GPP02 Presentation Time: 9:09 AM

Purpose

The adoption of IGABT is limited in LMIC. This could be from lack of training in contouring, evaluation of volumetric plan and access to MRI. In most of the centres CT scan was routinely done for at least one fraction with applicator in situ but dose to target and OAR was still reported and optimized to points. MRI was seldom done at any point during course of radiation and brachytherapy schedule was 3-4 fractions performed weekly prolonging total treatment duration to be more than 55 days.

Methods

Live and virtual workshop was performed over 1.5 days for hands on training with both physicians and physicists from all sites in December 2022. Workshop focused on use of sonogram for placement of applicator, CT scan-based contouring and planning with volumetric dose constraints, 3D MRI with T2 sequence whenever feasible, and use of hybrid applicator when available. First day was discussion on guidelines, contouring and data followed by hands on contouring of 3 cases on CT scan by all physicians. On second day entire workflow was demonstrated with live case with use of ultrasound, placement of hybrid applicator, contouring on CT scan and MRI and planning with clinical goals. Later most of the physicians were asked to perform IGBT procedure in the presence of an expert or a fellow physician practicing IGBT at their centre in this network. All participants were asked to share anonymized data for analyses of practice pattern after the workshop. The data was collected after 13 months from the initial workshop.

Results

Eleven out of 15 physicians from 6 sites agreed to share their dosimetry and early outcome data. All 11 physicians transitioned from point A to volume-based planning and treated 257 consecutive patients with IGBT (CT based 85% and MRI based 15%). 76% had MRI pelvis done before brachytherapy as part of workup. The commonest EBRT dose schedule was 45 in 25 fraction (60%) and HDR schedule was 21-28 Gy in 3-4 fraction (95%). For those who had EBRT in the network 97.2% received EBRT dose of 45 Gy in 25 fractions and HDR Schedule of 28 Gy in 4 fractions. Majority had intracavitary alone (86%) while 14% used hybrid applicator. Median D90 for HRCTV and D2cc for rectum, bladder, sigmoid and small bowel were 80.8Gy (79.28-85.05 Gy), 62.18Gy (57.5-66.8Gy), 63.87Gy (582-72Gy), 61.2 Gy (55.5-68.6Gy) and 55.1 Gy (45-63.6Gy) respectively. Overall treatment time was ≤ 50 days and ≤55 days for 64.9 % and 78.9% respectively for all patients and 72.2% and 88.9% for patients who received EBRT plus brachy at same location. The first follow up between 3-6 months was available for 148 patients and 138 (93.9%) had clinical and/or metabolic complete response.

Conclusion

This workshop model of Identifying baseline practice pattern with education and training focused on specific quality aspect of RT delivery showed significant changes with adoption of IGBT, use of MRI and reduction of overall treatment time. The transition from point based to CT/MRI based IGBT was with high adherence to clinical goals and excellent early response.