| Autor: |
T Stanescu, H.-S. Jans, B. G. Fallone |
| Rok vydání: |
2006 |
| Předmět: |
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| Zdroj: |
Medical Physics. 33:2658-2659 |
| ISSN: |
0094-2405 |
| Popis: |
Magnetic Resonance Imaging is the imaging modality of choice for target volume delineation required by radiotherapy planning (RTP) due to its superior soft‐tissue contrast. However, MRimages are affected by distortions that alter the imagespatial accuracy which is crucial for RTP. In the present work, we investigate a complete 3D phantom‐based protocol that determines and corrects both geometrical and object‐induced distortions. A 3D oil‐filled phantom consisting of parallel plastic grid sheets equally distributed inside the phantom was scanned on a 3T MR unit and CT (spatially accurate reference dataset). To determine the geometrical distortions we developed a novel automatic procedure. This allows us to accurately identify and register the MR and CT control points and to determine iteratively the 3D distortion field. To correct the sample‐induced effects we applied a standard method as per Chang and Fitzpatrick [1]. For the entire field of view the control points were located accurately within one pixel resolution. We found that the total distortion in the transverse plane is approximately 7 mm and the z‐distortion is around 4 mm for a 15×15×15 cm3 volume. The MRimages are corrected by applying a spatial and a pixel intensity 3D interpolation procedure, the residual distortion after applying these transformations being under one pixel resolution. We investigated a procedure that relies on a new system distortion correction technique and a standard sample‐induced correction method to successfully rectify the MRimages required by Treatment Planning. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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