CAMRT Radiography Practice Exam

How is the x-ray tube in a mammography unit positioned to take advantage of the anode heel effect?

1. The cathode end is closer to the chest wall

2. The anode end is closer to the chest wall

3. The tube is perpendicular to the breast

4. The tube is angled away from the chest wall

The correct answer is: The cathode end is closer to the chest wall

The positioning of the x-ray tube in a mammography unit to take advantage of the anode heel effect is based on the arrangement of the cathode and anode within the x-ray tube. When the cathode end is placed closer to the chest wall, it ensures that the more intense radiation emitted from the cathode side is directed towards the area of interest, which is the lesion or abnormality within the breast tissue. The anode heel effect refers to the phenomenon where there is a variation in x-ray intensity across the field due to the geometry of the x-ray tube. The x-ray beam is stronger on the cathode side and weaker on the anode side. When the cathode is positioned closer to the chest wall, the denser tissue located there receives more adequate exposure, enhancing image quality and contrast for adequate assessment. This positioning is particularly important in mammography, where differentiation between various tissue densities can be critical for accurate diagnosis. By leveraging the anode heel effect, radiographers can achieve improved imaging of breast tissue, particularly in areas where the density differences are most relevant for detection purposes.