Comparative study of a low-Z cone-beam computed tomography system
| Autor: | D A Roberts, Vibeke N. Hansen, M G Thompson, A Niven, Joao Seco, Gavin Poludniowski, Philip M. Evans |
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| Rok vydání: | 2011 |
| Předmět: |
Physics
Cone beam computed tomography Photon Radiological and Ultrasound Technology business.industry Phantoms Imaging Detector Electron Radiation Cone-Beam Computed Tomography Linear particle accelerator Optics Cathode ray Humans Radiology Nuclear Medicine and imaging business Nuclear medicine Image-guided radiation therapy |
| Zdroj: | Physics in medicine and biology. 56(14) |
| ISSN: | 1361-6560 |
| Popis: | Computed tomography images have been acquired using an experimental (low atomic number (Z) insert) megavoltage cone-beam imaging system. These images have been compared with standard megavoltage and kilovoltage imaging systems. The experimental system requires a simple modification to the 4 MeV electron beam from an Elekta Precise linac. Low-energy photons are produced in the standard medium-Z electron window and a low-Z carbon electron absorber located after the window. The carbon electron absorber produces photons as well as ensuring that all remaining electrons from the source are removed. A detector sensitive to diagnostic x-ray energies is also employed. Quantitative assessment of cone-beam computed tomography (CBCT) contrast shows that the low-Z imaging system is an order of magnitude or more superior to a standard 6 MV imaging system. CBCT data with the same contrast-to-noise ratio as a kilovoltage imaging system (0.15 cGy) can be obtained in doses of 11 and 244 cGy for the experimental and standard 6 MV systems, respectively. Whilst these doses are high for everyday imaging, qualitative images indicate that kilovoltage like images suitable for patient positioning can be acquired in radiation doses of 1-8 cGy with the experimental low-Z system. |
| Databáze: | OpenAIRE |
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