Related Experiment Video
Updated: May 21, 2026
Treatment of Liver Metastases Using an Internal Target Volume Method for Stereotactic Body Radiotherapy
Published on: May 8, 2018
Normal liver tissue density dose response in patients treated with stereotactic body radiation therapy for liver
Christopher C Howells1, Michelle A Stinauer, Quentin Diot
1Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
Purpose:
To evaluate the temporal dose response of normal liver tissue for patients with liver metastases treated with stereotactic body radiation therapy (SBRT).
Methods And Materials:
Ninety-nine noncontrast follow-up computed tomography (CT) scans of 34 patients who received SBRT between 2004 and 2011 were retrospectively analyzed at a median of 8 months post-SBRT (range, 0.7-36 months). SBRT-induced normal liver tissue density changes in follow-up CT scans were evaluated at 2, 6, 10, 15, and 27 months. The dose distributions from planning CTs were mapped to follow-up CTs to relate the mean Hounsfield unit change (ΔHU) to dose received over the range 0-55 Gy in 3-5 fractions. An absolute density change of 7 HU was considered a significant radiographic change in normal liver tissue.
Results:
Increasing radiation dose was linearly correlated with lower post-SBRT liver tissue density (slope, -0.65 ΔHU/5 Gy). The threshold for significant change (-7 ΔHU) was observed in the range of 30-35 Gy. This effect did not vary significantly over the time intervals evaluated.
Conclusions:
SBRT induces a dose-dependent and relatively time-independent hypodense radiation reaction within normal liver tissue that is characterized by a decrease of >7 HU in liver density for doses >30-35 Gy.
