ESTRO 2024 - Abstract Book

S354

Beachytherapy - Physics

ESTRO 2024

Figure 1. Dose difference in EQD 2 between IFO and FFO treatment methods for HR-CTV and OARs.

The results of the two sided signed-rank Wilcoxon test do not show significant dosimetric differences between both methods for HR-CTV and OARs (Table 1). The median (interquartile range) of the difference in applicator angle concerning the first fraction was 3.6 (4.8) degrees, with the maximum difference being 12.6 degrees. However, for the FFO method, the results of the Spearman test indicate that no statistically significant correlation was found between applicator angle insertion and inter-fractional dosimetric differences (Table 1).

Table 1. Statistical results of two tailed Wilcoxon signed-rank test (W: sum of ranks) and Spearman test (ρ s : Spearman correlation coefficient). P-value level set at 0.005 for statistical significance.

Regarding time management, considering the simulation, contouring, and treatment planning processes, it has been determined that the adoption of the FFO method would result in a time saving of one hour per fraction treatment for all the medical staff involved.

Conclusion:

No significant dosimetric differences were found between the application of FFO method compared to IFO method, in the context of using a single-channel vaginal cylinder and the fixation system employed in our center. The minor dosimetric discrepancies observed are primarily attributed to anatomical variations in internal organs between different fractions. Consequently, clinical implementation of FFO method in the endometrial cancer treatment is considered feasible, improving hospital resource management through the reduction of CT machine time, decreased patient radiation exposure in each CT scan and the optimization of medical staff time.

Keywords: cylinder, vaginal brachytherapy