visualize the suspicious are WITHOUT increasing the dose to the patient 1. re-scan the region using thinner slices 2. re-scan the region using a lower pitch 3. retrospectively reconstruct the slices so that they overlap *ANS* 3 The diabetes drug, metformin, has the same precautions as 1. Glucophage 2. Glucovance 3. Gadolinium *ANS* 1,2 Which of the following is NOT a typical indication of shock? 1. grayish skin tone 2. convulsive seizures 3. hypotension 4. tachycarida *ANS* 2 CPR must be administered to a cardiac arrest victim within a maximum of ___ mins before there is a risk of brain damage. a. 1 b. 4 c. 8 d. 12 *ANS* B Normal diastolic pressure range for adults *ANS* 60-80 mm of mercury Normal systolic pressure range for adults *ANS* 110-140 mm of mercury The most important consideration in the care of an unconscious patient is to ensure that a. air passage is clear b. body temp is decreased c. fluids are maintained d. no medications are administered *ANS* A A normal adult has ______ respiration's per minute *ANS* 12-20 Following the HIPPA guidelines, you may give a patient's medical information to another employee: a. if it is in plain sight on the CT console and the employee has already read it b. if the employee is related to the patient c. only if it is needed to do their job d. to joke about the patient's excessive weight *ANS* C Which of the following lab tests is often performed in conjunction with CT pulmonary angiography in order to rule out pulmonary emboli? a. GFR b. D-dimer c. INR d. platelet count *ANS* B For x-ray radiation, which of the following is TRUE? a. 1 rem = 1 rad b. 1 rem = 1 Gy c. 1 rad = 1 Gy d. 1 rad = 1 Sv *ANS* A Which of the following may result from exposing an embryo to x-ray radiation? a. mental retardation b. miscarriage c. deformities *ANS* A,B,C As measured by a pulse oximeter, normal oxygen saturation in the blood is ______% to __________% a. 50, 50 b. 70, 75 c. 85, 90 d. 95, 100 *ANS* D In a normal electrocardiogram, the _______ wave has the highest amplitude. *ANS* R Which of the following vital signs is considered abnormal? a. adult pulse of 75 BPM b. pediatric pulse of 110 BPM c. adult blood pressure of 160/100 d. oral temperature of 97 degrees *ANS* C Which is NOT a standard infection control precaution to use with all patients? a. use of an N95 respirator b. wash hands after touching patient c. disposal of needle in sharps container d. wear gloves when starting an IV *ANS* A Making up the ARRT Standard of Ethics are the Code of Ethics, which is _____ , and the Rules of Ethics, which are ____. a. a law, variable depending upon the state you're in b. a conduct guideline, variable depending upon the state you're in c. a conduct guideline, enforceable d. a law, recommended job descriptions *ANS* C Which of the following is a good estimate of the effective dose from a typical CT head scan? a. .3 mSv b. 2 mSv c. 5 rem d. 9 rem *ANS* B Which of following is the complete name of the laboratory test known as PTT? *ANS* Partial thromboplastin time, time for blood to coagulate A patient about to get a scan of her sinuses may wear: a. eyeglasses so she can see the technologist b. a nose ring c. her new belt with a large silver buckle d. earrings, to look her best *ANS* C The result of which of the following lab tests may impact the decision to administer IV contrast media: 1. BUN 2. creatinine 3. PT *ANS* 1,2,3 In a normal electrocardiogram, the _______ wave represents atrial contraction *ANS* P On a multi-row detector scanner, a radiation penumbra may be found: a. on every other slice b. only on the trailing edges of the slices c. on every slice d. only on the first and last slices of the slice volume *ANS* D In all states, patients are required by law to sign consent forms for the following reason: a. permission to administer contrast b. permission to perform a surgical procedure c. signed consents forms are not required by law in every state d. permission to administer sedation *ANS* C During a coronary calcium scoring study which technique will minimize the radiation dose to the patient? a. prospective cardiac synchronization b. retrospective cardiac synchronization c. no cardiac synchronization d. pitch <1 *ANS* A Which measurement of radiation dose accounts for helical studies on a multi-row detector scanners and considers the total volume of irradiated tissue? *ANS* DLP (dose length product) counts total number of slices and slice thickness Which of the following is the correct action to take if a patient arrives with an obvious head trauma, expecting a CT of the brain, but the paper requests a pelvic CT? a. perform only a scan of the pelvis b. request clarification from ordering physician c. perform both exams d. perform only a scan of the brain *ANS* B A normal pulse rate for an infant is ______BPM *ANS* 140 Which of the following conditions may be an indication NOT to use IV contrast media? 1. previous serious reaction to contrast media used during another diagnostic procedure 2. allergy to iodine 3. renal impairment *ANS* 1,2,3 Radiation shields used in CT 1. may be used to protect radiation-sensitive body parts 2. are typically made from tungsten antimony and bismuth 3. must be kept outside of the scan FOV *ANS* 2,3 Which of the following is a possible long-term effect of repeated exposure to radiation? 1. cataracts 2. cancer 3. decrease in life expectancy *ANS* 1,2,3 What should be done if extravasation is noticed at the injection side? a. apply ice and continue injecting b. stop the injection immediately c. slap the area d. apply head during the injection *ANS* B Which of the following is the order in which the phases of IV contrast enhancement occur? a. bolus, equilibrium, non-equilibrium b. equilibrium, non-equilibrium, bolus c. bolus, non-equilibrium, equilibrium d. non-equilibrium, equilibrium, bolus *ANS* C Which of the following oral contrast agents is better for opacifying the distal small intestine? 1. an ionic iodinated contrast agent 2. a non-ionic iodinated contrast agent 3. barium sulfate *ANS* 3 only The definition of osmolality is the __________ the contrast agent solution a. thickness of b. measure of dissociation of c. concentration of molecular particles in d. rate of injection of *ANS* C When a contrast agent is injected directly into the joint space it is known as ______ contrast. a. intravenous b. intrathecal c. oral d. intraarticular *ANS* D Which of the following characteristics of an IV contrast agent affects patient tolerance? 1. concentration of iodine 2. osmolality 3. viscosity *ANS* 1,2,3 The viscosity of IV contrast media can be reduced by: a. shaking b. stirring c. aerating d. heating *ANS* D The heating unit on a power injector is for _______ of the contrast agent a. increasing the iodine concentration b. decreasing the viscosity c. increasing the density d. decreasing the osmolality *ANS* B A difference in density of ____HU between the aorta and the inferior vena cava would indicate the non-equilibrium phase of enhancement a. 43 b. 35 c. 25 d. 8 *ANS* C A delay of about ___ seconds after the start of the IV contrast injection should be used for a helical scan of the chest. a. 60 b. 45 c. 30 d. 15 *ANS* C Barium sulfate oral contrast media would be selected instead of iodinated oral contrast media because: 1. it passes through the GI tract more quickly 2. the trauma patient may have a perforated bowel 3. the contrast media stays more dense in the distal GI tract *ANS* 3 only The most common catheter size used in CT is ______ a. 12-14 b. 15-17 c. 18-22 d. 23-25 *ANS* C If there is a doubt regarding the sterility of the contrast media, the contrast media must be: a. shaken b. diluted c. heated d. discarded *ANS* D An indication for IV contrast injection is to rule out: a. mastoiditis b. sinusitis c. meningioma d. Grave's disease *ANS* C The osmolality of plasma is _____mOsm/kg a. 175 b. 235 c. 285 d. 325 *ANS* C Which of the following is FALSE about the catheter used to administer iodinated IV contrast during CT exams? a. specially labeled PowerPICCs may be used up to 5 ml/sec b. standard peripherally inserted central catheter like those used for chemotherapy are required c. typically an 18-22 gauge catheter is selected d. larger catheters are used for higher rates of injection *ANS* B A delay of about _____ seconds after the start of the IV contrast injection should be used for a helical scan of the neck. a. 20 b. 35 c. 50 d. 75 *ANS* B According to the American college of radiology (ACR) guidelines, which of the following statements is TRUE about using iodinated IV contrast media with pregnant patients: 1. under no circumstances should IV contrast be administered to a pregnant patient 2. IV contrast may be administered when it is not prudent to wait to obtain the clinical information until after the pregnancy 3. IV contrast may be administered if the clinical information obtained will affect the care of the patient and fetus during pregnancy *ANS* 2,3 What is the appropriate care to give to a patient with diabetes? 1. if the contrast media required, use LOCM 2. if the patient is using metformin advise them to stop its use 48 hours before IV contrast is administered 3. if the patient is using metformin, advise them to resume its use 48 hours after IV contrast administration only after kidney function has been reassessed and determined to be normal *ANS* 1,3 Which of the following may help to reduce adverse reactions resulting from the administration of IV contrast media? a. use high osmolar contrast media b. administer an antihistamine prior to the IV contrast injection c. increase the rate of injection *ANS* B To best visualize the stomach wall, which of the following should the patient drink last? 1. iodinated contrast media 2. water 3. barium sulfate oral contrast *ANS* 2 There is a substantial enhancement of the liver compared to tumors during the ________ phase, but during the __________ phase, there is the possibility of tumor enhancement, which may make hepatic tumors isodense with liver tissue. a. bolus, equilibrium b. non-equilibrium, equilibrium c. non-equilibrium, bolus d. equilibrium, non-equilibrium *ANS* B Exams to rule out ___ would indicate the use of IV contrast media in the chest. 1. lymphoma 2. hilar mass 3. aortic dissection *ANS* 1,2,3 Which of the following is a typical scan delay following the start of the injection for helical CT examinations of the pancreas a. 50-60 sec b. 70-80 sec c. 80-90 sec d. 2-3 minutes *ANS* A Why is the cephalic vein a less desirable site for injection than the basilic vein? a. it is usually a very small vein with poor blood flow b. the blood must traverse the vessels in the head before reaching the heart c. it is a deep vein and not easily catheterized d. flow may be impeded as the patients arms are raised *ANS* D How long does it take to inject 150ml of contrast media with an injection rate of 2ml/sec a. 50 sec b. 75 sec c. 1 min d. 2.5 min *ANS* B Viscosity is a measure of a fluid's _________. *ANS* thickness Which of the following is a result of injecting a hypertonic solution into the vascular space a. there is a net movement of water into the vascular space b. there is a net movement of contrast media out of the vascular space c. there is a net movement of water out of the vascular space d. there is nothing noteworthy about injecting *ANS* A The portal venous phase occurs about ___ seconds after the start of the IV contrast injection. a. 20 to 30 b. 40 to 60 c. 60 to 90 d. 90 to 120 *ANS* C An injection rate of __________ cc/sec. will maintain a dense bolus of IV contrast media for a CTA examination and will be tolerated by most patients. a. 8-10 b. 7-8 c. 4-5 d. 1-2 *ANS* C Iodinated IV contrast agents perfuse normal: a. liver tissue b. brain tissue c. thecal sac d. lymph nodes *ANS* Which of the following is associated with a bi-phasic study of the liver? a. differentiation of lesions with arterial and portal venous blood supplies b. two injection rates used during the study c. two images for each slice position *ANS* 1,3 A CT study of the brain to visualize MS plaques may be made more sensitive by using ____ delay after the contrast agent has been injected a. 45 sec b. 15 min c. 45 min d. 2 hours *ANS* C Low Osmolar contrast media: a. typically has the same concentration of particles as the blood b. typically has a higher concentration of particles compared to blood c. tends to cause more adverse reaction than high osmolar d. is never used in CT *ANS* B The hepatic arterial phase occurs about _______seconds after the start of the IV contrast injection a. 0-20 sec b. 20-40 sec c. 40-60 sec d. 60-80 sec *ANS* B Which of the following is NOT a typical adverse reaction to oral contrast media used in CT a. diarrhea b. abdominal cramping c. flatulence d. hives *ANS* D What type of negative contrast agent is administered rectally for virtual colonoscopy studies. a. CO2 b. water c. barium sulfate oral agents d. iodinated oral agents *ANS* A Which of the following is TRUE regarding barium sulfate solutions used in CT? a. they are less concentrated than those used in conventional radiography b. they are the same as those used in conventional radiography c. they are in no way related to those used in conventional radiography d. they are more concentrated than those used in conventional radiography *ANS* A The contrast between a lesion and the surrounding tissue may _____ following the injection of contrast media 1. improve 2. remain unchanged 3. be degraded *ANS* 1,2,3 Contrast agents containing barium sulfate: 1. enhance structures because they are absorbed into the blood stream 2. enhance structures because they are absorbed through the small intestine 3. pass through the GI tract unchanged *ANS* 3 Which of the following types of contrast media has NO application for a CT study of the thoracic spine 1. intrathecal 2. intravenous c. oral *ANS* 3 In which of the following studies might cranial nerve XI be visualized a. soft tissue neck b. lumbosacral spine c. supratentorium d. internal auditory canal *ANS* A In order to generate a 3D shaded surface rendering of the hips, the _____ data is used directly by the 3D reconstruction software a. image b. raw c. unreconstructed d. projection *ANS* A Which of the following is the appropriate range of coverage for a coronal sinus study? a. from the internal auditory canals to the ethmoid sinus b. from the clivus to the anterior clinoid process c. from the fourth ventricle to the sphenoid sinus d. from the dorsum sella to the anterior aspect of the frontal sinus *ANS* D Which of the following is NOT a reason for using thinner slices in the posterior fossa compared with the more superior regions of the brain? 1. to reduce streak artifacts 2. to improve spatial resolution 3. to decrease radiation dose to the patient *ANS* 3 A localizer image in which of the following orientations should be sued to set up axial slices so that they can be angled parallel to the plane of a specific lumbar disc? a. AP b. transverse c. oblique d. lateral *ANS* D Which of the following statements is TRUE regarding CT exams of the spine? 1. IV contrast is usually not administered to rule out a herniated disc 2. the entire thoracic spine is not routinely scanned with transverse CT slices 3. sagittal and coronal images of an adult spine may not be directly collected from a CT scan *ANS* 1,2,3 Which of the following is NOT an indication of herniated disc 1. deformity of the posterior border of the disc 2. displacement of epidural fat 3. hypertrophy of the inferior articulating process and lamina *ANS* 3 Which of the following window settings provides the best tissue differentiation of the soft tissues of the supratentorium? a. WW=100, WL=30 b. WW=300, WL=60 c. WW=1000, WL=200 d. WW=2500, WL=350 *ANS* A On a CTA exam of lower extremity vasculature to assess atherosclerosis, coverage should extend from the ________ to the ________. a. abdominal aorta, ankles b. abdominal aorta, iliac arteries c. iliac arteries, femoral arteries d. iliac arteries, popliteal arteries *ANS* A What is the primary reason to have a patient letter "e" during a CT exam of the larynx a. it closes the pyriform sinuses b. it demonstrates vocal cord mobility c. it distends the laryngeal ventricles ventricles d. it provides definition of the epiglottis *ANS* B Which of the following combinations of scanning parameters is best for evaluating abnormalities within the petrous pyramids of the temporal bones? a. standard algorithm, window width =300, 0.5 to 2 mm slices b. soft algorithm, window width =300, 0.5 to 2 mm slices c. sharp algorithm, window width=2500, 0.5 to 2 mm slices d. standard algorithm, window width=2500, 4 to 8 mm slices *ANS* C Which of the following should NOT be part of a CT brain perfusion exam? a. the patients head should rest freely and should be unrestrained b. IV contrast is administered c. multiple scans need to be performed every 1-2 seconds for a period of about a minute d. low dose protocols are used *ANS* A CT brain perfusion: 1. replaces the need for CT angiography 2. is typically performed to evaluate stroke 3. evaluates blood flow through major vessels *ANS* 2 Which of the following is necessary to quickly and accurately diagnose the presence of a stroke? 1. evaluate for the presence of ischemic but viable tissue 2. evaluate for the presence of vascular occlusion 3. establish the presence or absence of intracranial hemorrhage *ANS* 1,2,3 Which of the following is FALSE about a CT runoff exam? a. the spatial resolution of the exam surpasses that of MRA b. the patient should be positioned feet first and supine c. coverage should extend from the upper abdominal aorta to the popliteal artery bifurcation d. IV contrast should be administered at a rate of 4ml/sec *ANS* C Indication for CT exams of the head include: 1. trauma 2. multiple sclerosis 3. stroke *ANS* 1,3 Which of the following is NOT a location where one would expect to find cerebrospinal fluid 1. subarachnoid space 2. subdural space 3. fourth ventricle of the brain *ANS* 2 Which scanning plane is best for evaluating the anatomical relationship between the pituitary and the sella turcica? a. transverse b. oblique between transverse and sagittal c. coronal d. sagittal *ANS* C Which of the following would NOT enhance during the first several minutes of a post contrast CT study of the neck a. vascular lesion b. lymph nodes c. jugular vein d. internal carotid artery *ANS* B What is the range of anatomy that should be covered for examination of one intervertebral disc space? a. from the pedicle of the vertebra above the disc to the pedicle of the vertebra below the disc b. from the spinous process of the vertebra above the disc to the spinous process of the vertebra below the disc c. from the apophyseal joint about the disc to the apophyseal joint of the vertebra below the disc d. from the superior articular process of the vertebra above the disc to the superior articular process of the vertebra below the disc *ANS* A In which of the following studies might cranial nerve VII be visualized? a. internal auditory canal b. cervical spine c. soft tissue neck d. supratentorium *ANS* A If we want to generate a diagnostic 3D surface reconstruction of the affected region of the cervical spine, how should the scan be performed? a. at orthogonal orientations through the affected region b. with fairly large gaps between the slices c. at various angles through each affected disk space d. at a single angle through the affected region *ANS* D Which of the following positions may reduce the lordotic curve, when performing a CT scan on a lumbosacral spine a. prone with knees bent over a wedge b. right decub position c. prone with knees straight d. supine with knees bent over a wedge *ANS* D For CT brain scans, the reference line for axial slices may be which of the following? 1. cantomeatal line 2. orbitomeatal line 3. infraorbitomeatal line *ANS* 1,2,3 Which of the following should be removed for a study of the sinuses 1. barettes 2. eyeglasses 3. nose ring *ANS* 1,2,3 How should the mAs be varied to compensate for an increase in apparent image noise casued by reducing the slice thickness? a. halve the mA and halve the scan time b. halve the mA and double the scan time c. decrease mAs d. increase mAs *ANS* D For which of the following conditions of the brain should IV contrast NOT be administered a. suspected atrophy b. evaluation of an aneurysm c. recurrent headaches d. evaluation of a mass *ANS* A For a routine CT exam of the pelvis, what gantry tilt is used? a. 20 degrees b. -20 degrees c. 10 degrees d. no tilt *ANS* D Which of the following are typical start and end locations for CT scans of the pelvis a. from the xyphoid process through the iliac crest b. from the sternal notch through the iliac crest c. from the iliac crest through the symphysis pubis d. from the sternal notch through the symphysis pubis *ANS* C Which of the following provides the best bone window setting for the pelvis a. WW=100, WL=-200 b. WW=140,WL=60 c. WW=1000, WL=2000 d. WW=2000, WL=350 *ANS* D Which of the following is a reason for inserting a tampon in the vagina for CT exams of the female pelvis? a. provides a high intensity on the image b. eliminates the need for IV contrast injection c. eliminates the need for oral contrast media d. helps visualize the vaginal canal *ANS* D For which of the following studies in the chest is IV contrast typically used 1. chest masses 2. hilar masses 3. cardiac masses *ANS* 1,2,3 Which of the following is the typical orientation for a localizer in a chest exam? a. AP b. transverse c. lateral d. oblique *ANS* A Which of the following should NOT be done in preparation for a CT colonography exam? a. fecal tagging b. colon cleansing c. rectal administration of barium d. colon distention *ANS* C Which of the following is NOT recommended for a screening CT colonography exam? 1. 200 mAs 2. both prone and supine scanning 3. post-processing to visualize inside surfaces of the bowel *ANS* 1 Which of the following is FALSE regarding a coronary calcium scoring exam? a. contrast media is not used b. it is often performed on patients with risk factors for coronary artery disease, but no actual symptoms c. cardiac synchronization is required d. a high calcium score is evidence of stenosis *ANS* D In order to assess cardiac function, the ___ ___ is evaluated. a. left atrium b. right atrium c. left ventricle d. right ventricle *ANS* C The _________ view is used to evaluate cardiac function a. short axis b. two chamber long axis c. four chamber d. axial *ANS* A Normal ejection fraction is greater than _____% a. 60 b. 70 c. 80 d. 90 *ANS* A A CT urogram study: 1. collects images during the nephrogenic phase by beginning to scan 30 seconds after the start of the IV contrast injection 2. requires 2 quarts of water to be consumed within 45 minutes of the exam 3. Evaluates the kidneys, ureters, and bladder *ANS* 2,3 Which of the following is a technique used to minimize artifacts from patient motion in exams of the chest 1. suspended respiration 2. shortened scan time 3. patient immobilization devices *ANS* 1,2,3 Which of the following is NOT contained within the mediastinum? a. esophagus b. heart c. bronchi d. lungs *ANS* D For CT exams of the chest, the patient is usually positioned: a. prone with arms at sides b. prone with arms raised over the head c. decubitus with arms raised over the head d. supine with arms raised over the head *ANS* D Typically what mAs is used in routine CT exams of the abdomen? a. mAs varies due to patient size and variables such as whether iterative reconstruction and dose modulation are applied b. 100 mAs c. 500 mAs d. 700 mAs *ANS* A Which of the following is the typical scan delay after the initiation of injection of contrast media for studies of the liver? a. 15-25 sec b. 70-80 sec c. 100-110 sec d. a few min *ANS* B Which of the following structures is NOT part of the GI tract? a. esophagus b. stomach c. duodenum d. spleen *ANS* D Which of the following window settings provides the best tissue differentiation within the liver? 1. WW=100, WL=-200 2. WW=140, WL=60 3. WW=1000, WL=200 4. WW=2500, WL=350 *ANS* B For a CT scan of the spleen, which of the following is typically used? a. only IV contrast b. only oral contrast c. both oral and IV contrast d. no contrast *ANS* C The result of the bifurcation of the abdominal aorta is the left and right ____ arteries. a. femoral b. common iliac c. popliteal d. quadriceps *ANS* B Which of the following statements is TRUE concerning the lobes of the liver? 1. the left lobe is more anterior than the right lobe 2. the left lobe is more anterior than the caudate lobe 3. the caudate lobe is more medial than the right lobe *ANS* 1,2,3 Which of the following affects the severity of metal artifacts? 1. the quantity, composition and shape of the metal 2. the slice thickness 3. the number of data sampling points *ANS* 1,2,3 Which of the following may occur if the patients arms are placed at their sides during a chest exam if the scan FOV is 33cm? 1. beam hardening 2. out of field artifact 3. cone beam artifact *ANS* 1,2 A ____________ artifact can be created when attempting to correct for a cupping artifact by applying a correction algorithm too aggressively to the data for a head image. This results in the _______ of the image appearing too bright. a. capping, edges b. capping, center c. edge gradient, edges d. edge gradient, center *ANS* B CT xray tube arcing can occur because of _________ the xray tube. 1. impurities in the oil outside 2. tungsten gas inside 3. tungsten solids in the oil inside *ANS* 1,2 Which of the following will have the least likelihood of producing edge gradient artifacts? a. thin slices with full scan b. thick slices with partial scan c. thin slices with partial scan d. thick slice with full scan *ANS* A _________ in the image is a possible manifestation of patient motion 1. Ghosting 2. Blurring 3. Streaks *ANS* 1,2,3 On a CT image of the brain a cupping artifact would appear brighter: a. at the anterior and posterior aspects of the brain b. at the periphery of the brain c. immediately around dense structures d. in the center of the brain *ANS* B A cone beam artifact may look like stars: a. at the center of the image b. coming from structures around the edge of the image c. coming from cone shaped structures d. from all structures with high CT number *ANS* B A variation in which of the following will affect the hardening of an x-ray beam? 1. tissue density 2. tissue thickness 3. kVp *ANS* 1,2,3 A CT artifact is: a. a parameter used to control the brightness of the image b. always a reason to call for repair of the CT scanner c. used to time the injection of contrast media d. an anomaly in the CT image *ANS* D Beam hardening refers to: 1. the increase in the number of photons reaching the detectors 2. the increase in the number of low energy photons reaching the detectors 3. the increase in the average energy of the photons that reach the detectors *ANS* 3 Which of the following could allow for a reduction of partial volume artifact while NOT increasing the appearance of the noise in the image? 1. increasing slice thickness while decreasing kVp 2. decreasing slice thickness while decreasing mAs 3. increasing slice thickness while increasing mAs 4. decreasing slice thickness while increasing mAs *ANS* 4 Which of the following would make noise in the image appear less noticeable? 1. increased window widths 2. increased mAs 3. increased slice thickenss *ANS* 1,2,3 The service engineer should be notified about which of the following? 1. frequent bad streaks on the inferior slices of head scans 2. a consistent circle on the images 3. frequent bad streaks throughout the entire image *ANS* 2,3 Which of the following strategies minimizes bean hardening artifacts from dense contrast media? 1. the contrast solutions can be diluted 2. the scan can be performed with a slight delay 3. the scan can be performed in the opposite direction *ANS* 1,2,3 Which of the following would display the greatest amount of partial volume artifact? a. a 10 mm slice from a 20 slice study b. a 5 mm slice from a 40 slice study c. a 5 mm slice from a 20 slice study d. a, b, and c would experience the same amount of partial volume artifact *ANS* A Which of the following strategies will minimize metal artifacts? 1. remove as much metal from the patient as possible 2. orient slices such that the metal is avoided if possible 3. inspect the localizer for any metal on the patient and remove any metal or avoid imaging it as much as possible *ANS* 1,2,3 Which of the following would eliminate a ring artifact> a. recalibration of the detector element b. removal of metal c. decreased matrix d. increased mAs *ANS* A Which of the following would increase the severity of the edge gradient effect? 1. a scanner with a small detector aperture 2. a scanner with a low data sampling rate 3. using thin slices *ANS* 2 Which of the following is a possible manifestation of beam hardening? 1. CT number inaccuracies 2. steaks in the image 3. cupping artifacts *ANS* 1,2,3 What is the cause of cupping artifact? a. the central tissues are not penetrated by the xray beam b. the tissues of the body attenuate low energy photons c. the mean energy of the photons that comprise the xray beam is lowered d. the interface between tissues with different densities causes the high energy photons to be absorbed. *ANS* B Which of the following may be the cause of two parallel lines seen on a localizer image? a. two faulty detector elements b. cone beam artifact c. tube arcing d. a problem with reconstruction algorithm *ANS* A Which of the following would reduce the partial volume effect? a. increased reconstruction FOV b. increased mAs c. decreased matrix d. decreased slice thickness *ANS* D Which of the following would decrease the effects of beam hardening artifacts? 1. increased kVp 2. increased mAs 3. increased scan time *ANS* 1 A ________ artifact is a streak artifact which arises from a high spatial frequency interface between tissues with a great difference in density a. tube arcing b. edge gradient c. cone beam d. ring *ANS* B In which direction are streaks from the edge gradient effect oriented? a. radially outward from the center of the image b. parallel to the direction of the sharp density difference interface c. perpendicular to the direction interface d. in a herringbone pattern across the image *ANS* B Which of the following strategies would NOT help us differentiate possible pathology from a partial volume artifact? 1. inspection of adjacent slices 2. collect additional thinner slices through suspicious region 3. rescan and decrease pitch (without changing slice thickness) *ANS* 3 Which of the following may reduce the out of field artifact? a. increasing the scan FOV b. reducing the reconstruction FOV c. reducing the slice thickness d. increasing the matrix *ANS* A Which of the following is a result of reducing the slice thickness to reduce partial volume effects? 1. increase appearance of noise 2. increased spatial resolution 3. decreased anatomical coverage with the same number of slices *ANS* 1,2,3 How would we expect metal to affect the appearance of a localizer image? a. the CT number of the tissues in the image will be misrepresented b. the metal object will be represented by high CT numbers and there will be no streaks c. the entire image will appear blurry d. streaks will emanate from the metal object in the image. *ANS* B What is the cause of cone beam artifacts? a. faulty detector elements b. the use of standard filtered back projection reconstruction when the xray beam is more than 20 mm thick c. hardening of the xray beam on multi row detector scanners d. inefficient xray tubes used on multi row detector scanners *ANS* B Which of the following may be the cause of metal artifacts? 1. earrings 2. zipper 3. dental fillings *ANS* 1,2,3 Which of the following may be a result of partial volume averaging? 1. decreased sharpness of edges 2. inaccurate CT numbers 3. ghosting of tissue boundaries *ANS* 1,2 Tube arcing might cause _____ on the images. a. star-like artifacts at the edges b. an increased appearance of noise c. shading and inaccurate CT numbers d. an appear of a circle or ring *ANS* B How would the artifact from a faulty detector element appear on a localizer image? a. a line perpendicular to the long axis of the patient table b. it depends on the orientation in which the localizer image is performed c. a circle in the center of the image d. a line parallel to the long axis of the patient table *ANS* D Which of the following affects beam hardening? 1. types of tissues the beam passes through 2. thickness of the tissues traversed by the beam 3. energies of the photons in the beam *ANS* 1,2,3 Which of the following might increase the possibility of motion artifacts occurring? a. explaining the procedure to the patient b. using a helical scanning technique to acquire the necessary slices in a single breath hold c. using no straps or pad so that the patient feels comfortable and unrestricted d. immobilizing the patient *ANS* C Which of the following would result if the filter at the aperture of the xray tube removed even more low energy xray photons? 1. beam hardening artifact would decrease 2. partial volume artifact would increase 3. beam hardening artifact would increase 4. partial volume artifact would decrease *ANS* A Which of the following if TRUE as the slice thickness is decreased? a. partial volume artifacts increase while edge gradient artifacts decrease b. partial volume artifacts and edge gradient artifacts decrease c. partial volume artifacts decrease while edge gradient artifacts increase d. partial volume artifacts and edge gradient artifacts increase *ANS* B Why must we choose a scan field of view which is larger than the anatomy to be scanned? 1. to achieve the highest spatial resolution 2. to minimize partial volume artifacts 3. to avoid out of field artifacts *ANS* 3