ESTRO 2024 - Abstract Book

S3550

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

4. Bogue J. et al.; Dosimetric comparison of VMAT with integrated skin flash to 3D field-in-field tangents for left breast irradiation. J Appl Clin Med Phys. 2019 Feb;20(2):24-29. doi: 10.1002/acm2.12527.

5. Liu H et al.; Evaluation of 3D-CRT, IMRT and VMAT radiotherapy plans for left breast cancer based on clinical dosimetric study. Comput Med Imaging Graph. 2016 Dec;54:1-5. doi: 10.1016/j.compmedimag.2016.10.001.

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Digital Poster

Dosimetric comparison between HALCYON and CLINAC iX for locally advanced head and neck cancer

Vibhor Patodi 1 , Parveen Ahlawat 1 , Tej Prakash Soni 2 , Sandeep Purohit 1 , Akash R Bellige 1 , Gerim Prasai 1 , Sauharda Lohani 1 , Aslam Najeem 1 , Apoorva Nayak 1 , Munish Gairola 1 , Sarthak Tandon 1 1 Rajiv Gandhi Cancer Institute and Research Centre, Radiation Oncology, New Delhi, India. 2 Bhagwan Mahaveer Cancer Hospital And Research Center, Radiation Oncology, Jaipur, India

Purpose/Objective:

Halcyon Linear-accelerator (LINAC) uses flattening-filter-free (FFF) mode beams (800 MU/min) and is configured with an alternative design for a dual-layer multi-leaf collimator (MLC). The aim of current study was to compare dosimetric performance, plan quality, treatment delivery efficiency of head and neck cancer between Halcyon 1.0 and Clinac iX LINAC.

Material/Methods:

Thirty patients with locally advanced head and neck cancer treated between March 2021 and March 2022 with radical radiotherapy to a dose of 70Gy in 35 fractions were evaluated. Volumetric Modulated Arc Therapy (VMAT) plans were created on both Halcyon as well as Clinac iX LINAC for all patients, and dosimetric comparison were done. Clinac iX was selected as a benchmark LINAC to compare with Halcyon 1.0 as Clinac iX is a conventional C arm LINAC with 6 and 10 MV flattened beam, a Millennium 120 MLC with maximum field size of 40x40 cm2. The parameters compared between the two plans were dosimetric performance, plan quality and treatment delivery efficiency. VMAT plans were created using the same prescription does and target coverage for both platforms. To evaluate delivery efficiency, actual beam-on time for patients were recorded and compared.

Results:

There was significantly better Homogeneity Index (HI), Conformity Index (CI), Intergral dose, monitoring units (MU) and treatment delivery time with HALCYON plan than CLINAC iX plan. Target coverage and doses to OARs were comparable between the two plans. Plan metrics and delivery parameters are compared in Table below.

Standard Deviation

Plan Metric

Machine

Mean value

p value

PTV D98%

HALCYON

68.45

0.74

0.064