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. 2026 Feb 17.
doi: 10.1007/s13246-026-01710-w. Online ahead of print.

An open-source motion platform that replicates time synchronised internal and external patient motion for real-time image-guided radiotherapy

Alicja Kaczynska #  1 , Chris Kuban #  2 , Abbas Zahr  2 , William Nixon  2 , Paul Keall  2 , Freeman Jin  2 , Ann Yan  2 , Daniel Mason  3 , Maegan Stewart  4 , Julia Johnson  2 , Jonathan Hindmarsh  2 , Chandrima Sengupta  2
Affiliations

An open-source motion platform that replicates time synchronised internal and external patient motion for real-time image-guided radiotherapy

Alicja Kaczynska et al. Phys Eng Sci Med. .

Abstract

Real-time Image-guided Radiotherapy (IGRT) technologies aim to track intra-fractional tumour motion during delivery of high radiation doses to tumours. For the development and safe implementation of real-time IGRT technologies into the clinic, there is a need for robust and repeatable quality assurance (QA) devices. Motivated by this need, this work presents the development and characterisation of a novel time-synchronised motion platform designed for QA purposes of real-time IGRT technologies that perform combined internal and external patient motion monitoring. The Internal-External Robotic Actuator (IntERAct) QA device was developed to integrate a 6-degree-of-freedom (6DoF) robotic arm with a 1-degree-of-freedom (1DoF) motion actuator, which replicate 6DoF internal tumour and 1DoF external surface movements, respectively. The IntERAct device was validated by performing tests which replicated patient-measured lung and liver motion traces on the 6DoF and 1DoF platforms. The device synchronised the internal and external motions to within 0.1 s with under two-millimetre geometric accuracy. The full details of the IntERAct device have been compiled into an open-source repository on GitHub for the medical physics community to use: https://github.com/Image-X-Institute/IntERAct .

Keywords: 6 Degree-of-freedom quality assurance; Intrafraction motion; Motion platform; Real-time image guided radiotherapy; Robotic motion phantom.

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Conflict of interest statement

Declarations. Competing interests: The authors have no relevant financial or non-financial interests to disclose related to this manuscript. Ethics approval: The authors confirm that this study did not require formal ethics approval as per the relevant institutional body.

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