Reduction in x-ray scatter and radiation dose for volume-of-interest (VOI) cone-beam breast CT—a phantom study
| Autor: | Xinming Liu, S. ge, Wei Tse Yang, Gary J. Whitman, Y. Shen, Tianpeng Wang, Chao Jen Lai, Tao Han, Y. yi, Yuncheng Zhong, Lingyun Chen, Huojun Zhang, Chris C. Shaw |
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| Rok vydání: | 2009 |
| Předmět: |
Image quality
Breast Neoplasms Iterative reconstruction Article Imaging phantom Flat panel detector law.invention law Calibration Humans Scattering Radiation Radiology Nuclear Medicine and imaging Breast Projection (set theory) Physics Models Statistical Radiological and Ultrasound Technology Phantoms Imaging business.industry Radiotherapy Planning Computer-Assisted X-Rays Collimator Equipment Design Female Tomography Tomography X-Ray Computed Nuclear medicine business Monte Carlo Method Algorithms Mammography |
| Zdroj: | Physics in Medicine and Biology. 54:6691-6709 |
| ISSN: | 1361-6560 0031-9155 |
| Popis: | With volume-of-interest (VOI) cone beam computed tomography (CBCT) imaging, one set of projection images are acquired with the VOI collimator at a regular or high exposure level and the second set of projection images are acquired without the collimator at a reduced exposure level. The high exposure VOI scan data inside the VOI and the low exposure full field scan data outside the VOI are then combined together to generate composite projection images for image reconstruction. To investigate and quantify scatter reduction, dose saving, and image quality improvement in VOI CBCT imaging, a flat panel detector based bench-top experimental CBCT system was built to measure the dose, the scatter-to-primary ratio (SPR), the image contrast, noise level, the contrast-to-noise ratio (CNR), and the figure of merits (FOMs) in the CBCT reconstructed images for two polycarbonate cylinders simulating the small and the large phantoms. The results showed that, compared to the FF CBCT technique, radiation doses for the VOI CBCT technique were reduced by a factor of 1.20 and 1.36 for the small and the large phantoms at the phantom center, respectively, and from 2.7 to 3.0 on the edge of the phantom, respectively. Inside the VOI, the SPRs were substantially reduced by a factor of 6.6 and 10.3 for the small and the large phantoms, the contrast signals were improved by a factor of 1.35 and 1.8, and the noise levels were increased by a factor of 1.27 and 1.6, respectively. As the result, the CNRs were improved by a factor of 1.06 and 1.13 for the small and the large phantoms and the FOMs were improved by a factor of 1.4 and 1.7, respectively. |
| Databáze: | OpenAIRE |
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