CAMRT Radiography Practice Exam

In CT imaging, increasing the window level affects which aspect of the image?

1. Brightness

2. Contrast

3. Sharpness

4. Noise

The correct answer is: Brightness

In CT imaging, adjusting the window level primarily affects the brightness of the displayed image. The window level determines the center of the range of Hounsfield units that are displayed on the grayscale. When the window level is increased, the image will appear brighter because the average density of the tissues within that range is raised, thus illuminating structures that correspond to higher Hounsfield values. For example, if the window level is set to a higher value, tissues such as fat may become less visible because they fall below the threshold of brightness that the higher setting displays prominently. Conversely, tissues with higher attenuation such as bone may appear even brighter. Understanding how the window level impacts brightness is crucial for optimizing image interpretation, allowing radiologists to distinguish between different types of tissues based on their density. While other factors in imaging such as contrast can also be adjusted via window width, it is the window level that directly correlates with the perceived brightness of the image.