ESTRO 2024 - Abstract Book

S5510

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

ESTRO 2024

1106

Digital Poster

Treatment reproducibility in brain stereotactic radiotherapy using a Shim mask versus standard mask.

Zaheeda Mulla 1 , Hane M Muamenah 1 , Victor Joseph Joseph John 2 , Rania Hashem 2 , Amina Weber 1 , AbdulHameed Khasim 2 , Huda M Altoukhi 3 1 King Faisal Specialist Hospital and Research Center-Jeddah, Oncology, Jeddah, Saudi Arabia. 2 King Abdul-Aziz University Hospital, Radiology, Jeddah, Saudi Arabia. 3 King Abdul Aziz University, Jeddah, Faculty of Medicine, Jeddah, Saudi Arabia

Purpose/Objective:

This study aimed to evaluate the immobilization accuracy of the new Shim mask with mouth bite in comparison to the standard full brain mask in SRT/SRS treatments for brain metastases or tumors. Additionally, the study sought to determine the time-efficiency benefits of the Shim mask by analyzing the reduction in repeat CBCTs.

Material/Methods:

A combined retrospective and prospective design was employed, involving 40 patients treated at our radiation oncology center. Patients previously treated using standard head masks immobilized using an IMRT reinforced head mask formed the retrospective cohort. Those patients treated with the new Shim mask with an integrabite inserted through the mask formed the prospective cohort. Refer to Figure 1. standard mask without (1a) and Shim mask with (1b) mouth bite below.

Both immobilization devices were secured to the treatment couch using an indexer to minimize movement. Patients were positioned supine on the couch in the designated treatment position, aligned using a 3-point laser. CT simulation was conducted with a 1mm slice thickness to encompass the entire head. These scans were then imported into the MONACO planning system. For enhanced delineation of the gross target volume (GTV), MRI fusion, utilizing the MRI