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significant dosimetric deviations, jeopardizing treatment accuracy. Studies have documented notable geometric variations in applicator positioning and demonstrated their significant impact on doses delivered to organs at risk( Kim et al., 1995; Hoskin et al., 1996; Garipagaoglu et al., 2006).
From a radiation therapy optimization perspective, these positional uncertainties present two critical risks: the potential underdosing of the clinical target volume( CTV), reducing tumor control probability, and the overdosing of organs at risk( OARs), increasing the likelihood of treatmentrelated toxicity. Maintaining the delicate balance between effective tumor irradiation and sparing of healthy tissues relies heavily on precise applicator placement and stable geometry.
Repeated imaging has been shown to reduce these uncertainties by enabling verification and adjustment of OAR volumes and dose distributions throughout the treatment course( Hellebust et al., 2001). Real-time imaging techniques such as MRI and cone-beam CT( CBCT) offer promising tools to detect and correct applicator displacements immediately before dose delivery( Damato et al., 2015), thereby improving treatment accuracy. The EMBRACE II study further emphasizes the crucial role of image-guided adaptive brachytherapy in managing anatomical variations and applicator positioning to optimize clinical outcomes( Pötter et al., 2018).
However, these imaging modalities have limitations. CBCT contributes additional radiation dose to the patient cumulative imaging dose from repeated CBCT scans can be clinically relevant( Islam et al., 2006) and both CBCT and MRI may increase treatment time and require specialized equipment, which may not always be available. Therefore, while real-time imaging is advantageous, its use must be judiciously balanced against these practical considerations.
4 Conclusion
Managing applicator displacement continues to be a significant concern in HDR brachytherapy, as it directly affects treatment precision and patient outcomes. Ensuring accurate dose delivery requires a comprehensive strategy that combines realtime tracking, adaptive treatment planning, and effective immobilization techniques. Tailored solutions such as patientspecific fixation devices, optimized vaginal packing, and robust optimization methods can help counteract the uncertainties linked to patient positioning. By integrating these approaches, clinicians can better protect organs at risk while maintaining adequate coverage of the clinical target volume, ultimately enhancing both the safety and effectiveness of HDR brachytherapy.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflicts of interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Data availability statement
Data will be made available on request.
Author contribution statement
Elmehdi Sadiki: Writing – review & editing, Writing – original draft, Visualization, Methodology, Investigation, Formal analysis, Conceptualization. Omar Berradi: Writing – review & editing, Writing – original draft, Investigation, Validation, Conceptualization. Mohammed Ait Erraisse, Kaoutar Soussy, Samia khalfi and Nourredine Slassi: Writing – review & editing, Validation, acquisition, Resources. Mohammed Najeh: Writing – review & editing, Validation. Rodouan Touti: Writing – review & editing, Writing – original draft, Visualization, Methodology, Investigation, Supervision.
Ethics approval
This retrospective study was conducted in accordance with the ethical principles of the 1964 Declaration of Helsinki and its later amendments. The protocol was reviewed and approved by the Ethics Committee of CHU Hassan II of Fez.
Informed consent The Committee waived the requirement for individual informed consent due to the fully anonymized nature of the clinical data used in this research. References
Damato A. L, Viswanathan A. N. 2015. Magnetic Resonance – Guided Gynecologic Brachytherapy. MR-Guid. Interv. 23, 633 – 642. https:// doi. org / 10.1016 / j. mric. 2015.05.015
Garipagaoglu M, Tunçel N, Dalmaz MG, et al. 2006. Changes in applicator positions and dose distribution between high dose rate brachytherapy fractions in cervix carcinoma patients receiving definitive radiotherapy. British J Radiol 79( 942): 504 – 509.
Hellebust TP, Dale E, Skjønsberg A, et al. 2001. Inter fraction variations in rectum and bladder volumes and dose distributions during high dose rate brachytherapy treatment of the uterine cervix investigated by repetitive CT-examinations. Radiotherapy Oncology 60( 3): 273 – 280.
Hoskin PJ, Cook M, Bouscale D, et al. 1996. Changes in applicator position with fractionated high dose rate gynaecological brachytherapy. Radiotherapy Oncology 40( 1): 59 – 62.
Islam MK, Purdie TG, Norrlinger BD, Alasti H, Moseley DJ, Sharpe M. B, Siewerdsen JH, Jaffray D. A. 2006. Patient dose from kilovoltage cone beam computed tomography imaging in radiation therapy. Med Phys 33, 1573 – 1582.
Jayarathna S, Hoang M, Badkul R, et al. 2023. Dosimetric impact of applicator displacement on three-dimensional image-guided highdose-rate brachytherapy treatments for cervical cancer. J Contemp Brachytherapy 15( 5): 334 – 343.
Kim RY, Meyer JT, Plott WE, et al. 1995. Major geometric variations between multiple high-dose-rate applications of brachytherapy in cancer of the cervix: frequency and types of variation. Radiology 195( 2): 419 – 422.