Dosimetric impact of cylinder size in high-dose rate vaginal cuff brachytherapy (VCBT) for primary endometrial cancer.

Dosimetric impact of cylinder size in high-dose rate vaginal cuff brachytherapy (VCBT) for primary endometrial cancer. J Appl Clin Med Phys. 2016;17(5):6182 Authors: Zhang H, Gopalakrishnan M, Lee P, Kang Z, Sathiaseelan V Abstract The purpose of this study was to evaluate the dosimetric impact of cylinder size in high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT). Sample plans of HDR VCBT in a list of cylinders ranging from 2.5 to 4 cm in diameter at 0.5 cm incre-ment were created and analyzed. The doses were prescribed either at the 0.5cm depth with 5.5 Gy for 4 fractions or at the cylinder surface with 8.8 Gy for 4 frac-tions, in various treatment lengths. A 0.5 cm shell volume called PTV_Eval was contoured for each plan and served as the target volume for dosimetric evaluation. The cumulative and differential dose volume histograms (c-DVH and d-DVH), mean doses (D-mean) and the doses covering 90% (D90), 10% (D10), and 5% (D5) of PTV_Eval were calculated. In the 0.5 cm depth regimen, the DVH curves were found to have shifted toward the lower dose zone when a larger cylinder was used, but in the surface regimen the DVH curves shifted toward the higher dose zone as the cylinder size increased. The D-means of the both regimens were between 6.9 and 7.8 Gy and dependent on the cylinder size but independent of the treatment length. A 0.5 cm variation of diameter could result in a 4% change of D-mean. Average D90s were 5.7 (ranging f...
Source: Journal of Applied Clinical Medical Physics - Category: Physics Authors: Tags: J Appl Clin Med Phys Source Type: research