Normal Liver Tissue Density Dose Response in Patients Treated With Stereotactic Body Radiation Therapy for Liver Metastases
- Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado (United States)
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 ({Delta}HU) 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 {Delta}HU/5 Gy). The threshold for significant change (-7 {Delta}HU) 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.
- OSTI ID:
- 22149617
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 3 Vol. 84; ISSN IOBPD3; ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
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