AustinWoman v2.0 Circulatory System AustinWoman v2.0 Brain AustinWoman v2.0 Respiratory System AustinWoman v2.0 Circulatory System AustinWoman v2.0 Digestive System

AustinWoman Electromagnetic Voxels

An Open Source Model Constructed from the Visible Human Dataset

Frequently Asked Questions

Questions

Answers

Q: What are the resolutions of the AustinWoman models?
A: The color cross-sectional images in the Visible Human Project dataset have a pixel resolution of 1/3 × 1/3 mm2 in the x-y plane and 1/3 mm resolution between slices in the z-direction. There are various resolutions in the AustinWoman model. The original segmentation and tissue identification was done at 1/3 × 1/3 × 1 mm3 size and has material boundaries that are generally accurate to within 3 pixels (±1 mm) of the actual boundary except at a few problem regions. This model has been coarsened to produce lower resolution models that have 1 × 1 × 1 mm3, 2 × 2 × 2 mm3, 4 × 4 × 4 mm3 and 8 × 8 × 8 mm3 voxel sizes.

Q: What are the sizes of the models?
A: Please refer to the Download Data section for information regarding the file size and number of voxels in each model.

Q: How accurate is the model?
A: The material boundaries are generally accurate to within 3 pixels (±1 mm) of the actual boundary except at a few problem regions.

Q: Which materials are identified in the model?
A: There were 58 materials identified in the AustinWoman v2.3 model at the image's original resolution. Please see the Download Data section for lists of materials and the slices that they appear in.

Q: What formats are the models stored in?
A: The models are stored in multiple formats: UCD ASCII (.inp), UNV (.unv), text files (.txt), 8-bit grayscale images (.png), HDF5 (.h5), and CST (.vox + .lat).

The UCD ASCII Voxel format is for an unstructured mesh that contains the material IDs and properties listed in the Material Properties section. Information about the UCD ASCII format can be found here: http://help.avs.com/Express/doc/help/reference/dvmac/UCD_Form.htm

The UNV format is also unstructured and contains the material IDs for each cell.

The text files are a series of files that form a structured grid. Their names indicate the z position for the data contained in each file. The x axis points from left to right along the columns and the y axis points from top to bottom along the rows for each file. The input.txt file includes the number of cells and grid spacing in the x, y, and z directions.

The 8-bit grayscale images are essentially a visual representation of the text files. They are a series of files that form a structured grid. Each file's name indicates its z position and the origin is in the upper-left corner.

The HDF5 files can be used with gprMax.

The CST files are contained in a zipped directory. The .vox file can be imported into CST using the Import>3D Files>Voxel Data... option. The model data is contained in the .lat file. The tissue material properties distritbuted with AustinMan and AustinWoman are stored in AustinMan_AustinWoman_Materials_900.txt.

Q: How do I convert the data to a different format?
A: Some visualization and 3-D modeling programs may allow you to open the model in UCD format and save it in another format. You may utilize a converter or write your own to convert the models to a different format.

Q: How can I view the model?
A: The UCD ASCII format is very common and several visualization programs can read it. Examples of visualization programs include ParaView (http://www.paraview.org/) and Amira (http://www.amira.com/).

Q: What is the frequency for the material properties used in the mode?
A: The material properties listed in the Material Properties section above and included in the models posted are for 900 MHz. Material properties at different frequencies can be obtained from http://niremf.ifac.cnr.it/tissprop/.

Q: How do I change the frequency?
A: You can obtain the appropriate parameters at different frequencies from http://niremf.ifac.cnr.it/tissprop/. Currently, you will need to create your own script to change the material properties in the models. Here are the steps required to change the material properties in the models:

  1. Use http://niremf.ifac.cnr.it/tissprop/ to generate new material properties for the frequency that you want to use.
  2. Use the TissueMaterialsID.txt (v1.0-v2.1) or TissueMaterialsID-v2_3.txt (v2.3) table to match the material IDs that are assigned in BRISKit to the names of the materials that have electromagnetic properties in http://niremf.ifac.cnr.it/tissprop/ [10].
  3. The material information is stored in two sections of the UCD file. The voxels are defined in the cell connectivity section and have the form (for AustinMan, cell_type = 'hex'):
    <cell_id 1> <mat_id> <cell_type> <cell_vert 1> ... <cell_vert n>
    The material properties for each cell are defined in the cell data section which has the form (for AustinMan, cell-data 1 = relative permittivity or εr and cell-data 2 = conductivity or σ):
    <cell­id 1> <cell­data 1> ... <cell­data num_cdata>
    The cell_id from the voxel definitions is unique and corresponds to the cell_id in the cell data section. For more information see http://help.avs.com/Express/doc/help/reference/dvmac/UCD_Form.htm
  4. Combining the information from the first three steps you can change rewrite the cell data section in the UCD with the electromagnetic properties at the new frequency.

Q: Why use an open-source model?
A: We chose to create an open-source model so that it will be easily accessible by anybody who wishes to use the model for research, teaching, or other non-commercial uses. Additionally, an open-source model will encourage others to use the model and improve it. If you find an error in the model or make changes to improve the models, please let us know using the information in the Contact section. Please include detailed information about the changes you have made and how to access the models. We will then update the models posted online accordingly.

Q: Can I use this model for commercial use or include it in my commercial package?
A: No, under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License, you may not. However, please contact us using the information in the Contact section to discuss applying for a different license.

Q: How can I obtain the data?
A: Please contact us using the information in the Contact section. We will provide you with a password to access the directory containing the models for you to download.

Q: What is Boundary and Region Identification Software Kit (BRISKit) and how can I obtain it?
A: The Boundary and Region Identification Software Kit (BRISKit) is a MATLAB user interface that was developed by Jackson W. Massey to identify, segment, and label electromagnetic materials with the images from the Visible Human Project. The software kit contains algorithms for image processing that are used to create the voxel models from the segmented images. The software code and documentation are available here.