Background: The aim of this study was to investigate the adrenal tumor motion law and influence factors in the treatment of adrenal gland tumor and provide a reference value basis for determining the planning target volume margins for therapy.
Materials and methods: The subjects considered in this study were 38 adrenal tumor patients treated with CyberKnife with the placement of 45 gold fiducials. Fiducials were implanted into each adrenal tumor using β-ultrasonic guidance. Motion amplitudes of gold fiducials were measured with a Philips SLS simulator and motion data in the left-right, anterior-posterior, and cranio-caudal directions were obtained. Multiple linear regression models were used to analyze influencing factors. t-Test was used for motion amplitude comparison of different tumor locations along the z-axis.
Results: The motion distances were 0.1-0.4 cm (0.27±0.07 cm), 0.1-0.5 cm (0.31±0.11 cm), and 0.5-1.2 cm (0.87±0.21 cm) along the x-, y-, and z-axes, respectively. Motion amplitude along the z-axis may be affected by tumor location, but movement along the other axes was not affected by age, height, body mass, location, and size.
Conclusion: The maximum motion distance was along the z-axis. Therefore, this should be the main consideration when defining the planning target volume safety margin. Due to the proximity of the liver, adrenal gland tumor motion amplitude was smaller on the right than the left. This study analyzed adrenal tumor motion amplitude data to evaluate how motion and other factors influence the treatment of adrenal tumor with a goal of providing a reference for stereotactic radiotherapy boundary determination.
Keywords: CyberKnife; adrenal gland; gold fiducial; influence factors; law of motion.