51 research outputs found
Development of a GPU-based Monte Carlo dose calculation code for coupled electron-photon transport
Monte Carlo simulation is the most accurate method for absorbed dose
calculations in radiotherapy. Its efficiency still requires improvement for
routine clinical applications, especially for online adaptive radiotherapy. In
this paper, we report our recent development on a GPU-based Monte Carlo dose
calculation code for coupled electron-photon transport. We have implemented the
Dose Planning Method (DPM) Monte Carlo dose calculation package (Sempau et al,
Phys. Med. Biol., 45(2000)2263-2291) on GPU architecture under CUDA platform.
The implementation has been tested with respect to the original sequential DPM
code on CPU in phantoms with water-lung-water or water-bone-water slab
geometry. A 20 MeV mono-energetic electron point source or a 6 MV photon point
source is used in our validation. The results demonstrate adequate accuracy of
our GPU implementation for both electron and photon beams in radiotherapy
energy range. Speed up factors of about 5.0 ~ 6.6 times have been observed,
using an NVIDIA Tesla C1060 GPU card against a 2.27GHz Intel Xeon CPU
processor.Comment: 13 pages, 3 figures, and 1 table. Paper revised. Figures update
Virtual 16 Bit Precise Operations on RGBA8 Textures
There is a growing demand for high precision texture formats fed by the increasing number of textures per pixel and multi-pass algorithms in dynamic texturing and visualization. Therefore support for wider data formats in graphics hardware is evolving. The existing functionality of current graphics cards, however, can already be used to provide higher precision textures. This paper shows how to emulate a 16 bit precise signed format by use of RGBA8 textures and existing shader and register operations. Thereby a 16 bit number is stored in two unsigned 8 bit color channels. The focus lies on a 16 bit signed number format which generalizes existing 8 bit formats allowing lossless format expansions, and which has an exact representation of 1, 0 and allowing stable long-lasting dynamic texture updates. Implementations of basic arithmetic operations and dependent texture loop-ups in this format are presented and example algorithms dealing with 16 bit precise dynamic updates of displacement maps, normal textures and filters demonstrate some of the resulting application areas
Image Registration by a Regularized Gradient Flow A Streaming Implementation in DX9 Graphics Hardware
The presented image registration method uses a regularized gradient flow to correlate the intensities in two images. Thereby, an energy functional is successively minimized by descending along its regularized gradient. The gradient flow formulation makes use of a robust multi-scale regularization, an e#cient multi-grid solver and an e#ective time-step control
- …