ESTRO 2024 - Abstract Book

S5490

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

Magnolia Rincón, Ignacio Navarro, Shaila Martín, Adriana Hurtado, Sylvia Gómez-Tejedor, José María Penedo, Daniel Martínez, Laura Guzmán, Jesús Olivera, Javier Luna, Walter Vásquez, José Vara, Claudia Díaz, Carlos Camacho, María Ángeles García, Ignacio Azinovic

Fundación Jiménez Díaz hospital, Radiotherapy, Madrid, Spain

Purpose/Objective:

Surface guided radiation therapy (SGRT) has been established as a good method for daily patient positioning and monitoring and to complement standard techniques such as volumetric cone beam CT imaging (CBCT). It has become widely utilized for variety anatomical sites, including extremities.

These patients are often immobilized with systems whose efficiency, accuracy and precision patient setup may be particularly challenging, soft tissue deformation and changes in the surface.

The aim of this retrospective study is to quantify the reliability and accuracy of SGRT in positioning extremity patients compared to conventional methods.

Secondary objectives include investigating improvement of workflow efficiency, reducing number of CBCT and reducing repeat positioning with SGRT.

Material/Methods:

30 patients treated for upper or lower extremities between September and July 2023 were analysed retrospectively (Group A). These patients were immobilised with vacuum bags, Moldcare, cushions, polystyrene blocks or excluding immobilisation. For daily positioning AlignRT software (VisionRT Ltd.) was used with 0.5mm and 1° tolerance. For the registration of the current patient surface with the reference surface a ROI has been chosen reasonable. On the other hand, another 30 patients treated between September and August 2022 using traditional setup (lasers and skin marks): 15 were immobilised with thermoplastic masks (Group B) while the other 15 patients were immobilised with other devices (Group C)

Data collected included percentages of translational distribution shifts-based surface shifts versus CBCT shifts (table 1) and setup timing.

Systematic (Σ) and random (σ) translational setup errors were calculated according to the British Institute of Radiology Working Party (table 2)