CT REGISTRY REVIEW

3D SSD are performed on CT: 1. image data 2. raw data 3. attenuation profiles a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

a

From which of the following can the most diagnostic multi-planar reconstruction be generated? 1. stacked transverse images from a helical scan 2. stacked transverse images from a conventional, serial scan 3. stacked localizer images a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

a

Increased ___ will increase the likelihood that a given x-ray will penetrate a material. 1. kV 2. mA 3. exposure time a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

a

The cathode filament: a. helps determine the size of the focal spot b. lights up the tube so it can be serviced by an engineer c. releases the x-ray photons d. focuses x-ray onto the anode target

a

The mA determines the : a. quantity of x-ray photons b. coefficient of attenuation c. slice thickness d. energy level of the x-ray photons

a

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 throughout the patient exam once it is initially positioned d. only moves after each slice is completed

a

Tube interscan delay time refers to: a. the time between the end of one scan and the start of the next scan during which the tube will cool b. a quality assurance test performed daily by the technologist c. the time required for the tube to make a complete 360 revolution about the gantry d. the length of time required for the production of photons to begin after applying the voltage to the tube

a

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 radiologists

a

Which of the following is common to both a localizer scan and a conventional, serial CT scan? a. they both produce digital images b. the patient table moves at a constant velocity c. they both produce cross- sectional images d. the x-ray tube makes complete 360 rotations

a

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 the reconstruction algorithm

a

Which of the following may reduce the out of field artifact? a. increasing the scan field of view b. reducing the reconstruction field of view c. reducing the slice thickness d. increasing the matrix

a

Which of the following statements is FALSE regarding the collection of CT data? a. long scan times are more desirable b/c they average out motion artifacts b. the reconstruction process used to create the image occurs in the array processor c. to collect the complete set of CT data, x-ray must passed through the body at many different angles d. the detectors measure x-rays which completely penetrate the patient.

a

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

a

Which of the following would decrease the effects of beam hardening artifacts? 1. increased kVp 2. increased mAs 3. increased scan time a. 1 only b. 1 & 2 c. 2 only d. 3 only

a

Which of the following would display the greatest amount of partial volume artifact? a. a 10mm 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

a

Which of the following would eliminate a ring artifact? a. recalibration of the detector elements b. removal of metal c. decreased matrix d. increased mAs

a

Which of the following would result if the filter at the aperture of the x-ray tube removed even more low energy x-ray photons? a. beam hardening artifact would decrease b. partial volume artifact would increase c. beam hardening artifact would increase d. partial volume artifact would decrease

a

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

b

A retrospective reconstruction, in which the reconstruction field of view is varied, uses: a. a reconstructed image in the sagittal plane b. CT raw data c. more photons d. CT image data

b

A(n) ______ artifact is a streak 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

b

Bremsstrahlung radiation does NOT include which type of electron activity? 1. collision between an incoming electron and the nucleus of the target atom 2. collision between an incoming electron and an electron in an inner shell of the target atom 3. slowing down of an incoming electron due to the effect of passing close to the positive charge of the nucleus of the target atom a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

b

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 a. 1 only b. 1 & 2 c. 2 & 3 d. 1, 2 & 3

b

CT is commonly referred to as al of the following names EXCEPT: a. computerized axial tomography b. digital subtraction angiography c. CAT scan d. computed tomography

b

CT x-ray tube arcing can occur b/c of _____ the x-ray tube. 1. impurities in the oil outside 2. tungsten gas inside 3. tungsten solids in the oil inside a. 1 only b. 1 & 2 c. 2 only d. 2 & 3

b

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.

b

If an algorithm to correct for the cupping artifact is applied too aggressively to the data for a head image, the ______ of the image would be too bright> 1. top and bottom 2. center 3. edges a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

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 of the sharp density difference interface d. in a herringbone pattern across the image.

b

Most of the commands from the technologist are received by the : a. array processor b. operator's console c. host computer d. amplifier

b

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

b

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 a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

b

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

b

What control does the operator have over the x-ray in the CT exam? a. the temperature and color of the x-ray can be tuned b. the energy level and the quantity of x-rays can be selected c. the volume and tone of the x-ray can be adjusted d. the phase and frequency of the x-ray can be adjusted

b

What is the cause for the cupping artifact? a. the central tissue are not penetrated by the x-ray beam b. the tissue of the body attenuate low energy photons c. the mean energy of the photons that comprise the x-ray beam is lowered d. the interface between tissues with different densities causes the high energy photons to be absorbed

b

What is the cause of cone beam artifacts? a. faulty detector elements b. the use of a standard filtered back projection reconstruction when the x-ray beam is more than 20mm thick c. hardening of the x-ray beam on multi-row detector scanners d. inefficient x-ray tubes used on multi-row detector scanners

b

Which of the following are NOT commonly used on today's commercially available CT scanners? 1. xenon detectors 2. fourth generation scanners 3. continuous rotation a. 1 only b. 1 & 2 c. 1, 2 & 3

b

Which of the following is NOT a part of the CT tube? a. tungsten target b. collimator c. rotating anode d. filament

b

Which of the following is TRUE as the slice thickness is decreased? a. partial volume artifacts increase while edge gradient artifacts decrease b. partial volume artifact and edge gradient artifacts decreases c. partial volume artifacts decreases while edge gradient artifact increases d. partial volume artifacts and edge gradient artifacts increase

b

Which of the following is TRUE regarding the slice thickness of an image reconstructed from a helical scan? 1. on a muti-row detector scanner, the thickness is equal to the beam collimation 2. on a single-row detector scanner, the thickness is equal to the beam collimation 3. on a single-row detector scanner, the thickness can be varied retrospectively a. 1 only b. 2 only c. 2 & 3 d. 1, 2 & 3

b

Which of the following may occur if the patient's arms are placed at their sides during a chest exam if the scan field of view is 33cm ? 1. beam hardening 2. out of field artifact 3. cone beam artifact a. 1 only b. 1 & 2 c. 2 only d. 3 only

b

Which of the following statement is FALSE regarding 3D SSD? a. helical image data is well suited for 3D SSD b/c there is minimal misregistration or gaps b. the volume data, from which the 3D SSD is generated, is created by combining transverse, sagittal, and coronal reconstructions c. the issue surface may be selected by using a threshold value equal to the tissue's CT number d. patient motion during the scan is detrimental to the quality of the 3D images.

b

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 an electron 3. the measured signal is enhanced by an amplifier a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

b

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 date sampling rate 3. using thin slices a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

b

Which technology do multi-row detector scanners employ? a. second generation b. third generation c. fourth generation d. first generation

b

X-rays are produced whenever fast moving electrons collide with any form of matter b/c : 1. the electron splits into two x-ray photons of equal energy upon impact with the matter 2. the electron loses kinetic energy which is converted into the emission of an x-ray photon 3. the electron converts the electron it collides with into an x-ray photon a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

b

_____ is the mathematical process used by single-row detector scanners to reconstruct CT images from raw data. a. Weighted averaging b. Filtered back projection c. The Fourier transform d. Integration of the area under the curve

b

A _____ scan uses only a single projection. 1. conventional, or serial 2. helical 3. localizer a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

c

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

c

A pixel is a: a. bright artifact on a film b. single 3D volume element within a volume of anatomical data c. single 2D picture element within the image plane d. range of gray levels on a CT images

c

Beam hardening refers to : 1. the increase in the number of photons reaching the detector 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 a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

c

In the diagram below, which x-ray tube position will produce a lateral localizer image? a. top of patient b. between a and c c. side of patient a. A b. B c. C d. the tube must make complete 360 rotations

c

Scatter radiation is caused by: a. miscalibrated detector b. x-rays generated spontaneously in the ambient atmosphere c. deflections from the original trajectory of an x-ray photon through the patient d. improper patient positioning.

c

The actual attenuation data measured by the detectors from all projections during a scan is contained in CT _____ data. 1. image 2. convolved 3. raw a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

c

The main purpose of the detector is to : a. provide additional collimation in order to reduce scatter b. limit the x-ray dose to the patient c. capture x-ray photons and convert them to a measurable signal d. amplify the measured signal

c

The number of electron that flow from the cathode to the anode in the tube is controlled by the . a. anode target b. collimator c. mA d. kV

c

Which of the following CT scanners design does NOT use an x-ray tube? a. first generation b. PET/CT c. electron beam CT d. MDCT

c

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 patient's body 2. the molecular composition of the tissues through which the x-ray photons pass 3. the type of detector material used a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

c

Which of the following is a component NOT normally located in the gantry of modern CT system? a. pre patient collimators b. solid state detectors c. array processor d. x-ray tube

c

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 a. 1 only b. 1 & 2 c. 2 only d. 3 only

c

Which of the following might increase the possibility of motion artifact occurring? a. explaining the procedure to the patient b. using a helical scanning technique to acquire the necessary slices in a single breath hold(assuming the patient can refrain form breathing for the required time) c. using no straps or pads so that the patient feel comfortable and unrestricted d. immobilizing the patient

c

Which of the following statements if TRUE? 1. kV is the voltage potential between the tube cathode and anode while mA ultimately controls the filament current and, thus, the temperature 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 the kV and the mA affect the operation of the CT x-ray tube, the two parameters have no bearing on the image quality a. 1 only b. 2 only c. 1 & 2 d. 2 & 3

c

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) a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

c

Which of the following utilizes convolution? 1. 3D SSD 2. Fourier transform 3. filtered back projection a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

c

Which system components converts the projection attenuation data into the proper digital form for the array processor? a. detector b. photodiode c. analog to digital converter d. host computer

c

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 a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

c

X-rays are used in CT b/c: 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

c

_____ scanner design was the first to acquire four slices in a single rotation. a. second generation b. third generation c. multi-row detector d. continuous rotation

c

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

d

A variation in which of the following will affect the hardening of an x-ray beam? 1. tissue density 2. tissue thickness 3. kVp a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Collimation: a. is accomplished by electrically blocking x-ray b. affects the scan time c. limits the low energy x-ray photons and passes the high energy photons d. is accomplished by physically blocking x-rays

d

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

d

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 a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

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? a. volume rendering b. multi-planar reconstruction c. maximum intensity projection d. 3D SSD

d

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 a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

The enormous heat that builds up in the CT tube is caused by the: a. intensity of the x-ray emitted from the tube b. electron beam between the cathode and the anode in the tube c. x-ray filter in the tube which absorbs the lower energy photons before they can enter the patient. d. collision of the electron beam with the tungsten target on the tube anode.

d

The operator's console may include: 1. monitor 2. keyboard 3.graphic input device a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

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

d

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 a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

The slip ring on continuous rotation CT scanners: 1. prevents the high voltage cable from winding up 2. allows the exam to commence more rapidly 3. eliminates the need for the reversal of the gantry frame rotation. a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Tungsten is used as the target material on the tube's anode b/c it has a __ atomic number and a __ melting point. a. low, high b. high, low c. low, low d. high, high

d

Using ____ reconstruction filter would decrease the appearance of noise in a CT image. 1. no 2. a sharp 3. a smooth a. 1 only b. 2 only c. 2 & 3 d. 3 only

d

Which of the following affects beam hardening? 1. the type of tissues the beam passes through 2. the thickness of the tissues traversed by the beam 3. the energies of the photons in the beam a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

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 a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following could allow for a reduction of partial volume artifact while NOT increasing the appearance of the noise in the image? a. increasing slice thickness while decreasing kVp b. decreasing slice thickness while decreasing mAs c. increasing slice thickness while increasing mAs d. decreasing slice thickness while increasing mAs

d

Which of the following is FALSE regarding CT systems? 1. they are limited to non oblique transverse scanning 2. they cannot generate a straight coronal or sagittal image 3. they have no moving parts. a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following is NOT an advantage of a helical study compared to a conventional, serial CT study? a. minimal anatomical misregistration sometimes caused by inconsistent breath holding b. shorter total exam time c. can retrospectively reconstruct a slice at any arbitrary position offers the best image quality for a brain exam d. offers the best image quality for a brain exam

d

Which of the following is TRUE regarding multi-row detector CT scanners? 1. the size of the detectors array 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 detector array may or may not be used a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

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 today 3. they can be used in both third and fourth generation CT systems. a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following is a possible manifestation of beam hardening? 1. CT number inaccuracies 2. streaks in the image 3. cupping artifact a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following is a result of reducing the slice thickness to reduce partial volume effects? 1. in creased appearance of noise 2. increased spatial resolution 3. decreased anatomical coverage with the same number of slice a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following may be the cause of a metal artifact? 1. earrings. 2. a zipper 3. dental fillings a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following statements is TRUE? 1. the amplified electrical signal obtained from the detectors must be digitized 2. digitial CT images are numberical representations of cross sectional anatomy 3. digital signals may be formed by sampling analog signals at discrete time intervals a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following strategies minimizes beam hardening artifact from dense contrast media? 1. the contrast solution can be diluted 2. the scan can be performed with a slight delay 3. the scan can be performed in the opposite direction a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following strategies will minimize metal artifact? 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. a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following would make noise in the image appear less noticeable? 1. increased window widths 2. increased mAs 3. increased slice thickness a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

Which of the following would reduce the partial volume effect? a. increased reconstruction field of view b. increased mAs c. decreased matrix d. decreased slice thickness

d

Which type(s) of storage media may hold CT image data? 1. internal hard disk 2. CD 3. re-writable optical disk a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

_____ in the images is a possible manifestation of patient motion. 1. ghosting 2. blurring 3. streaks a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d

_______ may have to be edited from the data set to get a diagnostic MIP of a CTA exam. a. Iodinated contrast media b. Vessels of interest c. Air d. Bones

d

___made helical imaging possible. a. Multi-row detector scanners b. The introduction of second generation scanners c. The introduction of fourth generation scanners d. Continuous rotation scanners

d

x-ray photons are produced by a fast moving electron: 1. colliding with an atomic nucleus 2. passing close to an atomic nucleus 3. colliding with an electron within an atom and ejecting it a. 1 only b. 2 only c. 3 only d. 1, 2 & 3

d