Flowgy Documentation

Everything you need to know about Flowgy to extraordinarily improve medical diagnosis and nasal surgery.

FLOWGY — the power of medical efficiency
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Flowgy is not yet certified for clinical use and is intended for research. Permissions and compliance with applicable regulations are the responsibility of the user.

CT Display

Point Tracking System

Real-time synchronization of the three anatomical visualization planes (coronal, sagittal and axial).

Synchronizing the segmented image

Synchronized display of the segmented image, which comes from the CT scan, with the original CT scan.

Scanning and pre-analysis of DICOM files

Automatic scanning of local directories to find studies in DICOM files in order to selection, preview and upload to Flowgy.

X, Y, Z coordinate tracking on the images

Synchronized tracking of mouse pointer position in the three anatomical views.

Brightness and Contrast

Manual adjustment of the brightness and contrast in the CT images to make them easier to display.

2D and 3D files formats

Flowgy supports among others the following file formats: DICOM, NRRD, JPG, PNG, TIFF, STL, OBJ...


Snapshot of each of the 3 anatomical views and save to hard disk in JPG or similar image format.

Segmentation & Virtual Surgery

Automatic sinus recognition

Flowgy automatically and selectively identifies and removes sinuses.

Automatic segmentation

Segmentation algorithms are applied automatically to the CT scan.

Filters on segmentation

Filters allow the user to modify the results of the segmentation to meet their requirements.

Segmentation importation

Flowgy supports segmentations made by other segmentation software for virtual surgery and airflow analysis.


All the CT scans are automatically readjusted in order to maintain the aspect ratio and increase their quality and definition.

2D Surgery Brush Tool

The user chooses the size of the scalpel with which, by moving the mouse over each CT image, the inside of the shape of the scalpel is transformed into either solid material or air, according to the user's selection. The resulting material/air can be synchronized with a previously generated virtual surgical 3D model.

2D Surgery Polyline Tool

The user can define closed/opened polylines with whatever number of points is required. These polylines can be applied to other CT images. At the same time, a spline is generated according to the point of distribution of the polyline. The inside/outside of the polylines, or its associated splines, can be filled with solid material or air.

2D Surgery Contour Polyline Tool

By creating a minimum number of polylines, Flowgy automatically generates a set of polylines in the remaining CT images. This is done by interpolation. The according set of polylines will be used to create the deformable surfaces that will be described on a later date.

Virtual 3D Surface Surgery

Selection of the diameter of the scalpel with which, by moving the mouse over the surface of the three-dimensional model, a pre-selected number of layers are removed.

Volumetric 3D Virtual Surgery

Selection of the shape and size of a three-dimensional scalpel which, once positioned on the 3D model, allows its interior to be filled with solid/air.

3D–2D Synchronization

3D virtual surgery (surface or volumetric) synchronized with CT images and vice versa. In such a way that all virtual surgery performed in the 3D model will be updated and shown in real time in the 2D model and vice versa.

Virtual surgery by means of 2D and 3D Surface Deformation

By means of the selection of polylines (generated in a nearly automatic way) a 3D surface is generated that can be deformed, thus allowing to perform a virtual surgery by means of the deformation of 3D surfaces.

Creation/Deletion of Material

Removal and/or creation of solid/air material by means of a variety of methods 2D or 3D virtual surgery.

Visualization planes

Flowgy allows us to define visualization planes in the 3D model, which will allow us to access the visibility of the interior of the 3D model in a much easier and more comfortable way.

Measurement tools

Measurements of distances, areas and volumes on the 3D models.

Virtual surgery on other 3D formats

3D virtual surgery on STL or similar models (without the need to previous  transform to a DICOM or similar).


Flowgy allows the generation of structures, in addition to the default ones (Solid and Air) in order to block them or use them as references. Using this method, a new selection can be created and a new type of structure can be assigned to it, so that only that structure is affected by the virtual surgery or that structure is not affected by the virtual surgery.


Surface mesh

It consists of the distribution of surface elements or cells (triangles and squares) over the entire surface of the geometry.

Volume mesh

It is the distribution of volumetric elements (tetrahedrons, prisms, hexahedrons and pyramids) inside the volume enclosed by the surface mesh.

Meshing for boundary layer resolution

This is a volumetric mesh composed of a series of layers of prisms and with a high aspect ratio distribution.

Automatic CFD mesh

Fully automated CFD meshing of the surface and volume of the nasal cavity including the patient's face, as well as the assignment of CFD boundary conditions and the generation of a mask outside of the nasal cavity.

CFD compatibility

Export and import of CFD surface to other formats (STL, OBJ,...)

Surface mesh optimization

Automatic closing of holes in the surface mesh, and automated detection of intersections of surface and volume elements. Algorithms for surface mesh improvement (removal of high nodes degree, needles, aspect ratio improvement, ...)

Mesh check

Mesh checks to validate the volumetric and surface meshes.

Mesh manipulation and repair tools

Computation of curvatures and thicknesses, layout tools for setting and handling boundary conditions, refined and edge collapsing with different criteria (curvature, thicknesses, ...) re-mesh of flat surfaces defined by the user, cuts of the surface/volume mesh with predefined planes, with separation and closure of the result of the cut, and the establishment of different types of computational domains (mask, infinity ...)


Display the main flow parameters

Display the main flow parameters (temperature, pressure, velocity, WSS, etc.). To facilitate the visualization of these flow parameters, Flowgy uses a cutting plane tool, in order to define a plane to cut the computational volume and to visualize the flow inside the computational domain.

Analysis and computation

Analysis, computation and storage of the mathematical estimators R and Phi, along with the rest of the fluid and geometric parameters of the patient. Computation of magnitudes in selected regions (areas, perimeters, volumes, mass flows), as well as curvatures and thickness fields (the result is analogous to an Acoustic Rhinometry)

Other displays

Display of isolines and vector fields.


Computation, display and disk storage of streamlines.

Detailed study of the airflow

Cuts of the nasal cavity with anatomical planes (axial, sagittal, coronal) and inclined planes, which allow the visualization of the internal air flow parameters.