Different 3D Volume Types in LEADTOOLS Medical 3D SDK
Using LEADTOOLS Medical 3D SDK technology, developers can
implement 3D volume generation using any stack of 2D
cross-sectional slices. The cross-sectional planes must be
parallel to each other in order to generate a meaningful 3D
volume, so LEADTOOLS provides functions that use DICOM tags to
identify, separate, and sort volumetric stacks.
Also, the LEADTOOLS Medical 3D SDK provides an interface to
define the 3D pixel volume (voxel) and patient orientation
for proper measurement, orientation labeling, and scaling
of the 3D volume and generated oblique and orthogonal slices.
Upon providing cross-sectional slices to the LEADTOOLS Medical 3D
SDK engine, developers can switch between different volume types
by simply setting a property to the desired volume type. The
following 3D volumes types are provided by the LEADTOOLS Medical
3D SDK engine (click on volume type for screenshot):
MPR (Multi Planar Reformatting): MPR is a two-dimensional reformatted image that is reconstructed secondarily in arbitrary planes from the stack of 2D image data. With LEADTOOLS, this is rendered as three different orthogonal plane views of the 3D volume by default. Users have the option to add up to three additional oblique planes. Additionally, there is an interaction between the position of the 2D and 3D orthogonal planes, so scrolling in any of the 2D planes will be reflected in the corresponding 3D MPR plane and vice versa.
MPR is regularly used for examining images of the spine to view
the inter-vertebral discs which are difficult to see in 2D images. A 3D view makes it easier to see
the position of one vertebra in relation to others.
VRT (Volume Rendering Technique): VRT generates a 3D volume from images of a 3D volumetric data set without explicitly extracting geometric surfaces from the data. With VRT, the optical model is used to map the data values using opacity and color. The advantage of VRT over the Shaded Surface Display (SSD) technique is that VRT uses the volumetric data as a whole and no information is discarded. The mapping of the data to opacity values acts as a classification of the data of interest which allows visualization of the interior of the volume data. LEADTOOLS also uses different 3D rendering techniques to improve the appearance of the 3D volume.
VRT, with support for clipping planes, can be used to remove obstructive anatomy from the 3D view. Another advantage to VRT is the ability to add transparency which allows bones to be displayed as semi-transparent to transparent for better views of the otherwise concealed anatomy.
MIP (Maximum Intensity project): With MIP, each voxel along a view line through the volume of data is evaluated, and the maximum voxel value with maximum intensity (i.e., dense structures) is selected for rendering. This provides a better view of hyper-dense structures.
Using MIP, a developer can create an application which makes it possible for physicians to more quickly and reliably identify pulmonary nodules.
MinIP (Minimum Intensity Projection): MinIP is similar to MIP, but only the minimum intensity along the view line of the 3D volume data is selected for rendering. This provides a better visualization of low-density structures with respect to surrounding tissues in a volume. For example, MinIP can be used for visualizing the bronchial tree since bronchi, the least dense structures of the thorax, are normally filled with air.
SSD (Shaded Surface Display): SSD is a technique which displays a surface model of the 3D object specified by the ISO threshold.
The LEADTOOLS Medical 3D SDK engine also contains properties and methods to check the target system's 3D capabilities.
3D Projection and Camera Manipulation
The LEADTOOLS Medical 3D SDK camera is functionally equivalent to the eye and creates a view of a 3D volume. With the LEADTOOLS Medical 3D SDK, the view of the generated 3D volume can be manipulated. Developers can control the LEADTOOLS Medical 3D SDK camera to zoom, pan, and rotate in a 3D space, and can set the projection mode to Orthogonal or Perspective. Unwanted or obstructive anatomy can be removed from the view without removing data from the volume by setting the far and near clipping planes.
3D Object Manipulation
The LEADTOOLS Medical 3D SDK provides complete control over 3D object crop, ISO threshold, pan, rotation, scale, and voxel opacity.
The viewer's Window Level interface provides easy 3D volume data classification by specifying an intensity range of interest using window center and window width. The change in window width (data range) changes the slope to affect the contrast. Changes to the window center alter the data inclusion from hypo-dense to hyper-dense structures. For better visual representation of an anatomy of interest, the LEADTOOLS Medical 3D SDK provides functions to set the transfer table values using linear, exponential, logarithmic, and sigmoid mapping.
Load and Save 3D Volume and Mesh
For faster 3D volume generation, the LEADTOOLS Medical 3D SDK includes functions to save and reload 3D volumes and 3D meshes to disk. The capability to load and save a 3D volume state that includes window level, offset, rotation, slab, and threshold value parameters is an important time saving benefit for physicians that may get interrupted while interpreting a study.
LEADTOOLS Medical 3D Control
The LEADTOOLS Medical 3D SDK includes an easy-to-use Medical 3D Control with built-in action tools. The LEADTOOLS Medical 3D Control is designed for rapid development and ease of use. With a few lines of code, the LEADTOOLS Medical 3D Control is easily integrated into the LEADTOOLS Medical Image Viewer Control, providing an advanced medical viewer with features comparable to high-end radiology workstations.
The LEADTOOLS Medical 3D Control provides the following interactive tools:
- Window Level—Control the brightness, contrast and transparency of the 3D object
- Alpha—Adjust the alpha factor of LUT curve
- Rotate 3D Camera—Rotate the view of the 3D object
- Translate 3D Camera—Pan the view of the 3D object
- Zoom 3D Camera—Zoom the view of the 3D object
- Rotate 3D Object—Rotate the 3D object
- Scale 3D Object—Resize the 3D object
- Translate 3D Object—Pan the 3D object
- Rotate Plane—Rotate the planes
- Translate Plane—Translates the plane in the container
The LEADTOOLS Medical 3D Control is also capable of generating oblique and orthogonal 2D MPR slices.
Typically, an MPR view involves displaying three orthogonal plane views of a desired structure at the
same time along with a way of navigating the volume. The LEADTOOLS Medical 3D Control allows each
generated 2D orthogonal plane (i.e., axial, coronal, and sagittal) to be associated with separate
LEADTOOLS Medical Image Viewer Control cells.
In this configuration, the LEADTOOLS Medical Image Viewer and LEADTOOLS Medical 3D Control
work together to provide interactive 3D cursor synchronization and stacking from any orthogonal plane.
Curved MPR generates a 2D panoramic image and paraxial cut images from a stack of 2D slices by utilizing an advanced perspective analysis algorithm to project the curved slice onto a flat surface. This Curved MPR is popular among dental and cardiac computed tomography (CT) specialists who regularly examine anatomies with curved geometry such as teeth and blood vessels.
Curved MPR features:
- Capability to add, delete, and move the panoramic points on a curved line
- One or more paraxial cuts can be created from each segment in the curve
- Properties that allow to easily control the curved line information, points on curve, paraxial distance, paraxial line length, colors, and more
- Export and save generated images
The Curved MPR feature is also supported by the LEADTOOLS Medical Image Viewer Control which allows developers to seamlessly add this feature into their applications. The Medical Viewer control provides interactive tools to draw the curved line, move the panoramic points, generate the panoramic images, auto create paraxial lines and generate paraxial images. The resulting images can be used with image analysis tools such as window level, alpha, pan, rulers, scroll, and zoom. It also provides the tools to perform image processing and annotations.
3D Volume Slab
3D volume slabs are special implementations of clipping planes and can be used from any of the six boundary box planes to "cut away" superficial structures to visualize anatomic structures and pathologic conditions within the volume. For example, one can hide the abdominal wall while investigating internal organs such as the heart or lungs. Crop Box and Crop Slab can be implemented using this feature.
The LEADTOOLS Medical 3D SDK provides interactive slab manipulation from 2D orthogonal MPR planes. When the 3D volume slab feature is enabled, the LEADTOOLS Medical Image Viewer Control can display slab boundaries as rectangles with dotted lines on each 2D MPR (axial, coronal and sagittal) plane. Using the mouse, users can adjust the clipping planes by dragging the dotted line.
Single and Double Cut-plane and MIP Slab
The cut-plane feature of the LEADTOOLS Medical 3D SDK allows the user to generate a slice that results from virtually cutting through a stack of images. A double cut-plane consists of two cut-lines (Cross-section Cut-line) that are perpendicular to each other. This allows users to evaluate an anatomy of interest by looking at the perpendicular slice of an object from all directions.
Developers can programmatically set the cut-line, the center of rotation of the cut-line, and the slice thickness on any arbitrary position in the volume stack. In addition, the LEADTOOLS Medical Image Viewer Control implements interactive single and double cut-lines. With the LEADTOOLS Medical Image Viewer control, users can interactively move and rotate cut-lines using the built-in handles and can select the slice thickness to view a thick MIP slab.