2020年11月
Quantification and correction of the scattered X-rays from a megavoltage photon beam to a linac-mounted kilovoltage imaging subsystem
BJR|Open
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- 巻
- 2
- 号
- 1
- 開始ページ
- 20190048
- 終了ページ
- 20190048
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1259/bjro.20190048
- 出版者・発行元
- British Institute of Radiology
<sec><title>Objective:</title> To quantify and correct megavoltage (MV) scattered X-rays (MV-scatter) on an image acquired using a linac-mounted kilovoltage (kV) imaging subsystem.
</sec><sec><title>Methods and materials:</title> A linac-mounted flat-panel detector (FPD) was used to acquire an image containing MV-scatter by activating the FPD only during MV beam irradiation. 6-, 10-, and 15 MV with a flattening-filter (FF; 6X-FF, 10X-FF, 15X-FF), and 6- and 10 MV without an FF (6X-FFF, 10X-FFF) were used. The maps were acquired by changing one of the irradiation parameters while the others remained fixed. The mean pixel values of the MV-scatter were normalized to the 6X-FF reference condition (MV-scatter value). An MV-scatter database was constructed using these values. An MV-scatter correction experiment with one full arc image acquisition and two square field sizes (FSs) was conducted. Measurement- and estimation-based corrections were performed using the database. The image contrast was calculated at each angle.
</sec><sec><title>Results:</title> The MV-scatter increased with a larger FS and dose rate. The MV-scatter value factor varied substantially depending on the FPD position or collimator rotation. The median relative error ranges of the contrast for the image without, and with the measurement- and estimation-based correction were −10.9 to −2.9, and −1.5 to 4.8 and −7.4 to 2.6, respectively, for an FS of 10.0 × 10.0 cm2.
</sec><sec><title>Conclusions:</title> The MV-scatter was strongly dependent on the FS, dose rate, and FPD position. The MV-scatter correction improved the image contrast.
</sec><sec><title>Advances in knowledge:</title> The MV-scatters on the TrueBeam linac kV imaging subsystem were quantified with various MV beam parameters, and strongly depended on the fieldsize, dose rate, and flat panel detector position. The MV-scatter correction using the constructed database improved the image quality.
</sec>
</sec><sec><title>Methods and materials:</title> A linac-mounted flat-panel detector (FPD) was used to acquire an image containing MV-scatter by activating the FPD only during MV beam irradiation. 6-, 10-, and 15 MV with a flattening-filter (FF; 6X-FF, 10X-FF, 15X-FF), and 6- and 10 MV without an FF (6X-FFF, 10X-FFF) were used. The maps were acquired by changing one of the irradiation parameters while the others remained fixed. The mean pixel values of the MV-scatter were normalized to the 6X-FF reference condition (MV-scatter value). An MV-scatter database was constructed using these values. An MV-scatter correction experiment with one full arc image acquisition and two square field sizes (FSs) was conducted. Measurement- and estimation-based corrections were performed using the database. The image contrast was calculated at each angle.
</sec><sec><title>Results:</title> The MV-scatter increased with a larger FS and dose rate. The MV-scatter value factor varied substantially depending on the FPD position or collimator rotation. The median relative error ranges of the contrast for the image without, and with the measurement- and estimation-based correction were −10.9 to −2.9, and −1.5 to 4.8 and −7.4 to 2.6, respectively, for an FS of 10.0 × 10.0 cm2.
</sec><sec><title>Conclusions:</title> The MV-scatter was strongly dependent on the FS, dose rate, and FPD position. The MV-scatter correction improved the image contrast.
</sec><sec><title>Advances in knowledge:</title> The MV-scatters on the TrueBeam linac kV imaging subsystem were quantified with various MV beam parameters, and strongly depended on the fieldsize, dose rate, and flat panel detector position. The MV-scatter correction using the constructed database improved the image quality.
</sec>
- リンク情報
-
- DOI
- https://doi.org/10.1259/bjro.20190048
- PubMed
- https://www.ncbi.nlm.nih.gov/pubmed/33324865
- PubMed Central
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7731796
- 共同研究・競争的資金等の研究課題
- 難治がんの放射線治療成績向上に向けた新規画像撮像法の開発
- 共同研究・競争的資金等の研究課題
- Visualizing implanted fiducials in pancreas on 2D kV and 3D CBCT image acquired during concurrent MV beam irradiation
- URL
- https://www.birpublications.org/doi/pdf/10.1259/bjro.20190048
- ID情報
-
- DOI : 10.1259/bjro.20190048
- eISSN : 2513-9878
- PubMed ID : 33324865
- PubMed Central 記事ID : PMC7731796