What is attenuation correction in PET CT?

This loss of detection of true coincidence events is called attenuation. … It is lower in the body surface than deep in the body, low in lungs, and especially high in dense tissues such as bones, leading to severe artifacts in PET image, unless it is corrected during image reconstruction.

How does attenuation affect an image?

Attenuation in ultrasound is the reduction in amplitude of the ultrasound beam as a function of distance through the imaging medium. Accounting for attenuation effects in ultrasound is important because a reduced signal amplitude can affect the quality of the image produced.