Beam-Hardening Artifact - Video Lesson

Welcome back. This CT artifact lesson is about beam hardening. So the hardness of the x-ray beam just refers to the average energy of the x-ray photons. And so beam hardening refers to an increase in the average energy. So here's how beam hardening artifact works. It's caused by an excessive amount of x-ray absorption by very dense materials in the body. And so the beam is literally hardened or increased in energy. Beam hardening then looks like streaks extending from those dense materials in the body. The image on the left is actually a very good example of the traditional appearance of beam hardening. This patient was shot in the face with a shotgun, so there's several little metal pellets inside of the face. These very dense pellets have a excessively absorbed or attenuated the X-ray beam. This confuses the CT processing algorithms and it results in the streaks that you see on the image. And the patient doesn't have to get shot in the face to cause beam hardening artifacts