Brachytherapy Seed Placement by Robotic Bronchoscopy with Cone Beam Computed Tomography Guidance for Peripheral Lung...

This study evaluates the feasibility of using robotic-assisted bronchoscopy with cone beam computed tomography (RB-CBCT) platform to perform low-dose-rate brachytherapy (LDR-BT) implants in a mechanically ventilated human cadaveric model. Postimplant dosimetry was compared with standard stereotactic body radiation therapy (SBRT) plans.

The RB-CBCT platform was used to place inert LDR-BT seeds into mechanically ventilated human cadavers with percutaneously injected pseudotumors. LDR-BT dosimetry plans were created a priori with a prescription dose of 100 Gy to the pseudotumor plus a 3-mm margin to define a planning target volume. Implant quality was assessed by postimplant dosimetry and seed placement accuracy. BT dosimetry was compared with standard SBRT treatment plans for the same cadaveric tumor volumes.

Eight pseudotumors were planned with a total of 41 LDR-BT seeds, with a median of 5 seeds to achieve appropriate target coverage. All 41 LDR-BT seeds were successfully implanted in the 8 pseudotumors using RB-CBCT. On postimplant analysis, the average (± SD) dosimetry to the pseudotumor was a V95% of 99.4% ± 3.3% and D90% of 128 ± 23 Gy. The average distance between the planned and delivered seed location was 3.8 ± 1.1 mm. In comparison with SBRT plans, LDR-BT dose conformity was superior for the ratio of the V50% to the volume of the planning target volume (2.3-4.0, P < .001) and V25% (5.0 vs 17.5, P < .001).

RB-CBCT may be a feasible technology for implantation of LDR-BT seeds in peripheral lung tumors and can achieve preplanned dosimetry goals with better dose conformity than SBRT. Further clinical studies are indicated to demonstrate the safety and efficacy of LDR-BT delivered by RB-CBCT for treating early-stage lung cancer.