Patient-Specific quality control applicator in gynecological Brachytherapy: Design, Production, and dosimetric...

This study aims to design and manufacture a novel Multi-Channel Vaginal Cylinder (MCVC) applicator capable of performing patient-specific quality control. The applicability and dosimetric performance of the applicator were evaluated.

Several tests were conducted to assess the water equivalence of the designed applicator in terms of Hounsfield Units (HU), structural homogeneity, and dose transmission for ¹⁹²Ir relative to water. Dosimetric evaluations were performed using calibrated thermoluminescent dosimeters (TLDs) to determine the clinical usability of the applicator. No patients were involved in the dosimetric tests; all measurements were conducted in a water phantom.

According to the HU examination results of the designed and manufactured applicator, it was ascertained that the structure was homogeneous, and the results obtained in terms of water equivalence were superior in comparison to those achieved by the Nucletron applicator. In the present study, average dose differences of + 1.26% (ranging from + 4.99% to -1.73%) and + 0.04% (ranging from + 3.00% to -3.64%) were observed when the ¹⁹²Ir conversion coefficient was applied and not applied, respectively, in the dose comparisons performed using the specially designed and manufactured applicator.

This study introduces a clinically applicable MCVC applicator compatible with TLDs for gynecological high-dose-rate (HDR) brachytherapy, enabling accurate pre-treatment and in vivo dose verification. The results support routine use of TLD based patient-specific quality assurance (PSQA) and highlight the need for more precise electronic dosimetry systems.