The present invention relates to quality adaptations in volume rendering for ultrasound imaging.
The quality of a three dimensional representation or volume rendered image by an ultrasound system is dependent on the acquisition quality as well as the rendering quality. Acquisition quality is determined by the ultrasound data acquisition systems, such as the beamformer's azimuthal beam density, elevational beam density (or frame density) and range sampling density of the echo data in a three dimensional space or volume. The azimuthal beam density and frame density can also be determined by an apparatus different and separate from the beamformer. This apparatus can directly control the azimuthal beam density (or frame density) of the ultrasound acquisition. The acquisition quality is dependent on the transducer, beamforming and backend signal processing parts of an ultrasound system. The acquisition quality trades off higher image quality with acquisition volume rate or speed. Higher sampling density is achieved by acquiring additional samples per beam, additional beams per frame, and additional frames per volume. Increasing the sampling density may result in a lower volume acquisition rate.
The rendering quality is determined by the density used to sample the acquisition space for volume rendering. The samples acquired by the ultrasound system are re-sampled to a rendering grid for volume rendering. Rendering quality is related to the volume rendering algorithm. Rendering quality trades off a higher quality rendered image with rendering rate or speed given fixed hardware rendering resources.
The settings used by an ultrasound system for the acquisition and rendering are independently set. Manual controls, such as knobs or dials, allow a user to select acquisition related parameters and associated quality. Separate or different knobs or dials allow a user to select rendering quality and associated parameters. Where a user manually changes parameters, such as associated with a slower acquisition rate, the rendering parameters may be maintained at the same values, resulting in a lower rendering resolution than is possible given the extra time available for rendering.
In volume rendering algorithms, higher quality rendering is more computationally intensive and therefore slower. Volume rendering algorithms use different parameters that determine the quality of the rendered image. The rendering quality parameters trade-off image quality with system performance. System performance may be indicated by rendering speed and/or system response time to user interaction. For example, two different states of volume rendering are provided. One state operates with streaming volumes. A plurality of different representations is sequentially generated as data is acquired and provided to the rendering algorithm. Another state is a manipulation state. The user interacts with the volume image, such as to perform a trace operation, adjust brightness, adjust opacity, rotate viewing angle or perform another manipulation or editing option. Different rendering qualities and associated resolutions are provided for the two different states. For example, streaming volumes are rendered. The user then manipulates or changes state for editing. As a result of the change in state, the rendering algorithm parameters are altered to provide a lower quality or lower resolution image in order to provide faster response time to user interactions and manipulations. To change the quality, the rendering sampling density in all three dimensions is altered.