CT Registry Review May 13,2010

The operator's console may include a monitor, keyboard, and a graphic input device. These components are commonly found in an operator's console as they are essential for monitoring and controlling various systems or processes. The monitor allows the operator to view important information or data, the keyboard enables input and interaction with the system, and the graphic input device can be used for tasks such as drawing or manipulating graphical elements. Therefore, all three options - 1, 2, and 3 - are correct.

Digital subtraction angiography (DSA) is a medical imaging technique used to visualize blood vessels. It involves the injection of contrast material into the blood vessels and the use of digital image processing to subtract the background structures, resulting in a clearer visualization of the blood vessels. CT, CAT-scan, and computed tomography are all different names for the same imaging technique, which uses X-rays and computer processing to create detailed cross-sectional images of the body. Therefore, the correct answer is digital subtraction angiography, as it is not a commonly used name for CT.

The analog-to-digital converter is the system component that converts the projection attenuation data into the proper digital form for the array processor. This conversion is necessary because the array processor can only process digital data, while the projection attenuation data is in analog form. The analog-to-digital converter takes the analog signal from the detector or photodiode and converts it into a digital signal that can be processed by the array processor.

A PACS system, or Picture Archiving and Communication System, is primarily used for the storage, retrieval, distribution, and display of medical images. It allows for long term data storage, digital distribution of images, and image display for radiologists. However, the reconstruction of the image from the raw data is not a function of a PACS system. This process typically occurs before the image is stored in the system and involves converting the raw data captured by the imaging modality into a visual image that can be interpreted by radiologists.

The operator has control over the energy level and the quantity of x-rays in a CT exam. This means that they can adjust the strength and amount of x-rays used during the exam, allowing for customization based on the specific needs of each patient.

Scatter radiation is caused by deflections from the original trajectory of an x-ray photon through the patient. When an x-ray beam passes through the patient's body, it interacts with the tissues and can change direction, resulting in scatter radiation. This occurs when the x-ray photons collide with atoms in the patient's body and change their path. Scatter radiation is undesirable as it can reduce image quality and increase radiation dose to the patient and medical staff. Proper shielding and positioning techniques are used to minimize scatter radiation.

CT image data can be stored on internal hard disks, CDs, and re-writable optical disks. Internal hard disks are commonly used for storing large amounts of data, including CT image data. CDs can also be used as a storage medium for CT image data, providing a portable and easily accessible option. Re-writable optical disks offer the advantage of being able to write and rewrite data, making them suitable for storing and updating CT image data. Therefore, all three options, 1, 2, and 3, are correct.

The mA (milliamperage) determines the quantity of x-ray photons produced during an X-ray examination. The higher the mA setting, the more photons are produced, resulting in a higher quantity of X-rays. This is because mA controls the amount of electrical current passing through the X-ray tube, which in turn affects the number of X-ray photons generated. Therefore, the correct answer is the quantity of x-ray photons.

The detector's main purpose is to capture x-ray photons and convert them to a measurable signal. This is important because it allows for the creation of digital images that can be analyzed and interpreted by medical professionals. By capturing the x-ray photons, the detector enables the visualization of internal structures and abnormalities in the patient's body. The conversion of the photons into a measurable signal ensures that the information can be accurately recorded and analyzed.

The slip ring on continuous rotation CT scanners serves multiple purposes. Firstly, it prevents the high voltage cable from winding up, which could lead to damage or tangling. Secondly, it allows the exam to commence more rapidly by providing a continuous flow of power and data transmission without the need for interruptions or pauses. Lastly, it eliminates the need for the reversal of gantry frame rotation, as the slip ring enables the transfer of power and data between the stationary and rotating parts of the scanner. Therefore, all three options - 1, 2, and 3 - are correct.

The electron beam CT does not use an x-ray tube. Instead, it uses an electron gun to produce a high-energy electron beam that is focused onto a tungsten target. This target then emits x-rays, which are used for imaging. In contrast, the other options mentioned - first-generation CT, PET/CT, and MDCT - all use an x-ray tube as part of their design.

The tube interscan delay time refers to the time between the end of one scan and the start of the next scan during which the tube will cool. This is important because the X-ray tube can generate a significant amount of heat during a scan, and it needs time to cool down before the next scan can be performed. If the tube is not given enough time to cool, it can overheat and potentially malfunction, leading to poor image quality or damage to the equipment. Therefore, it is necessary to have a specific delay time to ensure the proper functioning and longevity of the X-ray tube.

Tungsten is used as the target material on the tube's anode because it has a high atomic number and a high melting point. The high atomic number of tungsten allows it to efficiently produce X-rays when bombarded with high-energy electrons. Additionally, the high melting point of tungsten ensures that it can withstand the heat generated during the X-ray production process without melting or deforming.

Solid state detectors are able to generate a flash of light when exposed to x-ray photons, making statement 1 true. These detectors are commonly used in most CT scanners today, making statement 2 true. Additionally, solid state detectors can be utilized in both third-generation and fourth-generation CT systems, making statement 3 true. Therefore, the correct answer is 1, 2, & 3.

X-rays are used in CT because they have the ability to penetrate the body based on the specific attenuation characteristics of each tissue. This means that different tissues in the body absorb and scatter X-rays to different extents, allowing for detailed imaging of internal structures. The other options provided in the question do not accurately explain why X-rays are used in CT.

A collimator is not a part of the CT tube. The CT tube consists of a tungsten target, rotating anode, and a filament. The tungsten target is where the x-rays are produced, the rotating anode helps dissipate heat generated during the x-ray production, and the filament is responsible for heating the target. However, a collimator is a separate component that is used to narrow down and shape the x-ray beam before it reaches the patient. It is not directly part of the CT tube itself.

Multi-row detector CT scanners have the capability to vary the size of the detector arrays along the z-direction, which means that the size of the detectors can differ. Additionally, these scanners can combine the attenuation information from adjacent detector arrays to generate thicker slices, allowing for better image quality. Lastly, multi-row detector CT scanners have the flexibility to choose whether to use all of the detector arrays or not, depending on the specific imaging requirements. Therefore, all three statements are true regarding multi-row detector CT scanners.

A pixel is a single 2D picture element within the image plane. It is the smallest unit of a digital image and represents a specific color or intensity value at a particular location. Pixels are arranged in a grid formation to create the overall image.

The number of electrons that flow from the cathode to the anode in the tube is controlled by the mA (milliamperage) setting. mA determines the amount of current flowing through the tube, which directly affects the number of electrons emitted from the cathode. Increasing the mA setting will result in more electrons being emitted, while decreasing the mA setting will reduce the number of electrons. Therefore, mA is responsible for controlling the electron flow in the tube.

The array processor is not normally located in the gantry of a modern CT system. The gantry typically contains components such as the pre-patient collimators, solid-state detectors, and x-ray tube. The pre-patient collimators help shape and control the X-ray beam, the solid-state detectors capture the X-ray signals and convert them into electrical signals, and the X-ray tube generates the X-ray beam. The array processor, on the other hand, is usually located outside the gantry and is responsible for processing the captured data to create the final CT images.

The correct answer is the operator's console. The operator's console is where most of the commands from the technologist are received. This is the central control point where the technologist can input commands and monitor the system. It allows the technologist to interact with the equipment and make necessary adjustments or changes as needed. The operator's console is an essential component in managing and controlling the system efficiently.

The pencil in this context refers to a narrow beam of x-rays emitted by the x-ray fan beam. When this beam strikes a single detector, it is referred to as a "ray." A ray is a straight line that represents the path along which the x-rays travel from the source to the detector. Therefore, the correct answer is "ray."

The vast majority of this energy is emitted as heat while a relatively small amount of this energy is converted to x-ray production.

The correct answer is 3 only. A localizer scan uses only a single projection. This means that it captures a single image or slice of the body at a time, allowing for a more focused and localized view. In contrast, a conventional or serial scan captures multiple projections or slices in a sequential manner, while a helical scan captures a continuous spiral of images or slices. Therefore, only a localizer scan uses a single projection.

Bones may have to be edited from the data set to get a diagnostic MIP of a CTA exam. This is because bones can obstruct the visualization of blood vessels and other structures of interest in the scan. By editing out the bones from the data set, a maximum intensity projection (MIP) can be created that focuses solely on the vessels of interest, allowing for a clearer and more accurate diagnostic assessment.

The correct answer is 3 only. In CT scans, the actual attenuation data measured by the detectors from all projections is contained in the raw data. This raw data is then processed to generate images using techniques such as convolution. Therefore, option 1 (image) and option 2 (convolved) are incorrect as they refer to processed data rather than the original raw data.

Continuous rotation scanners made helical imaging possible. Helical imaging is a technique in computed tomography (CT) where the X-ray tube and detector continuously rotate around the patient, while the patient is moved through the scanner. This allows for the acquisition of volumetric data without the need for multiple stops and starts. Continuous rotation scanners provide a more efficient and faster scanning process, resulting in improved image quality and reduced patient discomfort. The introduction of continuous rotation scanners revolutionized CT imaging and made helical imaging a standard technique in modern CT scanners.

Collimation on a single-row detector scanner serves multiple purposes. Firstly, it controls the slice thickness, allowing for the adjustment of the width of the X-ray beam and consequently influencing the thickness of the image slices produced. Secondly, collimation helps minimize the X-ray dose to the patient by limiting the amount of radiation exposure to the areas outside the targeted region. Lastly, it reduces the detection of scatter radiation, which can lead to image degradation and inaccuracies. Therefore, all three options, 1, 2, and 3, are correct.

The given answer states that all three statements are true. Statement 1 is true because in order to process and analyze the electrical signal obtained from the detector, it needs to be converted into a digital format. Statement 2 is true because digital CT images are indeed numerical representations of cross-sectional anatomy, allowing for easier manipulation and analysis. Statement 3 is true because digital signals can be formed by sampling analog signals at discrete time intervals, which is a common method of converting analog signals into digital form.

The correct answer is 1 & 2 because statement 1 correctly states that kV is the voltage potential between the tube cathode and anode while mA controls the filament current and temperature of the cathode filament. Statement 2 is also true as it states that kV controls the energy level of the x-ray photons and mA controls the number of x-ray photons emitted from the tube. Both statements accurately describe the roles of kV and mA in the operation of the x-ray tube.

Multi-row detector scanners employ third-generation technology. This technology refers to the use of multiple rows of detectors in the scanner, allowing for faster and more accurate imaging. Compared to first and second-generation scanners, third-generation scanners provide better image quality and reduced radiation exposure. Fourth-generation scanners, on the other hand, use a different technology called stationary detectors, which are not applicable to multi-row detector scanners. Therefore, the correct answer is third-generation.

X-ray photons are produced by a fast-moving electron through all of the given processes. When the electron collides with an atomic nucleus (option 1), it can produce X-ray photons. Similarly, when the electron passes close to an atomic nucleus (option 2), it can also produce X-ray photons. Additionally, when the electron collides with an electron within an atom and ejects it (option 3), X-ray photons can be generated. Therefore, all three options are correct and contribute to the production of X-ray photons.

CT systems are not limited to non-oblique transverse scanning, as they can also perform oblique scanning. They can generate straight coronal or sagittal images, so statement 2 is false. Additionally, CT systems do have moving parts, such as the gantry and the table, so statement 3 is also false. Therefore, the correct answer is 1, 2, and 3.

Filtered back projection is the mathematical process used by single-row detector scanners to reconstruct CT images from raw data. This technique involves filtering the raw data and then back projecting it to form the final image. It is a common and widely used method in CT imaging that helps to reduce artifacts and improve image quality.

Xenon detectors and fourth-generation technology are NOT commonly used on today's commercially available CT scanners.

Increasing the kilovolt (kV) will increase the likelihood that a given x-ray will penetrate a material. This is because the kilovolt determines the energy of the x-ray beam. Higher energy x-rays have more penetrating power and can pass through materials more easily.

Collimation is a process that involves physically blocking x-rays. It is not achieved through electrical means or by affecting the scan time. Instead, collimation limits the low energy x-ray photons and allows only the high energy photons to pass through. This helps to improve the quality and accuracy of the imaging by reducing scatter radiation and enhancing the clarity of the image.

The CT x-ray tube rotates around the patient to generate projection views at different angles. This allows for a comprehensive and detailed image of the patient's anatomy to be created. By capturing images from different angles, the CT scan provides a three-dimensional representation of the patient's body, aiding in the diagnosis and treatment of various medical conditions. The rotation of the x-ray tube also helps to minimize artifacts and improve image quality.

A helical study does not offer the best image quality for a brain exam. Although a helical study has advantages such as minimal anatomical misregistration, shorter exam time, and the ability to reconstruct a slice at any position, it does not necessarily provide the best image quality specifically for a brain exam. Other imaging techniques or studies may be more suitable for obtaining high-quality brain images.

Stacked transverse images from a helical scan can generate the most diagnostic multiplanar reconstructions because a helical scan captures continuous data along the z-axis, allowing for reconstructions in multiple planes. This means that the images can be reconstructed in sagittal, coronal, and oblique planes, providing a more comprehensive view of the anatomy. On the other hand, stacked transverse images from a conventional, serial scan and stacked localizer images may not capture continuous data along the z-axis, limiting the ability to generate accurate multiplanar reconstructions.

Both a localizer scan and a conventional, serial CT scan produce digital images. This means that the images are captured and stored in a digital format, allowing for easy manipulation, analysis, and sharing of the images. Digital images also have the advantage of being easily accessible and can be viewed on various devices without the need for physical film or prints.

A retrospective reconstruction, in which the reconstruction field-of-view is varied, uses CT raw data. This means that the reconstruction process involves using the original raw data obtained from the CT scan. By varying the reconstruction field-of-view, different sections of the raw data can be selected and reconstructed into different images, such as the sagittal plane. This allows for flexibility in the reconstruction process and enables the creation of images from specific perspectives or regions of interest.

The multi-row detector scanner design was the first to acquire four slices in a single rotation. This means that the scanner was able to capture multiple images or slices of the body in just one rotation, improving efficiency and reducing scanning time. This advancement in technology allowed for faster and more accurate diagnoses, making it a significant milestone in the evolution of CT scanners.

CT images can be directly scanned in planes other than transverse by orienting the patient's body part so that it is not perpendicular to the x-ray beam and tilting the gantry. By adjusting the position of the patient's body part and the gantry, the CT scanner can capture images in different planes, such as sagittal or coronal, instead of just transverse. This allows for a more comprehensive evaluation of the anatomy and enhances the diagnostic capabilities of the CT scan.

Filtered back projection is the only option that utilizes convolution. Convolution is a mathematical operation that combines two functions to produce a third function. In the case of filtered back projection, it is used to reconstruct an image from its projections. Fourier transform is a mathematical technique used for signal processing and frequency analysis, while 3D SSD (Single Shot MultiBox Detector) is an object detection algorithm that does not directly involve convolution.

An Akernal is a filter applied to the CT raw data. It is used to enhance and improve the quality of the CT images by reducing noise and artifacts. The Akernal filter helps to remove unwanted information and improve the clarity and sharpness of the images. It is an essential step in the image reconstruction process of a CT scan.

3D shaded surface displays are performed on CT image data only. This means that the process of creating a 3D shaded surface display is done using the image data obtained from a CT scan. The raw data and attenuation profiles are not involved in this specific process.

Using a smooth reconstruction filter would decrease the appearance of noise in a CT image. This is because a smooth filter helps to average out the noise and create a more uniform image. A sharp filter, on the other hand, would enhance the noise and make it more prominent. Therefore, option 3 only is the correct answer.

The cathode filament helps determine the size of the focal spot. The focal spot size is an important characteristic of an x-ray tube as it directly affects the image quality. The filament heats up and emits electrons, which are then accelerated towards the anode target. The size of the filament and the current passing through it determine the number of electrons emitted, which in turn affects the size of the focal spot. A smaller filament and lower current result in a smaller focal spot, leading to improved spatial resolution in the x-ray image.

The correct answer is that the volume data, from which the 3D SSD is generated, is not created by combining transverse, sagittal, and coronal reconstructions. This statement is false because the volume data for 3D SSD is actually created by stacking multiple 2D slices together, rather than combining different types of reconstructions.