kilovoltage imaging
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BJR|Open ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 20190048
Author(s):  
Hiraku Iramina ◽  
Mitsuhiro Nakamura ◽  
Yuki Miyabe ◽  
Nobutaka Mukumoto ◽  
Tomohiro Ono ◽  
...  

Objective: To quantify and correct megavoltage (MV) scattered X-rays (MV-scatter) on an image acquired using a linac-mounted kilovoltage (kV) imaging subsystem. Methods and materials: 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. Results: 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. Conclusions: The MV-scatter was strongly dependent on the FS, dose rate, and FPD position. The MV-scatter correction improved the image contrast. Advances in knowledge: 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.


2015 ◽  
Vol 60 (24) ◽  
pp. 9437-9454 ◽  
Author(s):  
Chun-Chien Shieh ◽  
Paul J Keall ◽  
Zdenka Kuncic ◽  
Chen-Yu Huang ◽  
Ilana Feain

2014 ◽  
Vol 88 (4) ◽  
pp. 913-919 ◽  
Author(s):  
Yvonne Dzierma ◽  
Frank Nuesken ◽  
Wladimir Otto ◽  
Parham Alaei ◽  
Norbert Licht ◽  
...  

2012 ◽  
Vol 84 (3) ◽  
pp. 596-601 ◽  
Author(s):  
Gregory A. Russo ◽  
Muhammad M. Qureshi ◽  
Minh-Tam Truong ◽  
Ariel E. Hirsch ◽  
Lawrence Orlina ◽  
...  

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