Dosimetric and Treatment Delivery Analysis of Volumetric Modulated Arc Therapy systems for Pharyngeal Carcinoma

Document Type : Original Paper

Authors

1 Department of Radiation Physics, Basavatarakam Indo-American Cancer Hospital and Research Institute, Hyderabad, Telangana,500034, India

2 Department of Radiation Oncology, Basavatarakam Indo-American Cancer Hospital and Research Institute, Hyderabad, Telangana,500034, India

3 Department of Physics, University College of Science, Osmania University, Hyderabad, Telangana,500007, India

10.22038/ijmp.2026.88260.2554

Abstract

Introduction: This study evaluated the dosimetric performance and delivery efficiency of three volumetric modulated arc therapy (VMAT) techniques using different multileaf collimator (MLC) systems: MLCi2, Agility and HDMLC for the treatment of pharyngeal cancer.
Material and Methods: A retrospective analysis of 21 pharyngeal cancer patients was performed. For each patient, three VMAT plans were generated using a simultaneous integrated boost (SIB) technique, delivering 66 Gy, 60 Gy and 54 Gy to PTV66, PTV60 and PTV54 respectively, over 30 fractions. Plans were created in Monaco treatment planning system (TPS) with MLCi2 (VMAT1) and Agility (VMAT2) and in Eclipse TPS with HDMLC (RapidArc). Plan quality was evaluated using conformity index (CI), homogeneity index (HI) and mean dose for target volumes. Organ-at-risk (OAR) doses were assessed according to RTOG criteria, while treatment efficiency was analyzed using monitor units (MUs) and beam-on time (BOT).
Results: All techniques produced clinically acceptable plans. RapidArc demonstrated superior conformity for PTV66 and significantly improved homogeneity for PTV60 and PTV54. It also achieved reduced maximum doses to the spinal cord and decreased low- and medium-dose spillage to normal tissue compared with VMAT1 and VMAT2. RapidArc required fewer MUs and achieved shorter BOT (p < 0.05), indicating enhanced delivery efficiency.
Conclusion: While all techniques met clinical requirements, RapidArc with HDMLC achieved superior conformity, better OAR sparing and improved delivery efficiency. These findings underscore the pivotal role of MLC design and configuration in optimizing VMAT plan quality and treatment performance for head and neck cancers.

Keywords

Main Subjects

References

  1. Kumar SA, Holla R, Sukumar P, Padmanaban S, Vivekanandan N. Treatment planning and a dosimetric comparison study on two different volumetric modulated arc therapy delivery techniques. Rep Pract Oncol Radiother. 2012;18(2):87-94. doi:10.1016/j.rpor.2012.08.009
  2. Peiris GS, Whelan B, Hardcastle N, Sheehy SL. The effect of multi-leaf collimator leaf width on VMAT treatment plan quality. J Appl Clin Med Phys. 2025;26(5):e70018. doi:10.1002/acm2.70018
  3. Thakur N, Kaur H, Kaur S, Lehal P, Sudan M, Jain N, et al. Comparative analysis of VMAT and IMRT techniques: Evaluation of dose constraints and bone marrow sparing in cervical cancer patients undergoing chemoradiotherapy. Asian Pac J Cancer Prev. 2024;25(1):139-44. doi:10.31557/APJCP.2024.25.1.139
  4. Radhakrishnan S, Chandrasekaran A, Sarma Y, Balakrishnan S, Nandigam J. Dosimetric comparison between single and dual arc-volumetric modulated arc radiotherapy and intensity modulated radiotherapy for nasopharyngeal carcinoma using a simultaneous integrated boost technique. Asian Pac J Cancer Prev. 2017;18(5):1395-402. doi:10.22034/APJCP.2017.18.5.1395
  5. Kantz S, Söhn M, Troeller A, Reiner M, Weingandt H, Alber M, et al. Impact of MLC properties and IMRT technique in meningioma and head-and-neck treatments. Radiation Oncology. 2015 Sep 2;10(1):184. doi:10.1186/s13014-015-0447-z.
  6. Ohira S, Ueda Y, Kanayama N, Isono M, Inui S, Komiyama R, et al. Impact of multileaf collimator width on dose distribution in HyperArc fractionated stereotactic irradiation for multiple brain metastases. Anticancer Res. 2021;41(6):3153-9. doi:10.21873/anticanres.15101
  7. Park JM, Park SY, Wu HG, Kim JI. Improvement of VMAT plan quality for head and neck cancer with high-resolution fluences generated by couch shift between arcs. Phys Med. 2018; 46:1-6. doi: 10.1016/j.ejmp.2018.01.004
  8. Fathy MM, Hassan BZ, El-Gebaly RH, Mokhtar MH. Dosimetric evaluation study of IMRT and VMAT techniques for prostate cancer based on different multileaf collimator designs. Radiation and Environmental Biophysics. 2023 Mar;62(1):97-106. doi:10.1007/s00411-022-01011-2
  9. Chae SM, Lee GW, Son SH. The effect of multileaf collimator leaf width on the radiosurgery planning for spine lesion treatment in terms of the modulated techniques and target complexity. Radiat Oncol. 2014; 9:72. doi:10.1186/1748-717X-9-72
  10. Saez J, Bar-Deroma R, Bogaert E, Cayez R, Chow T, Clark CH, et al. Universal evaluation of MLC models in treatment planning systems based on a common set of dynamic tests. Radiother Oncol. 2023; 186:109775. doi: 10.1016/j.radonc.2023.109775
  11. Onizuka R, Araki F, Ohno T. Monte Carlo dose verification of VMAT treatment plans using Elekta Agility 160-leaf MLC. Phys Med. 2018; 51:22-31. doi: 10.1016/j.ejmp.2018.06.003
  12. Nithya L, Raj NA, Kumar A, Rathinamuthu S, Pandey MB. Comparative analysis of volumetric-modulated arc therapy and intensity-modulated radiotherapy for base of tongue cancer. J Med Phys. 2014;39(2):121-6. doi:10.4103/0971-6203.131270
  13. Chen J, Cui W, Fu Q, Zhang H, Huang X, Han F, et al. Influence of maximum MLC leaf speed on the quality of volumetric modulated arc therapy plans. J Appl Clin Med Phys. 2020; 21:37-47. doi:10.1002/acm2.13020
  14. Bosse C, Narayanasamy G, Saenz D, Myers P, Kirby N, Rasmussen K, et al. Dose calculation comparisons between three modern treatment planning systems. J Med Phys. 2020;45(3):143-7. doi:10.4103/jmp.JMP_111_19
  15. AbuEmira MH, Elshahat K, Khouqeer GA, ElSheikh R, Al Alhindi BS, Alqarni AA, et al. Comparison of two different VMAT radiotherapy TPSs for pancreatic cancer using flattening filter free photon beam energy. J Radiat Res Appl Sci. 2024; 17(3):100564. doi: 10.1016/j.jrras.2024.100564
  16. Kathirvel M, Subramani V, Subramanian VS, Swamy ST, Arun G, Kala S. Dosimetric comparison of head and neck cancer patients planned with multivendor volumetric modulated arc therapy technology. J Can Res Ther. 2017;13(1):122-30. doi:10.4103/0973-1482.187347
  17. Mrozowska M, Kukołowicz P. Relationships between various indices of dose distribution homogeneity. Rep Pract Oncol Radiother. 2015;20(4):278-83. doi: 10.1016/j.rpor.2015.03.007.

 

 

 

 

Iranian Journal of Medical Physics
Volume 22, Issue 6 - Serial Number 6
November and December 2025
Pages 423-429

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History

  • Receive Date: 18 May 2025
  • Revise Date: 10 February 2026
  • Accept Date: 02 January 2026

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