Feasibility of a mobile surface-guided camera-system for non-isocentrical Total Body Irradiation
PD-0319
Abstract
Feasibility of a mobile surface-guided camera-system for non-isocentrical Total Body Irradiation
Authors: Daniel Sakarli1,2, Vania Batista1,3, Oliver Schramm1,3, Benno Dömer2
1Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg, Germany; 2Pforzheim University of Applied Sciences, Technical Faculty, Pforzheim, Germany; 3Heidelberg Institute of Radiation Oncology, Radiation Oncology, Heidelberg, Germany
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Purpose or Objective
Introduction:
Non-isocentrical Total Body Irradiations (TBI) are commonly only visually monitored by RTTs through video cameras in the bunker, and the available IGRT techniques are limited. The aim of this work is to assess the feasibility of surface guided RT (SGRT) for intrafractional motion-monitoring in a non-isocentrical scenario.
Objectives:
• Evaluate the feasibility of a mobile system
• Assess if the spatial and temporal accuracy are within the clinical requirements
• Suggest a clinical workflow
Material and Methods
A one-camera system, adapted from a commercial AlignRT (VisionRT) system, AlignRT2TBI, was assembled in a moving tripod and calibrated to an isocenter at the treatment-room floor, with the best achievable resolution, FOV and framerate. Static and dynamic accuracy, reproducibility and other performance tests were designed to measure the performance of the system under TBI-setup conditions (see Figure 1).
Figure 1: A. Clinical Feasibility tests: subject under a spoiler in a ß-angle = 40° towards the camera. A topography-increased lung-block is on the left side of the subject's breast. B. Little Anne Phantom (Laerdal Medical AS) under a spoiler and a gantry in a ß-angle = 40° towards AlignRT2TBI during the Camera Obstruction tests.
Results
AlignRT2TBI was able to detect motions with an accuracy of 5 mm and 0,125 s, respectively. The practical requirements for applying this technique are: i) minimum ceiling-height of the bunker of 220 cm and a camera-patient-distance of approximately 348 cm; ii) additional 20 minutes required to setup the system in room; iii) need to adapt current workflows, define action levels, and train workers; iv) define regular calibration and QA procedures; v) define necessary ROIs: left/right lung-block and bony structures of the thorax.
Figure 2: A. ROI covering bony structures of the patient’s thorax for interfractional setup purposes (based on B). B. Proposed ROI by Sorgato et al. (doi: 10.1016/j.tipsro.2021.12.002) 
. C. ROI covering the left lung-block for intrafractional monitoring purposes.
Conclusion
The use of AlignRT2TBI for motion-monitoring during TBIs showed to be feasible, with reduced additional workload. In order to use the system clinically, a commercial product must be made available, and users need to ensure an adequate commissioning, adapted to the defined workflow.