American Registry of Radiologic Technologists (ARRT) Practice Exam

In electronic imaging, changes in brightness or density are primarily controlled by window level adjustments. The window level refers to the midpoint of the range of pixel values that are displayed within the image. When the window level is adjusted, it modifies the brightness of the image by shifting the range of values that are assigned to the grayscale, impacting how light or dark the image appears.

For instance, increasing the window level will make the image appear brighter, while decreasing it will darken the image. This adjustment is crucial for enhancing specific structures or areas within the image that may otherwise be too dark or too light to analyze effectively. Thus, understanding window level is essential for optimizing image quality and achieving the desired diagnostic outcome.

Window width affects the contrast of the image rather than its brightness directly. Image matrix size refers to the dimensions of the pixel grid in the image and influences resolution, but not brightness directly. Spatial resolution pertains to the detail and sharpness of the image, which is separate from the concepts of brightness or density; therefore, it does not influence brightness changes in the same way window level does.