Reporting of dose-volume specifications for "Martinez Universal Perineal Interstitial Template-based interstitial high-dose-rate brachytherapy for gynecological cancers" according to International Commission on Radiation Units and Measurements 58 with early clinical outcomes.

Purpose: The study is an audit of reporting dose and volume specifications as per the ICRU 58 for MUPIT-based interstitial brachytherapy in gynecological cancers. Correlation between total reference air kerma (TRAK) and isodose surface was also evaluated to understand the intensity of treatment in interstitial brachytherapy.

Methods And Materials: Forty-two patients underwent HDR MUPIT-based interstitial brachytherapy 20 Gy in five fractions after EBRT during 2017-2019. Treated volume, high and low-dose regions, mean central dose, Dose Homogeneity Index (DHI), organ at risk doses, and TRAK values were computed.

Results: High-dose regions V150 mean was 12.4 cc and V200 was 4.58 cc; and low-dose region was 75.92 cc. The mean treated volume was 59.8 cc. The mean central dose was 3.7 Gy. DHI was 79%. The mean D2cm bladder and rectum were 2.9 Gy and 2.8 Gy. The mean TRAK was 0.16 cGy per fraction per hour at 1 m. TRAK values showed significant correlation with various isodose volumes (TRAK and V100: r = 0.943 p < 0.0005; and TRAK and V50: r = 0.953; p < 0.0005). A positive correlation was observed between TRAK and the number of needles (r = 0.746; p < 0.0005). At a median followup of 16 months, 4 of 42 patients (9.5%) had local recurrences.

Conclusions: Our study shows compliance with ICRU 58 recommendations along with certain deviations. Local recurrence rate is acceptable. TRAK shows correlation with surface isodose in MUPIT-based brachytherapy and should to be evaluated in future studies.