The goal of this retrospective observational study is to investigate the safety of radiation therapy for liver malignancies by analyzing data from patients who have already completed this treatment . The main questions it aims to answer are:

What is the specific radiation dose level that leads to a visible change on CT scans called a Focal Liver Reaction (FLR)? Why do some patients develop these imaging changes while others do not, based on their scan features and clinical information? Researchers will compare patients who developed FLR with those who did not to identify the factors associated with this reaction.

This study uses existing medical records and images; therefore, participants will not need to undergo any new interventions or procedures.

Inclusion Criteria:

• Primary or secondary liver malignancies, including hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), and secondary liver tumors.
• Liver function of Child-Pugh classification A or B.
• Completed EBRT treatment as planned.
• No other local treatment of liver lesions between EBRT and the follow-up imaging examination.
• Complete imaging re-examination data.
• Three-phase enhancement CT scans showing typical Focal Liver Reaction (FLR).
• The registration effect of follow-up CT and planning CT is satisfactory.

Exclusion Criteria:

• History of upper abdominal radiotherapy or liver transplantation.
• Failure to complete radiotherapy as scheduled.
• Previous cancer treatment-related toxicities that did not return to baseline or grade 0-1 (except for hair loss and peripheral neuropathy).

Adult patients (≥18 years) with primary or metastatic liver malignancies who received liver radiotherapy (e.g., SBRT or IMRT) at the Third Xiangya Hospital of Central South University between July 2015 and September 2024 , and had complete dosimetric data and follow-up CT imaging available for retrospective analysis.