Evaluation of Deformable Image Registration (DIR) Methods for Dose Accumulation in Nasopharyngeal Cancer Patients during Radiotherapy

  • Wannapha Nobnop Faculty of Associated Medical Sciences, Chiang Mai University http://orcid.org/0000-0002-5266-2845
  • Imjai Chitapanarux Faculty of Medicine, Chiang Mai University
  • Hudsaleark Neamin Faculty of Associated Medical Sciences, Chiang Mai University
  • Somsak Wanwilairat Faculty of Medicine, Chiang Mai University
  • Vicharn Lorvidhaya Faculty of Medicine, Chiang Mai University
  • Taweap Sanghangthum Faculty of Medicine, Chulalongkorn University

Abstract

Abstract

Introduction: Deformable image registration (DIR) is used to modify structures according to anatomical changes for observing the dosimetric effect. In this study, Megavoltage Computed Tomography (MVCT) images were used to generate cumulative doses for nasopharyngeal cancer (NPC) patients by various DIR methods. The performance of the multiple DIR methods was analyzed, and the impact of dose accumulation was assessed.

Methods: The study consisted of five NPC patients treated with a helical tomotherapy unit. The weekly MVCT images at the 1st, 6th, 11th, 16th, 21st, 26th, and 31st fractions were used to assess the dose accumulation by the four DIR methods. The cumulative dose deviations from the initial treatment plan were analyzed, and correlations of these variations with the anatomic changes and DIR methods were explored.

Results: The target dose received a slightly different result from the initial plan at the end of the treatment. The organ dose differences increased as the treatment progressed to 6.8% (range: 2.2 to 10.9%), 15.2% (range: -1.7 to 36.3%), and 6.4% (range: -1.6 to 13.2%) for the right parotid, the left parotid, and the spinal cord, respectively. The mean uncertainty values to estimate the accumulated doses for all the DIR methods were 0.21 ± 0.11 Gy (target dose), 1.41 ± 0.72 Gy (right parotid), 0.487 ± 0.86 Gy (left parotid), and 0.141 ± 0.13 Gy (spinal cord).

Conclusions: Accuracy of the DIR methods affects the estimation of dose accumulation on both the target dose and the organ dose. The DIR methods provide an adequate dose estimation technique for observation as a result of inter-fractional anatomic changes and are beneficial for adaptive treatment strategies.

Five keywords

Deformable image registration, dose accumulation, nasopharyngeal cancer, MVCT, helical tomotherapy

Author Biographies

Wannapha Nobnop, Faculty of Associated Medical Sciences, Chiang Mai University

Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.

Imjai Chitapanarux, Faculty of Medicine, Chiang Mai University

Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.

Hudsaleark Neamin, Faculty of Associated Medical Sciences, Chiang Mai University
Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.
Somsak Wanwilairat, Faculty of Medicine, Chiang Mai University
Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
Vicharn Lorvidhaya, Faculty of Medicine, Chiang Mai University
Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
Taweap Sanghangthum, Faculty of Medicine, Chulalongkorn University

Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

Published
2017-11-27
How to Cite
Nobnop, W., Chitapanarux, I., Neamin, H., Wanwilairat, S., Lorvidhaya, V., & Sanghangthum, T. (2017). Evaluation of Deformable Image Registration (DIR) Methods for Dose Accumulation in Nasopharyngeal Cancer Patients during Radiotherapy. Radiology and Oncology, 51(4). Retrieved from https://www.radioloncol.com/index.php/ro/article/view/2832
Section
Clinical oncology