Investigation of leakage and transmission radiation through the MLC version i2 applied to the Elekta Synergy 6 MV photon beam linac

Document Type : Original Paper

Authors

1 Mohammed fi rst University, Oujda, Morocco.

2 National School of Applied Sciences, University Mohamed 1st, Oujda, Morocco.

3 LPMR, Faculty of sciences, University Mohamed 1st, Oujda, Morocco

4 LPMR, Faculty of sciences, University Mohamed 1st, Oujda, Morocco.

Abstract

Introduction & Aims: Monte Carlo simulation is extensively employed in nuclear medicine and radiotherapy to study the transport and particle interactions with matter. This task aims at investigating and simulate leakage and transmission (L&T) particles through the recent generation of Multi-Leaf Collimator version i2 (MLCi2) applied to the Elekta Synergy linac to generate 6 MV X-ray beams.

Methods: The developed model in this study involves all linac segments. Python phase space approaches and the new platform of clusters HPC (Slurm HPC-MARWAN, CNRST, Morocco) are employed to decrease MC simulation time. To study the transmission between MLCi2, a specific comparison of the dose distribution was performed. First with a treatment plan applying a collimated beam using XY Jaws, then with a plan without XY Jaws.

Results: Good agreement between MC Gate 9.0 simulation and experiment data is found with an error less than 1% and validation in terms of gamma index formalism, for 2%/2mm criteria of 99%. The results confirm the effects of the contamination particles (e-, e+) on the distributed dose inside the patient. These particles are present in the beam produced previously and which is assumed to contain only X-rays. Moreover, the three-dimensional distribution of dose inside the patient (CT-Scan) confirms the leakage and transmission L&T effect of the studied version of the multi-leaf collimator (MLCi2), with a dose range of around 70% of the delivered dose to the tumor, leading to secondary outcomes at the DNA structures.

Conclusions: Consequently, the production of a new generation of MLC that can limit this L&T effect should be encouraged.

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Articles in Press, Accepted Manuscript
Available Online from 05 April 2022
  • Receive Date: 23 December 2021
  • Revise Date: 23 March 2022
  • Accept Date: 05 April 2022
  • First Publish Date: 05 April 2022