KEY POINTS
- The study evaluated a semi-automated workflow called structure- and template-assisted multi-dose-level planning, or STAMP, in 30 previously treated patients receiving interstitial gynecologic high-dose-rate brachytherapy. The cohort included 20 cervical, six endometrial, and four vaginal cancers.
- All patients had received pelvic external-beam radiotherapy, usually 45 Gy in 25 fractions or 50.4 Gy in 28 fractions. Median brachytherapy prescription was 26 Gy in four fractions to the high-risk clinical target volume, while 19 patients also received a separate intermediate-risk prescription.
- STAMP automatically created optimization target volumes by expanding each target by 10 mm and subtracting overlapping organs at risk. Candidate dwell positions were then restricted to a combined dwell-activation volume before applying standardized VEGO inverse-planning objectives.
- High-risk target coverage was essentially identical: median D90 was 99.9% for both clinical and STAMP plans (p = 0.99). For the intermediate-risk target, all STAMP plans achieved D90 of at least 100%, whereas three of 19 clinical plans did not.
- Organ-at-risk doses were slightly lower with STAMP but not statistically different. Median total bladder D2cc was 76.6 versus 79.2 Gy EQD2, rectum 65.0 versus 66.6 Gy, sigmoid 61.5 versus 62.3 Gy, and bowel 52.5 versus 52.4 Gy.
- Both approaches met all EMBRACE I hard constraints. Fewer STAMP plans missed EMBRACE II soft limits for the bladder, rectum, and sigmoid, although the differences were small and largely reflected implant geometry rather than optimization alone.
- Mean normalized dwell time was similar at 228 seconds with STAMP versus 235 seconds clinically (p = 0.57). The workflow redistributed loading toward peripheral needles in some cases, reducing heavy central-needle loading and improving dose conformity around the target.
- Median STAMP planning time was 10 minutes, with a range of 7–12 minutes and a median of three optimization iterations. Representative manual cases required a median of 28 minutes, but this was a descriptive comparison using different cases rather than a controlled paired timing study.
CLINICAL TAKEAWAY
STAMP offers a practical way to standardize complex multi-dose-level interstitial brachytherapy planning and reduce dependence on individual planner experience. The dosimetric results support local implementation after commissioning, but the apparent time saving requires prospective paired validation across other applicators, planning systems, and institutions.