Topogram-based tube current modulation of head computed tomography for optimizing image quality while protecting the eye lens with shielding
| Autor: | Ming Fang Lin, Chia Wei Li, Chia Yuen Chen, Hao Wang, Leo E. Gerweck, Wing P. Chan, Yuan Hao Lee |
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| Rok vydání: | 2018 |
| Předmět: |
Image quality
Neuroimaging Computed tomography Radiation Dosage 030218 nuclear medicine & medical imaging law.invention 03 medical and health sciences Radiation Protection 0302 clinical medicine law Lens Crystalline Tube current modulation Image Processing Computer-Assisted Medicine Radiology Nuclear Medicine and imaging Eye lens Radiological and Ultrasound Technology medicine.diagnostic_test Phantoms Imaging business.industry Brain General Medicine Lens (optics) 030220 oncology & carcinogenesis Electromagnetic shielding Head (vessel) Tomography X-Ray Computed business Head Biomedical engineering |
| Zdroj: | Acta Radiologica. 60:61-67 |
| ISSN: | 1600-0455 0284-1851 |
| DOI: | 10.1177/0284185118770894 |
| Popis: | Background Multiple rounds of head computed tomography (CT) scans increase the risk of radiation-induced lens opacification. Purpose To investigate the effects of CT eye shielding and topogram-based tube current modulation (TCM) on the radiation dose received by the lens and the image quality of nasal and periorbital imaging. Material and Methods An anthropomorphic phantom was CT-scanned using either automatic tube current modulation or a fixed tube current. The lens radiation dose was estimated using cropped Gafchromic films irradiated with or without a shield over the orbit. Image quality, assessed using regions of interest drawn on the bilateral extraorbital areas and the nasal bone with a water-based marker, was evaluated using both a signal-to-noise ratio (SNR) and contrast-noise ratio (CNR). Two CT specialists independently assessed image artifacts using a three-point Likert scale. Results The estimated radiation dose received by the lens was significantly lower when barium sulfate or bismuth-antimony shields were used in conjunction with a fixed tube current (22.0% and 35.6% reduction, respectively). Topogram-based TCM mitigated the beam hardening-associated artifacts of bismuth-antimony and barium sulfate shields. This increased the SNR by 21.6% in the extraorbital region and the CNR by 7.2% between the nasal bones and extraorbital regions. The combination of topogram-based TCM and barium sulfate or bismuth-antimony shields reduced lens doses by 12.2% and 27.2%, respectively. Conclusion Image artifacts induced by the bismuth-antimony shield at a fixed tube current for lenticular radioprotection were significantly reduced by topogram-based TCM, which increased the SNR of the anthropomorphic nasal bones and periorbital tissues. |
| Databáze: | OpenAIRE |
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