Radioprotection 2026, 61( 2), 140 – 145 © E. Sadiki et al., Published by EDP Sciences 2026 https:// doi. org / 10.1051 / radiopro / 2025021
Available online at: www. radioprotection. org
ARTICLE Exploring the dosimetric impact of applicator rotations in HDR brachytherapy for cervical cancer treatment
E. Sadiki 1, 2, O. Berradi 1, M. Ait Erraisse 3, K. Soussy 3, S. Khalfi 3, N. Slassi 2, 4, M. Najeh 5, S. Chtita 6 and R. Touti 1,*
1 Laboratory of Advanced Materials and Applications( LM2A), Faculty of Sciences Dhar El Mahraz, Sidi Mohamed Ben Abdellah University, B. P. 1796 Fez-Atlas, Morocco. 2 Medical Physics Unit, Hassan II University Hospital, Fes, Morocco. 3 Radiation Oncology Department, Oncology Hospital, Hassan II University Hospital, Fes, Morocco. 4 Faculty of Science, Mohammed V University in Rabat, Morocco. 5 Faculty of medicine and pharmacy Hassan II University, Casablanca, Morocco. 6 Laboratory of Analytical and Molecular Chemistry, Faculty of Sciences Ben M ' Sik, Hassan II, University of Casablanca, Casablanca,
Morocco. Received: 23 February 2025 / Accepted: 7 August 2025
Abstract – This study aims to improve the safety and accuracy of HDR brachytherapy for cervical cancer by examining the effects of rotational movements of intracavitary applicators. It focuses on lateral( leftright), vertical( up-down), and axial( around the applicator axis) rotations to assess how these movements impact the dose to the high-risk clinical target volume( HR-CTV) and nearby organs at risk( OARs), such as the bladder and rectum. A cohort of 20 cervical cancer patients treated with intracavitary HDR brachytherapy was analyzed using CT-based treatment planning on the Varian TPS. Rotational displacements of ± 3 °,± 5 °,± 8 °, and ± 10 ° were simulated along each axis. Dosimetric metrics, such as HR-CTV D90 % and OAR D2cc, were evaluated using dose-volume histograms( DVHs). Vertical rotations caused the most significant dosimetric changes, with HR-CTV D90 % decreasing by up to 10.16 %, while bladder and rectum D2cc increased by 12.97 % and 16.6 %, respectively. Lateral rotations showed moderate variations, with HR-CTV D90 % reductions up to 2.49 % and OAR D2cc increases up to 2.13 %. Axial rotations had minimal impact, with changes in all metrics below 1.02 %. Applicator displacements especially vertical can cause significant dosimetric errors in HDR brachytherapy. These shifts may compromise tumor coverage and increase OAR toxicity. Integrating real-time imaging, adaptive planning, and motion correction strategies is essential to ensure treatment precision. Keywords: High-dose-rate brachytherapy( HDR) / cervical cancer / intracavitary applicator / radiation oncology
1 Introduction
High-dose-rate( HDR) brachytherapy remains a cornerstone in the treatment of cervical cancer, offering precise radiation delivery that significantly improves local control and overall survival rates while minimizing toxicity to surrounding healthy tissue. By placing the radioactive source either inside or close to the high-risk clinical target volume( HR-CTV), HDR brachytherapy ensures a highly conformal dose distribution. The integration of advanced imaging techniques, such as Computed Tomography( CT) and Magnetic Resonance Imaging( MRI), has further enhanced the precision of HDR
* Corresponding author: touti2007 @ gmail. com planning, enabling 3D treatment approaches that optimize dose delivery while sparing organs at risk( OARs), such as the bladder and rectum.
As Viswanathan et al.( 2012) and Kim et al.( 1995) have emphasised in their respective studies, precise applicator positioning is paramount to avoid hot or cold spots in the CTVarea. These studies underscore the critical importance of precise positioning to ensure optimal treatment outcomes. The optimization goal in cervical cancer brachytherapy is to achieve an ideal, pear-shaped dose distribution, effectively covering the HR-CTV while minimizing radiation exposure to nearby OARs. This delicate balance between maximizing therapeutic dose to the target and protecting critical structures is essential for achieving high local control rates with minimal side effects. Optimization methods rely on accurate
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