Velocity ai v 3

Our institutional database was retrospectively reviewed for patients with OPC who were treated at The University of Texas MD Anderson Cancer Center (Houston, TX) from 2005 to 2013 after institutional review board approval. Eligible patients who were diagnosed with OPC that was pathologically confirmed by either a biopsy or a surgical excision and who received their treatment on a curative intent were eligible. All patients with OPC were nonsurgically managed with radio-therapy with or without systemic therapy either in neoadjuvant or concurrent settings. Demographic, clinical, toxicity, and outcome data were collected for these patients.
For imaging data, contrast-enhanced CT scans at initial diagnosis before any active local or systemic treatment were retrieved to our commercially available contouring software (Velocity AI v3.0.1; Varian Medical Systems, Palo Alto, CA). The volumes of interest, including the gross primary tumor volumes, were manually segmented by a radiation oncologist in three-dimensional fashion and then inspected by a second radiation oncologist. The generated volumes of interest and CT images were exported in the format of DICOM and DICOM-RTSTRUCT to be used for radiomics features extraction.

All included patients had two sets of pretreatment CT scans available for review and analysis of volumetric data. The first CT scan was either done at an outside hospital for diagnostic and/or staging purposes or done at MD Anderson for diagnostic reasons. The second CT scan was performed after at least 2 weeks at our institution for diagnosis, staging, or radiotherapy planning. PET-CT scans were included, and segmentation was guided by PET if available. Volumetric data was collected using VelocityAI v.3.01 commercial software (Varian Medical Systems, Atlanta, GA) to segment primary tumor and significant nodal targets on both scans. Tumor volumes were initially measured by a medical student, and subsequently reviewed by two radiation oncologist with expertise assessing tumors of the head and neck (ASRM, CDF). Linear TGV and nodal growth velocity were calculated from the serial measurements as percentage tumor growth per days as illustrated in the following equation:
$$\left[\raisebox{1ex}{$\frac{\text{Tumor volume at time point }2-\text{Tumor volume at time point }1}{\text{Tumor volume at time point }1}$}\!\left/ \!\raisebox{-1ex}{$\text{duration between both scans in days}$}\right.\right]\times 100$$
Additionally, volumetric tumor doubling time was calculated as described by Mordecai Schwartz^{15 (link)}:
$$t_D=\frac{t\mathrm{log }2}{{\log }^{V_t}/V_0}$$
Where t_D is volumetric doubling time, t is time gap between the two scans, V_t is tumor volume at time point 2, and V₀ is tumor volume at baseline.