CT REGISTRY STUDY QUESTIONSBANK 2024\2025 |GUARANTEED PASS |FULL SET WITH ACCURATE ANSWERS, Exams of Nursing

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CT REGISTRY STUDY QUESTIONS 2024
CT REGISTRY STUDY QUESTIONSBANK 2024\2025 |GUARANTEED PASS |FULL SET WITH ACCURATE ANSWERS How do you reduce beam hardening - ACCURATE ANSWERS✔✔ 1. Increase dose

2. Reduce collimation--Reduce slice thickness
3. Increase window width At what level does the abdominal aortal bifurcate? - ACCURATE ANSWERS✔✔ L What is the typical scan delay after injection of contrast media for studies of the liver? - ACCURATE ANSWERS✔✔ 30-45 seconds What window settings provide the best tissue differentiation within the liver? - ACCURATE ANSWERS✔✔ window width= 140, level= 60

What is the window settings that provide the best bone window for the pelvis? - ACCURATE ANSWERS✔✔ window width=2000, window level= What mAs is typically used in routine CT exams of the abdomen? - ACCURATE ANSWERS✔✔ 200-300 mAs What is the result of the bifurcation of the abdominal aorta? - ACCURATE ANSWERS✔✔ The right and left common iliac arteries What is the anode target angle? - ACCURATE ANSWERS✔✔ 12 degrees At what level do the common carotids bifurcate into the internal and external carotid arteries? - ACCURATE ANSWERS✔✔ C3-C The floor of the orbit is formed by the __________ bones. - ACCURATE ANSWERS✔✔ maxillary and zygomatic The lateral wall of the orbit is formed by the ___________ bones. - ACCURATE ANSWERS✔✔ zygomatic and sphenoid The medial wall of the orbit is formed by the _________ bones. - ACCURATE ANSWERS✔✔ ethmoid and lacrimal bones

how do you calculate effective mAs? - ACCURATE ANSWERS✔✔ mAs/pitch define window level and window width - ACCURATE ANSWERS✔✔ LEVEL: a chosen midpoint in the grayscale WIDTH: number of grayscale values above and below the level.

• The width is DIVIDED in HALF and distributed above and below the level.
• Anything above the window is white
• Anything below the window is black The wider the window the more grayscale values, the lower the contrast! example: Level 100, Width 300 White = >+ Black = <- Level 100, Width 200 White = >+ Black = < Level 100, Width 150

White = >+ Black = < factors that affect spatial and contrast resolution - ACCURATE ANSWERS✔✔ Spatial resolution:

1. focal spot
2. detector width (aperture)
3. reconstruction algorithm - bone>soft tissue
4. slice thickness - thinner is better
5. pixel/FOV/matrix
6. pitch - decreased pitch means no gaps
7. nyquist limitations Contrast resolution: CNR
8. energy of X-rays - kVp - ↑ kVp ↓ contrast
9. number of X-rays - mA - ↑ mA ↓ mottle
10. slice thickness - thicker is better
11. reconstruction method - iterative > filtered
12. reconstruction algorthith - soft tissue>bone Give window levels for brain, lung, abdomen, bone - ACCURATE ANSWERS✔✔ Brain: W80,L+ Lung: W1500, L- Abdomen: W400, L+

Bone: W1600, L+ What is beam hardening? what are the two types of beam hardening artifact? how do you compensate for it? - ACCURATE ANSWERS✔✔ 1) as the X-ray beam passes through an object, lower energy photons are removed (like filtration!) leaving a "harder beam" of high energy photons. This causes two artifacts:

2. Cupping: the center of a round object is darker than the periphery due to hardening of the beam 360 degrees around the object. happens in the head
3. Streak: these are dark bands that occur in between two dense objects - nearly all the photons are removed in a line between the two objects
4. fixes: A) Filtration: pre-hardening the beam to remove low energy photons B) Calibration: using a phantom to set a compensated mA/kVp C) Correct software: iterative reconstruction may help D) Avoidance: tilting the gantry of positioning the patient to avoid areas that may cause hardening. ring artifact - ACCURATE ANSWERS✔✔ Calibration error or defective detector cause consistently erroneous reading at each angular position, resulting in a circular artifact

is the focal spot large or small? - ACCURATE ANSWERS✔✔ large 0.6- 1.2 - so as not to overheat the anode from such a high mA Which of the following will result in an increased voxel size: B increased slice thickness - ACCURATE ANSWERS✔✔ A)decreased reconstruction FOV B) increased slice thickness C) increased matrix D) none of these If a tissue with a CT number of +300 appears white on the image, which of the following are the window width and window level selected: A)window level =0, window width =500 B)window level= +300, window width= 500 C)window level =+100, window width = D)none of these - ACCURATE ANSWERS✔✔ A) window level =0, window width = What is the volume of a voxel if a slice thickness of 3 mm, a 512x matrix & a reconstruction field of view of 25.6cm are used A) 0.75mm³ B)1.5mm³ C) 6.0mm³ D)none of these - ACCURATE ANSWERS✔✔ A. Solve this by finding the pixel size first FOV/matrix size ... that is 0. ... now square that 0.25 .... multiply that by slice thickness and you get 0. Which of the following parameters is responsible for partial volume averaging: A) matrix size B) kVp C)slice thickness D) patient dose - ACCURATE ANSWERS✔✔ C Voxel equation - ACCURATE ANSWERS✔✔ pixel area x section thickness

What is interpolation? - ACCURATE ANSWERS✔✔ Mathematical method for taking SPIRAL data and viewing it as AXIAL images Bone windows - ACCURATE ANSWERS✔✔ 2000-4000 WW 200-400 WL Lung windows - ACCURATE ANSWERS✔✔ 1400-1600 WW (-)400-600 WL Modular Transfer Function? - ACCURATE ANSWERS✔✔ graphical representation of SPATIAL RESOLUTION measured in lp/cm, tells how small you can scan without blurring Decrease partial volume averaging? - ACCURATE ANSWERS✔✔ Reduce slice thickness Which portion of the pancreas is the most common site for tumors?; and where located? - ACCURATE ANSWERS✔✔ The head of the pancreas. It is located approximately at T LUNG WINDOW (-) IS AIR - ACCURATE ANSWERS✔✔ 2000 WW and -200 WL =

The Hounsfield unit that is -1000 most likely represents which of the following? - ACCURATE ANSWERS✔✔ Air Relative to CT topography, slice thickness is best represented by which of the following axes? - ACCURATE ANSWERS✔✔ Z axis What unit is the basis for exposure based on ionization in air? - ACCURATE ANSWERS✔✔ mR or C/kg What radiation unit considers the biological effectiveness of radiation exposure? - ACCURATE ANSWERS✔✔ mrem or mSv "Fan" beam technology first historically came on the scene with which acquisition geometries? - ACCURATE ANSWERS✔✔ Second "Rotate-rotate" applies to which of the following geometries? - ACCURATE ANSWERS✔✔ Third In CT what imaging plane is the pituitary best visualized? - ACCURATE ANSWERS✔✔ coronal The third ventricle of the brain communicates with the fourth ventricle through the - ACCURATE ANSWERS✔✔ Cerebral aqueduct refers to an excessive Amount of nitrogenous materials in the blood and is a symptom of renal failure. - ACCURATE ANSWERS✔✔ Azotemia

Which paranasal sinus is usually the last to fully develop? - ACCURATE ANSWERS✔✔ Frontal What is the average annual radiation dose? - ACCURATE ANSWERS✔✔ 2 rem 10 rem converted to Sieverts is what? - ACCURATE ANSWERS✔✔ 0.1 Sv convert 10 mSv to Sv - ACCURATE ANSWERS✔✔ 0.01 sV annual limit for adult occupational effective dose? - ACCURATE ANSWERS✔✔ 0.05 Sv annual limit of occupational lens dose - ACCURATE ANSWERS✔✔ 0.15 Sv annual limit of shallow dose equivalent to skin/extremities - ACCURATE ANSWERS✔✔ 0.5 Sv occupational exposure to embryo/fetus during pregnancy - ACCURATE ANSWERS✔✔ 0.5 mSv total effective dose equivalent to public

--also average background radiation - ACCURATE ANSWERS✔✔ 1 mSv Mild reactions to iodinated intravenous contrast media include - ACCURATE ANSWERS✔✔ nausea, vomiting, mild urticaria, and a warm flushed sensation Moderate reactions? - ACCURATE ANSWERS✔✔ Dyspnea, Hives (urticarial); wheezing (mild bronchospasm); change in pulse; facial edema; vasovagal response; hypo- or hypertension Severe reactions? - ACCURATE ANSWERS✔✔ Severe bronchospasm; anaphylaxis; Drowsiness; headache; fever/chills, Shock, pulmonary edema Osmolality - ACCURATE ANSWERS✔✔ Concentration of a solution in terms of number of dissolved particles per unit of water Non-ionic intravenous contrast media such as Omnipaque should have an average osmolality of - ACCURATE ANSWERS✔✔ 750 mOsm/kg water What drugs are administered for moderate reaction to injection of iodinated contrast medium - ACCURATE ANSWERS✔✔ Antihistamines Epinephrine

Prothrombin measures the amount of time necessary for a person's blood to coagulate - ACCURATE ANSWERS✔✔ normal limits: between 10 and 14 seconds why use an autoclave? - ACCURATE ANSWERS✔✔ The use of an autoclave for sterilization involves heat and steam under pressure to eliminate microbes. 1 rem= 1 rad - ACCURATE ANSWERS✔✔ When measuring the radiation dose from x-rays, rads and rems are equivalent. The units of Sv and rem are used to measure any kind of ionizing radiation where 1 Sv =100rem. The units of rad and Gy are used to measure specifically x-ray radiation where 1 Gy = 100 rads. When performing a multi-slice CT study, the slice thickness may be ___________ to cover the region of interest, in order to minimize the dose to the patient. - ACCURATE ANSWERS✔✔ Due to radiation penumbra, a multiple slice study results in a greater patient dose than the same number of individual slices. By covering a specific region of interest with fewer slices (increase in slice thickness) the resulting radiation overlap from adjacent slices is reduced, reducing the dose to the patient. A given CT exam yields a CTDI of 4.5 rads, with a slice thickness of 10mm, and a 2mm gap between slices, the MSAD for this exam is ________ rads. - ACCURATE ANSWERS✔✔ The MSAD is equal to the CTDI X the ratio of the slice thickness to the table increment. With a

2mm gap and a 10mm slice the table increment will be 12mm. The MSAD = (4.5 rads) X (10mm/12mm) --3.75 rads Calulate the DFOV for an image with a 320 2 matrix and a pixel dimention of .75 x .75 mm. A)36cm B)12cm C)24cm D)48cm - ACCURATE ANSWERS✔✔ Answer: C *The formula for DFOV is pixel dimension x the matrix size. 320 x. mm = 240mm or 24 cm DFOV The units rad and rem are equivalent when measuring radiation dose used in CT x-ray radiation. True or False - ACCURATE ANSWERS✔✔ Answer: True *When measuring the radiation dose only from x-rays, rads and rems are equivalent. The units Sv and rem measure any kind of ionizeing radiation (1 Sv = 100 rem). The units rad and Gy measure specifically x- ray radiation (1 Gy = 100 rads

Non-ionic contrast media include - ACCURATE ANSWERS✔✔ iopamidol (Isovue), Iohexol (Omnipaque), and iopromide (Ultravist) What is the normal pulse rate for an adult? - ACCURATE ANSWERS✔✔ 70-100 bpm What is the average normal adult respirations per minute? - ACCURATE ANSWERS✔✔ 12- Which of the following iodinated contrast media may NOT be used for an intrathecal injection? - ACCURATE ANSWERS✔✔ Iohexol(Omnipaque), metrizamide(Amipaque) and iopamidol(Isovue) are all non-ionic contrast agents that may be used for intrathecal injection. Meglumine is not considered safe for an intrathecal injection. A patient arrives with a central venous line in place. Which type of central venous line may be used for a CT examination requiring the administration of iodinated contrast media with an automatic injector? - ACCURATE ANSWERS✔✔ none.. indwelling catheters or central venous lines cannot withstand the pressure produced by an automatic injector The total quantity of radiation dose received by the patient from a CT scan series is termed - ACCURATE ANSWERS✔✔ MSAD(multiple- scan average dose) quantifies the amount of exposure to a patient from a series of CT scans. MSAD is calculated using a series of equations based on the CTDI(CT dose index). The radiation quantity per scan is measured using an ionization chamber.

Average pulse rate for an infant is - ACCURATE ANSWERS✔✔ 100- 180 bpm General signs of shock include: - ACCURATE ANSWERS✔✔ rapid breathing, tachycardia, hypotension, weak pulse, pallor, cyanosis, and cold, clammy skin. What is the average range for activated partial thromboplastin time? - ACCURATE ANSWERS✔✔ 28-34 seconds The average radiation dose to the pituitary gland during a CT head is - ACCURATE ANSWERS✔✔ 2 rads A CT exam is done with a slice thickness of 10mm, and a 2mm gap is between the slices, the pitch is 1:2 and the total scan time is 5 seconds. What is the table increment for this exam? - ACCURATE ANSWERS✔✔ *The table increment is determined by adding the slice thickness with the gap between the slices. 10mm + 2mm = 12mm table increment. The other information given is just that other information to distract you. What is medical asepsis? - ACCURATE ANSWERS✔✔ The reduction in number of infectious agents but not the complete elimination of all organisms.

Complete cardiac diastole correspond to which portion of the cardiac cycle on a electrocardiogram (ECG)? - ACCURATE ANSWERS✔✔ T- wave Gas accumulating within a degenerating intervertebral disk is termed - ACCURATE ANSWERS✔✔ vacuum effect Following the intravenous administration of iodinated contrast media, a hepatic hemangioma may become _________ and may no longer appear on the CT image. - ACCURATE ANSWERS✔✔ isodense -- The diagnosis of hemangioma is confirmed on CT by evaluation of its pattern of enhancement. Hemangiomas enhance from the periphery inward, until they become isodense with the surrounding hepatic tissue. Once isodense, the hemangioma attenuates the beam in the same way as the hepatic tissue. The CT numbers of the hemangioma and hepatic tissue become equal and the structures may become impossible to differentiate. During CT examination of the larynx, the patient is often instructed to phonate the letter "E" in order to properly evaluate the - ACCURATE ANSWERS✔✔ vocal chords The exaggeration of displayed calcification within the coronary arteries during a cardiac MDCT study is referred to as - ACCURATE ANSWERS✔✔ Blooming- refers to the potential overestimation of vessel calcification due to partial volume artifact

What describes a condition in which cerebral ischemia is caused by systematic hypertension? - ACCURATE ANSWERS✔✔ Vasovagal reaction Patients whose posterior descending artery branches from the right coronary artery, and whose left posterior ventricular braches arise from the left circumflex artery are said to be - ACCURATE ANSWERS✔✔ codominant - 7% of the population is said to be codominant... which means the PDA is supplied by the RCA.. and the left posterior ventricular braches arise from the LCX Which of the following window settings would optimally display CT colonography images? - ACCURATE ANSWERS✔✔ level= - width= 1600 CT colonography images are best displayed in wide "lung-type" window setting A CT scanner with a limiting resolution of 15 lp/cm can resolve an object as small as.. - ACCURATE ANSWERS✔✔ 0.3 mm The minimum object size that a CT scanner can resolve may be calculated by taking the reciprocal value of the scanner's limiting resolution. The reciprocal of 15 lp/cm is 1/15 lp/cm. This is equivalent to 10/15 lp/mm, which equals 0.6 mm/lp. Because a line pair is equivalent to a line and the space adjacent to it, this value may be divided in half to provide the minimum object that this scanner can resolve..0. The total length of a CT scan may be calculated by multiplying the scan time by the aperture size - ACCURATE ANSWERS✔✔ An example: If

the scan time is 15 seconds and the aperture size(slice thickness) is 1.0cm(10mm) the length of the scan will be 150mm. An abnormal density of the liver is found to be a fatty infiltrate. The CT number for this area would most likely be in the range of .. - ACCURATE ANSWERS✔✔ -100 Hounsfield units What is the HU of a pulmonary nodule? - ACCURATE ANSWERS✔✔ +200 hu The radiologist has requested a CT examination to identify the thymus gland in a young pre-puberty patient. The thymus gland is located - ACCURATE ANSWERS✔✔ anteriosuperior portion of the mediastinum To best image a possible Schwannoma found within the Schwann cells of the eighth cranial nerves, CT examinations should include which of the following - ACCURATE ANSWERS✔✔ internal auditory canal CT examination of the liver for hepatic tumor evaluation should NOT be performed during which of the following phases of contrast enhancement? - ACCURATE ANSWERS✔✔ Equilibrium phase The correct orientation for viewing CT images on the monitor is which of the following? - ACCURATE ANSWERS✔✔ Cross sectional anatomy is viewed from the perspective of looking up from the patient's

feet to the head and the image oriented with the left side of the patient on the right side of the viewer. Some CT scanners allow the CT technologist to outline an anatomic area on a series of cross-sectional images and then define the outlined area on the localizer(scout) image. This is called - ACCURATE ANSWERS✔✔ correlation A bolus injection of iodinated contrast media is administered to a patient scheduled for a CT examination of the liver, a delay of ________ should be applied - ACCURATE ANSWERS✔✔ 45 second delay will allow the portal vein to become completely opacified An acoustic neuroma would be found in which of the following cranial nerves? - ACCURATE ANSWERS✔✔ eighth cranial nerve When performing a dynamic CT study of the chest the interscan delay used would be - ACCURATE ANSWERS✔✔ 4 seconds (shortest possible) CT images acquired in a plane which divides the body into dorsal and ventral sections are considered ____________ images - ACCURATE ANSWERS✔✔ coronal A CT examination of the liver shows an abnormal finding of reduced density, which of the following is most likely the cause? - ACCURATE

ANSWERS✔✔ A fatty infiltrate - they greatly reduce the density of the liver To best demonstrate a tumor of the liver the CT scan should be performed during which of the following phases of contrast enhancement? - ACCURATE ANSWERS✔✔ Non-equilibrium phase-- Bolus phase, dynamic phase and equilibrium phase will not provide the best contrast enhancement needed for liver tumor evaluation. A contrast enhanced CT examination of the chest is completed, when viewing the image it appears small, making evaluation of the anatomy difficult. To improve image quality which of the following technical changes may be made? - ACCURATE ANSWERS✔✔ Decreased DOV---The image was obviously reconstructed in a display field of view larger than necessary. The image appears small because of this error. The DFOV chosen for an image should be slightly larger than the diameter of the area of interest. _____________ a specialized technique which uses narrow section widths and a low-resolution algorithm for image reconstruction. - ACCURATE ANSWERS✔✔ High resolution CT What is used to combat brachycardia during a vagal reaction to contrast?

• ACCURATE ANSWERS✔✔ Atrophine CT images containing areas of abrupt changes in tissue density are electronically represented by - ACCURATE ANSWERS✔✔ High spacial frequencies ---The spatial frequencies of the tissues within a

section control the contrast of a CT image. Adjacent tissues with large differences in density are represented by high spatial frequency signals The definition of conversion efficiency is - ACCURATE ANSWERS✔✔ Conversion efficiency is the percentage of x-rays colliding with the detector atoms which result in a measurable electrical signal Focal spot size is determined when choosing what? - ACCURATE ANSWERS✔✔ Slice thickness The CT number for blood is approximately - ACCURATE ANSWERS✔✔ +45 HU The dimensions of a voxel may be calculated as the product of which of the following? - ACCURATE ANSWERS✔✔ pixel size and section width The pixel is a two-dimensional representation of a voxel. The section width is equal to the length of the voel. To calculate the dimensions of a voxel, the pixel dimension must be multiplied by the section width Which of the following formulas may be used to calculate the dimensions of a pixel? - ACCURATE ANSWERS✔✔ Pixel Size=DFOV/matrix size

The dimensions of a pixel may be calculated by dividing the DFOV by the matrix size. Keep in mind that the pixel is a square with four equal sides and the dimension of one side is usually given in millimeters (mm). The area of the pixel is calculated by squaring the dimension, and the units are then adjusted to square millimetes (mm2). A CT image is reconstructed using a 512^2 matrix and a display field of view of 17 cm. What is the linear dimension of each pixel? - ACCURATE ANSWERS✔✔ 0.3 mm The dimension of a pixel may be calculated by dividing the field of view by the matrix size. The DFOV of 17 cm must first be converted into 170 mm. This is then divided by 512 mm, for a pixel dimension of 0.33 mm. Keep in mind that the pixel is a two-dimensional item, square in shape, and the measurement of 0.33 mm corresponds to only one side The portion of the nephron responsible for filtration of unwanted materials from the blood plasma is called the - ACCURATE ANSWERS✔✔ Glomerulus The glomerulus is the portion of the nephron responsible for filtering unwanted substances from blood plasma. The blood enters into the glomerulus through the afferent arteriole and exits through the efferent arteriole. The waste fluid leaves the glomerulus through the proximal tubule The ability of an MDCT system to freeze heart motion during a cardiac CT is described by its - ACCURATE ANSWERS✔✔ The temporal

resolution of an MDCT system describes its ability to freeze the motion of the heart as well as the arterial motion velocity within the coronary vasculature In multislice CT (MSCT), the beam pitch is equal to the table feed per rotation divided by the - ACCURATE ANSWERS✔✔ Total collimation The beam pitch, which is unique to multislice CT, is equal to the table feed per rotation divided by the total collimation. The total collimation is equal to the combined thickness of all of the sections that are simultaneously acquired with each gantry rotation Phantom measurement of the uniformity of a CT system is performed primarily to assess the negative effects of - ACCURATE ANSWERS✔✔ Beam hardening Which of the following components of the CT system is the most common cause of ring artifacts on the reconstructed CT image? - ACCURATE ANSWERS✔✔ Ring artifacts are typically cause by faulty detectors. An error in a detecor results in back-projection of an incorrect ring of density on the reconstructed CT image. Cardiac CT images are typically acquired during which phase of the heart's cycle? - ACCURATE ANSWERS✔✔ diastolic (relaxation) phase

The heart optimally imaged with the least artifact from motion during its period of relaxation, otherwise known as the diastolic phase of the cardiac cycle. Each iliac artery bifurcates into the internal and external iliac arteries at about the level of - ACCURATE ANSWERS✔✔ L5-S1 The volume of a voxel may be calculated by multiplying the pixel dimension (mm2) by the _____________? - ACCURATE ANSWERS✔✔ section width As a geometric cuboid, the volume of a voxel may be calculated as the product of the pixel area dimension (mm2) and the section width (mm). The pixel dimension (d) must be first calculated by dividing the display field of view (DFOV) by the matrix size. The area of the pixel may then be found by squaring the value of d (mm). The unit of measurement for voxel of volume is mm3 Which of the following is the primary interaction between x-ray photons and tissue during computed tomography? - ACCURATE ANSWERS✔✔ Compton effect The technique that provides the detail of the outer portions of the 3D model while maintaining the typical CT detail of the lungs inside is called - ACCURATE ANSWERS✔✔ Surface rendering

Computer programs are capable of constructing 3D models of anatomy with several different types of rendering techniques. A surface-rendered 3D model provides excellent surface anatomy while maintaining the normal cross-sectional anatomy apperance of the volume inside the model. During CT perfusion studies, the quanity of blood (in mL) contained within 100g of brain tissue is termed the - ACCURATE ANSWERS✔✔ Answer: C. cerebral blood volume (CBV) Which of the following is/are included in the signs and symptoms of hypovolemic shock? (1) hypertension (2) oliguria (3) pallor - ACCURATE ANSWERS✔✔ Answer: C. 2 and 3 only Hypovolemic shock is caused by an insufficient volume of circulating blood. The common signs and symptoms of hypocolemic shock are pallor (absence of color in the skin), hypotension, tachycardia, and oliguria (decrease urine output)

During a CT examination of the abdomen including intravenous administration of an iodinated contrast agent, which of the following abnormal findings could appear hyperdense in comparison with surrounding material? - ACCURATE ANSWERS✔✔ Gallstones Which of the following units is used to quantify absorbed dose? - ACCURATE ANSWERS✔✔ grays (Gy) Coronal imaging through the paranasal sinuses is typically performed with the plane of imaging: - ACCURATE ANSWERS✔✔ Perpendicular to the hard palate which of the following manipulations involves the use of image data? - ACCURATE ANSWERS✔✔ window width and level changes Cupping artifacts most commonly occur where? - ACCURATE ANSWERS✔✔ The brain Cupping artifacts occur when the periphery of the image has a much greater density than the center In patients who are left dominant, the posterior descending artery branches from the: - ACCURATE ANSWERS✔✔ Left circumflex artery 8% of population is considered left dominant