American Registry of Radiologic Technologists (ARRT) Practice Exam

What is indicated by an increase in contrast during an X-ray examination?

1. Fewer gray tones

2. Many shades of gray

3. Increased patient movement

4. Decreased radiation exposure

The correct answer is: Fewer gray tones

An increase in contrast during an X-ray examination indicates fewer gray tones in the resulting image. This means that the image will exhibit a more pronounced difference between the light and dark areas, leading to a clearer distinction between various anatomical structures. High contrast is often achieved by optimizing the X-ray settings or using specific contrast agents that enhance differences in tissue density, resulting in more defined borders and details. This is essential in radiology, as it allows for easier interpretation of the images. For instance, a high-contrast image is particularly useful for detecting bony structures or delineating between different types of tissues, particularly in instances where subtle variations need to be highlighted. In contrast, having many shades of gray generally corresponds to lower image contrast, where the distinctions between different tissues or structures are less clear. Increased patient movement can also lead to blurring of the image rather than an increase in contrast. Additionally, while decreased radiation exposure might be a result of various factors in X-ray technique, it does not specifically correlate with increased image contrast.