What refers to the effect of radiation dose being applied before and after the intended volume in CT imaging?

The phenomenon where radiation dose is applied before and after the intended volume in CT imaging is known as over-ranging. This effect occurs during the process of acquiring images, as the CT scanner needs to account for potential motion and ensure that the entire area of interest is adequately captured. The over-ranging mechanism helps to ensure that critical diagnostic information at the boundaries of the intended imaging area is included, which might be particularly significant in situations where precise anatomical boundaries are essential for diagnosis or treatment planning.

In practical terms, over-ranging can lead to slightly increased radiation exposure because the scanner irradiates additional tissue beyond the specific area of interest. This practice is important for maximizing diagnostic accuracy, as it prevents areas that might be important for diagnosis from being inadvertently omitted from the final images. By understanding over-ranging, technologists can better appreciate how CT imaging parameters and scanning protocols can impact both image quality and radiation dose.