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Dose-function Histogram Evaluation Using 99mTc-GSA SPECT/CT Images for Stereotactic Body Radiation Therapy Planning for Hepatocellular Carcinoma Patients: A Dosimetric Parameter Comparison.

BACKGROUND/AIM
We evaluated the influence of previous treatments on the parametric discrepancies between dose-volume histograms (DVHs) and dose-function histograms (DFHs) generated based on 99mTc-GSA SPECT images of hepatocellular carcinoma (HCC) patients treated with stereotactic body radiation therapy (SBRT).


PATIENTS AND METHODS
Twelve patients underwent SBRT at 30-40 Gy. Registration between planning CT and SPECT/CT images was performed, and DFH parameters were calculated as follows: Fx=(sum of the counts within the liver volume receiving a dose of more than x Gy/sum of the counts within the whole liver volume) ×100. The discrepancy between Fx and Vx (Dx) was also calculated.


RESULTS
The number of previous treatments for lesions other than SBRT-treated lesions (≥2 vs. <2) exhibited a significant influence on the absolute values of D10, D15, and D20 (p<0.05).


CONCLUSION
Previous treatment significantly influences the parametric discrepancy between DFH and DVH.