American Society of Radiologic Technologist (ASRT) Practice Exam

The spatial resolution of a detector is controlled by which factor?

1. Sampling frequency

2. Matrix size

3. Milliampere-seconds (mAs)

4. Analog-to-digital converter (ADC)

The correct answer is: Sampling frequency

The spatial resolution of a detector is primarily influenced by the sampling frequency. Sampling frequency refers to how often the continuous data from a detector is sampled to create a digital image. Higher sampling frequencies lead to a more detailed representation of the image, allowing for improved spatial resolution. This means that the ability to distinguish small structures within the image is enhanced because more data points are captured within a given area. While matrix size, milliampere-seconds (mAs), and the analog-to-digital converter (ADC) can also influence image quality, they do not directly control spatial resolution in the same way that sampling frequency does. For instance, a larger matrix size can improve spatial resolution up to a certain point, but it still depends on the sampling frequency used to fill that matrix. Similarly, mAs affects image density and exposure but has less direct impact on the granularity of spatial details. The ADC plays a role in converting analog signals to digital signals but is not the primary factor controlling spatial resolution.