How is the anode heel effect observed on a radiographic image?

The correct answer illustrates the concept of the anode heel effect, which describes how x-ray intensity varies across the radiographic image due to the geometry of the x-ray tube. In this phenomenon, the anode side of the tube has a lower intensity of x-rays compared to the cathode side because x-rays emitted by the target undergo differential absorption as they pass through the anode material. As a result, when imaging body parts, the area that is positioned over the anode will appear lighter on the radiograph, while the area over the cathode will appear darker. This leads to a variation in density across the image, highlighting the anode heel effect.

Understanding this effect is crucial for radiographers as it can help in positioning the patient and choosing the correct exposure techniques to ensure optimal image quality. It is particularly significant in chest radiography and other examinations where the thickness and density of the structures being imaged can significantly influence the final image.