Progress in Medical Physics (한국의학물리학회지:의학물리)

Korean Society of Medical Physics (한국의학물리학회)
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Analysis of the Multi-Leaf Collimator Quality Assurance for the HalcyonTM Linear Accelerator

  • Jin Jegal (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Hyojun Park (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Seonghee Kang (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Jung-in Kim (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Chang Heon Choi (Department of Radiation Oncology, Seoul National University Hospital)
  • Received : 2024.02.29
  • Accepted : 2024.04.17
  • Published : 2024.06.30
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Abstract

Purpose: Accurate operation of the multi-leaf collimator (MLC), a key technology in intensity modulated radiation therapy (IMRT), is essential for safe and optimal radiation treatment. The HalcyonTM linear accelerator has a collimator with low leakage and radiation transmission, making it suitable for IMRT. The limitations of the existing HalcyonTM MLC quality assurance (QA) method were supplemented with a mathematical method, and the results were analyzed. Methods: Electric portal imaging device (EPID) images obtained by performing the MLC QA plan on the HalcyonTM was analyzed using Python. The picket fence tests were performed and compared using the maximum pixel value and mathematical methods. Dose rate, gantry speed, and leaf speed variation plan were performed for dose transmission comparison. Results: For the maximum pixel value, the minimum distance between leaf junctions was 13.86 mm, and the maximum was 16.06 mm. However, for the mathematical method, the minimum and maximum were 14.54 mm and 15.68 mm, respectively. This suggests that setting the peak value to the highest value may cause an error in interpretation due to the limitations of the pixels of the EPID image. Performing QA on the remaining items confirmed that the measured values were within 3% of tolerance. Conclusions: The presented analysis method applied to the MLC QA can derive more reasonable and valid values than existing methods, which will help with MLC monitoring by reducing errors in excessive interpretation.

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References

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