Axial resolution refers to the ability to distinguish two structures that are close to each other along the path of the ultrasound beam.
Spatial pulse length (SPL) is the distance over which one pulse occurs, and it directly affects axial resolution.
Shorter SPL improves axial resolution because it allows better differentiation of closely spaced structures.
The axial resolution is improved by increasing the frequency of the transducer, which shortens the wavelength and hence the SPL. Reference:
ARDMS Sonography Principles and Instrumentation guidelines on resolution parameters and their impact on image quality.

Temporal resolution refers to the ability to accurately depict moving structures over time.
A narrow sector width reduces the area being scanned, which increases the frame rate because fewer scan lines are required per frame.
Higher frame rates improve temporal resolution, allowing for better visualization of fast-moving structures.
Other factors like scan depth and the number of focal zones also affect frame rate but typically reduce it when increased, thereby decreasing temporal resolution. Reference:
ARDMS Sonography Principles and Instrumentation guidelines on factors affecting temporal resolution and frame rate.

Dynamic range in ultrasound imaging affects the number of gray shades displayed in a 2-D image. Adjusting the dynamic range changes how echo signals are mapped to grayscale. A higher dynamic range means more shades of gray are displayed, providing a more detailed and softer image, which is useful for differentiating subtle tissue textures. Conversely, a lower dynamic range increases contrast by displaying fewer shades of gray, making the image appear more black and white. This adjustment is crucial for optimizing image quality based on the specific diagnostic needs.
Reference:
American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.

The dead zone in ultrasound imaging refers to the region closest to the transducer where imaging is not possible due to the high amplitude of the initial pulse. In a tissue-mimicking phantom, this is the area where no useful imaging data can be obtained. The purpose of evaluating the dead zone is to ensure that it is as small as possible to maximize the usable imaging depth. In the provided image, Option A represents the area closest to the transducer face, which is typically used to evaluate the dead zone. The other areas are further away and are used for evaluating other parameters such as resolution or depth penetration.
Reference:
American Registry for Diagnostic Medical Sonography (ARDMS) Sonography Principles and Instrumentation guidelines.

The quality factor (Q-factor) is a dimensionless parameter that describes the efficiency of the transducer in terms of bandwidth and operating frequency. It is defined as the ratio of the operating frequency to the bandwidth. A higher Q-factor indicates a narrower bandwidth relative to the operating frequency, resulting in more precise frequency characteristics but potentially reduced axial resolution. Conversely, a lower Q-factor indicates a broader bandwidth, which improves axial resolution but may result in less precise frequency characteristics.
Reference:
ARDMS Sonography Principles & Instrumentation Guidelines
Kremkau FW. Sonography Principles and Instruments. 9th ed. Philadelphia, PA: Elsevier; 2016.