The impacts of colors on the catalyst HD system: Gains, integral times, and setups in radiotherapy

作者：Peng, Haiyan; Jin, Fu^*; Li, Chao; Luo, Huanli; Liu, Qiang^*; He, Yang; Mao, Kaijin; Zhou, Juan

来源：Journal of Radiation Research and Applied Sciences, 2022, 15(4): 100485.

DOI：10.1016/j.jrras.2022.100485

• Surface monitoring system
• Radiotherapy
• Catalyst HD
• Color
• Setup error

Purpose: To build an image-scanning protocol of Catalyst HD and to investigate the impacts of different colors on gains (Ga), integral times (Ti), and setups using this system. Methods: Thirty-eight cards with different skin tones were studied, and the color difference Delta E was calculated based on a reference color in the RGB (R: red, G: green, B: blue) space. Correlations were investigated among Delta E, Ga, and Ti. After routine setup verification, the card position changed from-5 mm to 5 mm with a step size of 2 mm, and they were measured by Catalyst HD simultaneously. The position differences were calculated to evaluate setup errors. Results: As Ga changed from 100% to 1000%, the natural logarithmic function of Ti (lnTi) linearly decreased with a constant slope of-0.002. If the reference color had an RGB value of (200, 172, 153), lnTi increased linearly with slopes of 0.006 and 0.007 for the main and side cameras respectively, as Delta E increased. Moreover, there were significant positive correlations between measured positions and true values. The correlation coefficient rpos changed as a sigmoid function of Delta E. There was a Delta E threshold of 254.0 for color detection. The detection was different for different colors. Additionally, rpos depended on the RGB values, curvature, edge and area of a region -of-interest. Conclusions: There are close correlations among Delta E, Ga, and Ti, and Delta E has an impact on setup accuracy using Catalyst HD.

• 单位
  重庆大学