CAMRT Radiography Practice Exam

If the main tissue of interest is the lung tissue for a CT exam, which would be the most appropriate window level setting?

1. 50

2. 0 or the level of water

3. -600

4. 400

The correct answer is: -600

In CT imaging, the window level settings are essential for optimizing the visualization of different tissues based on their density. For lung tissue, which is primarily composed of air and has a low density, the most appropriate window level setting would be around -600 Hounsfield units (HU). Setting the window level to -600 is advantageous because it enhances the contrast of aerated structures while suppressing the appearance of surrounding high-density tissues like bones and soft tissues. This level effectively allows radiologists to observe subtle differences in attenuation within the lung fields, such as those seen in various pathologies like pneumonia, emphysema, or lung nodules. Other levels such as 50 or 0 are not suitable for lung imaging because they are centered around higher densities, which would not provide a clear view of air-filled structures. Likewise, a window level of 400 is more appropriate for evaluating soft tissue as it is still too high to accentuate the low-density characteristics of lung tissue. Therefore, selecting -600 as the window level allows for the best delineation and assessment of lung pathology, making it the optimal choice for this examination.