A new optical system for quality control and patients positioning in radiation therapy

Abstract

Introduction Measurements of distances with relation to user defined coordinate system (UCS) is one of the main task in quality control of radiotherapy. Purpose Introducing a new optical system for quality control, especially for all mechanical tests where position or distance is measured and for positioning of patients is presented. Materials and methods The standard version of the system consists of two optical cameras, a data collecting computer, specialized software and a set of markers. The system allows for the measurement of the 3D position of the marker center (X,Y,Z) and three vectors representing the position of the center with respect to UCS. The UCS is defined with a set of three markers. The uncertainty of the standard system with 0.8 megapixels cameras, 2 cm × 2 cm marker size, and the FOV of about 50 cm × 50 cm is ∼ 0.2 mm (1 SD). The position of the marker is defined thanks to mathematical operations on the pattern of the marker. This mathematical procedure and the pattern of the marker are waiting for patent. In general unlimited number of different markers might be printed, so the positions of many points may be measured in the same time. The marker may be printed on any material. The results of the quality control test performed to check the rotational precision of two IsoAligne will be presented. Results Both IsoAligne rotated very well around their centers; however we found some differences between them. For some rotational position there was a deflection from the ideal position of about 0.4 mm. Conclusion The system is a very promising tool for all quality control tests in which distance (position) has to be measured. Disclosure There is any relationship that may bias our presentation.