From machine accuracy to clinical precision: A multilevel quality assurance approach for pelvic radiotherapy in cervical cancer

Abstract

Author(s): Ahlam Azalmad* and Mohamed Hilal

Background and purpose: Accurate and reproducible dose delivery in pelvic radiotherapy for cervical cancer requires both robust machine performance and rigorous patient-centered Quality Assurance (QA). While International Guidelines Define Linear Accelerator (LINAC) QA standards, limited data describe the integration of machine-level QA with workflow-based and end-to-end clinical validation in resource-constrained environments. This study aimed to implement and evaluate a comprehensive multilevel QA framework for pelvic radiotherapy in cervical cancer.

Materials and methods: A structured Quality Assurance (QA) program was implemented for an Elekta linear accelerator delivering 6 and 18 MV photon beams and 9–18 MeV electron beams to ensure compliance with clinical and international performance standards. The clinical relative dose distribution, isocenter, mechanical accuracy, and electrical safety for both the photon and electron beam were assessed using the AAPM TG-142 and IAEA TRS-398 reports. The patient workflow was verified using simulation verification, treatment plan validation, and Image-Guided Radiotherapy (IGRT).

Results: The operational parameters of the medical linear accelerator regarding the electrical, mechanical and dosimetric domains were within prescribed/ established tolerance limits. Deviation of the mechanical isocenter was 0 mm, gantry and collimator angle deviations were ≤ 0.2°, MLC positioning/dose accuracy was maintained at an average of within 1 mm throughout the entire data capture range. Relative to commissioning data, TPR20/10 (Photon beam quality indices for 6 MV (0.683) and 18 MV (0.775)) and electron depth parameters were stable. Monthly and daily output constancy measurements indicated no clinically significant drift of output for each energy.

Conclusion: By utilizing a combination of machine-based quality assurance and structured workflow controls specific to the patient, a multi-level approach allows for translating technical performance into clinical precision. This combination of tools enables the delivery of safe, replicable, and dosimetrically accurate pelvic radiotherapy treatments for cervical cancers patients and validates the integration of comprehensive quality assurance programs within public oncology facilities with limited resources.

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