Example Simulations One electron producing 3 photons A single high-energy electron is simulated passing through a vacuum region, where few collisions occur. The electron path curls because a magnetic field is present. Here a single collision turns one particle into four. Here the program simulated a low-energy beam of electrons crossing the boundary from air to uniform tissue. Only electron paths are shown, the many photon paths are calculated but not drawn.
Many collisions cause the electrons to wander and eventually to stop.
Imagine how complicated things can get when intense radiation beams pass through dense matter such as bones in the human body. Each particle can collide many times and each new collision requires a calculation and results in more particles to track. To solve this problem, the EGS4 program was adapted to apply to medical physics - to figure out how particles will behave inside the human body.