Image artifacts caused by incorrect bowtie filters in cone-beam CT image-guided radiotherapy
| Autor: | Iris Z. Wang, Steven F. de Boer, Yanan Cao, Tianjun Ma |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Cone beam computed tomography
Computer science 87.55.Qr 87.56.Fc Image guided radiotherapy Imaging phantom 030218 nuclear medicine & medical imaging Image (mathematics) crescent artifacts image artifacts 03 medical and health sciences 0302 clinical medicine Medical Imaging Humans Radiology Nuclear Medicine and imaging Computer vision Instrumentation IGRT Cone beam ct Image-guided radiation therapy Artifact (error) Radiation business.industry Phantoms Imaging 87.55.km CBCT Cone-Beam Computed Tomography Filter (video) 030220 oncology & carcinogenesis bowtie filters Artificial intelligence business Artifacts Head Radiotherapy Image-Guided |
| Zdroj: | Journal of Applied Clinical Medical Physics |
| ISSN: | 1526-9914 |
| Popis: | Certain models of cone beam computed tomography (CBCT) image‐guided radiotherapy (IGRT) systems require manually placing the appropriate bowtie filter according to the relevant imaging protocol. Inadvertently using a wrong bowtie filter or no bowtie filter could cause unexpected image artifacts. In this work, CBCT image artifact patterns caused by different bowtie filter placement were evaluated. CBCT images of CT phantoms, that is, a Body Norm phantom, a Catphan® phantom and an anthropomorphic RANDO® phantom, were acquired at a Varian Trilogy® unit with an On‐Board Imager® (OBI) system. Three image acquisition protocols were evaluated. For Standard Head protocol, half‐fan bowtie and no bowtie filter were studied for comparison with the correct full‐fan bowtie acquisition. For Pelvis and Low‐Dose Thorax protocols, full‐fan bowtie and no bowtie were studied for comparison with the correct half‐fan bowtie acquisition. In addition, the possibility of reversed direction half‐fan bowtie was also discussed. All possible scenarios of bowtie filter misplacement caused distinct artifacts regardless of protocols. These artifact patterns are different from the characteristic crescent artifact when correct bowtie filter was placed. Based on the artifact patterns described in this study we recommend reviewing image artifacts at time of image acquisition. If unexpected artifacts appear in the CBCT images, one should verify the correct placement of the bowtie filter and retake the image if necessary. However, it should also be stressed that using a wrong bowtie filter or forgetting to place the bowtie filter can cause increased patient dose. It is always a good practice to verify the bowtie filter placement before acquiring CBCT images for image‐guided radiotherapy. |
| Databáze: | OpenAIRE |
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