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Background: Delay in time to treatment initiation (TTI) is associated with worsened survival outcomes in laryngeal squamous cell carcinoma (LSCC). It is unclear whether this is due to tumor growth or an increased risk of metastatic disease., Methods: This retrospective cohort study at one academic center included patients with LSCC who underwent radiotherapy/chemoradiotherapy between 2005 and 2017. We examined the association between tumor growth rate (TGR) and survival outcomes., Results: Among 105 patients (mean age, 63.8 ± 11.1 years; 72% male), the threshold between "slow-growing" and "fast-growing" tumors was >0.036 mL/day (survival) and >0.082 mL/day (recurrence). Faster growth was associated with worse overall survival (OS) (hazard ratio, 1.97; 95% confidence interval [CI], 0.94-4.13) and increased recurrence (odds ratio, 9.10; 95% CI, 2.40-34.4)., Conclusions: TGR >0.036 mL/day during TTI was associated with decreased OS, and >0.082 mL/day was associated with increased recurrence. Tumor measurement in patients experiencing delay may identify those who could benefit from escalated therapy., (© 2024 Wiley Periodicals LLC.)

Purpose: To assess clinically relevant image quality metrics (IQMs) of helical fan beam kilovoltage (kV) fan beam computed tomography (CT)., Methods and Materials: kVCT IQMs were evaluated on an Accuray Radixact unit equipped with helical fan beam kVCT to assess the capabilities of this newly available modality. kVCT IQMs were evaluated and compared to a kVCT simulator and linear accelerator-based cone beam CTs (CBCT) using a commercial CBCT image quality phantom. kVCTs were acquired on the Accuray Radixact for all combinations of kVp and mAs in fine mode using a 440-mm field of view (FOV). Evaluated IQMs were spatial resolution, overall uniformity, subject contrast, contrast-to-noise ratio (CNR), and effective slice thickness. Imaging dose was assessed for planar kV imaging., Results: On this kVCT system spatial resolution and contrast were consistent across all settings with 0.28 ± 0.03 lp/mm and 9.8% ± 0.7% (both 95% confidence interval). CNR strongly depended on selected mode (views per rotation) and body size (mA per view) and ranged between 7.9 and 34.9. Overall uniformity was greater than 97% for all settings. Large FOV was not found to substantially affect the IQMs whereas small FOV affected IQMs due to its effect on pitch. Technique-matched CT simulator scans were comparable for uniformity and contrast, while spatial resolution was higher (0.43 ± 0.06 lp/mm), and CNR was between 4% (140 kVp) and 51% (100 kVp) lower. For kV-CBCT, spatial resolutions ranging from 0.37 to 0.44 lp/mm were achieved with comparable contrast, CNR, and uniformity to kVCT. All kVCT scans exhibit imaging artifacts due to helical acquisition. Clinical acquisitions of megavoltage (MV) CT, kV-CBCT, and kVCT on the same patient showed improved and comparable image quality of kVCT compared to MVCT and kV-CBCT, respectively., Conclusions: Helical fan beam kVCT allows for daily image guidance for localization and setup verification with comparable performance to existing kV-CBCT systems. Scan parameters must be selected carefully to maximize image quality for the desired tasks. Due to the large effective slice thicknesses for all parameter combinations, kVCT scans should not be used for simulation or planning of stereotactic procedures. Finally, improved image quality over MVCT has the potential to greatly improve manual and automated adaptive monitoring and planning., (© 2021 The Author(s).)