ESTRO meets Asia 2024 - Abstract Book

S358

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

ESTRO meets Asia 2024

Surface-guided radiation therapy (SGRT) systems are commonly used for patient positioning in radiotherapy treatments for various body regions. The effectiveness of SGRT has been widely debated in terms of set-up accuracy and reduction of patient positioning or repositioning time. This study focuses on the advantages of using surface guidance for pre-positioning patients experiencing pain due to bone metastases. The aim is to reduce positioning time compared to the conventional method and to remove tattoos if set-up accuracy is maintained.

Material/Methods:

The study included 50 patients undergoing SBRT for bone metastases in 5 fractions. Half of the patients were positioned using laser tattoo alignment and the Varian Delta Couch Shift. The other half were positioned using Brainlab's Exactrac Dynamic surface guide without taking tattoos into account. Pain was assessed with the Numeric Pain Rating Scale (NRS). Treatment position was checked daily with CBCT and translational and rotational set-up error values were collected from 250 CBCTs. The set-up time was obtained from the Linac log files, from opening the patient at the console to imaging acquisition.

Results:

The use of SGRT resulted in a 30% reduction in positioning time compared to the conventional tattoo-based method, with an average time saving of 2.5 minutes. The average translational and rotational set-up errors were similar for both positioning methods, with a mean difference of ±0.04 cm (vertical), ±0.13 cm (longitudinal), ±0.10 cm (lateral) and a difference of ±0.1° (pitch), ±0.17° (roll) and ±0.02° (rotation).

Conclusion:

Reducing treatment time through the use of SGRT can be particularly beneficial for painful patients treated with higher doses. This may reduce the need to interrupt therapy for intra-fraction movements and the subsequent repetition of positioning and verification imaging. Increased compliance may also allow patients to treat multiple sites in a single session, potentially reducing the overall number of radiotherapy days.

SGRT also provides RTTs the capability of detecting and correcting possible set-up discrepancies with a touchless approach to the patient, making therapy sessions more tolerable.

The use of SGRT can improve compliance in patients experiencing pain by reducing on-couch time. The small mean difference confirms the equivalence of the two methods and the feasability of a tattoo-free set-up.

Keywords: SGRT, positioning, bone metastases

References:

Zhao H, Paxton A, Sarkar V, et al. (August 31, 2022) Surface-Guided Patient Setup Versus Traditional Tattoo Markers for Radiation Therapy: Is Tattoo-Less Setup Feasible for Thorax, Abdomen and Pelvis Treatment?. Cureus 14(8): e28644. DOI 10.7759/cureus.28644 Psarras, M.; Stasinou, D.; Stroubinis, T.; Protopapa, M.; Zygogianni, A.; Kouloulias, V.; Platoni, K. Surface Guided Radiotherapy: CanWe Move on from the Era of Three-Point Markers to the New Era of Thousands of Points? Bioengineering 2023, 10, 1202. https://doi.org/10.3390/ bioengineering10101202 Mannerberg A, Kügele M, Hamid S, Edvardsson A, Petersson K, Gunnlaugsson A, Bäck SÅJ, Engelholm S, Ceberg S. Faster and more accurate patient positioning with surface guided radiotherapy for ultra-