| Popis: |
Nowadays, 2D X-ray systems are used more and more for 3-dimensional rotational X-ray imaging (3D-RX) or volume imaging, such as 3D rotational angiography. However, it is not evident that the application of settings for optimal 2D images also guarantee optimal conditions for 3D-RX reconstruction results. In particular the search for a good compromise between patient dose and IQ may lead to different results in case of 3D imaging. For this purpose we developed an additional 3D-RX module for our full-scale image quality & patient dose (IQ&PD) simulation model, with specific calculations of patient dose under rotational conditions, and contrast, sharpness and noise of 3D images. The complete X-ray system from X-ray tube up to and including the display device is modelled in separate blocks for each distinguishable component or process. The model acts as a tool for X-ray system design, image quality optimisation and patient dose reduction. The model supports the decomposition of system level requirements, and takes inherently care of the prerequisite mutual coherence between component requirements. The short calculation times enable comprehensive multi-parameter optimisation studies. The 3D-RX IQ&PD performance is validated by comparing calculation results with actual measurements performed on volume images acquired with a state-of-the-art 3D-RX system. The measurements include RXDI dose index, signal and contrast based on Hounsfield units (H and ΔH), modulation transfer function (MTF), noise variance (σ 2 ) and contrast-to-noise ratio (CNR). Further we developed a new 3D contrast-delta (3D-CΔ) phantom with details of varying size and contrast medium material and concentration. Simulation and measurement results show a significant correlation. |
