Assessment and validation of glottic motion using cone-beam CT and real-time cine MRI.

PURPOSE: This study aimed to assess the margin for the planning target volume (PTV) using the Van Herk formula. We then validated the proposed margin by real-time magnetic resonance imaging (MRI). METHODS: An analysis of cone-beam computed tomography (CBCT) data from early glottic cancer patients was performed to evaluate organ motion. Deformed clinical target volumes (CTV) after rigid registration were acquired using the Velocity program (Varian Medical Systems, Palo Alto, CA, USA). Systematic (Σ) and random errors (σ) were evaluated. The margin for the PTV was defined as 2.5 Σ + 0.7 σ according to the Van Herk formula. To validate this margin, we accrued healthy volunteers. Sagittal real-time cine MRI was conducted using the ViewRay system (ViewRay Inc., Oakwood Village, OH, USA). Within the obtained sagittal images, the vocal cord was delineated. The movement of the vocal cord was summed up and considered as the internal target volume (ITV). We then assessed the degree of overlap between the ITV and the PTV (vocal cord plus margins) by calculating the volume overlap ratio, represented as (ITV∩PTV)/ITV. RESULTS: CBCTs of 17 early glottic patients were analyzed. Σ and σ were 0.55 and 0.57 for left-right (LR), 0.70 and 0.60 for anterior-posterior (AP), and 1.84 and 1.04 for superior-inferior (SI), respectively. The calculated margin was 1.8 mm (LR), 2.2 mm (AP), and 5.3 mm (SI). Four healthy volunteers participated for validation. A margin of 3 mm (AP) and 5 mm (SI) was applied to the vocal cord as the PTV. The average volume overlap ratio between ITV and PTV was 0.92 (range 0.85-0.99) without swallowing and 0.77 (range 0.70-0.88) with swallowing. CONCLUSION: By evaluating organ motion by using CBCT, the margin was 1.8 (LR), 2.2 (AP), and 5.3 mm (SI). The margin acquired using CBCT fitted well in real-time cine MRI. Given that swallowing during radiotherapy can result in a substantial displacement, it is crucial to consider strategies aimed at minimizing swallowing and related motion.

Role of induction chemotherapy in advanced-stage olfactory neuroblastoma.

OBJECTIVES: To evaluate the treatment outcomes in patients with advanced-stage olfactory neuroblastoma (ONB) who received induction chemotherapy (IC). MATERIALS AND METHODS: The clinical data of 38 patients with advanced-stage ONB who received initial IC were retrospectively analyzed. The response was defined using the Response Evaluation Criteria in Solid Tumors version 1.1. Patients with complete remission or partial remission were defined as responders. RESULTS: Seventeen (44.7%) patients responded to IC. The response rate was higher in patients with high Hyams grade tumor (III/IV) compared to those with low-grade tumors (I/II) (60% vs. 22.2%, p = 0.038). Overall, the 5-year cancer-specific survival (CSS) rate was 76.0%. Among nonresponders to IC, a significant difference in 5-year CSS rates was observed between surgery with adjuvant radiotherapy (RT) (100%) versus definitive RT or chemoradiotherapy (CRT) (68.6%) (log-rank p = 0.006). However, for responders, there was no significant difference in 5-year CSS rates between surgery with adjuvant therapy (75%) and definitive RT or CRT (51.1%) (log-rank p = 0.536). When only high-grade tumors were considered among responders, the 5-year CSS rate was significantly higher in patients who received RT or CRT (51.4%) compared to those who underwent surgery with adjuvant therapy (0%) (log-rank p = 0.008). CONCLUSION: In advanced-stage ONB, RT or CRT may be preferable for high-grade tumor responding to IC. Higher response rate and a potential role for induction IC in determining the optimal definitive treatment modality suggest a positive role for advanced-stage high-grade ONB.