Summary

METHODS
In this study, 10 cervical cancer patients treated with HDR brachytherapy were included in the study, and the patients" simulation tomography images were used in dose calculation. The high-risk clinical target volume (HR-CTV) was contoured as the primary target volume for all patients. The rectum, bladder, and sigmoid were delineated on each CT slice for the present study. 3D treatment plans were created using TG-43 dose formalism and Varian AcurosTM BV (GBBS) dose calculation algorithm in TPS. Dose volume histograms (DVH) were utilized for analyzing the plans dosimetrically. The values of CTVref, Vref, V150%, and V200% were obtained from DVH, which was used to calculate different quality indices: Coverage Index (CI), Dose homogeneity index (DHI), Overdose index (OI), External volume index (EI), and Conformity Index (COIN). The rectum, bladder, and sigmoid D2cc values were evaluated. The statistical analysis was performed using the Wilcoxon test (p<0.05).

RESULTS
In study, it was observed that there was no statistically significant difference between the sigmoid D2cc, bladder D2cc, CTV ref, Vref, V150%, DHI, OI, EI and COIN values (p=0.386, p=0.575, p=0.092, p=0.445, p=0.074, p=0.286, p=0.306, p=0.878, p=0.721 respectively), while significant differences were found in the rectum D2cc, V200% and Coverage Index (CI) values (p=0.037, p=0.05, p=0.043, respectively).

CONCLUSION
The TG-43 algorithm seems not to take into account tissue heterogeneity, attenuation and scatter in the titanium applicator, and the effects of the patient boundary.