ESTRO 2024 - Abstract Book

S5582

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

ESTRO 2024

Table 1: the mean absolute values of the IGRT corrections performed on the CINE images, and the final TRUFI scan.

The mean magnitude of the 3D correction vector is 0.16cm (±0.21cm) and 0.30cm (±0.27cm), for the CINE images and TRUFI images respectively.

In 25 out of 112 fractions (22%) an IGRT correction of greater than 0.30cm was observed in the TRUFI scan.

Median treatment length for all patients over all fractions was 48 minutes (±7.48 minutes).

Conclusion:

The mean IGRT corrections from the TRUFI scan reflects the residual IGRT corrections necessary after image matching on the CINE images. Since in 22% of the total fractions an IGRT correction greater than 0.30cm was observed, the TRUFI images will continue to be acquired in our clinical workflow. Further investigation will be conducted to assess the reasons for these remaining corrections.

Keywords: MR-Linac, Adaptive Radiotherapy, IGRT

2544

Digital Poster

The analysis of head and neck immobilisation for proton beam therapy

Sze Yarn Sin, Semaya Natalia Chen, Zubin Master

National Cancer Centre Singapore, Division of Radiation Oncology, Singapore, Singapore

Purpose/Objective:

Locally advanced or inoperable head and neck (HN) cancer is an indication for proton beam therapy in Singapore. Globally, this has been an emerging modality for the past decade as it allows a more precise dose deposition in the Bragg peak’s region and a lower integral dose to the proximate healthy organs. Immobilization and reproducibility are extremely crucial in proton as it impacts depth dose distribution and range uncertainty. Proton beam passing through different tissue thickness or material density will affect the overall beam deposition, and subsequently result in underdosing the target volume or overdosing of OARs. Our department has acquired the HP PRO proton compatible system, with HP Pro Nanor shell, Moldcare cushion and hand grips. Customized shell and headrest are the standard immobilization used for all HN patients in proton or photon irradiation. Uniquely for proton irradiation,