FREE Computed Tomography (CT) Questions and Answers

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X-rays of the body are captured from various angles during computed tomography (CT), which produces images that resemble 2- and 3-dimensional slices (cross-sections). All jewelry and metal objects, such as zippers and belt buckles close to the body portion being scanned, should be taken off by anyone getting a CT scan. Why are patients asked to remove metal before a CT scan?

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The objects could obstruct the X-rays and cause visual blur. However, they do not present a threat.

What is the purpose of a CT scout image?

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A CT scout image is a low-dose X-ray image used to estimate the size of the patient and determine the appropriate scanning parameters before the actual CT scan.

What part of the CT gantry measures photons that are transmitted and pass through the patient?

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The gantry of the CT unit has detectors. They gauge the transmitted photons from the X-ray tube that traverse the patient. By measuring attenuation, they turn the photons into electrical impulses. An X-ray photon must enter the detector, collide with the detection atom, and cause a quantifiable event of electricity or light to produce a signal. A very modest electrical signal from the detectors' detectable light or energy must be processed by the data acquisition system (DAS) before it can be amplified and converted into a real CT image. CT scanners from the first generation only have one detector. A linear detector array, or a collection of sensors arranged in a straight line, is a feature of second-generation scanners. The multiple detector array along a curve with full circular detector rotation is a feature of third-generation scanners. A rotating fan beam is contained within a fixed ring of detectors in fourth-generation scanners. With the advent of multi-row detector scanners, or MDCT, it was possible to gather data for each tube rotation from many anatomical slices. This enabled thinner slices, faster scans, and greater anatomical coverage. Third-generation technology is used by MDCT, which has several parallel detector arrays.

In CT imaging, what is a "Hounsfield Unit" (HU) a measure of?

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Hounsfield Units (HU) are used to quantify the density of tissues in CT images. Water is assigned a value of 0 HU, and other substances are assigned values relative to that.

Which type of CT scan is specifically designed for imaging the coronary arteries and assessing heart health?

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Cardiac CT is a specialized type of CT scan used to image the coronary arteries and assess the health of the heart.

For what group have weight-based CT protocols with color-coding been established to help lower patient doses?

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The effects of ionizing radiation are especially noticeable in the pediatric population. CT makers and radiology experts created color-coded weight-based procedure selections to help lower the radiation dose received by the pediatric population during each CT test. Thanks to these color-coded protocols, the technologist will be able to choose a protocol with specific technical parameters for a patient's size and weight.

Which type of contrast medium is often used in CT imaging to enhance visualization of blood vessels and other structures?

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Iodine-based contrast agents are commonly used in CT imaging to enhance the visibility of blood vessels and other structures due to their ability to absorb X-rays.

What does the term "slice thickness" refer to in CT imaging?

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Slice thickness in CT imaging refers to the spacing between consecutive image slices. It determines the level of detail and resolution in the resulting images.

A radiopaque contrast agent, a material that can be seen on X-rays to aid in identifying one tissue from another, may be administered to patients before a CT scan. Which of the following contrast agents is used with CT the most frequently?

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Iodine is the contrast material used in CT. Contrast agents in other imaging procedures, like magnetic resonance imaging and ultrasonography, offer other alternatives.

Which component of a CT scanner rotates around the patient during image acquisition?

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The gantry is the part of the CT scanner that houses the X-ray tube and the detector array. It rotates around the patient during the imaging process.

Which of the following is an advantage of CT over conventional X-ray imaging?

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CT provides better soft tissue contrast compared to conventional X-ray imaging, making it useful for visualizing various structures within the body.

Using CT and a radiopaque contrast agent, CT angiography creates 2- and 3-dimensional pictures of blood vessels to look for anomalies. Which of the following statements most accurately describes why CT angiography is frequently employed instead of traditional angiography?

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The CT angiography procedure is less intrusive and risky than traditional angiography because it only involves the insertion of a catheter into a vein rather than an artery.

What procedure results in a more monochromatic beam and lowers patient radiation exposure by reducing the longest wavelength photons?

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A polychromatic beam can become monochromatic with the aid of filtering. The highest energy or longest wavelengths are reduced. As a result, the radiation dose to the patient is decreased without significantly affecting the signal being monitored. The remaining X-rays are less susceptible to beam hardening and the artifacts it produces.

Which CT imaging technique provides detailed information about blood flow and perfusion in tissues?

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Perfusion CT is a technique used to assess blood flow and perfusion in tissues. It involves tracking the passage of contrast material through blood vessels to evaluate tissue viability.

What kind of detector is used now that is both effective and popular?

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The solid-state crystalline detector is the most prevalent and effective variety. The photon strikes the crystalline sensor after passing through the patient. The crystals transform the energy into light, which is then converted into an electrical signal. The xenon gas detector is an alternative sort of detector. These are ineffective and are used sparingly today. The xenon gas is ionized when an X-ray beam strikes the xenon gas detector. Ions move to areas with a positive charge, charge plates, and produce electricity. The crystalline sensors have been used in constructing all previous multi-row detectors and all new detector systems.

What is the fundamental principle behind Computed Tomography (CT) imaging?

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CT imaging is based on the principle of X-ray absorption by different tissues in the body. It uses X-rays to create cross-sectional images of the body's internal structures.

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