Final answer:
The effective focal spot is smaller on the cathode side due to the heel effect, which reduces radiation intensity. Radiation types like neutrons and alpha particles can cause significant biological damage due to secondary radiation and high ionizing power, respectively.
Step-by-step explanation:
The effective focal spot is smaller on the cathode side of an X-ray tube. Due to the heel effect, there is less radiation intensity on this side as well. The heel effect occurs because the X-ray beam's intensity is not uniform; it's higher on the side of the anode and falls off towards the cathode side due to absorption and scatter within the anode material itself. When considering radiation biology, it's important to understand that different types of radiation have different relative biological effectiveness (RBE). For example, though both neutrons and gamma rays are neutral particles with large ranges, neutrons are generally more damaging because they can cause secondary radiation. Similarly, alpha particles cause significant damage to internal anatomy if they are ingested or inhaled, because they have a high ionizing power and a short range, leading to concentrated damage.