ESTRO 2024 - Abstract Book

S4801

Physics - Quality assurance and auditing

ESTRO 2024

Keywords: MLC, Winston-Lutz, Radiation Isocentre

References:

Hanley, J, Dresser et al. AAPM Task Group 198 Report: An implementation guide for TG 142 quality assurance of medical accelerators. Med Phys. 2021; 48: e830–e885. https://doi.org/10.1002/mp.14992

Pylinac 3.16.0. https://pypi.org/project/pylinac/

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Digital Poster

Dosimetric validation of Total Marrow with Lymphoid Irradiation with Volumetric Arc Therapy

Reena Devi Phurailatpam 1,2 , Jeevanshu Jain 1,2 , Divya Patil 1 , Mahima Tiwari 1 , Sudhansu S Rana 1 , Jayant Shastri Goda 1

1 ACTREC,Tata Memorial Centre, Radiation Oncology, Mumbai, India. 2 Homi Bhabha National institute, Academics, MUMBAI, India

Purpose/Objective:

Planning, dosimetric validation and implementation of TMLI (Total Marrow with lymphoid Irradiation) using Volumetric modulated arc therapy (VMAT).

Material/Methods:

Four patients were accrued in the prospective study following approval of the institutional ethics committee VMAT plans were generated on Varian TrueBeam LINAC using Eclipse treatment planning system (version 16.1). Patients were immobilised in a vacloc with arms by the side and simulated taking two sets of non-contrast CT images acquired in headfirst supine (HFS) and feet first supine (FFS) position. Clinical target volume CTV TMI encompassed marrow sites-skeletal bone, including ribs and sternum. Mandible was excluded from the target volume to minimize dose to oral cavity. However, the ramus was included in the target volume. CTV TLI- encompassed lymphatic sites i.e. major lymph node regions and spleen. Mesenteric lymph nodes were excluded as target regions to minimize dose to gastrointestinal tracts. The brain and testis were contoured as CTVsanctuary sites. For planning target volume (PTV), 5mm margins were uniformly generated around CTV except in the region of the lungs where the CTV was expanded by 7mm to account for the respiratory excursion. PTV-TMLI encompassed the entire CTV TMI and CTV TLI and the CTV sanctuary sites of brain and Testis. VMAT plans were generated on HFS CT (upper PTV TMLI) while 3DCRT plans were generated on FFS CT(Lower PTV TMLI). For planning purpose, PTV TMLI was divided into upper TMLI and lower TMLI. During the planning phase, dose at the junction of HFS plan and FFS plan