Iranian Journal of Medical Physics

Iranian Journal of Medical Physics

Impact of Patient Arm Positioning on Ddose Distribution in Target and Organs at Risk in Right Bbreast Cancer Radiotherapy

Document Type : Original Paper

Authors
Bahareh Khalili Najafabad 1
Raed Saleh Majhool 1
Mahdi Ghorbani 1
Ahmad Mostaar 1
Mehdi Khosravi 2
Abdullah Ali 1
Meysam Tavakoli 3
1 Biomedical Engineering and Medical Physics Department, School of Medicine, Shahid Beheshti University of Medical Sciences,Tehran, Iran
2 Medical Physics Department, Radiation Oncology Center, Vali Asr Hospital, Qom, Iran
3 Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia, USA
10.22038/ijmp.2025.80785.2416
Abstract
Introduction: Breast cancer (BC) ranks as the second most frequently diagnosed cancer among women globally. The aim of this study was to evaluate the effect of the patient’s arm positioning on dose distribution in the organs at risk (OARs) and target in BC radiotherapy for mastectomy patients.
Material and Methods: Computed tomography (CT) scans of images of 30 right BC patients were collected. The patients were divided into two groups, each with 15 patients. The first group was with right arm-up positioning, and the second was with both arms-up positioning. The Monaco treatment planning system (TPS) was used for treatment planning. Radiotherapy included a prescribed dose of 50 Gy/25 fractions. For the planning target volume (PTV), the minimum dose (Dmin), mean dose (Dmean), maximum dose (Dmax), homogeneity index (HI), conformity index (CI), and tumor control probability (TCP) were calculated. For the OARs Dmin, Dmean, Dmax, and V20 Gy (%) for the lung and normal tissue complication probability (NTCP) were assessed. We compared the two groups based on PTV and OAR levels.
Results: There was no statistical difference between quantities for PTV and OARs for the lung, heart, and spinal cord, but a statistical difference was only found in Dmean and Dmax for the thyroid gland.
Conclusion: Although a statistically significant difference in thyroid dose was found, the absolute difference is small and within tolerance limits. Both positioning techniques provide comparable coverage of the target volume and sparing of the critical organs. With regard to patient comfort and ease of reproducibility during radiotherapy treatments, positioning with both arms up is generally favored, while positions with the right arm up may be an alternative if thyroid dose minimization is an issue.
Keywords
Breast Cancer
Radiotherapy
Arm Positioning
Treatment Planning System
Subjects
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Iranian Journal of Medical Physics
Volume 23, Issue 2 - Serial Number 2
March and April 2026
Pages 103-110

  • Receive Date 26 June 2024
  • Revise Date 08 December 2025
  • Accept Date 22 July 2025