American Registry of Radiologic Technologists (ARRT) Practice Exam

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Prepare for the American Registry of Radiologic Technologists Test with engaging quizzes and detailed explanations. Boost your test readiness with multiple-choice questions designed to enhance your knowledge and confidence.

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How does an increase in atomic number affect contrast?

It decreases contrast
It increases contrast
It has no effect on contrast
It may distort contrast

The correct answer is: It increases contrast

An increase in atomic number enhances contrast in imaging due to its effect on the absorption of X-rays. In radiographic imaging, different tissues and materials absorb X-rays to varying degrees based on their atomic number. Materials with higher atomic numbers, such as iodine or barium used in contrast studies, absorb more X-rays compared to those with lower atomic numbers, like soft tissues. This disparity in X-ray absorption creates a greater difference in the attenuation of the X-rays as they pass through various substances, resulting in a more pronounced contrast on the radiograph. The higher contrast allows for better differentiation of anatomical structures and improves the visibility of abnormalities. Thus, an increase in atomic number is directly correlated with an increase in contrast.