CT REGISTRY REVIEW

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d) digital subtraction angiography

CT is commonly referred to as all of the following names except: A)computer tomography B)computerized axial tomography C) CAT-scan D)digital subtraction angiography

c) the energy level & quantity of x-rays can be selected

What control does the operator have over the x-rays in a CT exam: A)the temp & color of the x-rays can be tuned B)the phase & frequency of the x-rays can be adjusted C)the energy level & the quantity of x-rays can be selected D)the volume & tone of the x-rays can be dialed

c) both a & b are correct

Which of the following statements is true: A)kV is the voltage potential between the tube cathode and anode while mA controls the filament current & thus ultimately the temperature of the cathode filament B)kV controls the energy level of the x-ray photons & emitted from the tube C)both a & b are correct D)none of these

c) the type of detector material used

Which of the following does not affect the quantity of x-rays that completely penetrates the patients: A)the distance that the x-rays must travel on their course through the patient's body B) the molecular composition of the tissues through which the x-ray photons pass C) the type of detector material used D) both a & b

C) in a system with a low voltage slip ring, the high voltage generator is stationary during a scan

Which of the following statements is false: A) the CT x-ray tube emits x-ray at the same time x-rays are measured by the detectors B) the CT tube rotates around the patient while projection data is acquired C) in a system with a low voltage slip ring, the high voltage generator is stationary during a scan D) none of these

D) long scan times are more desirable because they average out motion

Which of the following is false regarding the collection of CT data: A) the detectors measure only those x-rays which completely penetrate the patient B) to collect the complete set of CT data x-rays must be passed through the body at many diffrerent angles C) the reconstruction process used to create the image occurs in the array processor D) long scan times are more desirable because they average out motion

C) array processor

Which of the following component is not normally located in the gantry of a modern CT system: A) solid-state detector B) x-ray tube C) array processor D)pre-patient collimators

C)they penetrate the body according to specific attenuation characteristics of each tissue

Why are x-ray used in CT: A) they are easily produced by the high frequency generator B)they are less harmful then 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

B) the electrons loses kinetic energy which is converted into the emission of an x-ray photon

X-rays are produce whenever fast moving electron collide with any form of matter because: A) the electron splits into two x-ray photons of equal energy upon impact with matter B) the electrons loses kinetic energy which is converted into the emission of an x-ray photon C) the electron converts the electron it coilildes with into an x-ray photon D) all of these

B) collision between an incoming electron and an electron in an inner shell of the target atom

Bremsstrahlung radiation does not include which type of electron activity: A) collision between an incoming electron and the nucleus of the target atom B) collision between an incoming electron and an electron in an inner shell of the target atom C) slowing down of an incoming electron due to the effect of passing close to the positive charge of the nucleus of the target atom D) all of these

A) it has an high atomic number an a high melting point

Which of the following is the reason why tungsten is used as the target material on the tube anode: A) it has an high atomic number an a high melting point B) it has an low atomic number and a high melting point C) it has an high atomic number and an a low melting point D) it has an low atomic number and a low melting point

C) many more x-rays are produce from general radiation than those from characteristic radiation

What are the many reason that the majority of x-rays used in CT are derived from general radiation and not from characteristic radiation: A) characteristic radiation introduces artifacts in the images B) general radiation is more controllable with kV and mA C) many more x-rays are produce from general radiation than those from characteristic radiation D)general radiation is bremsstrahlung which constitutes a cleaner form of x-ray

B) the collision of the electron beam with the tungsten target on the tube anode

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

C) the mA

The number of electrons that flow from the cathode to the anode in the tube is controlled by: A) the kV B)the anode target C) the mA D) none of these

D) allof these

The continuous slip ring: A)prevents the high voltage from winding up B) allows the exam to commence more rapidly C) prevents the reversal of rotation of the gantry frame D) all of these

D) collimator

Which of the following is not a part of the CT tube: A)filament B) tungsten target C) rotating anode D) collomator

B) are relatively insensitive to scatter

Xenon detectors: A)are airtight because xenon oxidizes easily upon exposure to air B)are relatively insensitive to scatter C)can be used in fouth-generation systems D)all of these

D) analog-to-digital converter

Which system component converts the projection attenuation data into the proper digital form for the arry processor: A)photodiode B)detector C)host computer D)analog-to-digital converter

D) all of these

X-ray photons are produced by the following: A) fast-moving electron colliding with an atomic nucleus B)a fast-moving electron passing close to an atomic nucleus C) a fast moving electron colloding with an electron within an atom and ejection it D)all of these

D) all of these

Which of the following is true regarding solid state detectors: A)x-ray photons cause the detectors to generate a flash of light B) the detector material is more sensitive to scatter than xenon C) they can be used in both third- generation and fourth-generation CT systems D) all of these

A) the quantity of x-ray photons

The mA determines: A) the quantity of x-ray photons B)the energy level of the x-ray photons C) the coefficient of attenuation D) none of these

A) increased kV

Which of the following will increase the likelihood that a given x-ray will penetrate a material: A)increased kV B) increased mA C) increase exposure time D) all of these

B) is accomplished by physically blocking x-rays

Coillimation: A)is accomplished by electrically blocking x-rays B) is accomplished by physically blocking x-rays C)limits the low energy x-ray photons and passes the high energy photons D) none of these

B) deflection from the original trajectory of an x-ray photon through the patient

Scatter radiation is caused by: A) x-rays generated spontaneously in the ambient atmosphere B) deflection from the original trajectory of an x-ray photon through the patient C) miscalibrated detector D) none of these

C) fourth-generation has a complete ring of detectors and second-generation doesn't

Which of the following statements is true regarding the differences between 2nd & 4th generation CT scanners: A) 4th generation applies fan beam geometry and 2nd generation does not B) 4th generation uses multiple detectors & 2nd generation dose not C) fourth-generation has a complete ring of detectors and second-generation doesn't D) all of these

C) 4th generation scanners are capable of advanced scanning techniques which are impossible on 3rd generation scanners

Which of the following statements is false regarding the differences between 3rd & 4th generation CT scanner: A)the detectors in 3rd generation scanners rotate around the gantry & in 4th generation they do not rotate B) 4th generation scanners have more detectors than 3rd generation scanners C) 4th generation scanners are capable of advanced scanning techniques which are impossible on 3rd generation scanners D) 4th generation systems are limited to solid state detectors & 3rd generations systems can use only use xenon or solid state detectors

D) none of these

Which of the following is true regarding 4th generation systems: A) data acquisition is faster than on 3rd generation systems B) they are more sensitive to x-ray than 3rd generation systems C) they allow a lower x-ray dose to be administered to the patient compared to 3rd generation systems D) none of these

D) none of these

CT systems: A) are limited to normal, non-oblique transverse scanning B) cannot generate a straight coronal or sagittal image C) have no moving parts D) none of these

C) system console

Through which component are most of the commands from the technologist received: A) host computer B)array processor C) system console D) amplifier

D) all of these

The system console may include: A) monitor B)keyboard C) graphic input device(mouse) D) all of these

D) none of these

The patient table: A) may only move after each scan is completed B) remains stationary throughout the patient exam once it is initially positioned C) can never be positioned automatically by software due to safety precautions D) none of these

B) the photon is converted completely into an electron

Which of the following statements is false regarding occurrences after an x-ray photon penetrates the detector aperture: A) the photon may pass through the detector unmeasured B) the photon is converted completely into an electron C) the measured signal is enhanced by an amplifier D) all of these

B) tilting the gantry

CT images can be directly scanned in planes other than transverse by: A) post-processing software such as multi-planar reconstruction B) tilting the gantry C) changing the angle that the x-ray beam leaves the tube D) all of these

B) to generate projection views at different angles

Why does the CT tube rotate around the patient: A) to keep the tube cool B) to generate projection views at different angles C)to minimize the x-ray dose administered to the patient D) all of these

C) helps determine the size of the focal spot and the slice thickness

The cathode filament: A)lights up the tube so it can be serviced by an engineer B) focuses x-ray onto the anode target C) helps determine the size of the focal spot and the slice thickness D) none of these

B) by selecting the slice thickness

On modern CT systems, the focal spot size is usually determined: A) by kV B) by selecting the slice thickness C)by the tube current D) none of these

B) the time between the end of one scan and the start of the next scan

Tube interscan delay time refers to: A) the time required for the tube to make a complete 360° revolution about the gantry B) the time between the end of one scan and the start of the next scan C) the maximum amount of time required for the tube to cool D) none of these

D) all of these

Which of the following is true regarding collimation A) it controls the slice thickness B) it minimizes the x-ray dose to the patient C) it reduces the detection of scatter radiation D)all of these

B) convert x-ray photons to a measurable signal

The main purpose of the detector is to: A) provide additional collimation in order to reduce scatter B) convert x-ray photons to a measurable signal C) limit the x-ray dose to the patient D) amplify the measured signal

D) all of these

In order for an x-ray photon to be measured it must: A)enter the detector chamber B) be absorbed by the detector material C) be converted to a measurable event D) all of these

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