ARRT CT Registry Assessment 1 2023 with Complete Solutions 100% Pass

ARRT CT Registry Assessment 1 2023 with Complete Solutions 100% Pass 1. The normal range of respiration of an adult is A. 5- 10 breaths per minute B. 12-20 breaths per minute c. 20-30 breaths per minute D. 35-50 breaths per minute *ANS* B. 12-20 2 which of the following is a parenteral route of medication administration A. sublingual B. Intramuscular C. transdermal D. Oral *ANS* B. Intramuscular 3 The preperation for a contrast- enhanced CT exam of a patient with prior allergic reaction to iodinated contrast media may include A. pre medication with steroids and antihistamines B. administration of a negative contrast agent C. increase in fluids for 24 hours before the exam D. refraining from urination for 2 hours before the exam *ANS* A. premedication with Steroids and antihistamines 4 A patient in shock may exhibit which of the following symptoms: A. tachycardia B. rapid, shallow breathing C. cyanosis D. all the above *ANS* D. all the above 5 which of the following infection control techniques is required at the site of an intravenous injection of iodinated contrast media? A. contact Isolation B. surgical asepsis C. medical asepsis D. enteric precautions *ANS* B. surgical asepsis 6 A common site for the intravenous injection of iodinated contrast media is the A. cephalic vein B. antecubitlal vein C. basilic vein D. all the above *ANS* D. all the above 7 which of the following technical factors exhibits a direct effect on patient dose? a. matrix size b. algorithm c. milliampere-seconds (mAs) d window level *ANS* c. milliampere-seconds (mAs) 8 prior to an intravenous injection of iodinated contrast material, the patient should be questioned regarding 1. renal function 2. allergic history 3. cardiac history a. 1 only b. 2 only c. 3 only d. 1, 2, and 3 *ANS* d. 1, 2, and 3 9 used in determining the biologic effect of iodinated contrast media, the term ___________refers to the number of ions formed when a substance dissociates in solution. a. solubility b. osmolality c. concentration d. iodination *ANS* b. osmolality 10 which of the following laboratory values can be used to evaluate the renal function of a patient. a. blood urea nitrogen (BUN) b. partial thromboplastin time c. creatinine d. both a and c *ANS* d. both a and c 11 a(n) ________________ infection is one that patients acquire during their stay in a health care institution. a. blood-borne b. nosocomial c. iatrogenic d. staphylococcal *ANS* b. nosocomial 12 during CT examinations, patients should be shielded above and below because of a. the rotational nature of the xray tube b. extremely high kilo volt peak (kVp) techniques c. lack of filtration of the CT beam d. reduced collimation of the CT beam *ANS* a. the rotational nature of the xray tube 13 which of the following would be best suited for intravenous injection of contrast material with a power injector? a. a butterfly needle b. a central venous line c. a 23-gauge spinal needle d. an angiocatheter *ANS* d. angiocatheter 14 a(n) __________________ contrast material may be described as one that does not dissociate into charged particles in solution. a. neutral b. non-ionic c. osmolar d. ionic *ANS* b. non-ionic 15 thorough explanation of the CT procedure and proper communication with the patient is vital in ensuring that 1. breathing instructions are properly followed 2. misregistration does not occur 3. patient anxiety is kept at a minimum a. 1 and 2 only b. 1 and 3 only c. 2 and 3 only d. 1, 2, and 3 *ANS* d. 1, 2, and 3 16 the lumen of needles used for the injection of contrast media varies in diameter. the unit used to describe this diameter is called a. length b. cubic centimeter (cc) c. gauge d. pounds per square inch (psi) *ANS* c. gauge 17 direct contraindications to iodinated contrast material administration include 1. prior life threatening reaction to iodinated contrast material 2. multiple myeloma 3. allergies to penicillin a. 1 only b. 1 and 2 only c. 1 and 3 only d. 1,, 2, and 3 *ANS* b. 1 only 18. which of the following is an accurate method of verifying patient identity? a. calling patients by their full name b. checking the name listed on the medical record c. examining the patient's wrist identification band d. all of the above *ANS* c. examining the patient's wrist identification band 19. advantages of automatic power injectors over the manual bolus method of intravenous contrast administration include 1. increased tissue enhancement due to faster injection times 2. uniform contrast administration over the entire length of the study 3 decreased volume of contrast administered a. 1 only b. 3 only c. 1 and 2 only d. 2 and 3 only *ANS* C. l and 2 only 20 the average range for normal adult blood urea nitrogen (BUN) levels is approximately a. 1-4 mg/dL b. 5-20 mg/dL c. 23-30 mg/dL d. 45-60 mg/dL *ANS* B. 5-20 mg/dL 21 which of the following terms describes a condition in which cerebral ischemia is caused by systemic hypotension? a. vasovagal reaction b. myocardial infarction c. transient ischemic attack d. hydrocephalus *ANS* a. vasovagal reaction 22 which of the following interactions between x-ray beam and matter results in the largest amount of patient dose? a. characteristic b. Comptom scatter c. bremsstrahlung d. photoelectric effect *ANS* d. photoelectric effect 23 examples of mild adverse reactions to iodinated intravenous contrast media may include 1. nausea 2. dypsnea 3. warm, flushed sensation a. 1 only b. 1 and 2 only c. 1 and 3 only d. 2 and 3 only *ANS* c. 1 and 3 only 24 during which of the following CT procedures is the patient required to give informed consent? a. noncontrast chest examination b. radiation planning study of the prostate c. three-dimensional reconstruction of the hip d. abdomen scan with intravenous contrast *ANS* d. abdomen scan with intravenous contrast 25 ________________ is a medication commonly administered to sedate small children undergoing CT examinations. a. chloral hydrate b. lithium c. diazepam (valium) d. secobarbital stadium (sectional sadium) *ANS* a. chloral hydrate 26. which of the following are included as basic types of iodinated contrast media? 1. iothalmate 2. diatrizoate 3. metrizoate a. 2 only b. 3 only c. 1 and 3 only d. 1, 2, and 3 *ANS* d. 1, 2, and 3 27 which of the following is not a category of isolation technique? a. enteric precautions b. gram-negative isolation c. contact isolation d. strict isolation *ANS* b. gram-negative isolation 28 which of the following correctly states the difference between ionic and non-ionic iodinated contrast material? a. non-ionic contrast media have a higher osmolality than ionic media b. ionic contrast media contain iodine, whereas non-ionic contrast media do not c. non-ionic contrast media have a lower osmolality than ionic media d. ionic contrast media involve a lower incidence of adverse reactions than non-ionic contrast media *ANS* c. non-ionic contrast media have a lower osmolality than ionic media 29. which of the following terms is used to describe the intravenous injection of medication or contrast agent in one complete dose over a short period of time? a. infusion b. bolus c. intravenous drip d. infuse-a-port *ANS* b. bolus 30. an intrathecal injection before a CT examination of the lumbar spine places iodinated contrast material directly into the a. subarachnoid space b. dura mater c. vertebral foramen d. subdural space *ANS* a. subarachnoid space 31. accurate demonstration of _______________ would most likely require the intravenous injection of an iodinated contrast medium during a CT study of the chest. a. bronchiectasis b. pneumonia c. mediastinal lymphadenopathy d. pulmonary nodule *ANS* c. mediastinal lymphadenopathy 32 abnormalities of the middle and inner ear may be best demonstrated using ct sections of a. 1-2 mm b. 3-4 mm c. 5 mm d. 10 mm *ANS* a. 1-2 mm 33 which of the following is not a portion of the small bowel? a. duodenum b. jejunum c. ileum d. cecum *ANS* d. cecum 34 axial ct sections of the lumbar spine for intervertebral disk evaluation should be acquired with the plane of imaging a. perpendicular to the transverse plane of the patient b. parallel to the plane of the intervertebral disk spaces c. parallel to the transverse plane of the patient d. perpendicular to the coronal plane of the patient *ANS* b. parallel to the plane of the intervertebral disk spaces 37 which of the following is a typical protocol for a ct study of the brain for a patient with a history of dizziness? a. 10- x 10 mm sections from the skull base to the vertex b. 10 x 10 mm sections from the skull base to the posterior fossa c. 5 x 5 mm sections through the posterior fossa, 10 mm x 10 mm to the vertex d. 1.5 x 1.5 mm sections from the skull base to the vertex *ANS* c. 5 x 5 mm sections through the posterior fossa, 10 mm x 10 mm to the vertex An average range for activated PTT is: a. 10-12 seconds b. 17-21 seconds c. 25-35 seconds d. 43-55 seconds *ANS* 25-35 seconds which of the following is the correct angle of insertion for placing a butterfly needle into a vein for intravenous administration of a contrast agent. *ANS* 15 degrees A total volume of 125 ml of an iodinated contrast agent is administered intravenously via automatic injector in 50 seconds. The flow rate for this injection is: *ANS* 2.5 ml/sec The acronym CTDI is used to describe which of the following? *ANS* the radiation dose to the patient during a ct scan While one is obtaining a thorough history from a patient prior to the intravenous injection of an iodinated contrast material, these topics should be included *ANS* any prior allergic reactions to contrast media, history of asthma. Which of the following factors may affect a patients calculated glomerular rate (GFR) *ANS* age, sex, race Which of the following intravenous contrast agent administration methods provides the greatest overall plasma iodine concentration. *ANS* bolus technique A patient in shock may exhibit which of the following symptoms? *ANS* tachycardia, rapid shallow breathing, cyanosis The drug SOLU-CORTEF may be classified as which of the following? *ANS* corticosteroid Which of the following technical factors has a direct effect on patient dose. *ANS* mAs Which of the following is a non-ionic contrast material? *ANS* iohexol Which of the following terms is used to describe a patient who is having difficulty breathing. *ANS* dyspnea Which of the following devices is used to measure the patient dose from a CT examination. *ANS* Ionization chamber Which of the following describes the situation in which an assumption is made that an unconscious or otherwise physically unable patient consents to medical treatment. *ANS* Implied consent Complete cardiac diastole corresponds to which portion of the cardiac cycle of an electrocardiogram (ECG) *ANS* T wave During CT arthrography, iodinated contrast media is injected directly into the: *ANS* Joint space Which of the following is considered one of the iso-osmolar contrast media? *ANS* Iodixanol A common site for the IV administration of iodinated contrast media is the anterior recess of the elbow, otherwise known as the *ANS* antecubital space The potentially serious decline in renal function following the IV administration of contrast material is called. *ANS* contrast-induced nephrotoxicity The quantity of absorbed radiation dose based on the radiosensitivity of a particular tissue type is called *ANS* effective dose Advantages of a saline flush immediately following the IV administration of iodinated contrast material include: *ANS* Reduction in required contrast agent dose, reduction in the incidence of contrast-induced nephrotoxicity (CIN), reduction of streaking artifact from dense contrast agent in the vasculature. Which of the following medications may be administered to dilate the coronary vasculature prior to a cardiac CT examination. *ANS* sublingual nitroglycerine. A normal range for diastolic blood pressure in an adult is *ANS* 60-90 mm Hg Which of the following is a parenteral route of medication administration. *ANS* Intramusclar Which of the following methods may be employed to reduce the radiation dose to the pediatric patient undergoing CT *ANS* Reduce MA, limit phases of acquisition, increase pitch Radiation exposure and its potentially harmful effects have a relationship that is termed *ANS* stochastic Which of the following types of isolation techniques protects against infection transmitted through fecal material. *ANS* Enteric precautions Which of the following is considered one of the ionic radiopaque contrast media (RCM) *ANS* Iothalmate meglumine The radiation dose index calculation that takes into account the variations in absorption across the field of view due to beam hardening is termed. *ANS* CTDI(W) Direct contraindications to the administration of iodinated contrast material include. *ANS* Prior life-threatening reaction to iodinated contrast material Which of the following units is used to express the total patient dose from a helically acquired CT examination. *ANS* mGy-cm (millygrays per centimeter) Components of a comprehensive CT stroke management protocol typically include *ANS* Pre-contrast sequence of the brain, CTA of the brain and carotids, CT perfusion (CTP) of the brain Simple cysts of the kidney have average attenuation values in the range of: *ANS* 0- +20 Hounsfield units After initiation of rapid bolus administration of an iodinated contrast agent, the arterial phase of hepatic contrast enhancement occurs at approximately *ANS* 25-35 seconds The abdominal aorta bifurcates at the level of *ANS* L4 On an ECG of the complete cardiac cycle, at which portion of the R-R interval is the heart muscle in diastole? *ANS* 55%-75% The accumulation of gas within a degenerating intervertebral disc is called the *ANS* vacuum phenomenon During a spiral or helical CT examination, the scanner acquires data *ANS* Continuously as the patient travels through the gantry, in the form of a complete volumetric data set Which of the following CT studies of the head is typically performed without a contrast agent? *ANS* CT of brain to R/O subdural hematoma Which of the following phases of renal contrast enhancement best demonstrates transitional cell carcinoma (TCC) of the bladder *ANS* excretory CT examinations of the abdomen are often performed in the right lateral decubitus position to demonstrate the relationship between the: *ANS* Duodenum and pancreatic head Which of the following sets of section width and spacing would be most suitable for a general survey CT of the neck *ANS* 3mm thick every 3 mm The still viable ischemic cerebral tissue that surrounds the infarct core in a patient with an acute stroke is termed the: *ANS* Ischemic penumbra Complex fractures of the wrist are most common in which of the following carpal bones? *ANS* scaphoid A complete CT study of the orbits should include: *ANS* 2.5 mm x 2.5 mm axial and coronal sections High-resolution computed tomography (HRCT) is most commonly used for the evaluation of the *ANS* lungs During a general CT examination of the abdomen, an intravenous contrast agent is indicated and is administered with the aid of an automatic injector. Which of the following ranges of flow rate should be used. *ANS* 1.0-3.0 mL/sec Diffuse fatty infiltration of the hepatic parenchyma may be referred to as: *ANS* Steatosis During CT scanning of the head, the gantry should be angled: *ANS* 15 degrees above the infraorbital-meatal line (IOML) During CT examination of the larynx, the patient is often instructed to phonate the letter "E" in order to properly evaluate the: *ANS* Vocal cords During a CT examination of a female pelvis for a suspected malignancy, ascites may be present in an area posterior to the uterus and ovaries known as *ANS* The cul-de-sac Which of the following pathologic processes may be considered an interstitial disease of the lungs. *ANS* bronchiectasis An enterovesical fistula is an abnormal communication between the bowel and the *ANS* Bladder Prior to a CT colonography, the patient may undergo a process of bowel cleansing termed: *ANS* Catharsis Positioning the patient with the knees flexed over a foam cushion during a CT examination of the lumbar spine assists in *ANS* Making the patient more comfortable throughout the exam, decreasing the lordotic curvature of the lumbar spine The imaging plane that is parallel to the foots plantar surface is called the *ANS* Axial plane The condition of intermittent cramping pain in the legs due to poor circulation is called *ANS* Claudication The pituitary gland is best demonstrated during CT in which of the following imaging planes. *ANS* Coronal The most common site of organ injury due to blunt abdominal trauma is the *ANS* Spleen The adult spinal cord ends at what vertebral level *ANS* L1-L2 Which of the following protocols would provide the best image quality for a 3D disarticulation study of the hip *ANS* 1.5mmX1.0 mm sections, bone algorithm Which of the following terms is used to describe a fibroid tumor of the uterus. *ANS* Leiomyoma The section thickness that would demonstrate the greatest detail of the paranasal sinuses is *ANS* 3mm Which of the following anatomic organs is located within the peritoneal cavity. *ANS* Liver Which of the following may be included as part of a routine preparation for a general contrast-enhanced CT examination of the abdomen and pelvis. *ANS* Instructing the patient to take nothing by mouth (NPO) for 4 hours prior to the exam. 1200 mL of oral contrast agent administered 90 minutes prior to exam. During a complete CT scan of the pelvis, sections should be obtained from the *ANS* Iliac crests to the pubic symphysis The recommended scan field of view (SFOV) for a CT examination of the cervical spine is *ANS* 50.0 cm Because of its inherent iodine concentration, the thyroid gland appears __________ on CT images. *ANS* Hyperdense Air trapping within the trachea and bronchial tree may be optimally demonstrated with multiplanar volume reconstructions (MPVRs) of the thorax known as: *ANS* Minimum Intensity projections (min-IPs) Which of the following is NOT a portion of the small bowel *ANS* Cecum Which of the following is used as the IV-administered radiopharmaceutical during a PET-CT fusion examination *ANS* Fludeoxyglucose F 18 (FDG) The specialized CT examination of the bladder in which an iodinated contrast agent is directly administered under gravity into the bladder via Foley catheter is termed *ANS* CT cystography Which of the following best describes the shape of the x-ray beam utilized in MDCT *ANS* Cone shaped Collimation of the CT x-ray beam occurs: *ANS* at the x-ray tube, regulating slice thickness and before the detectors, limiting the amount of scatter radiation absorbed. CT numbers are usually provided in the form of: *ANS* Hounsfield units The mathematical technique allowing the reconstruction of motion-free images from helically acquired CT data is called *ANS* Interpolation The full width at half maximum (FWHM) of a CT scanner is used to describe *ANS* Spatial resolution A first generation CT scanner consists of an x-ray tube and two detectors that translate across the patients head while rotating in 1-degree increments for a total of *ANS* 180 degrees Which of the following abbreviations is used to identify a computerized network that stores, retrieves, communicates, and displays digital medical images. *ANS* PACS The CT "window" controls the _______________ of the CT image as it appears to the viewer *ANS* Contrast and brightness Voxels with equal dimensions along the x-, y-, and z-axes are referred to as: *ANS* Isotropic Which of the following artifacts is not affected by the CT technologist *ANS* RIng When one is viewing a multiplanar reformation (MPR) image, each pixel represents: *ANS* The average attenuation occurring within the voxel Statistical noise appears as ________ on a CT image. *ANS* Graininess An acquisition is made on a 64-slice MSCT system in which each detector element has a z-axis dimension of 0.625 mm. With a selected beam width of 40mm and the beam pitch set at 1.50, how much will the table move with each rotation of the gantry. *ANS* 60 mm, 40mm x's 1.5 The component of the CT computer system responsible for the data processing of image reconstruction is the *ANS* Array processor For single-slice CT (SSCT) systems, which of the following statements regarding retrospective image reconstruction is FALSE? *ANS* The slice thickness and SFOV may be changed. The loss of anatomic information between contiguous sections due to inconsistent patient breathing is called. *ANS* Misregistration Before a CT image can be reconstructed by a computer, a transmission signal produced by the detectors must be converted into numerical information by a (n): *ANS* Analog-to-digital converter (ADC) A CT image is formed in part by projecting back all of the attenuation values recorded during data acquisition onto a: *ANS* Matrix Which of the following archival media is capable of storing the largest number of CT images *ANS* Optical disk Areas of a CT image that contain abrupt changes in tissue density are electronically represented by which of the following? *ANS* High spatial frequencies The differences in Hounsfield value exhibited in the ROIs measured on this CT image of a water-filled phantom are most likely due to the phenomenon referred to as *ANS* Beam hardening Which of the following terms is used to describe a set of rules for solving a mathematical problem *ANS* Algorithm Which of the following factors does not affect the dimensions of a voxel *ANS* Kernel The size of the CT image displayed on a computer monitor can be enlarged by increasing the: *ANS* Image magnification The average photon energy of the primary beam of a CT scanner operating at a tube potential of 120 kVp is approximately *ANS* 70 keV MSCT systems typically employ which of the following detector geometries? *ANS* Third generation CT images of the chest should be acquired with the patient *ANS* At full inspiration The acquisition of a series of CT images at a single anatomic location over a set period is referred to as *ANS* Cine CT The rate at which a quantity of x-radiation emitted from a CT tube passes through a unit area over a unit of time is called the *ANS* Photon flux An average CT number value for bone is: *ANS* +1000 HU A standard CT image reconstructed on a 512² matrix has a digital size of approximately: *ANS* 0.5 MB The term used to describe the relationship between the linear attenuation coefficient of an object and the calculated CT numbers is *ANS* Linearity Quality control measurements to test the accuracy of the CT scanners calibration should be performed *ANS* Daily The 3D CT technique that includes all of the acquired voxel information in the reconstructed model with adjustments to its opacity is termed *ANS* Volume rendering Where is the high-frequency generator often located in a modern CT scanner? *ANS* Inside the gantry The smallest unit of information used in the binary language of computers is the *ANS* Bit The continuous gantry rotation required by helical CT acquisition is made possible by the application of: *ANS* Slip-rings The process of applying a mathematical filter to remove blurring from the reconstructed CT image is termed *ANS* Convolution Which of the following acquisitions may be characterized as contiguous *ANS* 3.75-mm sections reconstructed every 3.75 mm Pixels representing tissues with average attenuation coefficients greater than that of water have which of the following types of values? *ANS* Positive For a single-slice CT (SSCT) system, which of the following statements regarding pre-patient collimation is true *ANS* Pre-patient collimation directly controls slice thickness Digital CT images are networked and archived in accordance with a standardized computer protocol identified by which of the following abbreviations? *ANS* DICOM The contrast resolution of a CT scanner is NOT related to which of the following. *ANS* Focal spot size The average photon energy of the CT x-ray beam can be increased by *ANS* Increasing filtration Which of the following is a solid-state device used to record the light flashes given off by a scintillation crystal *ANS* Photodiode Automatic tube current modulation (ATCM) software is used in current MDCT systems to control *ANS* Patient radiation dose The type of MSCT detector array that contains multiple rows of detector elements, each of the same length, is called a(n) *ANS* Uniform matrix array A CT image is displayed in a window with a level of 0 and a width of 500. Which of the following statements is correct? *ANS* Pixels with values between -250 HU and +250 HU will be assigned shades of gray Reformatted CT image planes that lie perpendicular to the original plane of acquisition may be described as: *ANS* Orthogonal Segmenting the data acquisition process into separate components of smaller rotation angles may improve which of the following components of CT image quality? *ANS* Temporal resolution Which of the following image artifacts is unique to multi-slice CT (MSCT) systems. *ANS* Cone beam artifact Which of the following is considered an analytic form of image reconstruction *ANS* Fourier reconstruction, Filtered back projection A 16-slice MSCT system utilizes an adaptive array of 24 detectors, each ranging in size from 0.625 to 1.25 mm. What is the maximum number of sections the system can acquire with each rotation of the gantry. *ANS* 16 The measurement of transmitted radiation made by an individual detector is called a(n) *ANS* Ray sum The information included during the 3D reconstruction of a CT scan is controlled by the *ANS* Threshold setting As related to the cardiac cycle, the term ___________ refers to the relaxation of the heart muscle. *ANS* Diastole Which of the following may be considered one of the high-osmolar contrast media (HOCM) *ANS* Iothalmate meglumine, diatrizoate sodium Which of the following technical changes would serve to decrease patient radiation dose during a CT examination. *ANS* Decrease of tube rotation from 360 to 180 degrees Which of the following medications may be administered to a patient who is having a severe anaphylactoid reaction to iodinated contrast material *ANS* Epinephrine, diphenhydramine In an effort to reduce patient radiation dose, the technical factors of the applied CT protocol should be optimized on the basis of. *ANS* Size or weight The escape of contrast material from a needle or blood vessel into the subcutaneous tissues is called . *ANS* Extravasation Thorough explanation of the CT procedure and proper communication with the patient are vital in ensuring that *ANS* Breathing instructions are properly followed, motion artifact does not occur, patient anxiety is kept at a minimum. Which of the following is considered in the calculation of the MSAD for an axial (step-and-shoot) CT examination. *ANS* Bed index Risk factors for contrast-induced nephroxicity (CIN) include *ANS* Dehydration During CT examinations, the patient's body should be shielded above and below because of: *ANS* The rotational nature of the x-ray tube Normal range for oxygen (O2) saturation is *ANS* 95%-100% Which of the following laboratory measurements can be used to evaluate the renal function of a patient *ANS* BUN, creatinine Which of the following would be best suited for intravenous injection of contrast material with a power injector. *ANS* Angiocatheter Prior to the intravenous injection of iodinated contrast material, patients should be questioned regarding their: 1. renal function 2. allergic history 3. cardiac history a. 1 only b. 2 only c. 3 only d. 1, 2, and 3 *ANS* D. renal function, allergic history, cardiac history A(n) _______________ infection is one that a patient acquires during a stay in a health care institution. *ANS* Nosocomial CTDIw is a weighted index that Approximate's radiation dose on the basis of variations that occur across the field of view because of what? *ANS* Beam hardening Which of the following sets of values would be considered normal levels for creatinine and BUN, respectively. *ANS* 1.2 mg/dL; 14 mg/dL Which of the following sizes of butterfly needles allows for the most rapid administration of iodinated intravenous contrast media. a. 19 b. 21 c. 23 d. 25 *ANS* 19 gauge The embryo or fetus is most sensitive to ionizing radiation during which portion of gestation. *ANS* First trimester Which of the following technical maneuvers may be used to remove unwanted pulsation artifacts from cardiac motion during a CTA of the chest for pulmonary embolism. *ANS* Retrospective ECG gating The choice between ionic and non-ionic contrast media should be based on. *ANS* The allergic history of the patient, the age and physical condition of the patient. Which of the following is an example of a mild reaction to iodinated intravenous contrast media. *ANS* Vomiting During which of the following CT procedures is the patient required to give informed consent. *ANS* Abdomen scan after IV contrast agent administration The International Normalized Ratio (INR) is calculated to standardize which of the following laboratory values. *ANS* Prothrombin time (PT) Which of the following infection control techniques is required at the site of an intravenous injection of iodinated contrast media. *ANS* Surgical asepsis In order to uniformly expose the entire detector array in an MDCT system, the primary beam must be expanded beyond the physical extent of the array in a process known as: *ANS* Overbeaming Which of the following is a common site for the intravenous injection of iodinated contrast media *ANS* Cephalic vein, antecubital vein, basilic vein An intrathecal injection prior to a CT examination of the lumbar spine places iodinated contrast material directly into the *ANS* Subarachnoid space Automatic tube current modulation (ATCM) is employed by an MDCT system for the purpose of. *ANS* Reducing patient radiation dose. The range of serum iodine concentration for adequate tissue opacification during contrast-enhanced CT examination is *ANS* 2-8 mg/mL Components of the aseptic technique utilized for the IV administration of contrast agents include: *ANS* Thorough hand washing between patients, wearing of disposable gloves. The amount of x-ray energy absorbed in quantity of air is termed *ANS* Kerma Abnormalities of the middle and inner ear may be best demonstrated with CT utilizing _______________ *ANS* 1-2mm The lisfranc joint is the articulation between the *ANS* Tarsals and metatarsals The volume and density of calcium measured in the coronary arteries on MDCT examination are quantified with use of a value called the *ANS* Agatston score Which of the following is/are (a) component(s) of the adnexal area of the uterus. *ANS* Ovaries and Fallopian tubes A CT angiogram of the neck is performed primarily for the evaluation of the *ANS* Carotid arteries Which of the following contrast media may be utilized during the CT evaluation of the gastrointestinal tract *ANS* Diatrizoate meglumine (Gastrografin), Effervescent agents, Iopamidaol (Isovue) The liver has a dual blood supply and receives 75% of its blood from the *ANS* Portal vein Which of the following pelvic bones combine(s) to form the acetabulum *ANS* Ilium, ischium, pubis At what percentage of overlap should CT sections be reconstructed to improve the quality of multi-planar reformation (MPR) images *ANS* 50% A primary responsibility of computed tomography in combined PET-CT is to *ANS* Provide precise anatomic location of tumor activity The degenerative pathologic process involving the forward slipping of an upper vertebral body over a lower vertebral body is called *ANS* Spondylolisthesis Accurate demonstration of __________ would most likely require the intravenous injection of an iodinated contrast agent during a CT study of the chest. *ANS* Mediastinal lymphadenopathy Which of the following paranasal sinuses is usually the last to fully develop *ANS* Frontal A focused, thin-section axial CT acquisition through just the region of the vocal cords should extend *ANS* From just above the hyoid bone inferiorly through the cricoid cartilage The most common indication for CT-guided percutaneous biopsy is the *ANS* Confirmation of a malignancy Axial CT images of the knee may be acquired in four separate series with gantry angulations of 0, 30, 45, and 60 degrees in order to demonstrate the: *ANS* Patellofemoral joint Which of the following contrast agent administration techniques should be used for a general CT survey of the abdomen *ANS* 400-600 ml oral contrast agent 45-90 minutes prior to the exam, 250 ml oral contrast agent immediately before the exam During CT perfusion studies, the quantity of blood (in ml) that moves through 100 g of tissue each minute is termed the *ANS* Cerebral blood flow (CBF) An adequate volume of intravenous contrast agent for the SSCT examination of the neck would be *ANS* 125 ml The enhancement washout technique for CT characterization of adrenal masses includes *ANS* Thin-section pre-contrast acquisition through the adrenals, 10 to 15 minute delayed post-contrast acquisition through the adrenals Bowel obstruction due to loss on normal contractile motion in an area of intestine is termed *ANS* Ileus CTA of the renal arteries should be performed using a section width of: *ANS* 1.25 mm or less Th third ventricle of the brain communicates with the fourth ventricle through the *ANS* Cerebral aqueduct Complete CT examinations of the chest for investigation of bronchogenic carcinoma should include sections from the: *ANS* To of the apices through the liver The mediastinum includes which of the following anatomic structures *ANS* Superior vena cava, ascending aorta The proper scan field of view (SFOV) for a CT of the abdomen of a patient who measures 42 cm is *ANS* Large (48 cm) The kidneys are located in the retro peritoneum and are bound by a band of fibrous connective tissue called *ANS* Gerota's fascia After initiation of rapid bolus administration of an iodinated contrast agent, the portal venous phase of hepatic contrast enhancement occurs at approximately *ANS* 60-70 seconds The prone position may be used for a post-myelogram CT examination of the lumbar spine in an effort to *ANS* Reduce metrizamide pooling The bolus duration of any IV contrast agent administration can be calculated as the product of infection flow rate and *ANS* Contrast agent volume During the use of CT fluoroscopy for guided interventional procedures, which of the following technical considerations may be used to reduce occupational radiation exposure? 1. increased kVp 2. lead shielding 3. use of a needle holder *ANS* Lead shielding, use of a needle holder The intrathecal administration of an iodinated contrast agent in the patient in a lumbar spine would allow for greater visualization of the *ANS* Spinal cord, nerve roots After initiation of rapid bolus administration of iodinated contrast material, the pancreatic phase of contrast enhancement occurs at approximately *ANS* 35-45 seconds Following the IV administration of iodinated contrast media, a tumor that exhibits a greater density than the surrounding parenchyma is characterized as *ANS* Hypervascular The retroperitoneum contains which of the following anatomic structures a. spleen b. ovaries c. kidneys d. stomach *ANS* Kidneys Which of the following is NOT a component of the "triple rule-out" MDCT protocol for patients complaining of chest pain a. CTA of the pulmonary arteries b. prone HRCT of the lungs c. CTA of the aorta d. coronary CTA *ANS* Prone HRCT of the lungs During contrast-enhanced CT examinations of the chest, streaking artifact may obscure portions of the superior mediastinum because of dense concentrations of iodine in the: *ANS* Superior vena cava The component of the CT scanner responsible for the mathematical calculation of the image reconstruction process is the *ANS* Array processor Filament sizes for modern CT x-ray tubes range between: *ANS* 0.5 and 1.2mm Which of the following is used to archive a hard copy of a CT image. *ANS* Laser film Which of the following would serve to increase spatial resolution of a CT exam using a large focal spot size, 5mm sections and a 512x2 matrix *ANS* Change to small focal spot size, acquire 2.5 mm sections A CT image is formed in part by projecting back all of the attenuation values recorded during data acquisition onto a *ANS* Matrix The mathematical process that allows MDCT images to be reconstructed at any point along the acquired volume is commonly referred to as *ANS* z-filtering Fourth-generation CT scanners use a ______________ tube-detector configuration *ANS* Rotate-stationary Which of the following is considered an equipment-induced CT image artifact *ANS* Aliasing artifact The measurement of CT system performance through quality testing procedures and evaluation of the test result is referred to as. *ANS* Quality assurance During CT x-ray exposure, the product of the selected mA setting and the scan time is called the: *ANS* Constant mAs Which of the following mathematical reconstruction methods is used by most modern CT scanners *ANS* Filtered back-projection What matrix size was used to reconstruct an image with the display characteristics DFOV 25 cm and pixel area 0.25mm²? *ANS* 512 x 512 pixels When one is viewing a minimum intensity projection (min-IP) image, each pixel represents: *ANS* The minimum attenuation occurring within the voxel Which of the following statements regarding pre-detector collimation of the CT x-ray beam is true? *ANS* Pre-detector collimation removes scatter radiation before it reaches the detectors Which of the following equations shows the lambert-beer law, which describes the relationship between matter and attenuation *ANS* I=Ioe -ux Which of the following would be considered the best method to reduce respiratory motion on the CT image *ANS* Good patient-technologist communication Which of the following types of gas is commonly used for gas ionization CT detectors *ANS* Xenon Power output for a modern MDCT x-ray tube has an approximate range of *ANS* 60-100 kilowatts (kW) The mathematical manipulations required during the reconstruction of a CT image are accomplished using a(n) *ANS* Algorithm, kernel, mathematical filter function When an operator reduces the scan field of view for a particular body part, which of the following technical changes occurs? *ANS* A smaller number of detectors are activated The average CT number value for blood is *ANS* +45 HU The electronic combination of signals from adjacent detectors to form a CT image is called *ANS* Binning Which of the following technical adjustments may be employed to improve the temporal resolution of an MDCT system *ANS* Image segmentation, physiologic gating The streaking artifact that occurs in the area of the posterior fossa during a CT examination of the brain may be referred to as *ANS* The Hounsfield bar The relative accuracy between calculated CT numbers and their respective linear attenuation coefficients is referred to as *ANS* Linearity To maintain security and patient privacy when medical images are transmitted across a network the images may be coded in a form decipherable only by software at the destination location. This process is referred to as *ANS* Encryption Which of the following 3D imaging techniques is utilized to provide "fly-through" images during CT colonography *ANS* Perspective volume rendering. Which of the following sets of technical factors would yield an isotropic data set when an MDCT image is reconstructed using a 512² matrix *ANS* 0.625mm sections, 32cm DFOV Which of the following is NOT commonly used as a CT scintillation detector material. *ANS* Silver halide The mathematical technique that involves the estimation of an unknown value from values on either side of it is known as *ANS* Interpolation During which of the following CT examinations is a misregistration artifact most likely to occur *ANS* Abdomen In a single-slice CT (SSCT) system, which of the following technical parameters may be adjusted retrospectively *ANS* Section increment, reconstruction algorithm Bow-tie filters are employed in a CT x-ray system to reduce: *ANS* Patient radiation dose Which of the following technical factors is/are involved in the determination of section width for MDCT images *ANS* Beam collimation, detector configuration The fluctuation of CT numbers in an image of uniform, homogeneous material may occur because of *ANS* Noise A region of interest (ROI) measurement placed over a portion of a Ct image provides which of the following *ANS* Average CT number (HU) An MDCT image is reconstructed using a 512² matrix and a DFOV of 38cm. If the detector collimation is set to a section width of 1.25 mm, what is the volume of each voxel? *ANS* 0.69 mm3, 380mm÷512=0.74mm, 0.74×0.74=0.55mm, 0.55mmx1.25mm=0.69mmx3 Reduction of the artifact streaking for metal in teeth on a coronal MDCT view of the sinuses may be accomplished through *ANS* Coronal MPR images built from an axial acquisition First-generation CT scanners used a method of data acquisition based on a _______________ *ANS* Translate-rotate The maximum beam collimation for an MDCT system with a detector array of 64 detectors, each 0.625 mm wide, is *ANS* 40.00 mm 64×0.625 Compared with conventional radiography, computed tomography produces diagnostic images with better *ANS* Low-contrast resolution Writable CD and DVD media are optical disks that may be described as: *ANS* WORM A CT system measures the average linear attenuation coefficient of a voxel of tissue to be 0.0008. The linear attenuation coefficient of water for this scanner equals 0.181. The CT number assigned to the pixel representing this voxel of tissue equals *ANS* -956 HU, (0.008-0.181= -0.173), (-0.173÷1.81= -0.956) During data acquisition, a CT system may continuously adjust the mA relative to the measured image noise for a method of dose reduction referred to as: *ANS* Automatic tube current modulation Which of the following statements comparing the efficiency of scintillation and gas ionization detectors is correct *ANS* The scintillation detector has a higher capture efficiency The data acquisition system (DAS) of a CT scanner is responsible for *ANS* Measuring transmitted intensity, conversion of the transmission data into a digital signal, sending the digital information to the computer for processing Which of the following is used to remove image blurring during the back-projection method of CT image reconstruction *ANS* Convolution kernal During CT c-ray production, the electromagnetic steering of the electron beam from the cathode to two alternating targets is referred to as *ANS* Flying focal spot If a region of interest (ROI) measurement provides and average density of +1.9 HU. This material is most likely *ANS* Water Areas of a CT image that contain minimal changes in tissue density are electronically represented by: *ANS* Low spatial frequencies A CT image is displayed in a window with a level of +200 and a width of 1000. Which of the following statements is correct. *ANS* Pixels with values between -300 HU and +700 HU will be assigned shades of gray In the binary system, a byte is a series of ____________bits of information. *ANS* Eight During CT examinations of the chest and abdomen, the highly radiosensitive breast tissue can be protected with minimal image artifact with the use of specialized shielding composed of *ANS* Bismuth The use of water as an oral contrast material for CT of the abdomen and/or pelvis has several potential advantages, including *ANS* Increased palatability and improved patient comfort, better demonstration of enhancing bowel wall, no interference with 3D applications If all other technical factors remain constant, which of the following would serve to decrease patient radiation dose during a helical SSCT examination? *ANS* Increased pitch A patients blood pressure is measured as 140/70 mm Hg. The number 140 represents *ANS* The pressure within the arterial vessels during contraction of the heart A(n) ___________ contrast material may be described as one that does not dissociate into charged particles in solution *ANS* Non-ionic Which of the following radiation dose indices is a measure of the total radiation exposure for an entire series of CT images *ANS* Dose length product (DLP) Proper immobilization during a CT procedure may involve the use of *ANS* Soft, hook-and-loop (e.g., Velcro) immobilization straps, good patient communication The normal range of glomerular filtration rate (GFR) for men is *ANS* 70 +-14 mL/min/m² Effective dose is a relative radiation dose measurement term that accounts for the *ANS* Tissue radiosensitivity Risk factors for contrast-induced nephrotoxicity (CIN) include *ANS* Diabetes, advanced age The reduction in number of infectious organisms without a complete elimination is termed *ANS* Medical asepsis Which of the following is the preferred range for patient heart rate for optimal cardiac CT studies *ANS* 65-75 bpm Late effects of radiation, such as genetic mutations, may occur with even small doses of radiation and are termed *ANS* Stochastic Urticaria is which of the following *ANS* Hives Which of the following type(s) of oral contrast material could cause peritonitis if leakage from the digestive tract occurs form perforation *ANS* Barium sulfate Which of the following is not an advantage of an automatic power injector over the manual bolus method of intravenous contrast agent administration *ANS* Decreased risk of contrast-induced nephrotoxicity (CIN) Which of the following is/are severe adverse reaction(s) to iodinated intravenous contrast media *ANS* Anaphylaxis Which of the following laboratory values is the most dependable measure of renal function. *ANS* Creatinine Which of the following angiocatheter sizes may be safely used for the automated power injection of iodinated contrast agents at flow rates higher than 3 mL/sec *ANS* 18-gauge, 20-guage Which of the following portions of the electrocardiogram (ECG) corresponds to the period of atrial systole *ANS* P wave Which of the following statements is true regarding the relationship between multiple scan average dose (MSAD and image spacing during axial (step-and-shoot) scanning *ANS* MSAD increases with overlapping scans Which of the following terms is used to describe the intravenous injection of medication or contrast agent in one complete dose over a short period of time. *ANS* Bolus Used in determining the biologic effect of iodinated contrast media, the term ____________ refers to the number of ions formed when a substance dissociates in solution. *ANS* Osmolality The dosimetry index used to approximate the radiation dose for CT sections acquired during a helical scan is called the *ANS* CTDI vol The injection rate of an automatic injector is set at 1.5 mL/sec. What is the injection time for a contrast agent volume o 150 mL *ANS* 100 seconds Which of the following must be included when one is obtaining informed consent for an invasive procedure *ANS* Explanation of the examination techniques, the possible risks and benefits of the exam, alternatives to the procedure involved Which of the following techniques may be employed to reduce patient radiation dose during a cardiac CT examination. *ANS* Prospective ECG gating Which of the following may be considered a low-osmolar contrast medium *ANS* Iohexol Following the intrathecal injection of an iodinated contrast agent for a post-myelography CT study of the lumbar spine, the patient should be instructed to *ANS* Rest for 8-24 hours with the head slightly elevated Compared with a single-slice CT (SSCT), patient radiation dose during a multidector CT study may be higher because of *ANS* Use of a cone beam of radiation, acquistitions at thinner section widths Which of the following pharmaceuticals may be administered prior to a cardiac CT procedure in an effort to improve visualization of the coronary vessels *ANS* B-blocker, nitroglycerin A ___________ is a benign, highly vascular mass commonly found in the liver *ANS* Hemangioma Which of the following is the preferred contrast enhancement phase for CT acquistion of the spleen *ANS* Portal venous phase Which of the following terms describes the appearance of an acute subdural hematoma on a CT image of the brain *ANS* Hyperdense The angiographic assessment known as a "CT runnoff" evaluates the peripheral arterial tree from the renal arteries through the *ANS* Distal lower extremity During a PET-CT examination, the amount of FDG uptake in a anatomic region is directly proportional to the area's: *ANS* Metabolic activity Accurate demonstration of __________ would most likely require the intravenous injection of an iodinated contrast agent during a CT study of the chest. *ANS* A dissecting aortic aneurysm Vascular components of the brains blood supply known as the circle of willis include the *ANS* Internal carotid arteries, anterior communicating artery The benign mass of the eighth cranial nerve known as a vetibular schwannoma may also be termed a(n) *ANS* Acoustic neuroma The thick, layered portion of the peritomeum responsible for attaching portions of the intestines to the bowel wall is called the *ANS* Mesentery After initiation of rapid blolus administration of an iodinated contrast agent, the nephrographic phase of renal contrast enhancement occurs at approximately *ANS* 70-90 seconds Retrospective ECG gating utilizes which of the following portions of the cardiac cycle for image reconstruction *ANS* Cardiac diastole Which of the following is a common complication of CT-guided biopsy of the lung *ANS* Pneumothorax An enema is indicated prior to a CT examination of the pelvis to administer positive contrast material into the large bowel. Which of the following dosages would be sufficient to opacify the rectosigmoid region? *ANS* 150-250 mL A CT examination of the lumbar spine reveals a herniated disc at the level of L2-L3. Which of the following reformation planes would best demonstrate posterior compression of the disc material onto the spinal cord *ANS* Sagittal A common formula used to calculate the maximum dosage of intraveous iodinated contrast material used in any CT examination is *ANS* 2 mL per kg of body weight Which of the following MDCT examinations may include endobrachial views *ANS* Virtual bronchoscopy A Stanford type A dissecting aneurysm affects which portion of the aorta? *ANS* Ascending thoracic The average density of a mass within the kidney measures -75 Hounsfield units (HU). The mass is most likely a *ANS* Lipoma A Stanford type B dissecting aneurysm affects which portion of the aorta? *ANS* Descending thoracic The firm, outer portion of each intervertebral disc is called the: *ANS* Anulus fibrosus Which of the following refers to the surgical resection of the pancreas and duodenum for the treatment of pancreatic carcinoma *ANS* Whipple procedure During which of the following IV contrast phases does the bladder wall enhance *ANS* Nephrographic Coronary artery calcuim (CAC) quantitation by MDCT exam is used primarily to assess *ANS* Atherosclerotic disease The best method for targeeting the sacrum in a pelvis exam for detailed examination would be to *ANS* Retrospectively reconstruct the image using a small DFOV A specialized CT examination involving the administration of an enteral contrast agent directly into the small bowel via nasogastric tube is called *ANS* CT enteroclysis The epithelial lining of the urinary tract is called the *ANS* Urothelium A common area for inflammation, the primary drainage opening within the sinus cavities is referred to as the *ANS* Ostiomeatal complex During CT examination of the chest, the administration of a saline flush following the bolus injection of iodinated IV contrast media helps alleviate artifact from dense contast in the *ANS* Superior vena cava Delayed post-contrast acquisition of the lower extremities following a CTA of the pulmonary arteries is termed: *ANS* CT venography The overall quality of MPR and volume-rendered 3D images for a carotid artery CTA my be improved by *ANS* Reducing the kVp for an increase in displayed vessel opacification and contrast, retrospective reconstructions with a 50% overlap in section increment, bolus-tracking software to maximize contrast enhancement Which of the following is the most common sign of GI pathology on CT images *ANS* Wall thickening Often elevated during body CTA examinations, the branches of the celiac axis are the *ANS* Left gastric artery, common hepatic artery, splenic artery Vital components of a CT urogram (CT-IVP) protocol include *ANS* Thin-section excretory phase imaging of the entire urinary tract, volume-rendered 3D and maximum intensity projection (MIP) imaging of the urinary tract Arterial phase CT imaging of the liver is used to optimally demonstrate which of the following? *ANS* Hepatocellular carcinoma (HCC) Non-contrast CT of the urinary tract is a valuable tool in the investigation of *ANS* Urinary tract lithiasis Which of the following techniques may be used to improve visualization of the vocal cords during a CT examination of the neck *ANS* Scanning while the patient phonates the letter "E" Percutaneous drainage under CT guidance may be used for the aspiration of which of the following pathologic processes *ANS* Abdominal abscess The device constructed to house the x-ray tube and data acquisition system (DAS) for a CT scanner is called the: *ANS* Gantry Third generation CT scanners use which of the following scan geometries *ANS* Rotate-rotate A quality control procedure determines that the low-contrast resolution of a CT scanner is extremely poor. Likely causes are *ANS* Increase electronic noise, decreased tube output When one is viewing a maximum intensity projection (MIP) image, each pixel represents: *ANS* The maximum intensity attenuation occurring within the voxel A CT image is reconstructed using a 512² matrix and a display field of view of 40cm. What is the linear dimension of each pixel. *ANS* 0.78 mm. dfov is converted into 400mm, this is then divided by 512 Which of the following statements about collimation of the CT x-ray beam is false *ANS* Increases in collimation increase the intensity of the primary beam Which of the following terms may be used to describe the quantity of radiation emitted from the CT x-ray tube toward the patient *ANS* Photon fluence Which of the following mathematical techniques is used exclusively for image reconstruction with helical CT scanners *ANS* Interpolation A picture archival and communications system (PACS) is connected with imaging modalities and other peripheral devices on a computerized communications system called a: *ANS* Network The major disadvantage of the back-projection method of image reconstruction is the appearance of the *ANS* Star artifact The most effective method of reducing involuntary motion on a CT image is *ANS* Reduced scan times Soft copies of CT images are stored on which of the following media *ANS* Hard drives, magnetic optical disk The process of displaying CT images in a different orientation from the one used in the original reconstruction process is called: *ANS* Multiplanar reformation (MPR) The process of gray-scale mapping of the CT image may be referred to as *ANS* Windowing In the formula used to calculate the linear attenuation coefficient, I=Ioe-ux, the symbol Io identifies *ANS* Incident intensity First-generation CT scanners possess which of the following charcteristics *ANS* Pencil-thin x-ray beam The intensity of the x-ray beam after it passes through an object to a detector is called the *ANS* Transmitted intensity An accurate, modern CT scanner possesses a spatial resolution up to: *ANS* 25 lp/cm A high-resolution comb is utilized by an MSCT detector array in an effort to reduce *ANS* Scatter radiation The distance between the centers of two adjacent reconstructed CT images is termed the *ANS* Section interval The maximum number of simultaneous sections an MSCT system can acquire per gantry rotation is controlled by the number of *ANS* Data channels Matrix size describes which of the following? *ANS* number of pixels used to display image Th implementation of corrective actions to improve any identified performance inadequacies of the CT system is referred to as *ANS* Quality control The major disadvantage of the fan or cone shaped x-ray beams used In modern CT units in comparison with the "pencil-thin" beams of older units is *ANS* Greater patient radiation dose When choosing a scan field of view (SFOV), the CT technologist is controlling the *ANS* Diameter of data acquisition, number of activated detectors within the array, correction factors for the specific area of anatomic interest As the attenuation of a volume of tissue decreases, the transmitted intensity of a CT x-ray beam: *ANS* Increases Which of the following parameters or factors is improved by the selection of a smaller x-ray tube filament. *ANS* Spatial resolution The geometric efficiency of a CT detector is influenced primarily by the *ANS* Amount of interspace material between detectors Which of the following factors may affect the attenuation of an object during CT data acquisition *ANS* kVp An image that is reconstructed a second time with some change in technical factor is said to be *ANS* Retrospective The Feldkamp-Davis-Kress (FDK) algorithm may be applied to MSCT acquisition data to overcome image artifacts fromn *ANS* Beam divergence During HRCT of the lungs, edematous changes in the posterior lungs may be differentiated by positioning of the patient in the _______________ position. *ANS* Prone MSCT systems are typically capable of differentiating adjacent objects with attenuation differences as small as: *ANS* 3 HU The ability of an MSCT system to freeze motion and provide an image free of blurring is called: *ANS* Temporal resolution Ring artifacts on the CT image are associated with which of the following tube-detector geometries? *ANS* Rotate-rotate What is the maximum beam collimation for an MSCT system with 16 rows of 1.25 mm detectors *ANS* 20.0 mm, 16×1.25 The polyenergetic x-ray beam emitted from a CT x-ray tube is susceptible to artifacts due to the phenomenon know as: *ANS* Beam hardening In an MSCT system, which of the following technical parameters determines the reconstructed section width. *ANS* Detector collimation Daily air or water calibration of the CT system is performed to evaluate which of the following components of image quality? *ANS* Linearity The reduction in intensity of an x-ray beam as it interacts with matter is called *ANS* Attenuation Pixels whose average attenuation coefficients are less than the coefficient of water have which of the following types of CT number values? *ANS* Negative Which of the following actions would serve to magnify the CT image on the display monitor *ANS* Decrease display field of view The bit depth of a digital imaging system defines the number of information bits contained within each *ANS* Pixel The technical factor(s) necessary for the acquisition of an isotropic data set is/are *ANS* Thin detector collimation, small DFOV When one is assessing an MTF graph the limiting resolution is determined at a point where the signal frequency corresponding to a particular object has reached. *ANS* 10% In multislice CT (MSCT), the combined thicknesses of all of the sections simultaneously acquired with each gantry rotation are called the *ANS* Total collimation MSCT systems typically employ which of the following detector geometries? *ANS* Solid-state scintillation Which of the following technical adjustments may be employed to reduce step artifact in a multiplanar reformation CT image *ANS* Acquisition of an isotropic data set, overlapping section increment Which of the following is a manifestation of the partial volume artifact *ANS* cupping During volumetric CT acquisition, the slice sensitivity profile (SSP) graphically represents the: *ANS* Effective section width An increase in the sampling rate during CT data acquisition corresponds to an increase in: *ANS* Views per rotation