KEY POINTS
- This technical study developed a 3D-printable external irradiation jig using eight catheters connected to a clinical iridium-192 high-dose-rate brachytherapy afterloader. A dose of 500 cGy was prescribed to a flank tumor without interstitial source placement.
- Radiochromic film measurements were generally within approximately 5% of treatment-planning calculations. Optically stimulated luminescent dosimeter measurements differed by approximately 13%–16%, partly reflecting localization uncertainty within the phantom.
- Monte Carlo simulations estimated a mean tumor dose of 670 ± 70 cGy and confirmed dose uniformity within approximately ±10%. The simulated mean dose was 12.4% higher than the collapsed-cone calculation and 8.9% higher than the TG-43 calculation.
- The pilot in vivo study included five irradiated and five unirradiated mice bearing subcutaneous HEC-1A tumors. Tumor growth was significantly lower after irradiation (p<0.0001) and was 49.3% lower than in controls at 19 days.
- No observable radiation-induced toxicity was reported during 19 days of follow-up. One irradiated animal was excluded from the tumor-growth analysis after early euthanasia for anomalous tumor progression.
CLINICAL TAKEAWAY
The platform may provide laboratories with access to a clinical high-dose-rate afterloader an adaptable method for non-invasive external irradiation of small-animal tumors. However, the evidence is limited to a small pilot cohort, one tumor model, short follow-up, and appreciable dosimetric uncertainty, making this technically relevant rather than broadly validated.