Chapter 12 2D Imaging

When one element in a linear sequential array is damaged, it means that only the specific element is affected. In the context of an image, this means that only the portion of the image directly below the damaged element will be affected. The rest of the image remains intact and unaffected by the damage to that particular element. Therefore, the statement is true.

A mechanical transducer is a device that converts one form of energy into another, such as sound waves into electrical signals. In the context of the question, when a mechanical transducer is used to create an image, it typically produces a fan or sector-shaped image. This is because the transducer emits sound waves in a specific pattern, which then bounce off objects and return to the transducer. By analyzing the pattern of the returning sound waves, an image can be formed. The fan or sector shape refers to the scanning pattern of the transducer, which allows it to capture a wide area of the object being imaged. Therefore, the statement that the image created by a mechanical transducer is fan or sector-shaped is true.

If the PZT crystal in the mechanical transducer is damaged, the entire image is lost. The PZT crystal is responsible for generating the ultrasound waves in the transducer. These waves are then used to create the image. If the crystal is damaged, it cannot produce the necessary waves, resulting in the loss of the entire image.

The statement is suggesting that if the curvilinear array is damaged, only a portion of the image will be affected. This implies that the damage does not completely disrupt the functionality of the array, but rather causes a localized impact. Therefore, the answer is true.

The given correct answer is true because a trapezoidal image is a common term used in computer graphics to describe an image that has a shape similar to a trapezoid. This suggests that the vector array being referred to in the question has a trapezoidal shape.

The linear sequential transducer produces a rectangular-shaped image. This type of transducer is commonly used in ultrasound imaging to create a linear array of sound waves that can be used to generate a two-dimensional image. The rectangular shape of the image allows for a wider field of view and better visualization of structures that are longer or wider in shape.

A linear sequential array refers to a type of imaging technology that produces an image by scanning a linear array of pixels. In this case, the array has a 10cm footprint, meaning it covers a physical area of 10cm. The statement says that although this array can produce an image that is 8cm wide, it cannot produce an image wider than 10cm. This is because the array's physical size limits the width of the image it can produce. Therefore, the statement is true.

In a convex sequential array, the crystals are fired in a sequential manner but not all of them are fired at once. This means that only some of the crystals are fired while the others remain unfired. Therefore, the statement "some but not all crystals are fired" is true in the context of a convex sequential array.

Mechanical steering is used in mechanical beam steering to create the scan plane. This means that the movement and adjustment of the beam direction is achieved through mechanical means, such as the use of motors, gears, or other mechanical components. This allows for precise control and manipulation of the scan plane in the desired direction. In contrast, electronic steering would involve the use of electronic components and signals to control the beam direction, which is not the case here.

Mechanical transducers have a fixed focal depth, meaning that they are designed to focus sound waves at a specific depth within the body. This fixed focal depth allows for accurate imaging and targeting of specific areas during medical procedures. Unlike other types of transducers, mechanical transducers cannot be adjusted to change the focal depth. Therefore, the statement that mechanical transducers have a fixed focal depth is true.

Mechanical transducers use both internal and external focusing methods of fixed focusing. Internal focusing involves adjusting the position of the transducer elements to focus the beam at a specific depth within the body. External focusing, on the other hand, involves using a lens or acoustic mirror to focus the beam at a specific depth. By using both internal and external focusing methods, mechanical transducers can achieve precise and adjustable focusing for optimal imaging quality.

The correct answer is "elements". In the context of the given question, an array refers to a single slab of PZT (a type of material) that is cut into separate pieces. These individual pieces are known as elements.

A channel is a combination of an active element, wire, and system electronics. The active element is responsible for generating or detecting the signal, the wire is used to transmit the signal, and the system electronics process and amplify the signal. This combination allows for the transmission and manipulation of signals in various electronic systems.

The statement is true because the beam is indeed steered and focused using an electrical technique called phasing. This technique involves adjusting the timing and amplitude of the electrical signals sent to the different elements of the beam-steering system, allowing for precise control over the direction and focus of the beam. By manipulating the phase of the signals, the beam can be directed towards a specific target or focused to a desired point.

The statement is true because a phased array is a system of antennas that work together to create a beam of radio waves that can be electronically steered in different directions. This means that the focus of the beam can be adjusted or changed, allowing for multiple focuses or directions of transmission. Therefore, a phased array is indeed "adjustable" or "multi-focus" in nature.

The sound beam is focused when the spike line in a linear phased array is curved because the curved shape allows for the sound waves to converge at a specific point. This curvature helps to concentrate the sound energy and create a sharper, more focused beam. In contrast, a straight spike line would result in a broader beam with less concentration of energy. Therefore, the statement is true.

The active elements of annular array transducers appear as disc-shaped.

In convex array transducers, focusing is achieved electronically. This means that the transducer uses electronic signals to control the timing and intensity of the ultrasound waves emitted. By adjusting these parameters, the transducer can focus the ultrasound beams at a specific depth within the body. This electronic focusing allows for improved image resolution and clarity, as well as the ability to visualize structures at different depths. Mechanically focusing, on the other hand, would involve physically adjusting the position or shape of the transducer to achieve the desired focus, which is not the case in convex array transducers.

A mechanical transducer is a device that converts one form of mechanical energy into another. In this case, the correct answer is "disc shaped". This means that the mechanical transducer has a shape similar to that of a disc, which is round and flat. This shape is commonly used in transducers such as speakers or microphones, where the disc shape allows for efficient conversion of mechanical vibrations into electrical signals or vice versa. The disc shape also helps in focusing and directing the mechanical energy in a specific direction, enhancing the performance of the transducer.

The correct answer is "motor" because the question is asking about how the 2-dimensional image is built up. It suggests that the crystal is rotated with something, and the most logical and common device used to rotate objects is a motor. Therefore, a motor is needed to rotate the crystal and create the 2-dimensional image.

A linear phased array is a type of antenna array used in communication systems. It is designed to steer the radiation pattern of the antenna by adjusting the phase of the signals in each element. The elements of a linear phased array are typically spaced at intervals that are a fraction of the wavelength of the signal being transmitted or received. In this case, the correct answer is 1/4 to 1/2 of the sound's wavelength, which means that the elements of the linear phased array should be spaced at intervals that are between one-fourth and one-half of the wavelength of the sound signal. This spacing allows for effective beamforming and control of the radiation pattern.

In a linear phased array probe, all the active elements are fired simultaneously to create each sound beam. This means that all the elements in the probe emit sound waves at the same time, resulting in a focused beam of ultrasound. This allows for better resolution and imaging capabilities compared to other types of probes where only a single element is fired at a time. Therefore, the statement is true.

The explanation for the given correct answer is that in a linear phased array, the curved pattern of the array elements allows for the creation of a focused sound beam. By adjusting the timing and amplitude of the signals sent to each element in the array, the sound waves can be steered and focused in a specific direction. This focused sound beam is beneficial in applications such as medical imaging, where precise targeting of the sound waves is necessary for accurate diagnosis.

With linear sequential arrays, not all of the crystals are fired simultaneously to create each sound beam. This means that only some of the crystals are activated at a time to produce the desired sound beam. This technique allows for more control and flexibility in directing the sound beams, as different combinations of activated crystals can be used to create different beam patterns. Therefore, the statement "with linear seq. arrays, some but not all of the crystals are fired simultaneously to create each sound beam" is true.

Linear sequential array transducers can steer sound beams electronically. This is possible because these transducers consist of multiple small transducer elements that can be individually activated and controlled. By adjusting the timing and amplitude of the electrical signals sent to each element, the transducer can focus and steer the sound beam in different directions. This electronic steering capability allows for improved imaging and targeting in medical ultrasound applications.

In a convex array, each crystal is about 1 wavelength in width. This means that the distance between the highest and lowest points of the crystal is approximately equal to the length of one complete wave. This width is important because it allows the convex array to effectively transmit and receive ultrasound waves, as the crystal size matches the wavelength of the ultrasound waves being used.

they contain multiple active elements

The correct answer is 100-300. This range indicates that the linear phased array can contain anywhere between 100 to 300 crystals. The exact number of crystals will vary depending on the specific array and its design requirements.

The statement is true because a linear phased array consists of elements that are rectangular and narrow in shape. This configuration allows for precise control of the direction and beamwidth of the array's radiation pattern. The rectangular shape helps in achieving a uniform distribution of energy in the desired direction, while the narrow width ensures a focused and narrow beam. Therefore, the given answer is true.

The mechanical transducer holds only one crystal.

The image created by a phased array transducer is fan or sector shaped because a phased array transducer uses multiple small elements to steer and focus the ultrasound beam. By adjusting the timing and amplitude of each element, the transducer can create a beam that is electronically steered in a specific direction. This allows for the creation of a fan or sector shaped image, which is useful for visualizing structures in a specific area of interest.

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When PZT (lead zirconate titanate) crystals in a linear phased array are damaged, it can lead to inconsistent or erratic beam steering. Phased array systems use PZT crystals to control the direction of the ultrasound beam. If these crystals are damaged, they may not be able to accurately steer the beam, causing it to behave inconsistently or erratically. This can result in poor image quality and difficulty in obtaining clear and reliable ultrasound images.

When one ring of an annular phased array is damaged, only a portion of the image is lost. This is because an annular phased array consists of multiple rings of transducers that work together to create an image. Each ring contributes to a specific portion of the image, so if one ring is damaged, only the corresponding portion of the image will be affected. The remaining rings will still function and contribute to the overall image formation.

each crystal is 1 wavelength of width

The correct answer is "blunted sector shaped". A convex array transducer is a type of ultrasound probe that is used for imaging internal organs. It is designed with a curved surface that allows for a wider field of view. The blunted sector shape refers to the rounded or curved shape of the transducer head, which helps to improve image quality and reduce artifacts. This shape is ideal for obtaining clear images of structures that are deep within the body, such as the liver or heart.

The correct answer is 120-250. This means that the vector array has a range of 120 to 250 crystals.

The statement is true because with a mechanical transducer, the PZT crystal is physically moved to create the image. This means that the crystal is physically displaced or vibrated to generate sound waves, which then bounce off the tissues and create an image. This is in contrast to other types of transducers, such as electronic transducers, where the crystal is not physically moved but rather uses electrical signals to create the image.

When the spike line is straight in a linear phased array, it indicates that the sound beam is unfocused. This means that the sound waves are not concentrated at a specific point and instead spread out over a larger area. This can be useful in certain applications where a wide coverage is needed, such as in ultrasound imaging. Therefore, the statement that an unfocused sound beam is created in a linear phased array when the spike line is straight is true.

The annular phased array contains more than one crystal. This means that there are multiple crystals present in the annular phased array.

Apodization is a process that can be used to reduce the strength of the side and grating lobes. Apodization involves applying a weighting function to the elements of an array to taper the amplitude of the array's response. This tapering reduces the sidelobes and grating lobes, resulting in improved performance and resolution of the array.

The statement is true because in a phased array scanner, multiple active elements are fired simultaneously, or very close in time, in order to generate and control a focused beam of ultrasound. This allows for improved image quality and the ability to steer and focus the beam electronically without physically moving the transducer.

Mechanical scanning is a technique used in ultrasound imaging where a transducer is physically moved to produce images. Linear phased array is another technique where multiple small transducers are used to create images by electronically steering and focusing the ultrasound beam. Both techniques produce images that are similar in shape, as they both capture images in a linear fashion. Therefore, the statement that mechanical scanning produces pictures that are similar in shape to linear phased array images is true.

Annular phased array transducers use mechanical steering. This means that the transducer is physically moved or rotated to change the direction of the ultrasound beam. Mechanical steering allows for a wider range of steering angles and greater flexibility in focusing the beam. Electronic steering, on the other hand, involves electronically manipulating the timing and phase of the individual elements in the transducer to steer the beam. However, annular phased array transducers typically rely on mechanical movement for steering.

The face of a linear phased array is about 1cm on each side. This means that the array is relatively small in size, with each side measuring approximately 1cm. The size of the array is important as it determines the beamwidth and directivity of the antenna. A larger array would result in a narrower beam and higher directivity, while a smaller array would have a wider beam and lower directivity. Therefore, a linear phased array with a 1cm face size would have a relatively wider beam and lower directivity compared to larger arrays.

A convex array can have anywhere from 120 to 250 crystals.

A vector array is a combination of linear sequential and linear phased array. This means that the vector array consists of elements arranged in a linear sequential manner, where each element is connected to the next in a straight line. Additionally, the vector array also incorporates linear phased array technology, which involves adjusting the phase of the signals emitted by each element to create specific beam patterns and steer the direction of the transmitted or received signals.

The statement suggests that many active elements fire at almost the same time in a mechanical scanner. However, this is not true. In a mechanical scanner, active elements such as sensors or motors operate sequentially rather than simultaneously. They are designed to move or capture information one at a time, ensuring the accuracy and efficiency of the scanning process. Therefore, the correct answer is false.

Multiple pulses can overcome the difficulties of two-dimensional images because they provide a more comprehensive and detailed representation. Two-dimensional images often lack depth and can be limited in capturing complex information. By using multiple pulses, more data can be collected and analyzed, allowing for a more accurate and complete representation of the image. This approach helps to overcome the limitations of two-dimensional images and provides a more robust and informative result.

The linear seq. array carries a range of crystals between 120 and 250.