A novel dynamic robotic moving phantom system for patient‐specific quality assurance in real‐time tumor‐tracking radiotherapy

Abstract

In this study, we assess a developed novel dynamic moving phantom system that can reproduce patient three-dimensional (3D) tumor motion and patient anatomy, and perform patient-specific quality assurance (QA) of respiratory-gated radiotherapy using SyncTraX. Three patients with lung cancer were enrolled in a study. 3D printing technology was adopted to obtain individualized lung phantoms using CT images. A water-equivalent phantom (WEP) with the 3D-printed plate lung phantom was set at the tip of the robotic arm. The log file that recorded the 3D positions of the lung tumor was used as the input to the dynamic robotic moving phantom. The WEP was driven to track 3D respiratory motion. Respiratory-gated radiotherapy was performed for driving the WEP. The tracking accuracy was calculated as the differences between the actual and measured positions. For the absolute dose and dose distribution, the differences between the planned and measured doses were calculated. The differences between the planned and measured absolute doses were <1.0% at the isocenter and <4.0% for the lung region. The gamma pass ratios of γ 3 mm/3% and γ 2 mm/2% under the conditions of gating and no-gating were 99.9 ± 0.1% and 90.1 ± 8.5%, and 97.5 ± 0.9% and 68.6 ± 17.8%, respectively, for all the patients. Furthermore, for all the patients, the mean ± SD of the root mean square values of the positional error were 0.11 ± 0.04 mm, 0.33 ± 0.04 mm, and 0.20 ± 0.04 mm in the LR, AP, and SI directions, respectively. Finally, we showed that patient-specific QA of respiratory-gated radiotherapy using SyncTraX can be performed under realistic conditions using the moving phantom.

Analysis of dosimetric impact of intrafraction translation and rotation during respiratory‐gated stereotactic body radiotherapy with real‐time tumor monitoring of the lung using a novel six degrees‐of‐freedom robotic moving phantom

“…17,18 Our previous study reported a dynamic robotic phantom system that could reproduce 3D respiratory motion for the QA of motion management systems. 19 Recently, a 6DoF motion platform was developed to compensate for head movements during stereotactic radiosurgery, thus allowing for frameless and maskless treatment. 20 The geometric accuracy and reproducibility of this system were evaluated using an anthropomorphic head phantom and infrared optical tracking system.…”

“…However, most phantoms can only replicate the one‐dimensional (1D) or 2D motion of a target 17,18 . Our previous study reported a dynamic robotic phantom system that could reproduce 3D respiratory motion for the QA of motion management systems 19 …”

Robotic Systems in Radiotherapy and Radiosurgery

“…The authors reported a reproducibility of the motion traces of 0.3 mm and 0.5 deg. Shiinoki et al developed a patient-specific procedure for respiratory motion QA using a MZ07-1 robot (Nachi-Fujikoshi, Tokyo, Japan) [39]. Here, respiratory motion of the patient was recorded and a 3D printed model of the patient anatomy was placed inside a water basin.…”

Implementation of six degree-of-freedom high-precision robotic phantom on commercial industrial robotic manipulator

“…We have proposed a trajectory correction algorithm using its velocity and acceleration to compensate for the network transmission lag, and showed experimentally that the tracking errors for four lung tumor trajectories fell within the clinical 1mm tolerance. It was shown to enable high precision QA for translational motion of a tumor [8]. We also developed a six DOF version of the robotic phantom by using joint level angle trajectories corrected in the same manner.…”