Why choose -175 and 250 as a_min and a_max?

[qimaqi]

Hi there I am wondering why the a_min and a_max values for ScaleIntensityRanged in train.py are set to -175 and 250. The normal range for intensity is typically -1000 to 1000. Is there a specific reason for this setup? It seems that using these parameters clips out many values?

[ljwztc]

The range is specifically designed for the abdominal area. The answer from gpt may help you understand this: In CT imaging, different tissues and substances have characteristic HU values. For example:

• Air: around -1000 HU
• Lung: around -500 HU
• Fat: around -100 to -50 HU
• Soft tissues (e.g., muscle, liver): around 0 to 100 HU
• Bone: 700 HU and above By focusing on the range from -175 to 250 HU, we can enhance the visualization and analysis of soft tissues, which are often the primary areas of interest in many diagnostic scenarios.