원문정보
초록
영어
To improve accuracy of dose calculation on kilovoltage cone beam computed tomography (kV CBCT) images, a custom-made phantom was fabricated to acquire an accurate CT number to electron density curve by full scatter of cone beam x-ray. To evaluate the dosimetric accuracy, 9 volumetric modulated arc therapy (VMAT) plans for head and neck (HN) cancer and 9 VMAT plans for lung cancer were generated with an anthropomorphic phantom. Both CT and CBCT images of the anthropomorphic phantom were acquired and dose-volumetric parameters on the CT images with CT density curve (CTCT), CBCT images with CT density curve (CBCTCT) and CBCT images with CBCT density curve (CBCTCBCT) were calculated for each VMAT plan. The differences between CTCT vs. CBCTCT were similar to those between CTCT vs. CBCTCBCT for HN VMAT plans. However, the differences between CTCT vs. CBCTCT were larger than those between CTCT vs. CBCTCBCT for lung VMAT plans. Especially, the differences in D98% and D95% of lung target volume were statistically significant (4.7% vs. 0.8% with p = 0.033 for D98% and 4.8% vs. 0.5% with p = 0.030 for D95%). In order to calculate dose distributions accurately on the CBCT images, CBCT density curve generated with full scatter condition should be used especially for dose calculations in the region of large inhomogeneity.
목차
1. INTRODUCTION
2. MATERIALS AND METHODS
2.1 Electron density vs. CT number
2.2 Generation of VMAT plans
2.3 Calculation of dose-volumetric parameters
2.4 Data analysis
3. RESULTS
3.1 Mass density and electron density vs. CT numbers
3.2 Changes in dose-volumetric parameters of headand neck VMAT plans
3.3 Changes in dose-volumetric parameters of lung VMAT plans
4. DISCUSSION
5. Conclusion
REFERENCES