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Updated: May 7, 2026
Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
On the robustness of the Transit-Guided Radiation Therapy technique against variations in linac operating conditions
Artur Latorre-Musoll1, Sergi Serrano-Rueda1, Núria Jornet2
1Servei d'Oncologia Radioteràpica - Institut del Càncer i Malalties de la Sang (ICAMS), Hospital Clínic de Barcelona, Barcelona, Spain.
Purpose:
To evaluate the robustness of the Transit-Guided Radiation Therapy (TGRT) technique against variations in linac operating conditions using Monte Carlo simulations.
Methods:
End-to-end simulations using PRIMO and PENELOPE/penEasy software were conducted to simulate radiation beams and transit portal images (TPIs) of ten clinical plans under unaltered and modified scenarios (including changes in output dose, beam symmetry, EPID strip sensitivity, and MLC positions). The TGRT technique was used to estimate patient position errors from the TPIs with known errors introduced. Residual errors post-TGRT correction, relative to the magnitude of the known errors, served as a figure of merit for TGRT performance. Results from the modified scenarios were compared to unaltered ones to assess the impact of the modifications on TGRT performance.
Results:
TGRT performance was impaired at rates ranging from 0.0135 to 0.0439 per percentage change in output dose, beam symmetry and EPID strip sensitivity. For changes in MLC positions the impairing rate was 0.28/mm. Given that the TGRT performance was 0.44 ± 0.19 under reference conditions, minor changes in linac operating conditions (within typical machine QA tolerances) resulted in negligible impairment of TGRT performance. No overcorrections were observed within these tolerances.
Conclusions:
The TGRT technique demonstrates high resilience to variations in linac operating conditions, maintaining performance within clinically acceptable limits. These findings support the robustness of TGRT for clinical application, ensuring reliable patient position monitoring and correction in radiotherapy treatments.
