Dicom image pixel value (grayscale value) converted to CT value

The Unit of CT value is Hounsfield, referred to as Hu, the range is-1024-3071. It is used to measure the absorption rate of X-rays in human tissues, and to set the water absorption rate at 0Hu.

In the dicom image reading process, we will find that the pixel value of the image may not be this range, usually 0-4096, which is the pixel value we often see or grayscale value, which requires us to the image pixel value (gray value) into the CT value.

First, you need to read two dicom tag information (0028|1052): Rescale Intercept and (0028|1053): Rescale slope.

Then pass the formula:

Hu = pixel * slope + intercept

The computed CT values are obtained.

Dicom image pixel value (grayscale value) converted to CT value